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- I've got the first revision of the new secondary arm cut and fitted. Unfortunately I left off the part that would act as the connection between the free rotating linkage and the shaft so I have to re-cut it. It's just as well though, as there are a couple things I want to change about it anyway. The throttle stop is also a success (it's part of the same piece), although it's a bit of a pain to adjust as I have bend it ever so slightly - perhaps later down the road I'll add provisions for a set screw.
- More parts are plated! I swear this is the most boring and tedious part of the whole process, but they sure look good when they're done. I've figured out that with the current mixture of everything (mentioned somewhere above) that 35 seconds is about perfect for the color if I dip the parts within a half hour of being plated and right after being 'polished' with steel wool. This whole process would be quicker if I had a media blaster, but alas, I don't. My most prized piece yet is the main fuel line assembly (excluding the return as it's separate, although also completed). It took around four hours - not all of which I was actively working on it - and I think it came out the best. It's also the latest part I have done, so the most experience has gone into it. Here's a couple pictures (do note that the color is quite what it will be in these photos as it hasn't fully cured, although it's pretty close):
And here's one from just before the chromate ('polished' zinc only) for comparison sake:
Progress is slow, but the parts are progressively getting cleaned up. The next to be done is the throttle bracket, for which I have chosen a spare SA one as it's a little simpler in design, and easier to clean/prep considering I'm doing everything by hand. Hopefully all the parts will be done by Wednesday night, but we'll see - the goal is to assemble the remaining parts and install the carb Thursday for testing.
The SA throttle cable is located closer to the carb than the FB. You're going to have a misalignment.
Oh my. Well thank you for pointing that out - for some reason I never thought to check that. Conveniently I haven't started plating it yet so I haven't wasted much time.
Things have been done, and I'll say there sure is a difference... Also just to clarify before I move on, I did end up using the SA throttle bracket as my FB one was a little mangled and will need some resurrecting. To compensate for the misalignment I just reordered the linkages (moving the throttle arm to where the cruise control would normally be fixed the issue just fine).
Now then, the carb... It ended up that I was rather behind schedule and as such I had to skip a few things (for now). However, I did get the carb installed yesterday and on first start up it sounded as though I had magically gained a port job (high idle @1100ish, sort of choppy like some exhaust overlap would cause). Turned out my myriad of throttle stops were holding the secondaries open a hair, and so with a little tweaking I'm idling around 800rpm depending on electrical load. Cold starting will be first seen later today, but based on the initial start up I'm quite impressed. I had to change my starting procedure a little though - before the swap I would pull the choke **** and flip my choke hold switch (the car is running ECU-less now, so I had to rewire the choke magnet to a toggle switch; without any harness cutting might I add). Anyway, after the choke was held I'd turn the key while depressing the throttle slightly and the car would start every time in less than a second or two (hot and cold procedures were the same although omitting the choke for hot). Now to start I have to pump the gas a couple times, turn the key, and then set the fast idle after it catches - it seems like this is a more common method anyway. Regardless, the car idles just fine now and might I say, this is the first time I have ever installed a carb on this car that didn't flood once or need follow up float adjustments with using new needles.
Driving wise the car is great, but certainly not perfect. Free rev response is stellar, but going from a stop the car rather consistently wants to stall for a split second before catching itself - it feels like an AP issue perhaps. Once moving though, I can fairly consistently mat the pedal (not secondaries yet) and there's no bog providing I'm above 2k or so. As for the secondaries, well, I think I may have made them open too quickly. If I can tune the AP better I bet the issue will go away, but regardless of what rpm - although it does get better the higher the rpm - there is a hard bog and then the car takes off. This bog is noted from starting at max primary throttle and then punching through the secondary hard spot. Due to the mods I did on the secondaries, they are either on or off as there is no way to feather them or try to smooth the transition via thy foot. Right now the AP extension is at 1 1/8" center to center on the holes, and while this allows for some adjustment, it doesn't allow for as full a stroke. I'm planning on making a shorter extension to see if I can get more movement as I think the secondary transition, and perhaps even the primary opening, could use a bit of a larger squirt. There will be more experimenting regardless.
Something else I've noticed is that while cruising it's rather difficult to get back on the gas smoothly, which isn't problem, it's just more pronounced than it was previously. Also upon letting off the gas, this carb is the first to not experience a dipping idle. In fact, the last couple hundred rpm above idle is a very slow (relatively) and smooth decline to settling right back where I set it.
So I mentioned that I had to skip some stuff in order to get the carb installed. Well... essentially that meant not plating all the parts I had originally planned on. Probably this summer the car will be down for a bit while I redo my exhaust (again) and also look into hogging the venturi's, so I figure I can do the remainder then. Anyway, here's a couple pictures of the carb before I got everything hooked up (don't mind all the rusty bits around the engine bay - it's been a slow process in bringing this car back from its prior 16 years in a field):
I'm not a huge fan of the brushed appearance that the carb has taken up, but really there wasn't any other way to clean it as this thing was filthy and I don't have a media blaster (I'll try and find some before pictures sometime here). Also, here's a few photos of my linkages. You can see the throttle stops I built for the secondaries, and also the way I did my mechanical secondary mod (that notch - you'll see what I'm referring to - is not supposed to be there. I cut it by accident after thinking there was some fitment issue, although regardless it works, so it's staying).
Anyway, that's about it for now. I'll be reworking the AP over the next while so there will be some updates for that and also overall changes at time progresses. If anyone has some thoughts about the secondary bog throw them on out here. Also consider that at this time I don't have a wideband (I know... it's been on the list for a while and I really should make the investment, although I know it will happen before I start messing with the venturi's). Otherwise, thanks everyone for all the help. This carb is going to change over time so I'll be sure to post updates when that happens, and hopefully I'll get a wideband sometime here so I can do some proper tuning.
So uh... cold starts are interesting - and I'm sure cooler temps will amplify that fact. Now then, I go to start the car, pump the gas a couple times, turn the key and it catches. I'm used to blipping the throttle a little to keep the car going however this time, that killed it instantly. So I started over and didn't blip it this time and the idle held around 500 but was sort of rough. Soon it sounded like it was going to die so I slowly blipped (touched?) the throttle again from instinct and I killed it. Third time I let it be for a minute or two and then I could very carefully and slowly set the the fast idle. The carefully and slowly bit is more so that there is a hypothetical notch that I had to get above or else it would stall, then I came back down and set the fast idle. To me this sounds like a combo issue between either the AP or the idle mixture (which is a bit in right now, probably a little less than 3 full turns). Thoughts on this? I can experiment more later today when the car cools down again. As for driving, no real changes since yesterday which is good since I didn't mess with anything.
Something else to note is that my secondaries might still be open a hair at idle, although I'll have to check - again that will be tomorrow most likely. To go with that, my idle adjustment screw is backed nearly if not all the way out, so again this is probably part of the issue. However, in the case that it may not be, I'd still appreciate some opinions.
Another day, another cold start. Here's the run down: 40 degrees outside, relative humidity of about 40%. By pumping the gas twice and then starting it - while not touching the gas or anything (no accessories on either) - the car will catch every single time. However, if I so much as touch the gas, put on the lights, heater fan, etc. or just let it run for a couple of seconds, it will almost inevitably die. After repeating this about ten time it managed to hold idle, albeit rather low and somewhat rough. After about another two minutes I put the fast idle on to get it warmed up faster and left it be for another two or so minutes. Then I took off the fast idle, put on lights and other accessories, and drove off. The car was still very touchy on the gas pedal and I stalled twice just getting out of the neighborhood. Shifts also have a hiccup in them that is sort of a jerk or stutter when I go to engage the clutch and get back on the gas.
So in the process of warming up I did a little experimenting (this was over the course of the ten tries and also as the car was warming up). The mixture screw did not affect its ability to start in any noticeable way (the car seems to like about two and a half to three turns out once it's all warmed up, and doesn't seem to care much when it's cold). The secondaries are also hanging open just a hair as I was able to drop the idle by maybe 50 rpm by just torquing the shaft by hand. Also the primaries might be getting hung up on an overly tight throttle cable, but as of now I can still idle from 750 to 900 depending on electrical load - on start up I was idling at around 500. So is this sort of issue common with a choke delete, or is there some other problem this might be pointing to? I figure once I can get the 120 air bleeds installed that will help a bit (they're 150's as of right now). It also still seems like the AP is being an issue, perhaps if the slightly shorter arm doesn't fix it, I might need to try drilling the banjo bolt and nozzles by just a hair? Thoughts on this and the cold start issues?
You've done a lot of work in a short time. I don't know what your issues could be other than they were caused by the mods. Hmm... 120s will help, but probably won't be the miracle cure you are looking for. The last time I worked on a carb where someone had modded the shafts to make them thinner, it was having issues similar to yours due to all the damage that was introduced (nicks and scratches in the soft brass butterflies as just one example). It was a real Yaw carb, and was so poorly assembled by him I really couldn't believe it. It didn't even run (it required a ton of fixes and even then was never as good as it should have been). Yours is a lot better I'm sure, but the fact it instantly stalls as soon as you touch the pedal is concerning. This problem is beyond a simple accel pump adjustment. Makes me think your idle circuit (with 150) is partly to blame, but I also think the transition circuit is not doing its job for some reason. The main primaries are also supposed to start emitting fuel pretty early on. The sooner the better. Sounds like you have a vacuum leak somewhere. Could be secondary butterflies not fully closed due to the mods.
To answer your question about common issues from a choke delete, well, not the way I do it. It will idle low or not at all if cold, but that is common to carbs. All I have to do is rev it a few times and hold the RPM high enough to keep it running. Pretty common. And if it does stall, it starts back up fine.
Oh, and I think you overstretched your secondary linkage piece. I have had best luck getting about 75% primary opening for the secondaries to open 100% within the last 25% of primary travel.
One good way to clean the carb metal is to just use a wire brush and then give it a wash with degreaser and a toothbrush. It keeps the surface looking more even because the brush is larger than a tiny dremel bit. There is no need to polish the metal as aluminum takes a nice shine without much effort from a brass wire brush. The main body will sort of gray a bit in a few days so no need to polish it. I try to keep as light a touch as possible.
It has been a lot of work in a short time indeed, and this sure is a weird one too. The last time I had an issue with the 'insta-stall' was when my vent solenoid died, but even then it wasn't this bad. The rev it a few times method is what I'm used to too, it's just so bizarre that it dies if I so much as touch the pedal. Also for clarification, the only mods I did to the throttle shafts were on the secondaries, and even there, all I did was cut off the top (un-threaded) portion. I did file off the excessive length of the butterfly screws, but that shouldn't have caused any problems. I also cleaned the butterflies themselves and was extra careful to not nick the edges or anything of the sort - I had not been so cautious on a previous rebuild, although even with a couple dings it turned out fine. I can confirm that the primary boosters are releasing fuel evenly and seemingly correctly as on the first start my bowls overfilled so it was running rich for a bit while they settled back down, during which I could see the excess fuel dripping out of the boosters at idle - although those shouldn't have been an issue anyway, still good to know they're not. Once the bowls returned to the correct level the fuel stopped visibly dripping. Perhaps I ought to just remove the carb and blow out the passages again as I don't know how many times that has actually solved some issues of mine, although regardless, it won't be able to happen until later this week which is unfortunate. I am quite curious what might be causing the poor throttle response issues, and yeah, it does sound like something in addition to the AP like the transition or idle circuits as you mentioned - whatever it is, it's definitely a lack of fuel somewhere.
In terms of vac leaks I can think of only a few likely possibilities: the swapped SA secondary shaft (although it seemed fine), and the lack of the secondaries closing all the way which can be remedied. The car is running rats nest-less with the exception of the original purge valve system that has been rerouted to accommodate the now missing vent solenoid. I've capped the idle compensator and of course the ACV is blocked off too. All unused vacuum nipples are covered with good condition OEM bind caps and even had those failed, the majority of these lines don't go anywhere or are internally blocked off in the intake or carb.
I also agree with the possibility of the secondaries not being closed completely (although I'm fairly certain they're relatively close). If and when I take the carb off here, I'll look into that further and also change the opening timing - I think right now they are closer to the last 20 degrees of the primaries; whatever they are they're quite literally the maximum they could be without creating a longer connecting rod between the two arms.
As for the cleaning, I did try a brass brush and Dremel tip but much nothing was happening (also I couldn't fit a larger brush in all the small spots, hence the Dremel again). The main body and airhorn had sat in a tub of degreaser solution for a good lot of time before I went on cleaning them, but the parts were just too corroded for the lighter brass wheels and brushes to do much of anything. I think the only way I could have gotten everything cleaned up without scratching parts inconsistently would have been a media blaster, but alas, that is a trial for the future.
One interesting thing about the pedal feel and how it relates to secondary opening is that the pedal is not linear. The pedal gives more resolution at the beginning of its travel and almost none at the end. This translates to a lot of ability to just slightly idle the RPM up with your foot. But toward the end of the travel, you don't have this ability. When I said I set my secondaries to open at 75% of primary throttle opening, that actually feels like 90% at the pedal with my foot. Does that make sense? It feels like a hard spot that is a lot easier to feel than the original 50% primary opening on a stock length linkage, which feels a bit more like 75% at the pedal. This hard spot is also harder to feel while driving. I appreciate a definite hard spot to have to push past to get the secondaries to open. It just makes more sense feeling like it is at the last 10% at the pedal when in reality it is only about 75% at the carb. It feels more natural I guess.
If I were to lengthen the linkage any further, it would require a lot more effort due to decreased leverage in exchange for more travel, and put wear on the throttle cable. It could also cause some flexing of the short part of the shaft where the linkage is, increased wear on the linkages, and can also flex the pedal's steel backing bar and puts more wear on the hardware down there. Heck, my 75% mod puts a little bit of increased wear on all that stuff compared to stock too, but I do oil all the parts on the carb and it feels great.
Yep, totally get what you mean. It's basically the same case for me, the last little bit of the pedal - about the last 10% of travel like you mentioned - is what opens my secondaries too. The hard spot is noticeable for sure, although it might be just a bit too stiff (I'm curious if my linkage is getting hung up slightly due to being too long causing the rod to contact the other linkage). Really it's a great pedal feel, the only issue is the hard bog that occurs when I open them. This is probably somewhat, if not directly linked to my other issues, but we'll see as I get more time to experiment and work on the car. I hadn't thought about oiling the assemblies, that's a good idea you've got there.
Relating back to my 'insta-stall' issue, even just laying my foot on the throttle pedal can kill it (when cold), which as you mentioned is practically no movement at the carb due to the movement being non-linear. Something is surely amiss here and I'll be glad to figure out what it is. The secondaries will be so much more enjoyable too when I can tune out the bog - it honestly feels as though someone romps on the brake for a split second - to where it's a smoother, albeit it probably not perfect (that's what vacuum secondaries are for ), transition . I also get this bog issue if I start from a stop, engage the clutch normally and then nail the primaries. Same hard bog issue, if not worse, as with opening the secondaries.
To me it sounds like your idle circuit is working fine but in between idle and almost WOT its not feeding the right mixture. Could be leaning out or too rich, hard to tell without a wideband. When accelerating from idle and when you initially go WOT for the secondaries I think you are hitting the same functional areas on the carb. I'd have to study the carb details more to really describe it correctly. My first guess is the AP but it may be else where.
Well yesterday I did get a chance to look at the AP shot and it's a bit weaker than I'd think would be ideal. I really didn't have time when I installed the carb to do any trouble shooting (basically the deal was if it worked well enough, I'd deal with minor issues until I had more time to work on it, otherwise I'd swap back for the time being, which, as is now obvious, I didn't). So anyway, I'll recheck the float levels next time I get a chance, they might be lower than I had thought, perhaps the rear in particular which would affect the AP. They looked fairly well centered at a minutes glance, but I didn't really look much further.
Here's another symptom/running condition if it might help trouble shooting more. Starting the car this morning was difficult like it was yesterday, however I noticed that if I pumped the pedal slightly after it had started, I could get the rpm high enough that it wouldn't stall, sometimes... However, even at 2k I could not set the high idle until it was warmed as after a second or two of being held there the car would drop suddenly and die - and that was after just holding the pedal (fast idle). I didn't try any higher as my car is rather loud - it needs a new exhaust as the current one is and was destroyed - and it was relatively early in the morning. To me this seems to point more towards the general mixture or the transition circuit once again. The car is also dipping idle when I let off the gas now (once warm and driving around), but I think that's just because I leaned out the idle mixture a hair as an experiment. So any further ideas that this would suggest? Hopefully I'll have a little time Tuesday and Wednesday afternoon to do some poking around, providing it won't rain of course.
And thanks regarding the plating .
Last edited by Benjamin4456; 04-01-19 at 01:25 PM.
So I got the carb apart yesterday and I found some interesting things - none of which have actually solved my issue. First off, on taking it apart I found that every single screw holding the airhorn on was loose. Not sure why that was as I thought I double checked them but honestly, I probably forgot. After getting everything disassembled I found this on the T-body:
Almost looks like lung mustard which is... odd.... Anyway, I cleaned that up and then proceeded to blow out everything (without taking out jets since I was short on time). I fixed the hanging secondary butterfly's and also lubricated the shafts.
As for results: the car idles rock solid at 500rpm (this is not as low as the throttle speed screw can allow either, however I'll probably raise it so that my alt will actually charge stuff at idle, we'll see). The secondary transition is perhaps a small bit smoother, but hardly at all if it even has changed. The cold start stall issue persists.
Other things to note: floats are and were dead on, and in addition to the cold stall issues, there is an issue with getting back on the throttle smoothly after coasting, which is most pronounced in 3rd gear around 2600 to 3100 rpm. There is also a heavy blueish cloud after shifting 1 - 2 at WOT and also increased backfiring on decel over my previous carb (which did not have any anti-afterburn equipment installed.
I'm thinking I'll try putting the 92's back in and see if that changes anything. Perhaps I'm actually getting a rich bog, who knows.... It seems like that wouldn't be the case with the secondaries though.
I've never seen so much oil there before. Too much OMP oil? And the moisture is a mystery to me. Did it rain on your carb? Heh.
The amount of oil I see is strange. Maybe the gasket you are using is the thin one from the rebuild kit. Those are notoriously thin and cause vacuum leaks. The OEM gaskets are actually thicker for a reason. I make my own out of blue paper from those aftermarket Mr Gasket Co kits. It's meant for coolant. It isn't really the right material to use with oil but it is thick enough that it works great here.
The aftermarket rubber cap you have on the altitude compensator nipple will crack and leak soon. Look for a better material to use here. I like to use the original neoprene stuff from these carbs because it won't go bad.
The moisture I think you're seeing is actually just some remanent gasoline from disassembly. As for the oil, yeah, I really don't know either. I haven't touched the OMP settings since I got the car so doubt it's that for this particular case. I did use a little WD for installing the fuel lines though so perhaps that's what it's from - seems odd that it would stick around though, and that I didn't notice this anywhere else.
I am using the uber-thin replacement gasket for the t-body, however knowing that they cause issues (not to mention that they're really easy to tear if you just have to check something) I traced it onto some blue paper before I assembled the carb the first time. I haven't cut it out yet but maybe I should soon here.
I'm using the OEM neoprene caps everywhere but this spot ironically. The nipple for this is slightly larger than the rest and the normal hard ones don't fit particularly well. I found this one on a spare rats nest and it seems of better quality than the aftermarket ones I've seen. Plus, I always keep a couple of cheap caps with me for emergency purposes.
Here's something I forgot to mention as a symptom/observation. While coldish (not cold start but not operating temp), the car will stall completely and cleanly if I begin opening the primaries and then stop and hold them a bit open (say the amount that would equate to somewhere around 3k rpm). At the moment that the car is about to stall I can see a bunch of fuel get sucked out of the primary boosters, then it disappears (I'm assuming this is it just atomizing properly) as the car begins to die. I never thought to observe my previous carb in this situation, but it seems odd that this would happen. Am I mistaken or might this also point to something? Really I'm just trying to make note of everything that seems like it could affect something.
Edit: I forgot to mention that I'm also going to see if can get vacuum advance back even though my spacer (particularly the second from front nipple) deadheads. I need to check my other carb, but I think the position of the other t-body vacuum line will provide the correct timing, and now that it's free from emissions purposes it's available for alternative use.
Last edited by Benjamin4456; 04-04-19 at 04:22 PM.
...The aftermarket rubber cap you have on the altitude compensator nipple will crack and leak soon. Look for a better material to use here. I like to use the original neoprene stuff from these carbs because it won't go bad.
A very timely reminder for me Jeff, thanks. I have some of these on the baseplate on the exhaust side and just checked them and both were split and leaked. I think this explains my hard to start cold issue recently and the idle ticking up a bit as well. Will know when I test it out later today. I put those rubber caps on when I hogged the nikki, so maybe 4 years ago and the were cracked and rotten already. Gonna buy a bunch and change them yearly.
So I got the carb apart yesterday and I found some interesting things - none of which have actually solved my issue. First off, on taking it apart I found that every single screw holding the airhorn on was loose. Not sure why that was as I thought I double checked them but honestly, .
This happened to me last year as I came home from DGRR. The car was running rough and dying at lights sometimes, really strange. When I got into the garage I parked it and unpacked and left it till the next day. Came out, opened the hood and could turn the screws by hand they were so loose and there was crud all around the carb cause things leaked. Made sure the gaskets were ok and tightened it all down real good. Fixed my issues. Lesson for that day was to check these things on the regular, the engine vibrations cause them to get loose. And no I will not put locktite on them.
Ah, so I'm not as special a case as I had thought - those screws were definitely a surprise. Anyway, I fixed those and there was no change so that's that. I also added vacuum advance successfully by T-ing into the line on the carb that hooks up to the PCV - works great for vacuum advance if you're not running the choke system which normally occupies it. With the added vac advance the cruising throttle issue has improved, I'd say to nearly the point where the old carb was (which had vac advance too). However, the cold start issue remains unchanged. Like I've said before, the car will catch every time, but throttle input will kill it.
That leads me to something I had not remembered until now. I realized earlier today that with my previous carb I had a very similar issue, although since I set the high idle before I started the car I rarely noticed it. Before it was more prevalent if I let the idle drop below 1500-1600 rpm while warming up, in which case the car would drop quickly and die, much like it does now. As I said, I hadn't thought about this until now as with the different start-up procedures it just seemed unrelated. Now then, the question is what the heck would cause this for two carbs. The particular issue is that the car cannot run between about 900 and 1700 rpm while cold. It doesn't seems like it would be an issue with fuel pressure/flow, or ignition, or really anything that I can think of. Theories?
Something else I noticed today was that when the car wasn't quite warm yet and I tried to set the fast idle, the rpm's would alternate relatively smoothly between 1500 and 2000. No clue what that would be considering that the throttle was being held steady. I also haven't tried the 92's yet as Oregon weather has been rather unpredictable as of late.
Any thoughts about the fluctuating fast idle and the other things mentioned in the previous post?
Well it's been what, six days or so? Nothing has really changed and I still haven't had a chance to play around with the 92's or a different AP arm - thanks Oregon... Anyway I figured I'd just make a small update as to what's happening. Earlier today I ordered a good lot of metric bits ranging from 0.9mm to 1.30 and then 1.60 to 1.85mm. They're in increments of 0.05mm and should give me enough of a spectrum to play around with jetting when I finally get a wideband and start milling the venturi's. I ordered all of them now since I need the 120 (1.20) for the air bleeds and being that shipping is more than the price of many bits, it just made more sense to purchase an assortment now. Hopefully over the next couple weeks I'll get a chance to install the 120's and 92's (I don't believe I have any 91's, but I'll double check - that's why I purchased a 90 bit, so that I could make a smaller, or stock, jet when I pick up some). The .023" Holley air bleeds are on back order right now but since I'm not changing the venturi's at this time anyway, that should be fine for the time being. I'm also only 200 ft above sea level so hopefully the 92's will work out well with the relatively low altitude.
As for driving, I've gotten in the habit now of letting the car warm up (at the cold equivalent of idle speed) for about five minutes prior to leaving. This works fine for now, but I'm hoping the smaller air bleeds will aid in this issue. The cold stalling does still exist, but as soon as things are warmed up it goes away. I can also nail the car anywhere above 4k, but if I let the primaries out fully to get up to speed and then nail the secondaries there is a noticeable bog. However, essentially no bog is present if I'm above 3500 and then nail it with the primaries having only been at part throttle prior to the 'maneuver'. All this time I have had yet to actually test my fuel pump, although regardless of its performance I had already planned to do the Carter mod to help keep up with the venturi's when I eventually get to them, though I still feel that the current cold start issues show no similarities to a fuel supply problem.
Oh, and I just remembered; the idle mixture the car likes cold is obviously richer than it prefers warm. However, when I set the idle mixture so that I even have a chance of cold starting/idling, I get rich misfires when up to temp. I realize the car wants the richer cold idle with the lack of a choke, so I'm just curious if the 120's might help even out this issue a little bit too. Right now I have the mixture set so that I can still cold start and idle decently (after four or fives tries), but that I only get very occasional misfires when up to temp under relatively high electrical load. With the lights down, heater off, and wipers off the car idles up a hair - not surprising - although the misfires increase in their frequency by a fair margin.
So anyway, that's about it for now. If anyone has some theories about the cold start issues throw them on out, otherwise I'll update again when I either discover something new or get the 120's in.
120 air bleeds should help you but they aren't miracle workers. Sounds like other things might still be amiss.
Not really expecting them to be either, although anything that can help with be welcomed. And yes, I do believe there is still some other issue. Hopefully when I do the 120's I'll have time to also look into other things a bit deeper. The most confusing part for me is how the car runs so well (not perfect, but not far from it considering the lack of tuning) when up to temp, but so poorly when cold. But like I just said, I still have a bit of digging and testing to do, I was really just curious if there was something obvious standing out that I'm missing.
Looks like things will get delayed a little bit. Unfortunately my clutch is beginning to slip after having been engaging fairly high up for a while now. Parts will be on their way soon, although I don't know when I'll have time to drop the tranny again. For now I'll be taking it easy since this is my daily and it needs to last as one (the clutch only slips now under hard acceleration). Good news is that the drill bits have arrived and although I'm now unable to test power changes, I'll still see how things affect cold starts. Jetting work will probably happen next weekend or the following.
Well I'm impressed. Okay yes, the 120's have not magically solved all my issues, although things are definitely improved in most regards. So anyway, it turned out that I had more time than expected this past weekend and I ended up replacing my clutch, installing my new SS lines all around, and further simplifying my engine harness (as of now I'm down to five wires for my whole engine harness save the ignition system).
Now then, the 120's have been in for a couple days now and so here is what I've noticed:
- Semi-easier cold starts. The tendency to die with throttle input has decreased, although still not completely (also note that it's now warmer in the mornings; say mid 40's). The car is also willing to hold idle sooner after start-up than before.
- Once warm the car pulls great all across the board, no sputtering or the like.
- From what I can tell so far, after a wide open pull then shifting and keepin' on a going, the smoke plume has decreased or vanished (not sure which yet)
- The idle mixture screw is much more sensitive. It's about a half turn from hunting to rich misfiring. Also I believe I misspoke before and said lean misfires, I had meant rich. Also I should mention now that the 92's are in too. I started out with just them - no air bleed changes - and driveability was slightly decreased; it acted like it wasn't fully warmed up or something. Also, in order to relieve (or at least limit) rich misfires I have to decrease the idle mixture to where on deceleration the idle speed dips before catching itself. I also now have bucking at anything below 2000rpm and before it was closer to anything below 1500rpm.
-The secondary glitch is decreased, although still present depending on the situation.
Also consider that I now have the 'competition' transmission mount - every time I cross 1800 -1900rpm I wonder if I'll regret that decision. However, this has probably helped to reduce some of the shunting that was felt while getting on and off the gas, and the shifter definitely stays in place now. The engine also shakes a fair bit at idle - it seems like more than before the work - but as soon as it's above 1000rpm or so it just sings and sits there whirring away. I also fixed my chassis ground which was at 30 ohms but that changed nothing noticeably. Spark plugs were looking fine, although perhaps a little on the rich side. Leading's were showing some wear (wahoo wasted spark DFI) so I swapped them with the trailing plugs but again, no noticeable difference. I'm halfway curious if my plug wires might need replacing...
So then, with that hodgepodge of info does anything stick out? I can of course clarify some things if I didn't explain it well. I'm beginning to wonder if my everlasting (over multiple carburetors) tuning issues are due to a worn engine. Not sure if anyone remembers, but I first posted back when I got this engine un-seized (and it took a lot of work). Not sure if it was rust or carbon or what (16 years in a field couldn't have done much good), but one of these days I'll get it compression tested to put that theory to rest. I do have a second engine that will be getting opened up, inspected and probably ported this summer though that's not something for the issue at hand. It'll probably be another couple weeks before I can do any major work with the carb, but I'll have plenty of road time to test things out over that period. That said, my bet's - and hopes - are still on carb issues. Does any of the new discoveries suggest anything to anyone. Any and all theories welcome.
03-25-19, 11:07 PM
), transition . I also get this bog issue if I start from a stop, engage the clutch normally and then nail the primaries. Same hard bog issue, if not worse, as with opening the secondaries.
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