Running a Little Bit Hot Tonight!

To quote David Lee Roth from Van Halen's Panama, "We're running a little bit hot tonight."

Pertinent Details:

1. Edelbrock aluminum heads
2. Big 2 core aluminum radiator
3. Same temp sending unit as previous motor
4. 180F thermostat
5. New airtex water pump, looked good
6. No heater, short looped hosed
7. 5W30 break-in oil, good oil pressure
8. 25 miles, 2 hours of total engine time
9. Large 6 balde flex fan and shroud, same as previous motor
10. Good pressure cap

I admit to being a bit paranoid with a new motor and lots of new parts and trying to get it all nailed down and stable. This is not my only problem but I don't believe the others affect this one materially. (stumble - carb, loose rocker)

My old motor was a decent 9:1 455, small valve iron heads, B4B, Comp Cams 268, 160 thermostat, 30 year old leaky water pump, 6 blade big flex fan, shroud and brass 4-core radiator. It ran about half way on the factory temp gauge at the highest.

My new motor is a 462 9.5:1, Edelbrock aluminum heads, Performer, TA 212, 180 thermostat, new water pump, same six blade flex fan & shroud with a brand new aluminum 2-core radiator. It will hit 3/4 on the factory gauge and even a smidgen higher before the thermostat opens and stabilizes at 3/4.

When I shoot the thermostat housing with the infrared thermometer, it shows 200 and the intake behind the thermostat is 210. The radiator cap is good and it did bubble some when I first capped it off but not now. When cool the radiator is full in the neck.

Oddly, the heads at the exhaust ports only read 250-275F while the upper radiator hose at the radiator end is only 135. I'm going to get a regular gauge and plumb it into the stock temp bung so I can see what it is really doing but I'm half afraid of what it will reveal.

I have no heater and have looped the heater hose from intake to front cover. Should I block that to keep hot water from being sucked back into the motor? What's the best way to block off the front cover heater hose nipple?

Do you think my thermostat is wrong or stuck at a higher temp? It will eventually settle at half the gauge after it gets a chance to idle. I can't believe the big old aluminum radiator won't cool this thing! It took about 4 gallons to fill it up!

 

I'll check on those block offs. Can't hurt to block them off can it?

Not sure what would be wrong with the radiator. Thoughts on that? It seems to flow well, no leaks, has the right size inlets and big cores. I do have the old radiator still sitting in the garage. I'm inclined to change the thermostat first though to see where that goes. Easier and same one from the old motor. If that fails I will probably have the old radiator cleaned and checked. It had weak looking seams with green oxidation around the tank edges.

 

What's the status of your vacuum advance? At what driving speed do you see what you think is a hot temp?

 

No vacuum advance for the last 30 years. Something like 14 initial and 34 total at about 2200 is what I'm observing. I had a few degrees more but it rattled when it fell into overdrive/lockup at low cruise so I backed off.

Anything above an idle under load rises well above the half mark. It runs at 3/4 at 40MPH in overdrive and at 3/4 at 40MPH in 3rd. At a stop light it will settle to half in about 3 minutes. That's why I'm going to cap off the heater nipples, it seems like I'd be recirculating the hottest water from the front of the intake right back into the inlet side of the water pump, bypassing the radiator.

It heats up VERY fast, from cold start to .7 of a mile from my drive way it has climbed to half on the temp gauge, which is mostly level and down hill. As soon as I turn at .7 mile to head up hill, it will climb to 3/4 on the gauge and stay there.

 

Update for today. Fixed the rockers with poly locks and moved on to temp issues.

Added in a real gauge with numbers. At 180 (thermostat temp) it shows 1/2 on the factory gauge. It will climb to 220 at a fast idle (1,000 RPM) while adjusting valves. We had an 18" fan going in the garage with the doors open.

Factory gauge shows about 230 to be the top notch.

Not sure what is wrong here. Brand new carquest water pump, brand new aluminum radiator has 2 cores of 1.25", big tanks, factory hose connections, 15lb cap and no trans running through the tank. It is built to be like a 4 core old style radiator. Tig welded all around.

Today I capped off the heater hose nipple on the front cover and use the intake nipple spot for the new temp gauge.

At 220, it is definitely too hot to handle.

Tomorrow, I'm going to pull the thermostat and see how it acts in water on the stove. I'm going to put my old 160 that ran in the previous motor in and see what results that gives.

 

I need a basis for your theory to test. It is a huge radiator, holds a lot of water and has big tubes and factory style in/out. Shooting the tanks with my thermal gun shows they are a lot cooler than the motor or the outbound radiator hose.

I can put the old brass one back in but it seems like a fine radiator with more capacity than the old one.

I'm going to try the thermostat first since I don't have to drain the whole thing.

 

This is the radiator: http://www.ebay.com/itm/1971-1974-C...rican-Eagle-/141622045655?hash=item20f954ebd7

If I can see into the radiator and see the fluid running out of the cores, when I look down the neck, it is flowing as well or better than the old brass one.

I don't care what country it came from, it is a solid piece with very nice welds.

A radiator is a very simple piece. It would take a lot to screw it up to the point it wouldn't cool a mild aluminum headed 462.

 

2 core radiator seems a bit small for a big block. My 3 core has a tough time staying under 200 on a 95-100 degree day.

 

How about a picture of your flex fan and shroud? From your link, it looks like the tanks are epoxied on to the core. Big flag right there.

 

If it runs warm at highway speeds and cools down at slow speeds and idle, that points to efficiency (or possibly timing/advance). My stockish 455 did that with the original '68 radiator. Put in a parts store 3 row aluminum and problem solved. Another thought is the water pump--if its impeller isn't the same size and fin setup as stock (a generic 'close enough' or just plain wrong) it may not be moving the coolant fast enough at cruise rpm. Airtex quality isn't what it could be. But hey they paid the money to be a NASCAR licensee, they must be good, right?
Patrick

 

It shows no epoxy any where. It overheats during all conditions. It will idle and overheat and it will cruise and overheat. If I let it run downhill in overdrive it will cool down to about 180.

I'm using the same large flex fan as I did with the old motor. It is the same size as a clutch fan without the clutch.

I'm going to try the old thermostat and seeing what that does.

 

The way I have my EFI programmed during warm up, which is to get it up to operating temperature as fast as I can, it climbs 0.50-.75 degree's per second. That is running a ~13.5 AFR and between 5-10 more advance over normal. By about a mile from my house I have good heater use and another mile later its usually at thermostat temp, and this is when morning temps are in the 20's and 30's. Mornings like today where it was 65F, its practically at operating temperature before I hit the end of the block (conversely, my 2014 Silverado is about the same rate). And obviously, the harder you run the engine while cold, the faster it'll warm up, I just meander up the street at 25mph and up to 35mph a 1/4 mile later.

With the carb stumble, I'd be looking at the fuel side. Running overly rich won't be doing you any favors in the cooling department.

On average, a 1" aluminum tube should cool to the equivalent of a 3-row brass radiator. So a pair of 1" tubes should be equivalent to an unobtainum 6-row brass radiator. It just has better cooling potential than any brass radiator on the market. Personally I've never had issue cooling with a 4-core brass radiator, and my Centurion still has one, but they are getting harder to find and if the one goes out in my Centurion, it'll get a 2-row aluminum one.