66' Fairlane 429 cooling problem

I posted this earlier, but for some reason it's not on here. So, if it shows up twice, sorry about that.

I have a 66' with a 68' 429 and C6. Keeping it cool is about to drive me crazy. It is a stock 429, stock water pump, 160 thermostat, Griffin Aluminum radiator (P/N-1-26222-x), a mechanical 17" fan, and a shroud I fabed up this weekend. Driving down the road it runs a cool 170, but as soon as I stop and let it idle, it will heat up over 195. I have tried a 16" electric fan, 2 10" Spal electric fans and now the mechanical fan and still have the same problem. Is it me or is everything pointing to the radiator being the problem? I had a 428 in the car before the 429 and had the same problem. The engine had a 180 thermostat in it when I purchased it and it also ran hot. I have tried taking the thermostat out and even cutting the center out of the thermostat, thinking it might be a flow problem. But got the same results. I have almost made up my mind that the radiator is the problem, but I wanted to see what someone else thought before I go out and buy another radiator and not fix the problem. Any suggestions?

Bryan

Hiya bwebb, I was wondering do you have anything mounted in front of the radiator like maybe a condenser or tranny cooler? I'm also wondering about that radiator....is it the same one you had mounted in there with the 428? If it's the same radiator then I'd say you need it checked out. I'm not familiar with the specs on that radiator but is it close to stock size for that engine? If the radiator checks out fine then I'd say it's the pump....get a high volume one for sure. I know not running a thermostat isn't good so I'd stick the 160 back in. Have you pressure checked the system?
One more thing....has that 429 been bored out?

Hiya bwebb, I was wondering do you have anything mounted in front of the radiator like maybe a condenser or tranny cooler? I'm also wondering about that radiator....is it the same one you had mounted in there with the 428? If it's the same radiator then I'd say you need it checked out. I'm not familiar with the specs on that radiator but is it close to stock size for that engine? If the radiator checks out fine then I'd say it's the pump....get a high volume one for sure. I know not running a thermostat isn't good so I'd stick the 160 back in. Have you pressure checked the system?
One more thing....has that 429 been bored out?


I do have a tranny cooler mounted to the front of the radiator. Yes the radiator is the same one I had with the 428. I put the radiator brand new in the car when I built the 428 and had this same problem. This is why I think the radiator isn't big enough or there are so many fins on the radiator that it will not allow enough air through at idle. I did notice that it says my radiator is a "Circle Track Radiator". So, I'm guessing the fin count is higher per inch than a street radiator. I have not pressure checked the system. If I did have leaks, wouldn't I see water leaking, or water in the oil? I have seen none of this. I only took the thermostat out for a short idle session in the driveway and learned that flow wasn't the problem. I have had the 160 in it every since. As far as I know, the 429 has not been bored. From what I can tell, the bottom end is all stock. I haven't removed the cylinder heads to look at the top of the pistons though.

Thanks for your response! I was starting to wonder if anyone was going to reply at all!
I am open to all suggestions with this problem.

Do you have both the hood to cowl seal, as well as the hood to rad. support seal on your car. They do alot to promot flow through the radiator, and not through the other open areas. I don't think this would cause as extreme as a problem as your having, but it might be a good place to start.

Also, are you running a fan shroud with the mechanical fan? They are very important at promoting flow through the radiator. A semi-decent way to see if you're pulling enough air is to put a piece of paper infront of the radiator. If it falls, you're not pulling enough air through the radiator.

One last thought, what is your base timing set at?

I can't remember what my base timing is. I set the timing with a vacuum gauge and if I recall it was between 16 and 17 in. I made a shroud this past week and installed but did not solve the problem. Although it did seem to slow it down from heating up as fast, but eventually did overheat. I do not have the seals along the radiator support to hood. I am running an Imperial 17" flex fan. Are the 385 series engines known for overheating or am I the only one with the problem? It feels like it's pulling quiet a bit of air through the radiator, but I don't think it's enough to hold a sheet of paper to it.

The response is much appreciated!

bwebb, Have you called Griffin and asked them if that radiator you have is right for your application? Might shed some light on the problem.

No but I will do that right now. I think I'm affraid of what they will tell me; "wrong radiator". That just means more money! Great!!

Alright I just got off the phone with Griffin. According to the tech guy, if your engine stays cool while driving down the road but heats up while sitting traffic, then your radiator is NOT the problem and start looking somewhere else. If it heats up while driving down the road and stays cool while in traffic, your radiator is the problem.
According to Griffin, this radiator (P/N 1-26222-X) is suitable for the street as well as "circle track". Although he did say it is slightly small for a big block but should do ok. He seems to think I have a water flow problem, or I'm not moving enough air through the radiator while idling. I will have to measure my crank pulley and water pump pulley to see what ratio I have. Griffin told me that the water pump pulley shoud be 30-35% smaller than the crank pulley for proper water flow at idle. I was real impressed with the support Griffin gave me over the phone. The guy I spoke with's name is Benji. If anyone needs tech support from Griffin, I would talk to this guy. Very informative!

I would look at air flow as the problem. If it cools when you are moving then the radiator is adequate.

When it is idling where does the hot air go? Make sure you have the proper baffles to prevent hot air from recirculating through the radiator. Seal between the core support and grill so air can't flow back from the engine compartment.

When it's idling, I can definetaly feel some hot air coming between the hood and the radiator support, but I don't think it's enough to make the engine run hot. I checked my pulleys last night and the water pump is 5 11/16" and the crank pulley is 7". The ratio is off slightly but not terribly bad. According to Griffin's preferred ratio, the water pump pulley should be between 4.5" to 5". I am affraid that finding a pulley that is 4.5" is going to be a tough job. I think I will install my electric fan in conjuction with the mechanical fan and see how that does before I go hunting another pulley.