mfpvette80

I've got a 1980 with a 290HP crate motor and RV cam. I rebuilt the Q-jet and the car runs great and starts great when cold. When warm however, it's a bear to fire up. Need to crank with the pedal down for 4-5 seconds. Didn't remember this problem before the rebuild. The rebuild was performed due to leaking gaskets and loose shafts. Any thoughts?

MelWff

After the car has fully reach operating temperature, turn it off. Then look down the carburetor throat and see if gas is dripping.

Easy Mike

Do you have the factory starter heat shields in place?

my 76 ray

With a carb that's working properly all you should need to do for a warm engine is turn the key. If you are in the habit of giving it gas because it needed rebuilt then you might be flooding it.

AGVI

I have the same problem. Car starts easily, but is hard to start after it's hot and I notice that the carb is dripping gas.

I installed a heat shield and a spacer, but the problem persists.

Could the fact that my charcoal canister is hooked up incorrectly or the fact that my fuel return line is not being used?

mfpvette80

Good thoughts. I have a high torque mini starter on the engine and have a heat shield blanket around it. I can see cranking speed would be an issue if the starter was overheated. I had this happen before.

I don't see gas dripping other than that from the accelerator pump. I'll check this again. When I rebuild the carb I sealed the plugs as per Cliff Ruggles fine book.

Seems to be excess fuel from somewhere. When holding the pedal down and cranking it starts, but is on the verge of flooding.

Mashman

Another thing to check when having a 'hot start' issue, is the connection of the wire from the starter to the coil. It's purpose is to provide additional power during startups. If this connection is loose or frayed, then the additional heat, will cause additional resistance on this wire, and it will not be able to do it's job.

MelWff

If you used Cliff's book are you sure you set the float level correctly, may be too high. Do you have a fuel return line, if not the pressure may build after shut down causing level to rise.

jackwabbit703

When I had issues with hard start, cranking over slowly when warm, I backed 2 degrees in initial timing and it resolve the issue.

longbros

I am having the same issue with my 70. It is not a starter issue, it spins over fine. It is a fuel/flooding issue when hot. I have checked and rechecked the float level. I have looked down inside the carb for fuel dripping, etc., and have seen none. It clearly is loaded up after sitting a few minutes when hot, and it takes some spinning to clear the fuel out before it starts. I am not pushing on the throttle, so that is not the problem. Somehow, fuel is spilling into the intake manifold, but I can not figure out from where.

Invader Sandstone

Ive been fighting this issue since I got my car a few months ago. Still no luck.

calwldlife

have you tried to give it a little gas AFTER you start cranking?

BigBlockk

If the exhaust heat riser valve is stuck shut it will overheat the intake manifold. This is more than enough to boil the gasoline out of the engine.

BigBlockk

Later.....

Avette4me

I had a similar issue on a quad. Sent it to Lars and he said that some of the quad castings were porous allowing fuel to drip. That was the case with mine, just something to consider.

mfpvette80

I'd rather not mess with the timing since that will effect the otherwise good performance. The timing is right where it "should" be according to what Lars and other have taught us. I do not have a fuel return.

I've corresponded with Cliff Ruggles who, very kindly, has replied quickly to my questions. He posits that the plugs might be leaking. I did seal them with epoxy, but of course, used the stuff that works the worse for this application: JB Weld. I'll have to pull the carb and pressure test it for leaks.

As an aside to this, the fuel mileage has dropped off after the rebuild also. Another indication of excess fuel is the inability to lower the idle speed. All things point to a fuel leak.

mfpvette80

Got the engine up to temp yesterday, and took a good look down its throat. Lots of vapor. Am I correct that this indicates either leaking plugs in the Q-Jet or a float set too high?

avner

I had this problem with my both Vettes, the problem was the original starter when he heat up he doesn't want to rotate the engine all the current go on the coils of the starter.
I bought a small high torque starter (sorry it Chinas) install it in my both Vettes and it spin the engine easily when its warm or cold and it cost ~$60.
Avner

bashcraft

Doesn't anyone read the posts before replying?

bashcraft

Yes, lots of vapor indicates excess fuel.

AGVI

His native tongue is obviously not English, so perhaps he misunderstood something along the way? Give the guy a break and give peace a chance.

Les