vapor lock?

[1duster]

ok i have another problem.
I have a '71 duster 440. The car runs extreamly strong untill.....the engine temp reaches 200degrees and the tach reaches 4000 at which point the car heeves forward and backward fairly violently. Is this vapor lock? How do i fix it? Should i just put an electric fuel pump at the back of my car to feed my mechanical? or do i have to dump the mechanical ( which i want to keep by the way).

[dirty dan]

That sounds like a good plan.
Install the electric as close to the tank as possable.
It will pump through your manual pump should it fail
to get the job done.
I have had good results with that set up.
And it makes for quicker starts.

[dynorad]

Are we talking about full throttle or part throttle? If you are concerned about vapor lock a low budget solution is insulating the fuel line. I think there might be a couple things to check first unless you want the electric pump and are planning to put it in regardless.

[amoparman]

I run a carter street perfomance pump on my 440 duster and it works fine. First I had a stocker on there and it wouldn't do the job, brand new and it was crap. Sure its vapor lock?

[dave571]

A carburetor heat shield will also have a good effect.

They're fairly inexpensive, and easy to install.

[mtrv8n]

check your float height and fuel filter. Mine was clogged, and caused bucking over 3000 rpm, when I let her idle a bit, ran fine until fuel demand went high.

[6pakman]

vapor lock is caused buy excessive heat build up under the hood. the gas does just that, it vapors before it reaches the carb. which causes a lock in the fuel line. elec pump or keep lines away from heat source will help. lots of crome under the hood radiates heat which can also cause excessive heat under there.

[1duster]

we are concerned with full throttle, car runs great on the street but when we go to the track our power completely falls off after 4000rpm mostly when the car is hot which is most of the time(it was 108 last night at the track)people at the track last night told us we should dump the edelbrock and put on a holley, our edelbrock is a 800. ony thoughts??????

[mtrv8n]

still think its a fuel clog

[6pakman]

man i'll tell ya, with out being there its hard to tell. it's touch and go. in my opinion sounds like a fuel problem. but im not there to really find out. anybody else?

[1duster]

we know we need a electric fuel pump....and im setting one up today, but i think we might have to switch to a holley....reason? last night i ran 14.2 on my small 205-70-15 ( 5 inch tread, not tall tire) I then let the car cool and put on my other tires which are 265-60-15's which is a fairly taller tire. Whith those on my car stoped pulling at right about 4000rpm's. I was racing a 440 roadrunner last night and the guy said he had the same problem untill he dumped the edelbrock 800 and went with a holley 750.

[usdart]

I had a week fuel pump on my 340. When the engine got warmed up it would DIE and not restart until it cooled off COMPLETELY. Finally after LOTS of parts ,changed fuel pump and problem solved!!!

[dynorad]

It seems like a lot of guys will tell you to throw away your carb and replace it with the one they like. If you got enough money to do that, great. But I think that this kind of thing is usually related to tuning instead of the carb brand.
I can see chucking the carb if there is some basic design flaw, but seems like it might worth a call to their (edelbrock) tech support first.

[jensen32000]

Check your fuel pump pushrod length. I had one wear about 3/16" and would act up when hot!

[amoparman]

I would put a fuel pressure guage in line, one of the permanant ones, so you will know for sure if the fuel is getting to the carb. Even if you already changed the fuel pump. I have found it very usefull to diagnose problems like plugged filter, weak or broken pump, and it looks cool too. Is that an EPS 800? They just track tested that in mopar muscle and it made more HP and torque than thier tuned to combo holley! If the pump doesn't work call edelbrock.