gschaerer

We have a 327 SBC (overbore .030) , no Ac, PS, or PB, in our '66 convertible. The entire car has been rebuild/restored to include the engine. We are having problems with overheating in traffic. Everything is standard 327 with a Crane bluprinted "151 cam. Holley generic aftermarket carb (~650 cfm). All pulleys are original stock ones.

The entire cooling system is new to include new DeWitts radiator, surge tank, heater core, hoses, 180* "fail open thermostat. The distributor is set to 10 degrees static advance with a Petronix II setup to include flamethrower coil. We are using the original, non modified, shroud and stock cooling fan and fan clutch. Fan is half in and half out of the shroud. The temps creep up to 220+* in traffic and has overtempted once (shut off immediately) and resulted in puking all over the place. Runs at 180* on highway. Coolant is 50-50 Prestone.

We know something is wrong. Until tis is resolved, we do not drive it in Northern Virginia (Fairfax) traffic, only on clear roads/interstate. I suspect it might be the water pump but am not sure.

Is there any difference in the water pump (form, fit, function) between a 300 HP base engine and this, essentially, L79. I so, what are the differences as to front to back dimension and water flow rate, etc.? What are the part numbers for both pumps, if there is any difference.

We and the restorer are tearing out our hair on this. Please help us out with answering above questions.

BarryK

generally speaking, most low-speed or idle speed cooling system issues are caused by bad airflow (typically the fanclutch) or incorrect ignition timing.

1. double check operation of your fan clutch. Get motor up to operating temp and turn off motor while you watch your fan. If the fan stops rotating withing 1-3 revolutions the fanclutch is good. If it takes significantly longer to stop turning or it just freespins than the clutch is bad.

2. double check your timing. You say your timing is at 10º initial timing - so you have vacuum advance connected and is it hooked up to a manifold vacuum source (not ported vacuum) and are you getting the ful level of vacuum advance you should be - usually an additional 15-16º over your initial timing so that at idle with the vacuum advance connected your timing should really be reading 25-26º.

The fact that is runs at good operating temps on the highway tells us your new radiator is fine and coolant flow thru the waterpump, hoses, t-stat, etc is all good.

knight37128

What's your timing?

MikeM

Forget the timing. If everthing else is new, 10* initital timing with no vac advance will not cause overheating.

You fan at idle won't blow enough air to take your hat off but it should move quite a little bit of air. I really don't know how to quantify it but I'd be looking at the fan clutch.

Forget the water pump too. Functionally, all first generation SBC water pumps are the same.

Dream*66*

I do NOT use a fan clutch.I take that out of the equation. 7 blade fan, extender to get it 1/2 in 1/2 out but pulls continuously. Not in the least bit worried about loss of HP. I drive it, not for judging. Could not be more satisfied with that setup. I can hold my hand on the bottom front of Rad, running, and feel the cool of the metal! My 2 cents! TC

bonehead2

It is not your pump, I believe you may have an engine problem. Is it a brand new build?.Idleing, how fast does it up come up to over temperature say just sitting in your driveway?. You probably know where I'm going with this.

65 vette dude

I agree with BarryK. I had the same problem, and it turned out to be a bad fan clutch. There was a interesting thread in the last few days by Salty Waders, on how to adjust the fan clutch spring so that it will engage the fan at a lower temperature. Of course this won't help if the clutch is bad to start with. I bought a new one from the Parts Ladi for 95 dollars. Its made by Eaton who was a original supplier,and its almost exactly like the original fan clutch.