I have not tryed the infrared reader just yet as I dont have one.... I will run down today and see if I can pick one up.... thanks for all the help guys.... I was realy hoping that someone was going to have an awnswer that I had not allready investigated... The bottom line is that I do know how to diagnose and I do know my way around this engine, it is just down right frustrating that I know 90% of the time it is something simple right under your nose.... It doesnt apear that this is the case this time.....

BZZZZZT, wrong answer. 5 psi max...5 psi max...5 psi max.
You have to understand that any more pressure than this will over-power the needle and seat, resulting in blowing fuel into the motor from the over-full float wells. MORE PRESSURE WILL NOT MAKE MORE HORSEPOWER. It will only introduce tuning problems into the equation. Volume is more important than pressure in a carbureted system. 3/8" lines for a daily driver, 1/2" lines for a street/strip car. 5 psi max...5 psi max...5 psi max...5 PSI MAX !!!!!!!!!!!!!!!

There's the kicker. I am sorry that someone has not had an immediate solution for you. Did you call GM ?

By junk in the block I meant casting sand from the foundry. It has been discovered by some in the past that this casting sand was not totally removed prior to assembling a new engine = coolant circulation restriction. I have not personally encountered this situation.

Here are two more down-to-the-wire really off the wall possibilities that I would try on one of mine if I put the radiator cap on and it overheated.

1. Disconnect heater hoses and cap them off. I use 1/2 inch copper tubing with a cap soldered on the end and a hose clamp. Take a funnel and fill both hoses. Water pump or lowest connection first.

2. Cold engine. Chock the rear and jack the front as high as I possibly can and still maintain alll safety precautions. Lower vehicle. Uncap and check the heater hose at the highest connection(intake manifold). If it's not full to the top like you left it then you are making progress in the right direction.


Posting the solution when you find it will help others in your same situation.


Happy 4th
Enjoy

This is going to sound like a stupid question but it’s important to know the answer to help solve your problem. Are you running hydraulic lifters?

yes when I finaly find the cause I will post so that it may help someone down the line....Thanks for your thoughts on sand in the block.. Does anyone have ideas on how to flow check the block?

I have no idea if you were answering my question or somebody else’s.

If you were answering yes to hydraulic lifters then that may be your problem. They may not be adjusted properly causing your engine to overheat.

To correct this, pull your valve covers and disconnect coil wire. Turn engine by hand on each cylinder individually until both intake and exhaust valves are closed fully. Back off the bolts on each rocker. Then by hand tighten until snug. Then use wrench one full turn on each only. See if your overheating problems go away after assembling parts removed.

I’ve had 2 jobs come to me with similar overheating problems last week and that was the cure.

You need more timing.

I don't care what summit says.

Smogger 350 heads need timing. They are covering their butts with very low timing recommendations.

But suit yourself. You can lend a horse to water but you can't make it drink.

I'm running almost 30 at idle (mech plus vac) with a very mild big block, 3.08 gears, and stock converter in a 4500 pound truck. Runs great.

I am running a 383 lift hyd. cam and I have not adjusted the valves as this was a built long block shipped ready to fire and run.... You may be on to something here with them being to tight.... It has been my experience that when you have them to tight it will cause the engine to run poor and this just simply isnt the case... This thing runs like a top..... As for the timing I could bump it up a little more and see if this helps keep it cool but its not a heavy super cam in this engine..... I am fairly sure that running it at 32 degrees of total mechanical then another 8 degrees of vacume is just fine...

I may be wrong but It seams like I am not getting enough fuel with 5psi..... I have had a couple people tell me that a mechanical pump should not be able to overpower the needle and seats on this carb.... I am wondering if maybe I have something wrong with the carb.... I do have a holly pressure regulator on it and set at 5psi but then when I open her up and let her drink the pressure drops down 2-3 psi.... I have just a single in single out pump and it is pulling fuel through an electric pump in the tank.... could this electric pump in the tank not let the fuel go back into the tank be causing me problems? I am not sure how the mechanical pump works when you shut it off if it is supposed to blead back to the tank or hold pressure in the line?? This is where the problem starts is when you turn the engine off it starts dripping fuel out on the the intake from the shaft that upens the secondaries..... This was cured by the holly regulator.... But like I said I am not sure that I should need a regulator with a mechanical pump that is rated from 5.5-6.5 psi.... I would realy love to get to the bottom of all of this... I am greatfull for all of the help I am getting with this build....

another thing that I have noticed with this build is the more timing I give it the more cold blooded it gets.... I cant even stick it in gear untill it warms up or it starts spitting and popping with a load until its warmed up..... It has a realy tall gear ratio though... I have 4:11 gears with 39.5 tires and a th350 transmission.... Once the engine is warmed up it runs great but not when its cold....

Actually running poor was not the case with the two cars I worked on. Both were performing pretty well on the street. They adjusted them up higher in an attempt to gain higher lift. More or less experimenting trying to reinvent the wheel on the cheap. In addition, both have stage two cams and weren’t getting that rumble at idle that they wanted to hear because of the hydraulic lifters.

That sounds real close to what these guys were complaining about until the engine warmed up.

I will have to try adjusting the valves today.... But on another note I just pulled some random plugs to have a look.... it apears to be a little on the lean side by reading the plugs.... I do have a slight hint of tan but I am not sure about the A/F at this point.... I had a little bit of oil on the plugs as well I am not to concerned with this as the rings have not had time to seat as i cant keep it cooled off long enough to run it...

after playing with this thing today I decided to try and burb the system again and fired it up with the front end jacked way up in the air... it did the same thing as it had in the past running about 1500rpm it started heating the coolant in the radiator before the it even reached a temp where the thermostat would open.... once the thermostat opened alot of tiny bubbles emerge at the mouth of the radiator.... like salt in your beer makes.... I realized that the times I had done this before the heater was on and so I kicked the heater off..... This sure made it heat up to 200 alot quicker.... I added an overflow and hose to the setup today and am hoping that this will force it to burp or not let it suck air back in at the least.... So my original post saying that the with the cap off the radiator it doesnt heat up was in correct.... I think it was just taking longer because the heater was running....

All this time I had assumed you already purged any air out of the system.