First off, I have a '86 F-150 with a 351w, an Edelbrock 1406 carb, mechanical fuel pump, Weiand Stealth intake.

When the truck sits for a couple of days, it takes a lot of cranking and pumping to get it going (once started, it runs great). If it sits for just a couple of hours since last run, it starts right away.

Could it be the fuel pump letting the gas siphon back? Do the pumps have a check valve in them? It's kind of embarrassing cranking on it that long.

If I remember right, it got a new pump a couple years ago, maybe a bad one?

Another question, what can I do to keep more heat out of the carb? I get a little vapor lock when the engines real hot.

 

I will bet you this is your problem, all the gas in the bowl is evaporating.

The carb on my 400 used to get so hot I could hear the gas boiling, and there were little wisps of white "smoke" coming from the "smokestack" (breather) on top.

I got one of these, a wooden carb spacer, to keep the heat away.

 

ctubutis - What you are saying sounds like what my problem is.

I'm going to ramble a bit here.
This is the spacer that's on it right now - 1"

I don't remember what center is in it though.
The problem got better when I installed this, compared to the all aluminum one. I also re-routed the fuel line from the pump to the carb. to give it a little more "air".

Here's kind of a comparison - On the '83 I had, basically the same engine, same carb, 4spd. I had a 3 row copper/brass radiator in it. The gauge almost never went over 1/4 way up. Right now on the '86, it has a one row aluminum/plastic, the temp is always at or just above 1/2. This always concerned me as it seemed to run too hot like the radiator could barely keep up, but never over heated.

I have from the '81 a 4-row, extra cooling size, brass/copper unit I've been debating putting in.(Cost me $300 to get built so might as well use it) I would just have to put some holes in the core support for the lower mounts and use the older top mounts ( I saw it done on a truck in the junk yard and everything fit nicely). Also have a nice set of electric fans to use.

If I could keep the engine temps down more, this may also help with the fuel issue? I'll look into the wood and phenolic spacers and pick one up too.

 

I wouldn't at all trust a factory temperature gauge, wouldn't make decisions based on what it was telling me.

How many degrees is "O"?

 

I hear what you're saying. I do have an Autometer gauge here also I could hook up and take it for a "typical" drive and see just where it's at. I'll do that first.

I do need to do something about the radiator that's in there though. It has a small leak (stupid o-rings) when it warms up, but when hot, no leaks.

 

Gary knows what all of the letters represent as far as temps go.

 

Did a little test. I hooked up the Autometer gauge and did some running around.
Results:

Outside air temp - 45 degrees, approx. 20-25 minutes (not much traffic)

After about a 5 minute warm-up
Sensor located in intake right by the thermostat (output to rad.).

Right after about 12-13 miles on the highway



After 10-12 miles through town



After idling for 10 minutes


After 10 minutes of heat soak


So, now I know actual temps (and truck gauge positions at given temps), it gives me a little different perspective. When first on the highway, it did peak to about 205 degrees, but as soon as the thermostat opened, dropped down to 180-185. Once the cooling system was fully up to temp, it never went above 200 degrees. Even after heat soak, I still wasn't seeing temps I thought I would.

I would like to repeat the same test when air temps are 70+ degrees, just to see what happens.

So, the radiator is keeping up with the heat. Yeah, yeah, I was wrong. I'll admit it.

Besides the different carb spacer, what else can I do to keep the heat off the carb?

 

What engine?

 

It's got a 351w.