Hi guys!

Driving it a lot now, so discovering the small problems.

The underhood temps on this car just seem to be way too high. It runs at a perfect 180 degrees on the gauge with the new radiator. But it keeps feeling like a hot engine.
A lot hotter than any other engine I've seen ( some European cars, 67 mustang and c4 corvette).
The intake is way too hot to touch after driving.
And lately it has been acting a tad weird :
The weather here is 80-90 degrees atm, and when you pull away after sitting in traffic for a while it sometimes stumbles.
To me it feels like its either vapor locking,or boiling the fuel in the intake.
Wanted to floor it yesterday after waiting a while at a crossroad, but that failed miserably as it just started jerking and stuttering, after 40-50 meters it seemed like it had enough cold fuel again and all was fine again.

Could the reason be I m not running a phenolic spacer/insulator? ( Hood clearance is very tight with the edelbrock intake and carb).
Or should I look into a better option of sealing the exhaust crossover? I used one of those gaskets without the crossover port, but apperantly those burn through quickly.
Exhaust temps seem hot too. The muffler tips are too hot to touch for example after a drive. Again, not sure if something else is wrong or if it's just normal for the car). Timing is set to 36 degrees at around 2500 rpm, static timing is about 16°.

Cheers!

 

? ... and you're complaining about what make, model, year vehicle ?

 

Sorry, is mysignature not showing?

79 C3 with a 350 crate making about 300-350 hp

 

have you verified the 180 with a known good gauge?

 

And probably an open element air cleaner right?

 

Yes it is very hot under the hood of a c3.

https://www.corvetteforum.com/forums...g-results.html

you pretty much need to use the thick gasket to minimize percolation.

 

Indeed!

& and thanks for that link reevlav8r

 

You mention foreign models and how much cooler they run as to a C3. A lot of those little sports cars had four cylinders too. The C3 has a tight engine bay, a small sports car griil that barely lets any air in and to compound the hot problem, the radiator is at about a 45 degree angle.

If you are running 180*, buy a lottery ticket, because you are lucky. And you will get use to the heat from the engine compartment. Its just the way it is. Poor air circulation.

As far as the vapor lock, your ideas work, but I always thought that the fuel line needs to be isolated away from heat to begin with. What was GM thinking running the gas line right up next to the big gob of hot cast iron known as the cylinder head?

 

I had a cool running motor before I started getting bigger cams and it was on the high end of 180*. But it had similar problems as you with peculation and boiling. I Had an edelbrock carb and intake as well. My solutions were a phenolic spacer, sealed the crossover with block cement (which may be more than you need), and installed a fuel pressure regulator. All of those things eventually solved the issues. I also added a cold air intake as well.

But I also have an L88 hood so I have plenty of room for a one inch spacer, you could probably get a way with a 1/4" or 1/2 inch spacer and a low rise air filter base.

 

The hot air isnt helping either.

 

Make sure your heat riser valve is locked open (or gone completely). An L82 intake could help. Instead of 180 degree air, the engine will be breathing ambient air.

 

You are "assuming" the stumble is from a hot situation and it probably is, however the stumble could be from a poor shot from the accelerator pump. Check one thing at a time.

 

I'm 90% that's the problem, because it doesn't do it when I brake to a standstill and then floor it. Only when I have to wait a bit.
Fuel also boils when I shut it off, but of a dangerous situation too imho. Phenolic spacer should arrive tomorrow, I'll see how it runs after that

 

If you have a poor accelerator pump shot it should stumble when cooler as well, or any time you suddenly add a lot of throttle. Way I read it is it only stumbles when hot after idling a bit?
Another thought is if you are drawing under hood air and you give it the same accelerator shot as when the air is cool under the hood, that shot could now be too much due to the less dense hot air and it momentarily floods the engine.
Also air flap adjustment on the secondaries could be out of adjustment.

 

Couple things that helped me in the Texas heat.

1. Intake gaskets that block off the crossover port

2. Insulating the fuel line. Not pretty but functional

3. A good 1/4 in spacer

4. I have electric fans. They blow down at an angle which is fine until summer. Then I install a flex fan also to push some air through the compartment. I don’t have a shroud so it’s easy to change.

Good luck
john