C-2 Pulleys

[Patrick F. McInerney]

My '64 Convertible, 365HP SHP, no PS or AC, is on the road for 300 plus miles since complete restoration. With thorough block cleaning, a new aluminum radiator,rebuilt water pump,160 degree thermostat, new thermostatic fan clutch and correct timing the engine continues to run over a range of 160 to 220 degrees.

In rebuilding the engine I reused the pulleys that were previously installed. There are no part numbers so I assume they are aftermarket.

To satisfy this issue could someone with a '64 365 SHP engine similarly equipped with factory pulleys give me the OD measurements on crankshaft, water pump and alternator pulleys? The belts are Quantas repros, 3L, 3/8" by 7/32" and pulleys are 2 groove with idler.

Thank you all for your help.

Pat McInerney #37445

[Patrick H.]

Re: C-2 Pulleys

Pat,

Did you replace the temp sender or gauge?
Are you SURE your temperature reading is accurate? I'd make sure you verify it with an IR temp gun before you go chasing other theories. It's common for a replacement temp sender and/or gauge to be calibrated differently than your original, and deliver erroneous readings.

I'm sure that Jack Humphrey could give you the exact specifics on why. I'll keep it simple and just say "it happens."

Patrick

[Jack H.]

Re: C-2 Pulleys

Staying in Pat's vein of keep it simple...many of today's replacement temp senders are built based on 'omnibus' specifications (one sender fits/works over a wide range of factory original sender specs) at the expense of minor (10-15F) inaccuracy.

On the gauge issue, the factory originally calibrated gauges by 'inducing' the electrical profile (voltage and branch current) of an operating engine about to overheat. Then, depending on specific year of temp gauge, they either installed the pointer needle in the appropriate position or picked from a selection of precision t******* resistors to 'shunt' the gauge to force it to read properly.

Bottom line, if the guage has been out and handled by 'Bubba' you can't guarantee it's still in factory original calibration...

[Joe L.]

Re: C-2 Pulleys

Pat----

crankshaft pulley-----GM #3766987----6-3/4" OD (GM #3858533 replaces and is same OD

waterpump pulley------GM #3770245----7-1/8" OD

alternator pulley-----GM #3829193----3-5/8" (GM #3871242 replaces and is same OD)

Also, your application originally used an idler pulley.

The carnkshaft and waterpump pullies are still available from GM. The alternator and idler pulley assembly are discontinued, but available in reproduction.

[John H.]

Re: C-2 Pulleys

With that wide a temperature range swing, could be a sluggish generic thermostat that's causing it to "cycle"; put a Robertshaw #330-180 (180*) balanced-flow thermostat in it (or the same one repacked and sold by Mr. Gasket). They're calibrated much closer and are more responsive than the generic parts store thermostats.

[Patrick F. McInerney]

Re: C-2 Pulleys

My thanks to Joe and all who responded to my question.

The pulleys are the correct diameters and dash guage temp has been closely verified with hand held contact and non-contact thermometers.

I think that the aftermarket thermostat is at fault and I'm going to switch to Robertshaw as John suggested.

Thanks again!

Pat McInerney