Vapor lock?

[BB72CHEVKT]

Do you think this metal filter touching the valve cover is causing vapor lock? I will correct it as it is an easy fix but was wondering what others thoughts are on this. I replaced the carb, fuel pump and installed the filter you see in the pic. I have driven it about 75-100 miles and I am having problems with it cutting out but has only died once. I also think there is a filter installed between the tank and hard lines coming down the frame rail which may be clogged and causing the problem as well. I will correct both problems this evening but have about 25 miles to go to get to the house and was wondering if I should rearrange the move the filter in the pic before leaving work. I am in dress clothes so I can not change the one below the truck until this evening.

[Shyguy]

The filter touching the valve cover probably would not cause a vapor lock because it is after the pump. I would however put a small piece of rubber between them.

If any thing is causing a vapor lock problem it is the one between the tank and fuel pump. Most people do not recommend having one there unless the tank is real dirty and you change the filter often.

A little off subject, but what Edelbrock carb do you have and what engine?

[BIG69GMC]

i dont think it would as i have it set up very similar. though looking at your pic you might be able to move the filter closer to the carb so its raised off the engine. Or you could probly even cover or wrap the filter with some type of insulation like rubber to keep it from lying on the engine? like i said i have pretty much the same set up and i thought about it when i put it in, but havent had any vapor lock problems. (knock on wood) haha!

[BB72CHEVKT]

it is a 750 edelbrock on a 402

[Shyguy]

My son has a 402 in his '72 C-10 and has the same setup. He said the 402 is not original to the truck.

I am still not sure if I am going with an Edelbrock or Holley on my 454 in my '71 C-10.

I sure like the looks of of your engine.

[heavy70]

You need to run a phenolic carb spacer, that should fix it if not take the edelbrock carb off and put a holley, the edelbrock gets to hot on the intake, put a phenolic spacer so it doesnt transfer too much heat!! thats my thoughts!! Thats if its not a plugged fuel filter..

[BB72CHEVKT]

Originally Posted by heavy70

You need to run a phenolic carb spacer, that should fix it if not take the edelbrock carb off and put a holley, the edelbrock gets to hot on the intake, put a phenolic spacer so it doesnt transfer too much heat!! thats my thoughts!! Thats if its not a plugged fuel filter..

There is a one inch square bore to spead bore adapter on there now. I hope it is the filter.

[cdowns]

not if its a metal adaptor// in thier instructions edelbrock used to always warned customers to use the phenolic spacers that didnt conduct heat like metal adaptors do

[Longhorn Man]

I have run Edelbrock AFB carbs exclusivly since 98, always with aluminum spacers, and never had any real issues with vapor lock. (that includes a few years in texas too, not just ohio)
I would get that filter off the valve cover, and also I would remove that lower filter all together. Check the fuel lines to make sure they are away from exhaust popes, I like 2 inches space personally, but i hear people say that one inch is enough.

[vectorit]

I'd be willing to bet that your issue is not a vapor lock problem.
Are you sure that your ignition is up to snuff?
What kind of distributor are you running - Electronic?

[BB72CHEVKT]

Originally Posted by vectorit

I'd be willing to bet that your issue is not a vapor lock problem.
Are you sure that your ignition is up to snuff?
What kind of distributor are you running - Electronic?

I am running a HEI distributor and I changed the ignition module at the same time as carb and fuel pump. If the fuel filter is not the problem I am going to start looking at changing the distributor since it is a little crusty looking.

[Shyguy]

Originally Posted by Longhorn Man

I have run Edelbrock AFB carbs exclusivly since 98, always with aluminum spacers, and never had any real issues with vapor lock. (that includes a few years in texas too, not just ohio)
I would get that filter off the valve cover, and also I would remove that lower filter all together. Check the fuel lines to make sure they are away from exhaust popes, I like 2 inches space personally, but i hear people say that one inch is enough.

I agree on the at least 2 inches away from the exhaust pipe.

Filters before a fuel pump causes a pressure drop and with heat added can cause vapor lock.

Years ago I had a motorhome and there was a in-line filter under the cab at least 2 inches from the exhaust pipe and it caused a vapor lock problem when going across Arizona in the heat of the summer.

Once I realized what the problem was I wrapped a wet towel around the filter until I could get to a place to remove it.

[BB72CHEVKT]

Originally Posted by cdowns

not if its a metal adaptor// in thier instructions edelbrock used to always warned customers to use the phenolic spacers that didnt conduct heat like metal adaptors do

I am using the Edelbrock adapter they recommended for my application. Edelbrock part#2696 if I remember correctly. I will remove the first filter and get the top one off the vavle cover. I also just ordered a Skip White HEI.

[LONGHAIR]

I am in agreement with those who say to remove the filter that is before the fuel pump. It can cause a negative pressure situation, which can indeed casue vapor locking problems. ANything you can do to getthe fuel lines away from heat sources is helpful too.

[BB72CHEVKT]

WOW! Removing this will have to help.

[Longhorn Man]

that would cause both a pressure drop that could cause vapor lock... and a lack of fuel fed to the carb.

[BB72CHEVKT]

I also bent the hard line from the carb to get the filter away from the valve cover. I also want to replace the cheap chrome filter with a new one that is see thru. I know not to use the glass ones.Any suggestions?

[70jnktrk]

looks like you found the problem...this may seem basic but have you checked the 'sock' on the fuel pickup/sender? mine had collasped and shredded..

[jmedero]

I was having problems with my nova on the power tour. It turned out to be poor venting on my gas tank. I replaced the venting tube and added a bigger vent. Problem solved.

[Longhorn Man]

there is nothing wrong with the glass ones if you use common sence. Keep up off the engine, have it secured where it won't move and smack something, and make sure it doesn't leak when installing a filter. People are afraid of the glass, but they used glass filters on engines for 50+ years, and even up into the 80's

[epashhans]

Originally Posted by BB72CHEVKT

I also bent the hard line from the carb to get the filter away from the valve cover. I also want to replace the cheap chrome filter with a new one that is see thru. I know not to use the glass ones.Any suggestions?

I have always used the clear plastic ones. Nice to see whats going on in there with fuel flow, if there is a build up of junk, and they are affordable and available everywhere. Longhorn man is right with the glass filter, but in my opinion why bother or take the risk. You never know when mr. murphy and his law might show up.

[FriscoDave]

I was having a similar problem. Turns out my choke was sticking.

[heavy70]

wow is rite! man thats bad

[storm9c1]

Yeah, I bet all of that garbage in there is the root cause of the problem.

I've had similar problems before with old vehicles. My diagnostic procedure has been to put a tee on the fuel line just as it entered the carb and run a 5' piece of rubber fuel line from the tee to a fuel pressure gauge through the window into the cab (of course temporarily). Do a couple of hard accelerations with this setup. In my case, fuel pressure would drop to zero. I knew I had a fuel delivery problem. The root causes ranged from a filter BEFORE the pump (bad), to rust in the tank, to a carb that was too thirsty for the pump (needed a higher volume pump). The temporary gauge was instrumental for diagnostics.

[BB72CHEVKT]

removing the filter has solved the problem