karista

I am looking to restore my original 63 Fan Clutch. Any recommended shops that do these restorations??
Also, I bought a after market fan clutch, for temporary use, my SB engine is running hot (220) at 3500 rpm cruising speeds. How are fan clutches checked to see whether they are functioning correctly?

JohnZ

Fred Oliva rebuilds Eaton and Schwitzer OEM fan clutches, but he's swamped right now and turnaround is about six months. There's no precise test for thermo-modulated fan clutches, but it's generally accepted that when you shut off an engine at full operating temperature, the fan clutch shouldn't make more than three revolutions or so before it stops if it's still in spec.

Suggest you order a GM #3916141 clutch - it's the Eaton replacement, and is nearly identical in appearance to the original; GMPartsDirect.com has them for about $120 (GM list is around $180).

If you're running 220* at 3500 cruise (have you checked your gauge accuracy with an I.R. gun?), that has nothing to do with the fan; at highway cruise speed, airflow isn't an issue, but radiator heat rejection capability ("cooling capacity") is - what kind of radiator do you have and how old is it?

karista

John
I just installed a new direct fit aftermarket brass/copper radiator and a new water pump. She consistently overheats only at the higher cruising speeds, not at normal city driving, (below 3000rpm).

ghostrider20

I would bet that is your problem. Just a guess.

JohnZ

That's your problem - the C/B replacements have about 30% less heat rejection capability than the original stacked-plate Harrison aluminum radiator; been proven over and over again. Get a DeWitts reproduction of the original and you can watch the scenery instead of the temp gauge.

karista

John
I hear you, but this doesn't make any sense! Why would a manufacturer built a direct retrofit radiator that is incapable of cooling the engine? The shop that installed it indicated that the radiator has a LT warranty and was made as a direct replacement. I hate to tear it out after just spending $500 having it put in.

JohnZ

Just because it "fits" physically doesn't say anything about its cooling capacity, which is what matters when you buy a radiator; tube surface area and fin count is what matters, but the generic replacement C/B radiators don't come close to having the same cooling capacity as the original aluminum Harrison. My '67 had a brand-new C/B replacement like yours in it when I bought it, and it wouldn't do the job either; it's now in the corner of the garage, in the DeWitts box my GOOD radiator came in.

Talisman51

With a cold engine my fan clutch does not give AT all. I havent tested it hot yet. Is this normal? I recall in my last FO restored clutch that the clutch gave away even on a cold engine.

Thanks,

GCD1962

C/B replacements were built by aftermarket firms as they did not have the special tooling for the aluminum factory ones. For a period of time the only readily available radiators were the C/B ones. It wasn't until DeWitt came around that the correct ones once again were available. Remember that when the C-1, C-2s were built probably 99% of the radiators in all other new cars were C/B. It's easy to see why an aftermaket producer would assume C/B would be an ok replacement for the Corvettes - that thinking (uncorrectly) continues to this day. I had to replace the radiator in my '62 and at the time the only one available was a C/B. Needless to say I had the same problem as everyone else. Sit in traffic for only a couple of minutes and it would start to overheat. Even an electric fan didn't solve the problem. Finally when Dewitt's became available I bought one and the problem was solved. My C/B, like many others, sits in the top of my barn - I hope the mice enjoy it!

65air_coupe

I just went through the same dilemma...had a freshly recored C/B radiator that was marginal for cooling before, but once I put on the new A/C condensor coil, this slight reduction in airflow through the radiator pushed me over the limit. I sprung for the Dewitts and have no problems now.

Hitch

Lots of things don't make sense but product is out there to say otherwise. I have to ask though does $500 dollars include the radiator and what other work did the shop do? Hey Garner you out there? , opening a shop is looking better and better if shop work is demanding this type of pay. Not to say that's a lot but just lucrative.

The most probable way to correct this problem is as John said make sure you have a problem first. More than likely you do the way to fix this is 695 dollars in the form of a DeWitts radiator. Then what ever it costs to remove and install... Dave

mrg

For the cam break-in procedure I recently fired up my fresh 327 rebuild with the thought in mind that I should have one of those electric box fans running in front of the car to provide air flow through the radiator. As it turned out I didn't need the box fan, after all. I didn't have an IR gun to verify but even without the electric box fan on and running the engine temp. never went past 1/4 scale on the gauge.

The radiator? ... The DeWitt's aluminum repro and stock fan more than held their own keeping the engine cool - even without the 'extra' airflow.

Rich427

If you are considering sending your fan clutch to Fred Oliva make sure you have a replacement to use because it is going to be a while before you get it back. I know someone said that he is six months behind, but I sent him my original '69 BB clutch in October of 2004. Fred told me he would turn it around in 3 to 4 months. I got it back from him 1 year later. It looks great and appears to work fine.

He was very responsive to my emails when he was quoting the rebuild cost for me. But once I sent the fan clutch to him and I did not get the clutch back in 4 months as quoted, he would not respond to any of my email inquiries. About a year after I sent it to him, I got a bill in the mail for the repair with no other comments and received the clutch about 10 days after sending him my money.

Someone else may have had a different experience with Fred, but for what its worth, this is what I experienced.

63C2splitter

Identical to what happend to me. My 63 would have a tendency to run a little hot when I was at slower speeds or stopped in traffic. After installing Vintage Air, I couldn't keep it from running hot. I installed electric fans, which helped some, but still would get hot at low speeds. I finally (at the sugestion of others on this forum), replaced the relatively new reproduction copper/brass radiator with a Dewitts Aluminum radiator. I still have the electric fans, but I think they have only came on a couple of times in the last year. I plan to remove them completely - they are just restricting air flow, and wouldn't need them at all with the added flow. If wish I had gone with the aluminum radiator in the first place. It is well worth the extra money.

Good luck resolving your overheat problem.

Dave

karista

[QUOTE=youwish2bme]Lots of things don't make sense but product is out there to say otherwise. I have to ask though does $500 dollars include the radiator and what other work did the shop do?

The $500 included the new Radiator, removal of the original radiator and installing the new one, including antifreeze coolant and new hose.

SILENT BOB

Is GM #3916141 fan clutch a correct restoration replacement for a 67 with a L79 with AC?

rongold

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According to an old GM parts book that I have, the 3916141 is the correct "replacement clutch" for all 1960-1970 Corvettes, regardless of engine displacement or horsepower. As John Z said above, it's not a duplicate, but very close in appearance.