Overheating on Hwy 350 SBC

[JPMSK5]

Ok, i found the piston info i need. With a 72cc head chamber volume, .041" compressed head gasket thickness, -3.5cc piston dome volume, assuming .020" deck height, with a bore of 4.030" you're looking at 9.89:1 compressio ratio. That is too much compression for an iron headed engine in a 6000lb truck. Also, unless you have a cam with alot of valve overlap that engine is going to ping badly on the upper RPM's probably anything over about 4500 or so. If you do have a cam with lots of overlap then it's the wrong cam to be using for a truck engine expecting to make torque down low.

Ok, I think you are right on the money, the cam is a RPM Edenbrock cam, dont know the overlap, only ping the engine has had is timing problem, never heard or noticed ping at any other time.
So what is your advice, alum heads, deeper gears, to get into higher rpms?
I have got a dist I am putting in tonight I hope if it gets below a 100 outside sometime today.

 

[4X4HIGH]

Ok, I think you are right on the money, the cam is a RPM Edenbrock cam, dont know the overlap, only ping the engine has had is timing problem, never heard or noticed ping at any other time.
So what is your advice, alum heads, deeper gears, to get into higher rpms?
I have got a dist I am putting in tonight I hope if it gets below a 100 outside sometime today.

It's hard to give advice without knowing what your intentions are for this vehicle. Are you looking for top end HP or low end Torque? Camshaft and heads are going to determine where you go with this.

 

[Mike D]

After reading several pages of CK5 responces, one thing that wasn't mentioned was the mechanical fuel pump. As you know a mechanical fuel pump generates its highest pressures at idle. As the RPM increases the fuel pressure decreases until it barely meets the engine requirements. Therefore your poor throttle response could be inadequate fuel pressure ( and volume ) at highway speed. Inadequate fuel volume could result in a lean(er) A/F ratio causing higher engine temperatures. Many responders mentioned timing, fan and radiator as areas to investigate. All good ideas.
Since this is a racing engine, perhaps it shoud be plummed with 1/2 " fuel line to a high volume electric fuel pump. A high quality adjustable pressure regulator shoud be used maintain 6 psi fuel through an insulated 1/2" line to the carb. I would also use a good ( Holly ) 1/2" insulator between the carb and the manifold ( this should keep the fuel from perculating in the carb ). Use a 3/8" line to return excess fuel from the regulator back to the tank.

 

[JPMSK5]

It's hard to give advice without knowing what your intentions are for this vehicle. Are you looking for top end HP or low end Torque? Camshaft and heads are going to determine where you go with this.

well somewhere in the middle would be nice, that was my plan to begin with, I have been around several engines that had 9.5:1CR with the RPM kit, heads, intake, carb, cam, timing chain, and had awesome results in trucks, I was orginaly trying to do this but I knew I had to have larger cc heads and I felt the heads I got was comparable to flow with runners and valves to the alum. Edelbrocks. Never thought about the material of the heads.

 

[dyeager535]

I would think (someone correct me if wrong) that if it were lean enough to cause serious overheating, heavy pinging followed shortly by carnage would be evident.

Certainly not saying it can't be lean, but engine destruction is the reason you don't want it running lean in the first place.

 

[JPMSK5]

it dropped to 98.9 outside so I put in the dist., huge difference, 10 times the bottom end, and it seems the trans that was suppose to be built up, has came to life, its a little hard to explain, I even doubled checked the TV cable in case I hit it or something putting in the dist., but its got crisper shifts, and holds a higher rpm before it shifts to the next gear holding it WO. gained some vacuum cursing, so maybe I am heading in the right direction, still need to fatten up the carb and see what that does.
back to the heating problem, it still has that but doesnt loose power now, its still got go when getting hot now.

 

[Mountain_man]

Yay I was partially right! lol Fatten up the carb and see but.. if you're overheating still then well... Keep on the motor end of things.

 

[JPMSK5]

Yay I was partially right! lol Fatten up the carb and see but.. if you're overheating still then well... Keep on the motor end of things.

4x4High is on to something maybe with the heads, still waiting to see what his opinion is. The same problem though with heads is you cant find large camber heads very easy.

Speaking of hot, I seen a BB in an RV that runs cool and the exhaust manifolds glow red I dont know how that works but several RV mechanics told me thats just the way it is.

 

[4X4HIGH]

You can buy heads with a chamber larger than 72cc's. For instance i just re-calculated with a 76cc head and CR would be 9.374:1 much more acceptable for an iron head in a 6000lb rig.

 

[JPMSK5]

its running at 195 now. needs more tweaking but its helped alot.

 

[kgblazerfive]

Am I reading correctly that you have a pusher fan and a flex fan ?

If so get rid of your pusher fan it is blocking the air coming into your radiator.

At around 40 mph more air will flow through your radiator, as long as it can, then your flex fan or any other fan can pull. It will also take the path of least resistantance so make sure that it is sealed to the radiator support because the air will go around it before it goess through it.

Pm me for my address for the reward money

I had a V8 Astro with a three core radiator, stewert pump, high flow stat, and coated headers it ran so cool that in the winter in AZ I had to put a winter cover on it to get it to get to 180"

 

[JPMSK5]

alright, other than the compression deal, I got a good dist in it and fatten the carb up alittle and I havent seen it go over 195 with the 180 deg thermostate, so that is probably pretty close to being right. Its seems now to drink the gas although, and I think I have more engine than trans., but I had never been impressed with that trans anyway, you get what you pay for. I want to try 33's, or just through in some 4.56 gears in the back and see how it acts.