MountainDew67

Ok, I got my 67 bug home with the 12a motor in the back of it. I got a few questions... I have did a search and pretty much know a few answers,but looking to ask anyway,cant hurt!

I got a racing beat intake/holley carb set up on the car. THe power is not smooth and stumbling, I have read about acc pumps,bigger and smaller squitters, different jetting, but theres not much set in stone.

How do I figure out the size of the holley carb (1848-1 1142 was on the top of the carb, I found a 3559 on front bowl)?

How do I truly know this is a 12a and not a 13b?

This bug is only 16-1700lbs, will this effect whats needed, when it comes to modifying the carb?

Last but not least RIGHT THIS SECOND...being that I have a racing beat intake, can I adapt another make of carb on it? Im more looking for a out of the box carb, but racing beat wants 533$ for it. I can get a carb guy to modify my holley to whatever is neccessary most likely for well under that. What are my options...this stumbling is not fun, feels like she wants to get busy!!!

thafox

i can answer one of your question's....just look on the rotor housing's it should say 12a or 13b....do u have any pic's of the bug?

RgrWalker

Because 12a will say 12a and 13b will say 13b, that's about all I know about your questions. sorry

perfect_circle

the width of the rotor houseings, i believe the 12a is like 10mm or something....im not really sure, if you search you will probably find it...

rxtasy3

iTrader: (2)

is the stumbling during normal cruise and light acceleration going uphill? that's probably the worn spot on the a/p cam. as for the carb size, if it's a stock port engine, it's probably a 465cfm carb.

MountainDew67

When going steady in 3rd gear, car seems fine....under full throttle it feels like spark is breaking up or the carb not tuned properly. In a v8 car, I would say spark, but this isnt a v8, so im here! I have read numerous Holley carb post about stumbling, and thats what the car is doing. Im going to check to insure my coils are in tip top condition here soon. I test drove the car a few minutes ago and feels pretty good, and feels like its gonna be a quick sob when its smooth. Its got NGK plugs with autolite plug wires. The coils are two chrome ones, but normally....either the coil is good or bad, not a low voltage situation to think its the problem. Oh, and 4th gear, well, the way the transmission is, 4th gear was ok during steady pedal cruising, but I should shift till 4th till around 50-60mph because its so long winded, these motors are. hmmmmm Im still brain storming...

BMS2004

always stumbling when full throttle or just after to punch it? Either way i would guess its running too rich.....does the exhaust make your eyes water? haha and when are you going to post a pic?

Ron

kettlman

iTrader: (2)

first for the stumbling i would replace the fuel filter and see if that helps. also find out how many psi's the fuel pump is pushing. for a holley you should be runnin 6,7 or 8 psi. that would starve it from fuel. if thats all good and still does it, i would check the jetting. once you go that far, you can get more answers.

MountainDew67

I will borrow my buddies digital camera this week, hopefully early this week. Get you guys some pictures!

I have a holley red pump literally 12-14"s from the carb. They mounted it on the firewall behind the carb, and I would say theres 12-14"s of hose in between. There is no fuel pressure regulator and the fuel filter looks new and is before the holley red pump. I was gonna ask the question about the fuel pressure, but you guys beat me to it when I came back to check my post.

At this point, the easiest thing I see to do is put a screw between the linkage to have mech secondaries and see what happens. Im reading post after post about holleys...I hardly see satisfied rx7 owners with holleys..but they were out there...


Stumbles pretty much when you give it gas, I did dump the clutch once and it spit out of the hole pretty fast then as I proceeded to floor it after the initial jump it just stumbled. When I kept the rpms steady it did ok, specially in 3rd gear, did real well. Felt like it did ok at the end of 1st gear,cant remember 2nd gear and never got all the way through 3rd. 3rd gear takes forever, bug transmission is not geared properly for a rotary, I will have get a close ratio 3rd and 4th prostreet trans for this car. What I liked the most that is gonna be so much fun...it litterally jumps out of the hole..I was trying to burn rubber and dumped the clutch and everything grabbed......wheeeew...this is gonna be tooo much fun....

813KR$

Defffinetly convert to the mechanical secs with the screw trick. Put a fuel press reg and gauge set at 6psi. The trans should be fine as long as it will hold up? If you have the vac secs it is probably a 600 and you need to buy a sec metering block to chnge sec jets. It sounds like you may be running too rich? The higher the rpms the richer Holleys usually get? I usually have my jets in the 60's.

A friend of mine has a tube frame manx dune buggy with a street ported 6 port with EFI micro-tech pushing 226 to the ground wieghing 1400 pounds with hiim in it, sitting on 20's ! ! !

check it out:

rotaryshirts.com

on the 1 bad buggy page.

MountainDew67

In a couple of hours I will be going outside to fool with the car a little bit.

I have the 465cfm carb. So far its the perfect fit for my 12a motor. How do I tell if it has been ported/bridgeport....?

BMS2004

well you can't judge a book by its cover.... hmmm not sure how to tell without tearing it apart...unless you checked the exhaust ports by pulling off the header...

If i read that correctly or undertsood it at all... I would play with the acclerator pump b/c you said its ok on constant throttle, sounds to me like its dumping gas when you pump it.

Another thing that comes to mind is what rpm are you smashing the gas at and trying to cruise at? If you try to go full throttle at low rpm it will bog and stumble...

Just trying to help never claimed to be an authority though. =)

Ron

813KR$

How does it sound? The lumpier the idle the bigger the port ! ! !

If it sounds like a beast, it is . . .

MountainDew67

I havent been around RX7's EVER so I wouldnt know how to compare sound. There is a guy with a rx7(dont know what year yet) that goes to the pool hall I go to on a weekly basis(Monday night ladies night) so I will see if I catch the tone, and year.

WELL ITS FIXED! I took off the vacumn secondaries linkage piece and took it out and it barely stumbles in first gear(you guys said it would, no biggy tho)but is still goin GREAT, 2nd and 3rd gear are VERY SMOOTH. 4th gear I dont know, I was on a 40mph street and didnt think it was a good idea, I dont know the car very well anyway, as in brakes and all that (new pads,but 4 wheel drum) etc. The car feels GREAT performance wise, happy as all hell, came back juiced up, cant wait to fix the cooling problems and get this thing on the road as a daily driver. Im overwelmed with the performance. I have drivin 17.5 to 11 second cars on the drag strip, but with the car being short wheel based,16-1700lbs, with aprox 150 horsepower, it feels awesome. Thanks guys for the help, and thanks to the old posts that I read, that helped too....Im sure I will have more questions

ANother Mech linkage disconnect happy customer! (doesnt make sense,but I know what im trying to say...lol)

kettlman

iTrader: (2)

hgelp me out here. if you disconected the linkage to the secondaries......... then you only runnin with 1/3 the holley? no secondaries to kick in? of course it's smooth. if that helped it. go buy a spring set from the parts store. change the secondary spring 1 up and see what happens. the set will tell you the tensions in order. also check the cam. you should want a green cam on it. then check the accelerator sprayer thingy(don't remember what its called) let me know what you you got. should be in the 30's. that will help alot. or just be satisfied with what you got and drive the hell out of it. but a properly tuned holley is what it's about.

rxtasy3

iTrader: (2)

electric fuel pumps push better than they pull, move the pump closer to the tank. i'm pretty sure all the holley carbs rb sells have vac secondarys, i have a 465cfm with vac secs. the holley requires 6 lbs fuel pressure, if ur pump is higher, use a regulator.

MountainDew67

THeres no possible way this thing is only getting 1/3 of the holley. The car flat out moves,grabs/chirps 2nd gear insanely,hit 3rd and you really feel how smooth and quick this thing is. I will probably try the spring idea just for kicks later on, but im off to the cooling part of the car, because at this point, I cant figure anything out until I can drive it further and more consistant. THe squitter is squittering fuel very hard, you can hear it hit off the inside of the carb, and it sounds like its trying so hard to get out of the squitter asap. You know, you can hear the rush of the gas squirting. Im not gonna say it might not need a bigger one, but at this time, atleast I know its all in the holley! The cool thing is, I dont think theres much else to do to this engine to make it run faster....its got a RB intake, 465 holley,ngk plugs,autolite wires(could change this out),exhaust is about 4 ft in total length including muffler, so thats a plus, I do have a borla (130$ muffler one) muffler that I could throw on it, but I havent checked the brand of the one I have yet. I got fuel, might look into a regulator just because. Im pretty sure the exhaust is NOT stainless so Im looking toward that. Stainless steel shoulnt rust should it? How do I tell if its stainless? Next best thing is a prostreet vw tranny to get this baby goin good!

813KR$

If the secondaries are not opening you still have alot of power not being used! Throw a screw in the linkage and make the secs come on quicker! Then you will see fast ! ! !

Also set the cam to squirt as much gas as possible by adjusting the cam likage position.

813KR$

A pic of the screw trick:


http://artisticperformance.com/v-web...-Gallery/screw

MountainDew67

I have seen that picture over and over the other day during my searches...

I dont understand how that would work, is the screw STUCK in there? If so, what size because when you kick down the secondaries, wont the screw just move anyway? Please explain, I don see the theory in this.

I took off that snake looking linkage piece next to the screw.

Im just not in full understanding.

kettlman

iTrader: (2)

well, the snake looking linkage thingamajigerbobber is what helps open and close the secondaries. when you fit a screw there it acts like a block. when you accelerate, the "snake" pulls back, catches the screw, and opens the secondaries. so it pretty much cuts out the vacuum opening.all you gotta do is get a little screw wide enough, screw it in tight and it doesn't come out enless you get too skinny of a screw, but that would be stupid. question. when you said you took out the snake thingy, did you do anything else? cause that thingy is pretty much just a safety rod. it doesn't let the secondaries open too fast or too far from your throttle position. if thats all you did, then your secondaries are still opening through the vacuum. i've never heard of anybody doing that. but if it works. go for it. other than that. have fun and just do what works for you.

MountainDew67

Thats interesting about the last part of the paragraph about the snake and still opening through vacumn. Now you got me wondering why it worked then. I obviously eliminated something, I need to talk to some holley gurus are get a manual. I had a holley tuning book somewhere! Well, I took out my radiator today, I think ill have it pressure tested tomorrow to see if I can get this thing on the road. Im gonna start a new thread on the cooling,vw guys cant help ~

RXvedub

iTrader: (1)

Let me know if I can help in any way

rxtasy3

iTrader: (2)

i've got either a 6-32 or 8-32 machine screw with nut in mine and positioned to where the secondaries start to open when the primaries get not quite 1/2 open.