Hello. I have a 65 GS Skylark with the 401. When I got it 9 years ago the engine was screwed. We had it rebuilt. It was already done once according to the rebuilder. We had to bore it .060 over. Could this be the problem. It is under control with an added electic fan. It runs 220 in any weather. We have checked EVERYTHING. Well as far as I know. Any suggestions would be appreciated. John
Does the fan have a fan clutch? Ever replace it? If not, replace it. What temperature thermostat do you use? Make sure it is not installed upside down. (Don't laugh. Happens more often than you think.) Does the waterpump impeller have 3 blades or 5? Does the car have A/C? How old is the radiator? How many rows of tubes does it have? Might just need a new one. if so, get 4 rows of tubes in core. Jim
1. check water pump 2. do you have a shroud, i had a finger protector and replace with shroud from postons. made a difference. 3. check radiator and thermostat 4. do you mean every thing is fine with the elec fan as a boost. if so i bet it is the shroud and maybe water pump. or fan clutch.
Hi Guys . Like I said, I have tried everything I can think of. The car has no AC so no clutch fan. There was no shroud so I got a similar one to fit and no difference. I just recently put a NOS 3 blade impeller waterpump(GM) in where a 5 blade was. No diference. Tried 160 180 195 stats. The 180 works the best and is in correctly. The timing is correct. I could go on to tell you numerous other things I have tried with no luck I had the rad recored to 4 rows 2 years ago. No difference. The car had no stat in when I got it so I believe the problem has been around for a while. Could there be a blockage in the block? I`m sure this would have been dealt with when it was rebuilt. Still need some ideas. John
i am like Scott, I would be suspicious of the gage itself. All of the changes that you made in the past , some of them should have made it read a different temp. Have you checked for combustion gas in the cooling system???????? Rad shops have a sniffer that will do this and is usually cheap. Nail heads DO NOT run any hotter than any other engine. even running hot from too much overbore can be solved by increasing radiator size and capacity. You did all this and there was no change in the reading??????? Suspect the gage.
Last year we rebuilt the 425 in my 64 cat. The engine started running hot, we replaced the radiator with a custom made aluminum unit, still no change, new water pump, heavy duty fan clutch, radiator fan shroud , no change it still over heated. I called Carmine Faso, and we went over the engine piece by piece. Turns out, when we re-assemble the engine we used a fan spacer that was too short and the fan wasnt close enough to the radiator. We switched it for the extended version, dropped in a new thermostat of 180 degrees, and I havent had the problem since. Carmine told me the fan must be within a fingers distance to the radiator, and mine was way too far back for that 4 blade fan to do much good.
A friend of mine did a 0.060 overbore in his '65 Riviera. It's run hotter, but never dangerously hot since he did this. The water pumps you're refering to, are they new or rebuilt. LOTS of rebuilders will clean up the impellers on the old pump to make them look good. They grind away the corroded parts of the impellers making them much smaller; then there is too much clearance between the face of the block and the impellers. The impellers will just cavitate the water and not move it. Look for a new pump if you're using rebuilt ones. Shrouds were only OEM on a/c cars. The a/c cars had 5 blade impellers whereas the non a/c cars had 3 impellers. Ed
Not sure I follow Mark's post. Generally, you want the blades of the fan half in and out of the shroud opening and the 4 blade fan is for the the non A/C and non-shroud. But, yes-otherwise the fan does need to be close to the radiator
You definitly need a 7 blade fan and either /or 3/4'' from the rad or with a shroud that covers 360 deg. and a 7 blade fan into the shroud by 3/4 of its depth. [the fan not the shroud] The other alternative is a high cap electric fan and shroud. One like is on the factory air Lincoln mkv. 2500 cfm. Once you get above 35 or so mph the fan doesnt help much, forward motion supplies the needed air flow. below that is where it is critical. That is why flex fans are nice.
What are you guys running at temp wise? Mine ALWAYS runs at 210-220*. The motor was rebuilt and the radiator recored about 10 years ago. There's about 10-15k on the rebuilt components and the heater core has been bypassed. I was going to put in a universal aluminum radiator w/electric fan from Summit this spring but I've gotta redo the exhaust and put a new carb on first. Probably won't have enough cash left to do the radiator.
Dan, On my 64, it is a non a/c car. Therefore there was no fan shroud, and I had a 4 blade fan. In my case the fan sat too far back from the radiator to do any good at all. I had grabbed the wrong size spacer when we put the fan back on the engine. I have since added a shroud over the radiator, and moved the fan closer to the radiator to let it pull air better. Now I dont have the over heating problem I did have. I could let mine idle for 10 minutes and it would boil over, now, cool as the underside of the pillow
If the engine doesn't idle and cruise at or near the temp of the thermostat, something is probably wrong. The tricky part is figuring out what things--and how many--are wrong. rapid acceleration, trailer towing, or other heavy throttle use can cause even a good cooling system to increase temperature. In general; overheating while parked or at low speed is an airflow issue, while overheating on the highway is a coolant flow issue. There can be exceptions. Lean fuel mixture, too-tight piston-to-cylinder clearance, and retarded ignition timing including a non-functioning vacuum advance also can cause overheating without being part of the cooling system.
Hi Guys. Thanks for all the input. As for the heater core it was replaced with new a few years ago. The gauges that were in the car when I got it have been replaced with new. Everything reads the same. The fan spacer is the correct one. Has the part # on it and the fan is 1 inch max from the rad. I tried a flex fan a couple of years ago. Same. The temp seems the same when idling and accelerating. John
I replaced the waterpump from a 5 blade to a 3 blade GM NOS recently. We even changed the timing cover with a good used one as someone had repaired the old one. Looked like a waterpump blade had come loose and damaged. Still the same. John
on a hot humid july day in ohio, while stopped in traffic with the air on, my nail will go to 210. it cruises at 185 to 190 at the most hot days.
A nail was designed to run at 165 to 180 deg. 200 was ''warm'' 220 was ''hot''. Shut down was 225 deg.
Timing? The nailhead was timed at 2 1/2* BTDC, and used manifold vacuum to the vacuum advance so that it idled at about 18* BTDC. If you use ported vacuum, the engine will run hot at idle in traffic. Make sure the mechanical advance is operating correctly.
Could the fan and fan clutch from an A/C car be used on a non A/C car without having to convert anything? Would there be adequate spacing? I'm just thinking I'd like to do this to my '63 Rivi 401 just to gain a little power.
