Haven't played with the toy in a while, and did today at lunch. Interesting findings....

(81, no computer, no smog, 750 EB carb, New distrib, new intake.)

I have been going back and reevaluating my circumstances and the problems I have been having with overheating (had to go to a 160 degree t'stat), not running good, backfiring, stumbling, running good at wot, not running good on part idle, the whole thing....No way I was telling myself that I should have to runner two steps richer than stock on a 750 cfm carb to get it to run half way decent. Was getting wild readings from A/F gauge, sometimes steady, sometimes going out all lean....

I unhooked every vacuum line on the car running to the intake except Pcv, vac advance, and brake booster and took her out. (Unhooked lights, and two old vac lines not sure where they were going). Ran totally different. Didn't want to get out of 2 gear with rpm's running way up, almost felt like a tranny problem (which hasn't been showing before). Came back to the garage (didn't want to do any damage) and checked the timing with vac off (car almost died) and it was showing 15 on initial, but I couldn't rev her up without it trying to die. (wasn't having this problem before). She also seemed to be running hotter.

Am I suffering from a timing issue related to a vacuum leak?

Why did the car not want to shift out of second?

Hopefully this is enough info. that someone can reply.

 

If you pulled all your vacuum hoses off, you also disconnected the tranny vacuum modulator. This will prevent the tranny from shifting.

 

arrrrhhhhhhhhhhhhhhhh........me dummy, you smart! Thanks Lars, I think I know which one it is......Going out for test two.........

 

Hook up a vacuum gauge. You should see about 20 in of vacuum. Vacuum can leak from almost anywhere. Some guys use carb cleaner to spary at fittings, carb base etc to find the leak. When a leak source is sprayed, you should see the vacuum gauge jump and even a change in the rpm's.

 

o no!! not you again!!!
agteacher hasnt picked up that 600 yet, if you want to try it just let me know.

 

yep, hang on....here we go again.....

Good Luck!

 

Well.....that wasn't it (not those two vac hoses anyway, still might be coming from my intake install however).......I have tried spraying around and checking for leaks, and can't find any. But I did spring a leak in the radiator at the bottom somewhere......looks the the radiator cleaner did it's job!! That also explains my overheating issues. Guess the dang thing is clogged up. Where to get a radiator? Any suggestions?

Somebody please explain to me why the carb I have will only run "decent" jetted and rodded two steps richer, and the IM screw liked to be turned rich?

Hook....I may come get that carb and try it. Is it an EB carb? Or if it's not to you have the adaptor for the Rochester that goes on the performer intake?

 

yeah man it's the EB 600cfm 1406 i think. will bolt right up were your 750 is now, allmost the same carb.
may can help ya out on a rad too. remember i got a hole in my new one from that top screw? well i going to have my old rad re-cored and you can buy this one and have it fixed. it's for a auto tran. car. make ya a smoke'n deal. it's brand new i paid like $265 for it. $100 and u fix it...sound good?

 

What's it gonna take to fix that hole Hooker?

Also, I may come get your carb this weekend if you don't mind.....are you coming up this way anytime soon?

I freakin' give up

 

Have you pulled all the plugs yet ?
They will indicate which cylinders are running lean.
If all are lean, you have a common problem ... carb, vacuum line, etc.
If only one or two are running lean, then it is more likely a
leak in the intake manifold gasket to the head.

If I were you (at this point), I would try a loaner carb. If the loaner
runs good, you nkow the problem. If the loaner acts similarly, you
might need to pull the intake and reinstall with new gaskets
and good sealer.

But hey ... at least you are driving yours.

 

Didn't take long to shut me up this time....two quick spins, and I'm done until I get the rad fixed....

 

Don't forget about the CorvetteForum Loaner Carb Program... the Program is still in operation if you need to use it.

 

The Peformer intake will accept a QJet as a bolt on. I'd recommend trying one of Lars loaner QJets -- send him an email. A Lars carb WILL make you smile!

 

I still have an 85 year qjet.....the number on it is 17085226, which best I can tell is Rochester, 1985, 49 state emission, Chevy, Auto trans. Not sure what the cfm is, but someone said it probably an 800 or so and that it would work on my car. (It was working on the old intake).

The bolt spacing is different than the EB, but I think there are two sets of holes on the performer. Gotta fix the dang rad first though.

 

Try a carb from an earlier, pre-computer L48. Say mid-70's or so. I'm sure Lars has one in his pile...

In the meantime, while you arrange this, you can get the rad fixed up.

The Performer has 2 sets of holes like you said: one for QJets, and one for squarebores like Edelbrock Performer, Holley, etc.

 

i got money on need to pull the intake and reinstall with new gaskets
and good sealer.
i think your do'n all the right stuff on your tune'n and this is about the only thing you have'nt redone and redone.
the rad going bad is just the way it is for old car's.
you'll be doing hose's, water pump, belts, starter, alternator all in the next 6 mo. to a 1yr. i bet too.

 

Replace the radiator hoses while you're at it!!!

 

Hoses, belts, and alternator all look new....so blahhhh (sticking out tongue)

 

Hey Msvetteman, keep us posted on your discoveries, this post is sooo much more intrieging than the Da Vinci Code...

 

good you a little ahead of the game then