Recently took my 57 pontiac for a drive, as soon as pull in the driveway it decides its not gonna idle anymore. I'm running a pontiac 400 in it, now I re-checked the timing, its at 16, and 34 all in at 2500rpm, checked for vacuum leaks ,found none. pulled the carb (edelbrock 600cfm, jetted 4%richer than stock) and made sure there were no sticky seats or bowls. Carb is brand new btw. After re- setting of idle mixture i realized it would idle so long as i kept the vacuum disconnected from the distributor. its a bone stock 400, except for a single plane edelbrock intake (not my choice). So figure maybe the distributor needs a re-build?? Figure I can still drive the car with the vacuum plugged, right? just gonna sacrifice some fuel mileage and performance. Any one got any other thoughts , or just the distributor?
If you are running 16* initial with the vac plugged and then hook up vac to manifold you end up with way to much advance. Try ported vac,none at idle but still get the bennies down the road. 16* initial sounds like to much on a stock engine 8-10 more like it.
Also look for a vacuum leak.... Check the vac line that comes up from the trans too the intake or carb... Those lines do get "baked" from the heat and get brittle and crack...
Tried less timing before I had this issue, and it wouldn't idle in drive with any less. Made no vacuum without bumping the timing up.
Did you verify that your marks are correct with a piston stop test. Them balancers can slip and make your timing light tell you lies.
That is sounding like a very good idea, gotta hit a kids bday party, first thing tomorrow I think that's where I'm gonna start. Only thing is I got about 600miles of trouble free driving before yesterday. Why would it be ok And then not?
Last time I saw that, it was a cracked vacuum line going to the vacuum advance module on the trans. Vacuum is a funny thing. Chase leaks with ether. If you spray it on a line and the idle races, you found the leak.
OK so what's common here. The hose going to the vacuum can. Could be a can with a leak Can pulling too far Or You didn't specify if the hose was plugged to idle or open to idle. If left open you induced a vaccum leak and it idked. If plugged you eliminated the vacuum advance.
Had a customers 40 chevy, sbc rpm intake nothing wild, in for the same thing drove me nuts, unfortunately his problem was the cam was wiped out. He didn't know they took the zinc out of the oil. The motor only had about 100 miles on it, hope that's not your problem but check it out.
I was actually fighting the same problem in my dodge.... Turns out after messing with my 600cfm edelbrock, when you bottom out the mixture screws it wouldn't die.... Vacuum leak somewhere.... A mechanic friend said it was definitely and internal leak In the carb and I need a new carb, or rebuild the one I have. Im running a mechanical advance distributor, and have no vacuum lines to my 904.... Any ideas??
Well, unfortunately you were right about the cam. Took the top end apart, and pulled the cam and sure enough it's gotore than a couPle wiped out lobes. Guess that's what you get for a junk yard engine. So I'm not gonna mess around, total re build, now just to decide stick with Pontiac power or do a sbc.
I had the same problems a while back and my coil was not getting enough voltage so you might test that.
My 409 engine stopped idling in drive. Same thing as yours I lost an intake lobe on #1 and was running on 7 cylinders.
Perhaps a blown diaphragm in the vac advancd cannister? When it is not hooked up no vac leak when it is hooked up big vac leak. Try squirting some starter fluid on it with it hooked up at idle.
Ya, I definitely think the pontiac in a pontiac makes the car that much cooler, hard to argue the reliability and cost effectiveness of a sbc. But I guess if you want reliability and cost effectiveness you prob shouldn't be building hot rods, lol. I'm gonna stick with the old 400 even if it kills me.
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