Hot Rods overheating 302

I am stuck and I need a little help. I bought a 1978 ford 302 to put in the 46 Merc I am building. After it was all together, the motor was overheating. Noticed the oil pressure would drop after a few minutes. Checked the bearings and they were shot. In comes a new Jasper 302 long block. Came with heads: gaskets installed correctly. Put everything back together and it still boils over after 15 minutes of run time. Changed the thermostat (spring side towards the block), water pump, bother upper and lower radiator hoses have a spring in them to keep from collapse. I have a Champion aluminum radiator and a Summit 16 inch pusher fan (no clearance for a puller fan or water pump fan) that come on at 160 degrees and I can feel the air flow through the radiator). Radiator has no leaks and I put on a ford radiator cap (champion cap didn't seal tight). It has an overflow tank with a small breather hole in the cap. I have an edelbrock 289 performer intake on the car.

I suspect the motor was an EGR. The intake on the car does not have a rear coolant crossover. Edelbrock does make a 3721 that has a rear coolant crossover.

Why is this overheating? What else can I check? Would the intake make a difference? My mechanics used the intake gaskets that came with the EGR block when they reinstalled the edelbrock 289 performer intake. Could it just be the wrong gaskets for that intake?

Help.......

 

I've never seen an intake or intake gaskets cause over heating unless they were leaking.
Are you driving it or just sitting when it over heats?
And you are sure the head gaskets are correct (openings at the rear, one looks upside down when installed correctly)?

 

Have you checked the radiator? it may be clogged or not big enough to do the job.

The fan may not be moving enough air.

What kind of car have you installed the engine in? HRP

 

What water pump and/or timing chain cover is on it? Did you check that the pump matches the ports in the cover and rotates accordingly? I know you said "302" but 5.0l engines changed rotation when they went serpentine and with the serpentine off you have to know what to look for to tell.

 

302's were bad at trapping air in the cooling system, did you burp the engine after assembly?

 

Why 2 threads on the same subject??????........

 

Maybe it overheated twice?

 

Timing cover / timing pointer / vibration damper timing marks and water pump rotation must all be compatible.

I have the same problem on a 302 built from a mishmash of parts. In my case, I think the timing pointer / damper mismatch is the issue. Engine is on a stand, waiting its turn....

 

Water pump rotation, timing , air lock in cooling system. Not enough air flow . These are a few items to check before you go deeper.

 

Is the rad cap the highest point in the cooling system?
If not then you won’t get all the air out.

I have a 302 powered car and I have to jack the front end up 2’ to get the rad cap high enough, or else I have to fill it through the thermostat housing.


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Make sure that the coolant is circulating through the system when the engine is hot by leaving the rad cap off.

I have had small block Fords for many years, and agree that it is difficult to get the air out. What would always happen when I took a test drive is that the engine would get super hot, then the thermostat would open, and the air would get released. The rad could then be topped up and all would work correctly.

Well I did have one that kept overheating because I forgot to cut coolant passage holes in the gasket I made for the back of the timing cover.

 

So I drove it again tonight. Overheated again. I stopped, left the electric fan running while I took a 5 minute walk to a lake. It was at 220 degrees. When I started it back up, coolant flowed and dropped to 170. Does this mean, fan isn't big enough moving enough air? It seems like fan isnt keeping uo

 

Leaving the fan on is just cooling the water in the radiator. HRP

 

You may also want to verify that your tune-up is correct. Late ignition timing and/or advance mechanisms in the distributor that aren't working properly will cause overheating.

A 1600 CFM fan is kinda on the wimpy side. I'd try one that is somewhere north of 2500 with a good shroud and installed on the back side of the radiator, if you can adjust your radiator to allow for it.

 

Electric fans typically don’t move as much air as mechanical fans.

 

Has to be a pusher. No clearance at all. Summit sells a flex o lite that pushes 3300 cfm. That is my next step. Will check timing too.