SinfulC3

Have a 76 with the L48 and 4spd trans.
Up top I have an Edelbrock Performer intake and on that is an Edelbrock Carb. Idle set to 750RPMs 3 days or so of messing with the idle/air control screws and I'm pretty close to having her spot on.
I think that is the important information.

Now to the problem. err... one of my problems
I get in my super cool vette and go for a ride. Nothing too long, 15 minutes because I take the long way to the grocery. Time to be up to operating temps. Shut her down go grab some things, 15 minutes in the store? Come out and holy crap starting this thing is not the most fun.
I can get it to start by mashing the gas to the floor but then I have to feather the throttle for a few minutes to get it back to idle correctly.
Or I can just hold the key for 5-10 seconds. It will start up but idle quickly tries to fall below 500RPMs so feather the throttle for a few minutes until she can idle on her own. That's if it does anything more than just crank and crank and never fire.

I ONLY have this issue when the car is up to temp. Starting cold requires a quick pump of the gas, turn the key and she fires right up and starts singing.

It gets hot, and I mean HOT up top. The intake will remove your fingerprints if you touch it kind of hot.

I don't see anything dripping in the cab when it's sitting and have no idea how to get the heat away. If I let the car sit long enough to cool off she'll fire right up.

Thoughts? Ideas? Suggestions? Shot-put this carb and intake and go with something else?

I'll try to post some pictures of the offenders.

Thanks,
Nick

BOOT77

Normal stuff are you running a return fuel line, if not you should. I see form your 2nd pic your not using a 1/4" thick isolator gasket to prevent carb heat soak. It should be a sticky for all corvette guys to use one of those.

dpw21562

Have you thought about using a heat shield? I have a copy of one for a Holley but you can use it for an Elderbrock , send me a PM if you want a copy.

ddawson

And are you still allowing the exhaust gases to pass though the intake manifold?

SinfulC3

I'm a bit embarrassed to say, I have no idea if there is a fuel return line. But I plan to find that out after I get off work today!

Doing some research on the 0.250in carb gasket I have stumbled on a new question... 4 hole or square bore?

dpw21562 - A heat shield - Where? I'll shoot you a PM and hope to learn something more.

ddawson - I honestly do not know the answer to that question. I just picked up the car and I did not install the intake. I would hope that it has them blocked off but judging by the feel of it... I'd say they are open still.
Easy as pulling the intake and replacing with a gasket that has the blocks in place? I live in northern Indiana but have zero plans to have the car out on the roads in the salt drenched winters.

Thanks for the help guys. This is my first corvette and as with all makes/models... they all have their own "unique" qualities that you have to learn.

Nick

BOOT77

It depends on the gold colored thin adapter between the carb & intake and if you can get an eddelbrock carb style insulator. If the adapter is open, then 4 hole on top is fine but not below. If the adapter is 4 hole then 4 hole either side will be fine.

gungatim

is your choke working/adjusted properly?

looks like you've got some leaks to deal with. Around intake bolts and carb base. fix those first before worrying about heat soak. I have same setup (cept a holley) and have never had to use a heat shield.

SinfulC3

Check the current plate and go from there, check.

Does the choke actually work... I'm leaning towards no. I'm pretty sure that they choke plate is stuck in the full open position. I've not seen it closed, ever, and if I'm recalling correctly I went to try to manually close them and they weren't having any of that. Is that due to an electronic choke holding it open? Doesn't sound right to me. Sounds more like there is a bind in there or something is put together incorrectly and keeping it from ever closing. But wouldn't they be wide open when the car is hot anyway?

I agree looks to be some leaks. thought about trying to just retorque things but I'm not sure if that's the best idea or if I need to pull it all off, get new gaskets, and put it all together again.

Should there be any type of sealant on the bolts going through the intake and/or carb?

ddawson

Electric chokes are adjustable. It may be adjusted all the way open.

Try loosening the cap and see if it turns.

Do you see a second return line down by the fuel pump?

Jazzyced

I have the exact same set up on my 76: a performer intake with a 1406 Edlebrock atop.

Mine was in a very similar condition when I bought it: oily and dirty. A fellow forum member suggested that (and encouraged me to) I should remove the carb and rebuild / clean it. He was right, not too difficult of a task and made quite the difference!

Sticky oily components do not help... be generous withe carb cleaner...

No need to change all of the gaskets etc.. yet, a good can of carb cleaner and a bit of patience were enough. Once clean, it will also help you locate where the leak is coming from.

Don't forget to check the choke as the little pin actuator inside may have jumped out...

If you need some pointers and documentations, I will be happy to help, PM me.

Jartanyon

I have the same issue now for a year. Runs very lean when I get it started again (according to my A/F meter). Garage smells something fierce after it sits for 20 to 30 minutes. To date, I have filled exhaust crossover in intake, installed oil valley splash shield, run a heat shield, run a phenolic spacer, backed off timing advance to 16 degrees, run premium fuel....and I still have the issue. I didn't have it before and the only thing I can think of that changed is my fuel source. Where do you fill up?

dpw21562

Link to views of heat shields. I have full size diagram.

https://www.google.com/search?q=holl...emwN_ZR9st0%3D

gungatim

yes, sealant on the bolts, aftermarket intakes have huge bolt holes, you will get oil leaching up through the threads. no on the carb bolts.

If it were me, and it was about 3 weeks ago with my '76, with the exact same problem, pull the intake and put new gaskets on. do it right, you'll know if the exhaust crossover is bypassed, you'll know the bolts are sealed and torqued right, it will be easier to clean the intake, etc...

if you just tighten them up more, you risk possibly damaging the gasket even more and getting a vacuum leak to boot...

mikem350

It helps if the engine runs cooler. Use a 180 thermostat.

aussiejohn

Sinful, someone did a butcher job on the fuel line. They cut the steel line (I bet it does not have a flare next to the cut!) and put in some rubber line, a filter and more rubber line to the carb. Not the way GM designed it. I suggest you replace the whole line from the pump to the carb with a one piece steel (factory type) line and if the pump does not have a return line, then replace it with one that has. Buy the correct "S" type Corvette rubber line from the chassis mounted steel line to the pump (DO NOT use straight fuel line and bend it!!!) and the correct return line from the pump to the chassis mounted steel return line.

Do not overtighten the carb to the manifold. If the base of the carb is flat then the engine should run without tightening the nuts, the vacuum will hold it to the manifold. Tightening the carb-to-manifold bolts too much will warp the base of the carb and THEN you'll have an air leak.

HOpe this helps.

Regards from Down Under.

aussiejohn

SinfulC3

Lots of ideas, awesome.

You're right, Aussiejohn. They did hack it and there is no flare. I was hoping to flare it and keep the rubber up top as oppose to putting in all new fuel lines. It's my understanding that's a lift the body to access type thing. I don't know how much flack I'll get for going that route... hopefully it's a fairly safe/doable plan.

I wasn't able to make it out to tinker last night due to weather so I still don't know if there is a return fuel line but my guess is there is not and I understand that that problem WILL need to be rectified for proper operation. Also, thank you for the carb bolts tip, I was wondering how much these needed to be torqued down.

Have some vacation time coming up at the end of the month and that sounds like the perfect time to go ahead and pull the intake to reseat/seal everything and know it is being done correctly.

Really my biggest worry/hope right now is - please god let there be a return fuel line that I have overlooked!!!!

ddawson

On the left of this picture. look at your frame and see if the small line has a cap on it.

cooper9811

On the fuel return line - it's possible that if you have the stock pump, that is using the return line described above. However, if fuel is boiling in the line just prior to the carb, that line does no good. I had a hot start issue a couple years ago that was determined to be fuel boiling in both the inlet line and bowls after shutdown.

For this situation, the best answer was a return line that goes from the carb (just after the cab inlet) back to the tank (either via the intended return line or an alternative of your choice). I also added a heat shield.

This relieved any fuel boiling just prior to entering the carb. The combination of a return line from carb to tank, and a heat shield to deflect heat away from the 4150 bowls, solved all of my hot start issues.

This may or may not be your problem, but is an avenue to explore.

SinfulC3

Ok guys, here's what we're working with....

It appears both lines run into something on the front lower part of the motor, from there a single line runs out to the carb.

So metal lines on the frame to the front. Switches to rubber to go into un named device... Fuel pump up on the motor?

augiedoggy

Thats a fuel pump...

Put a thicker gasket under your carb or better yet a 4 hole wooden carb spacer(thats what I used) and be done with it... No need for all this work.
http://www.jegs.com/i/Edelbrock/350/8723/10002/-1


I had the same carb until about 3 months ago and no issues with the spacer.. just make sure you have hood clearance ...