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Forgive me if stating obvious, but since the trailing drives the tach signal, have you tried swapping the leading ignitor and coil with the trailing and see if it occasionally flakes out? My theory here is that the trailing really doesn't do that much so maybe the only obvious symptom is your occasionally flaky tach needle.
I may try that (swapping the igniters), but I was working from the assumption that since the engine seemed to work fine even when the tach was 'sticking' that it would have to be the tach at fault. That assumption could be completely bogus though, and swapping (or at least looking at) the trailing igniter probably should have been an earlier step in my process. I will likely take a look prior to the new chip arriving, but I still feel like the signal I'm seeing coming out of IC1 doesn't kosher to me...
I didn't feel like putting the cluster back in today, so I decided to go ahead and rip all the A/C bits out from under the hood for a good cleaning before sealing it back up and charging it...
it was fairly uneventful except I couldn't figure out how to get to the nut holding the flexible hose to the condenser. I ended up removing the driver side radiator mount in order to get the condenser and hose out as a single assembly:
Found more remnants of past mouse nesting under the battery shelf...
Of course, now I'm thinking there wont be a better time to pull the radiator and get that cleaned up and painted as well.
This also gives me pretty clear access to the headlight assemblies, so I imagine I'll just go ahead and do them as well...
I went ahead and put the instrument cluster back in and started the car -- the tach now appears to be completely dead. Of course it's always possible I did something dumb like forgot to plug the board into the meter . In any case I decided to take a look at the signal driving the tach. So I hooked a jumper wire to the igniter signal where it's fed into the tach assembly and hooked up a scope to check out what I'm getting out of the igniter. Not being entirely certain what I should be seeing, the trace looks perfectly reasonable to me:
And the stability of the signal when revving looks good as well:
Of course, since the tach is now refusing to move at all I can't really rule out that flakiness the igniter signal was causing the 'stickiness', but I'm still kinda leaning towards IC1 on the tach board being the culprit. Maybe I'll find out in a month or two when the replacement shows up...
Since I've decided to pull the radiator and give it a new coat of paint I thought it would be prudent to flush the coolant system prior to pulling it. So I drained all the old coolant out - it was only a year old and looked pristine. I then filled the radiator with a bottle of flush and distilled water. When draining the system I took out the engine block drain plug as well, and when filling it back through the radiator it seemed like the block wasn't getting any water... So I pulled the thermostat housing and filled the block with distilled water through that port. Everything seemed to be going ok, except after running for a while the temp gauge was going up, but the radiator was remaining stone cold (and I was getting no heat from my new heater core). Once the temp hit the half-way point on the gauge I decided to call it, stop the car and ask for advice from the forum: https://www.rx7club.com/1st-generati...dvice-1154398/
I got a helpful reply from t_g_farrel which pretty much confirmed my suspicion of it probably being the thermostat. I pulled the t-stat out and started the car again - this time the coolant in the radiator was visibly flowing and was getting noticeably warmer. The coolant and the car never really got "hot" though - I assume because the radiator was just doing its job and keeping everything cool. I did get some heat from the heater though, and as I mentioned the water was getting warmer than ambient, so I'm pretty sure I was getting nice flow through the block. I let it run for 15 minutes or so, then drained it again (rad and block), then refilled with distilled water. Let it run for a few minutes, then drained that. Then I put some actual antifreeze and more distilled water into the system. I know most of the antifreeze will end up wasted when I pull the radiator, but my plan was to make sure that I didn't have pain water left in the block or the core after I pull the radiator.
So - I figure I'm done - I go to start it one last time to circulate the new antifreeze - and she wont start
No juice making it to the starter. I've had this happen a time or two before (once earlier today even) and jiggling the connector going to the starter solenoid generally takes care of the problem (I'm pretty sure that unprotected spade connector is in pretty rough shape). Anyway this time that doesn't help - still no starter... sigh - I'll deal with it tomorrow...
Wow, you've had quite the day! Great photos, I've wanted to put a scope on the igniter and see what I'd get, but I never tried it out. I have that same Rigol. You might have some fun with the frequency counting in the math functions. Maybe 2 probes going to compare leading and trailing (not that it helps your tach issue at all). Perhaps that 4ms drop and return is the coil recharging? Would be cool to see how it changes at various rpms.
According to this diagram you should be seeing 2 spark plug firings per 360° rotation. Your scope shows 70ms total time from spark 1 = 180° rotation + spark 2 = another 180°. So that would be 857 rpms.
Who needs a tach, maybe just leave your scope connected :P
Just a quick update - I've had a few mini-projects going on the last few weeks. I've pulled all the air conditioning bits from under the hood for cleaning before reinstalling and recharging. Decided to go ahead and pull the radiator as well. Then went ahead and pulled the headlight mechs. Most time has been spent replating the various hardware bits. I'm following Frankenrex's lead here, but have a process down that seems to be working pretty well for me. Here are some before and after shots of what I've been doing. First a couple of befores to give an impression of what I started with:
Now the afters:
I'm pretty happy with the results so far...
The replacement chip for the tach also showed up (a month quicker than I was expecting). I took a screen shot of the original operating (on the bench with a test signal driving it):
Blue trace is the input signal, Yellow is the signal driving the meter (M+).
I then replaced the original chip with a socket and plugged the "new" chip in:
Basically it behaves exactly the same.
So, while it's not the output signal I would expect to be driving the meter, it is apparently working properly anyway (or the replacement chip is also bad in the same way, which I tend to doubt). The meter has always responded in a way that appears to be correct, so I have to assume that the IC just doesn't work the way I would have expected.
Anyway - I can't put it back into the car to test until I get the radiator and a/c put back together...
Sure. First to give credit where it's due - Frankenrex's build thread is were I got turned on to this process. He did a great job explaining the gory details, so I would suggest going direct to the source for those. The following is mostly just small tweaks to his work to make it a little easier for for me...
The recipe I used for the zinc electrolyte is one I found online (I mixed up a half batch):
At first I was using copper wire to hang parts in the solution, but I got sick of bending and unbending the wire and trying to keep small bolts from falling off. So I ordered a set of these alligator clips from amazon: https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1
For the single-ended clips I bend the free end of the wire to make a hook for hanging.
I pulled the clips off the double-ended ones to make these:
Those allow me to process 10 small parts at a time. I'm using rather small containers for the electrolyte and chromate solutions. They are just plastic pails I got from the dollar store:
For the chromate solution I purchased the concentrate from Caswell Plating - it wasn't cheap (about $50 shipped). I've since located a recipe for making it yourself on this site: https://www.forbbodiesonly.com/mopar...ry-look.63715/
I have not tried that approach though - if I ever run out of the caswell stuff (which is unlikely) I would give that recipe a try.
I am using a small bench supply (30V 10A) to control the plating current.
So that's basically it for the setup. Here are my (fairly detailed) notes on the process I follow for doing the parts:
Initial Prep
(1) Really grimy parts can be cleaned first (perhaps in the ultrasonic cleaner), but most don't seem to need it
(2) Muriatic acid soak
The point here is to get any old finish or heavy rust off
In general it's soak until it stops bubbling, but be careful of things with threads as they will continue to bubble, even after clean (and this would be losing metal)
(3) Tap Water rinse
(4) Any parts with visible rust after the acid soak should be sand blasted
All parts could be blasted, but for the small stuff it doesn't seem necessary
I would recommend blasting any larger parts
(5) Wire Wheel the parts
(6) Chase any threaded shaft or hole in the parts to dig any remaining crap out of the threads
(7) Parts can be bagged and stored at this point before moving to next step
Plating Step
(1) Large parts (too big for the alligator clips) should be have hanging wires attached to them
(2) Alcohol (91% IsoPropyl) wash to remove any lingering finger oils
Touch parts only with a gloved hand from this point
(3) Muriatic acid dip
This is to remove any final crap and any flash rust that may have formed since prep
(4) Tap Water rinse
(5) Small parts should go back in the alcohol bath (to remove any finger oils and help prevent flash rusting)
(6) Small parts should be mounted on the alligator clip tree
(7) Large parts and filled alligator tree should be tap water rinsed
(8) place in plating solution
(9) Plate for 20 minutes or so (looking for a complete solid layer of the grey)
I figure ~80mA per square inch of surface, but keep an eye on it to make sure no burning of corners!
(10) When solid coverage achieved (looks like parts have been painted grey), remove from plating solutions and tap water wash
(11) Card/Polish the surface of all parts with a soft brass brush
I find it's easiest to do this with bare hands (not gloved)
(12) Repeat steps 5 through 11 one more time (second zinc coating)
(13) Parts can be bagged and stored or move on to next step
Chromating Step
(1) Remove parts from bags using gloves
(2) Clean parts in alcohol to remove any finger oils
(3) Wire up large parts or secure small parts to alligator clip hangers
(4) Use heat gun to dry alcohol from parts
(5) Repeat steps 6 though 12 for each part
(6) Holding part by hanger, give it a Tap water rinse
(7) Spray part with Distilled water
Idea is to displace the tap water with distilled water
(8) Dip part in Chromate solution for 10 seconds
(9) Spray part with Distilled Water (draining back into chromate bucket)
Idea is to displace any chromate solution with distilled water
(10) Optionally blot part on soft paper towel to remove some water
Be very gentle you do not want to wipe the chromate off
(11) Using a heat gun dry the part (try to keep heat low)
(12) Hang part up to harden over night (24 hours in theory, but overnight seems plenty)
So far I've probably done close to 100 piece-parts using this approach, and once I worked through a small learning curve I haven't had any failures.
I'm definitely pleased with the results I'm getting and other than it being a bit tedious working through all the small parts, I think it's definitely worth giving a try.
I do wish I had purchased some of the Blue Chromate when I placed my order for the Yellow from Caswell because I think leaving some parts silver would be nice as well. I have not found a DIY recipe for Blue Chromate. If anyone find ones - please let me know!
Thank you for the post and the thread, that I'm following with great interest.
I too have restored a few parts of my 1982 RX-7 using DYI zinc plating with yellow finishing. The result is good and the feeling of doing it by myself is priceless
I have professional platers nearby, but they are not too happy to deal with small stuff, and tend to loose some from time to time
For rust removal, after ultrasonic cleaning, for small parts I use Evaporust. I think it's just great - and even more so when used in the ultrasonic cleaning machine. It does an amazing job.
For larger parts, to avoid the cost of using large quantities of Evaporust, electrolysis works great and is very cheap.
In most cases, if the parts have some structural function, I subject them to dehydrogenation (2-3 hours in the oven at 200°C - 400°F) to make sure they are not embrittled.
Incredible job plating your hardware! This can save a ton of time and money on a restoration and the old hardware will look new when finished! I think I want to give this a try!
Thanks! I definitely recommend trying it - it's turned out to be easier than I expected.
It does burn up a lot of time (at least doing it the way I'm doing it), but if you've got the patience I think anyone could do it successfully.
Since the weather turned cold I've moved the plating process into my basement and haven't encountered any issues (no smells, etc). I am very careful that all the chromate solution stays in the chromate bucket - and I still store and do all the acid dips outside.
I've sorta been stalled by looking for a container to plate the headlight buckets in - thought for sure that a pretzel (or cheese ball) barrel would be perfect, but they are about 1/4" too small
(for some reason I just don't want to beak down and buy buckets for this)
I wasn't sure how these were going to turn out, but I took a shot at replating the compression connectors on the A/C soft lines this afternoon. Here's the first one I did:
Before (looks better in the pic than it did in person, also this is probably the least rusted one of the four):
I plugged the end with a rubber stopper and stripped the parts using a muriatic acid soak. After stripping:
After three cycles of plating:
And finally, after chromating:
Took a total of about 2 hours from start to finish. I did one end of the other hose after that and it turned out about the same.
Note, I didn't do any sand-blasting or wire-wheel with these - just the acid dip for cleaning. I'm happy with the results.
The A/C hardlines are aluminum (with steel compression nuts) so I won't be able to use the acid dip to clean those. I've wire-wheeled the nuts and will probably just try plating after a good degreasing with acetone. Not sure at all whether the aluminum lines will plate or not (hoping not)...
I was prepping my radiator for a new coat of paint today when I realize that I haven't yet fixed the fan shroud mounting tab that I twisted off sometime last year. So, I decided to look into how to reattach that tab. The tab itself is steel and it attaches to the copper top section of the radiator. It looks like it was originally attached with either a spot weld or brazing. I decided to try to braze it using a tig welder and silicon bronze welding rod... The good news is that it seemed to work pretty well for attaching the tab - the bad news is that I obviously put too much heat into the radiator and blew a hole in it...
My attempt to fix that hole entailed trying to solder a small piece of copper over it:
It's not too pretty, but it doesn't seem to leak... Probably should have just soldered the tab on to begin with...
With the weather getting warmer it's time to get back to work on this thing...
Over the last couple of months I've cleaned, prepped and repainted the radiator. Here it is waiting for reinstall:
But first I reinstalled the headlight mechanisms, after painting the brackets and zinc coating all the lever arms. I also managed to break a couple of the nylon swivel joints, so I replaced those with ones I got from member @Kutukutu. I can't say enough good about these. They fit and seem to work great - and the price is so reasonable I wasn't even tempted to try to reverse engineer and print them myself. Highly recommend them!
Once the headlights were in I installed the A/C bits and pulled a vacuum on the system to verify it's sealed properly. It held a vacuum on the first try, so I'm pretty happy about that. I haven't charged the system yet, but the plan is to charge with R152a refrigerant (canned air) per instructions found on this forum by @GLSSEFormMe...
Then I reinstalled the radiator and gave that a pressure test -- also success, so it looks like my patch is holding up.
(I realize the high/low lines for the A/C manifold are hooked up in reverse there, but I was only pulling a vacuum, not running anything.)
I also reinstalled the gage cluster and gave the car a test start yesterday - it started great, and is idling nice and steady. Did not take it for a test drive yet. However, the tach is still acting like it always has - dead, or almost dead when cold, seems to warm up and begin working better/smoother as the car warms up... I've tested the actual tach mechanism, both in and out of the cluster, so at this point I find it hard to believe it's a problem with the tach. Leaving either the signal from the igniter or the wires carrying it to the cluster. I need to drag the scope out to the shop and try to probe the signal while the engine is running...
I only recently started spending a little more time with the Rx7 again...
I've got a punch-list of things to work on that is surprisingly short.
One of the things on the list was to remove the linkage on the carb that the hot-start normally attaches to. This linkage looks like it could hang down (without the hot-start cable attached) and jam up the other throttle linkages - so I want to replace it with a spacer to avoid this potential problem. In order to get to that linkage I needed to pull the carb out again. Since I've got the carb out I decided I'm going to go ahead and re-plate everything I can reasonably get to. So, I'm pulling the carb apart again and run into this issue:
How is the dashpot remove from the bracket? Everything you see there is quite tight, so It's not obvious which bits are supposed to move relative to the other bits.
I assume that the nut to the right is a jam-nut and the bracket is also threaded, so loosen the nut, then unscrew the dashpot from the bracket?
When I try to loosen the nut it doesn't want to move - and I don't want to force it until I'm certain it works the way I think it does (too many times I've forced things that didn't actually work they way I assumed). So confirmation (or correction) on how it comes apart would be much appreciated.
Thanks!
The carb is back together at this point. I didn't try to restore or replate any of valve components, so there is still a fair bit of (character building) crud on the carb, but overall I'm pretty happy with how the refresh turned out:
And best of all - no leftover parts
So - I'm ready to reinstall the carb on the engine (for hopefully the last time) and I'm considering disabling the shutter-valve. My Anti-Afterburn Valve #2 is not working, so I've already capped where that originally fed into the intake manifold. Originally I was planning to just leave the AAV#2 on the carb (just not doing anything), but I'm now thinking I'll just go ahead and leave it off. But that has me thinking that maybe I should just go ahead and disable the shutter valve as well? I'm not planning on doing a rats-nest removal, and the shutter valve does seem to be working as of the last time I had it running, but I'm thinking just as an ounce of prevention going ahead and disabling it.
Figured it was time for an update...
Carb went back on the car smoothly. I did leave the shutter valve disconnected from the vac line at the rats nest - capped the vac line at the nest. Also just left the Anti-Afterburn Valve #2 off - also capped its vac control line at the nest. Car started and seems to run ok - I do feel like there's a "bad" spot at right about 1500 RPM though. Not certain if that is my imagination, or a symptom of something...
I finally gave up on trying to repair, or find used replacements for the A-Pillar interior trim. Mine had completely crapped out:
I had bought a replacement from someone on this site, which supposedly came out of another '83 GSL, but they were shaped different and wouldn't fit over the side window vents on my car. So, anyway I finally broke down and ordered a NOS set from some shop in Australia (available only in black). Price for the parts was reasonable, but shipping almost doubled it. Anyway, they arrived eventually, but unfortunately both were damaged in shipping:
I let the vendor know - and told them I didn't want to send them back as I could probably fix them. Did ask if they would be willing to refund a few bucks since they arrived damaged. They refunded the shipping cost entirely (which as I mentioned was a pretty big piece of the overall price.
Anyway, I fixed the small tabs back on with JB-weld and a wire embedded in it. Since they were black instead of burgundy I ordered a can of the SEM 15063 Burgundy color coat and figured it was going to have to be 'good enough'...
After painting the parts with some Duplicolor Adhesion Promoter, then the SEM color coat - I am shocked at how good they look. So shocked I apparently forget to even take a pic of them.
Anyway, after that I decided to go ahead and shoot the trim pieces in the back that had a lot of sun fading:
And After:
It is really hard to express how much better the trim looks after the painting. It doesn't look or feel like it's been "painted" at all. I would say the color is just about a perfect match to the original color (of course, all of the rest of the interior trim has faded slightly as well, so you can tell a difference where the parts meet - but it really is subtle enough that it's not obvious or annoying. I'm really just very impressed with the SEM color coat.
In fact, I was so impressed I decided to also give it a shot on my door panels. The top (vinyl) sections of both doors had been baked by the sun and looked horrible:
I have been trying to figure out how to go about restoring them and decided to try just reapplying some adhesive to try to stretch out the vinyl a little (honestly I don't think this made much difference) and prepped and painted those sections of the panels. I was basically in "it can't make it any worse" mode, but I've very pleased with the results:
Obviously it doesn't fix any of the cracks or wrinkles, but I feel like they look 1000% better.
Today I decided to go ahead and recharge the air conditioner. I had previously cleaned up all the parts, replaced the dryer, vacuum tested the reassembled system, etc. So today was just pulling a vac for 45 minutes, then charging the system (per @GSLSEforme 's excellent instructions - may he RIP) using R152a (canned air). No pics of that either, but the car is now blowing nice cold air, so it seems to have worked fine.
And with that, I believe I am actually "Done" with my refurnishing of all major mechanical systems - YAY! The only things left on my list are exterior finish related. I have a windshield chip to fill (which I'm thinking is trivial) and then it's dealing with the paint...
The car spent many a year under a car cover and the paint on the hood, sunroof and roof (just behind the sunroof) have some damage. Difficult to capture it in pics, but here's an attempt. The sunroof is the worst of it:
In that pic you can see the section behind the sunroof, and the hood is similar, but not as bad.
I am definitely looking for ways to improve these - know I can't make it perfect without a complete repaint, not really looking to get into that though...
The sunroof does have a few rust spots, so it may need to be repainted (that I would consider). Shots of some of the rust as an example (finger included for scale):
And while I'm here asking for paint restoration advise; the hood and front end both have a ton of tiny chips:
Again, I know that this can't be really fixed without a complete paint job - but is there anything I can do to make it better without going all the way to repainting?
Open to suggestions - thanks for listening...
Amazing work as always!! The fading on the roof is bad enough that it should be repainted. You can attempt to wet sand and buff the rest of the car if the clear coat is not sun baked like the sunroof. Its not going to help much for the stone chips, but you could carefully touch them up with some color match paint before wet sanding and buffing. The only drawback would be that the touched up areas may be much brighter than the original paint and more noticeable.
No real updates. It's been sitting in my shop for the last year without being touched...
I did take it out for a test drive and the 1500 RPM dead-spot was still there - I plan to pull and rebuild the carb once again, hoping to clean some little bit of something out of somewhere and have the problem (magically) disappear. But like I mentioned, haven't done anything with that in the last year.
I also tested the AC this past spring and it no longer blew cold air. Very disappointing I had used the fluorescent oil when charging it, so a little inspection with a UV light leads me to believe the leak is from one of the fittings on the dryer. After thinking back on it, it wouldn't surprise me if I actually forgot to go back to those fittings for the final snugging up after installing all the plumbing. Of course I was able to pull and hold a vac for 45 mins when I did the original testing, so who knows. The oil definitely looks like it was leaving from one of those fittings though, so new drier and some new cans of the R152a to give it another go. Again - didn't manage to get that addressed this year either...
I do think I replaced the bushings in the steering idler arm after my last post and before I put the car away for the year. I couldn't locate one of the beefier replacements, so just went with replacing the bushings with OEM. The originals were basically missing when I took the arm off. Don't think I even managed to test drive the car after doing that...
Now of course it's too cold to get out into the shop, so maybe next year?
You mentioned following a thread by GSLSEforme to recharge your A/C. Do you have a link to the thread? I searched his started topics but did not see one with step by step instructions. Thx.
11-14-21, 11:23 AM
. In any case I decided to take a look at the signal driving the tach. So I hooked a jumper wire to the igniter signal where it's fed into the tach assembly and hooked up a scope to check out what I'm getting out of the igniter. Not being entirely certain what I should be seeing, the trace looks perfectly reasonable to me:
