Tonight I took my demon to the 1/8 mile for the first time.

It's a 76 360, heads ported, 2.02 intake valves, about 9.5 compression. Cam is about a .440 lift. Edelbrock airgap intake, capped with an edelbrock 750. It has mopar performance electronic ignition, orange box. 3.55 rear. The fuel pump is a standard mechanical pump, and the carb has no spacer. This was a /6 car, and I'm still running the 5/16 fuel lines. The air temp was 85, and my engine temp was about 205-210.

On most all of my runs, the motor acted like it was starved for fuel. Usually, this would be at higher RPMs, but not always. Several times it starved from the start, and I was not on it hard at the start, because I have an open rear.

My first thought is that the sock in the fuel tank may be plugged, and I'm gonna remove that this weekend. Next, I'm thinking vapor lock, and then float settings in the carb. What do you all think?

My best run was 9.05 at 80.865. It was really the only run where it pulled hard the whole way. On some runs, it lost almost all power right from the start, and I just nursed it through the line.

I did manage to beat a 72 Chevelle 2/3 times, and would have been 3/3 except for the fuel starve!
O

How hot does the intake and carb get ? .... it could be vapor-lock.

The TRUTH will be told if you put a fuel pressure gauge on it.

What would be the carb/intake temp that would cause vapor lock? I am at about 600 ft. above sea level.

What track were you at ? ...what was the temperature outside?

REreading your post I think it IS V L ... because it happened at low and high rpms.

This is where my thoughts are ... unless you have a failing fuel delivery system.(bad mech or electric pump, pinched line - etc)

Outside temp was about 85 degrees. Clarksville Speedway in Clarksville, TN.

85 degrees? ... not very warm outside to cause VL. If you have VL - there are other factors there.

Three things to check .... how hot the intake a carb gets. What is the water temp? And what the fuel pressure is at idle and at 5000rpm or so ...down-track in 2nd gear.

Ditch the edel carb thats most of the problem. years ago when I ran that style carb on a warm day I never made it to the end of the track. Now I can run a 195 stat on a 90+ degree day and never have a problem. get a electric pump to back up the mechanical get a holley witha t least a 1/4 =inch spacer or more I prefer 1" 4 hole for torque. What was true engine temp? With a good electric pump I can run over 205 and not have a problem For the heck of it set the floats a little higher and put a 1/4 insulated spacer under the carb and see what happens, or make a cool can out of PVC pipe and fuel hose. One way to elimnate fuel question put racing gas in the car and try it? Just my 10 cents Good luck

Sounds like mostly carb problems, but I would also add a high volume pump, even a mechanical pump.

Quote:

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The TRUTH will be told if you put a fuel pressure gauge on it.

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Easiest way to find out before your start taking things apart. mike

Ditch the carb and 5/16 fuel line. Try to get a fuel pressure gauge on it. If it's acting like that on an 1/8 mile run, you got problems.

Patiently waiting for the 5/16 line feeds 440's crowd...

Checked the floats, they are set fine. Got an infra-red thermometer to check the carb/intake temp. Friday I'll round up a fuel pressure gauge and see what I find. Also I'm going to replace the fuel filter, and have a look inside the old one.

If all that checks out okay, I guess I'll trash the carb! Thanks for all the advice here.

well 5/16 line feeds 440's so .....

personally, the motor doesnt sound all that big to need more fuel line. thats a small cam.

i would be checking fuel pressure before I started changing stuff. What rpm is it dying at? maybe valve float.

btw, I put 3/8in mine though- just to make sure

The RPM that it dies at varies. Usually it was at a relatively high rpm 4500-5500. But a couple of times, it was right out of the hole before the motor was turning much.

it couldnt hurt to put a better mechanical pump on it. i run the carter street/strip mechanical pump (i think its the 6902)

The fuel filter had some rust in it, so I pulled the tank. The sock was pretty stopped up, but the tank was not very rust at all - it appears to have been replaced at some point. I cleaned the tank out out, and decided to upgrade to 3/8 inch line and pickup while the tank is out.

One thing I noticed - the fuel line on the passenger side seems to be routed very close to the header where it connects to the exhaust. Maybe 1.5 inches away. Should I change the route of the line, or put a shield over it?

A shield should work. You would be suprised how much fuel you can flow through a 5/16 line, of course an upgrade to 3/8 is good, if everything else is working. The filter and sock should help most, but I found that a high volume pump makes a great difference too.

Ok, just got back from the garage. I've got the 3/8 in. pickup installed in the tank, and have the new 3/8 in. fuel line plumbed from the tank to the fuel pump. The line to plumb from pump to carb has not come in yet - I should have just bent that one.

I assume I will need to change the fittings on the fuel pump for the 3/8 in line. The pump is just a cheap mechanical one. What are the specs of the fittings, and where do I get them? The barb on the fuel pump inlet does not look like it's changeable, but it may be. Is it?

I had fuel delivery issues with 2 stock pumps on my warm 360. Switched to the Carter street pump and the problems were cured. the Carter street pump comes without hose barbs on both sides, you can pick them up at your local hardware store.

AVS carb design needs at least a 1/2" phenolic or wood spacer beneath the carb, or they will get vapor lock. Mine (and most) showed up on hot restarts, as the fuel would boil out of the carb and leave it full of vapor (which will not pump). Never had a vapor lock problem while the car was under way (but did have the mentioned fuel delivery problems where the stock pump could not keep up with the engine requirements).

I couldn't find a pump locally that would accept 3/8 line, so I left the stock pump on it, and stepped the 3/8 line down to 5/16 before the pump.

Looks like it's fixed. I have not taken it to the track yet, but under hard acceleration, there has been no hint at all of fuel starve.

Not sure if it was the pickup filter, or rust/constriction in the fuel line.