I was given a rebuilt and run 318 that was bored 060. I freshened the motor up with new rings, bearings, cam, bowl ported #302 heads bigger valves etc. Nothing radical 9:1 CR, mopar .455 lift flat tappet cam. yadda yadda.

Put it into my 66 dart with a recored high efficiency 2 row 22" radiator, stock shroud, 7 blade thermal clutch fan, 8 blade water pump with an anti-cavitation plate on it. Car runs about 220F in 70-80 degree weather, idling or cruising. base timing is set at 12 * BTDC. Using an old 625 AFB thats in good condition. About 4 hours running time on the motor at this point.

I am beginning to think that the cylinder walls are causing my heating issue.

Anyone dealt with this problem before ?

Yep, I'm dealing with the exact same thing at the moment. I have it narrowed down to what I think is the same thing you are dealing with. I am going to try advancing the timing to 18 before. Stumpy has had good results lowering his temps 10 degrees by doing a 2 degree advance on his motor.

If I find anything out I will PM you.

Only having a 2 core radiator might be more of an issue to consider as well..

thermostat OK

Thanks for the replies.

Let me know if advancing the initial timing helps. I've tried this with limited results.

Last nite I set the initial at about 15* BTDC and it might be better, but I havent driven it to test.

I checked the input and output temps on the radiator using an infrared digital thermometer - its 220 at the top of the radiator and around 155 or 160 at the bottom. So the radiator is working.

Robertshaw 180 thermostat checked on the stove with water and a mercury thermometer - it opens as it should at 180.

I've been toying with the idea of getting an Aluminum radiator but dont want to spend the $ if this wont correct it.

Anybody tried an AL radiator in this kind of situation ?

What kind of temps does it run at 30-60 mph ? ... have you ever considered a high-output puller electric fan ?

With thin cyl walls ..I would be equally concerned with the possibility of not-so-good sealing piston rings.

At 30-60 Mph it runs at 220F.

Im not too concerned about ring seal, it makes plenty of power, it scoots real well when you get on it!

I talked with the radiator shop this morning, and described the entire situation. He says the outlet water temp should be okay - cool enough to keep the engine in line, and thinks the thin cyl walls are the issue. He recommended driving it as is and letting it break in more. I asked him about another radiator or going to a higher row content. He didnt think that would help. Which leads me to believe he is reliable and not lying to try and sell more product.

Im going to try talking with some outfits making Al radiators and see what they have to say about this whole situation.

Meanwhile please feel free to add comments or ideas to try.

I'd really like to hear from someone who has solved a similar problem !

the thin cylinder walls aren't helping but whats the build ? if its not a 500HP monster then it shouldn't be transferring that much heat .

whats the oil temp and whats the exh temp look like ?

I'm just saying here but if a bigger radiator wouldnt help then why dont we all run single core 18" slant six radiators?

Get an aluminum radiator.

Same amount of heat is being generated by a .030 engine or a .060 engine. I don't see how an extra .015 off the cylinder wall thickness can add up to very much.

I had a 350 chevy in my truck that I thought was .060 over. It ran hot. When I finally retired it for the 400 I pulled the heads off the 350 and it was only .030 over. I blame the stock style water pump I ran on it.

I would look at your jetting or maybe a bigger/thicker radiator.

I know a guy who has a built 408 in a 65 b-cuda and it runs very cool with the stock 273 radiator, no shroud, and a small flex fan a mile from the radiator.

Anyway to tes the fan clutch maybe it is looking at a higher temp. Also what about the heater core could be clog. Last did the machine shop get all the crud out of the motor sometimes you have to really clean out the coolant passages boiling doesn't get it all out.

Thanks for the replies !

The build is pretty tame. 60 over 318, purple shaft .455 lift cam (268/272) grind. 9:1 compression, shortie headers, #302 (late closed chamber) casting heads pocket ported, 1.88/1.60 valves, single plane 273 4 bbl intake, 8 blade water pump, impeller is 4 3/8 diameter, with an anti cavitation plate on it. Probably 300-350 hp. Running a stock shroud on the stock high efficiency brass/copper 2 row recored radiator, 7 blade 17 inch fan, new thermal clutch, heater core is new. hoses are new. 180 robertshaw thermostat. Nothing adds up at this point.

When I built the motor I put the freeze plugs in it and flushed the jackets. Motor was hot tanked in a caustic water hot tank.

Keep em coming.

I'll measure the exhaust temp this evening. I assume the tailpipe temp is what would be suggested ?

I am not sure how to measure the oil temp. Maybe point the infrared thermometer at the oil filter ??

no temp at the manifold just off the heads , check all cylinders .

Spring in the lower radiator hose in place?

I'm at 200 top and 190 bottom, looks like my radi. might need some rodding.........