65 Vette

[Brian D.]

I have a 65 roadster 327 365HP, runs hot in stop and go traffic also on highway 70-75 MPH
Engine is original (rebuilt) new aluminum rad.
I would rather not go to an electric fan if possible.
Any advice??

[Joe C.]

Re: 65 Vette

I have a 65 roadster 327 365HP, runs hot in stop and go traffic also on highway 70-75 MPH
Engine is original (rebuilt) new aluminum rad.
I would rather not go to an electric fan if possible.
Any advice??

1. If it's not boiling over, then you should verify actual coolant temp with an IR temp gun aimed at the thermostat housing. Chances are that your temp gauge is not registering actual coolant temp due to a replacement temp sender.

2. If it IS boiling over, then we need more information, beginning with the exact radiator installed.

3. Your car is not a roadster. It's a convertible unless someone replaced the glass side windows with plastic curtains.

[Mike T.]

Re: 65 Vette

Brian - If after checking with an Infrared Gun you find that it's really overheating, fill us in on as much detail as you can including how long this has been going on, what's been changed, when the 'overheating began and if it occurred with some change to the engine, properly operating fan clutch unit or not, initial timing, drivability issues happening, and so on. And, I refer to them as 'Roadsters' too ;-).

[Don H.]

Re: 65 Vette

Hi Brian
welcome to the club and the TDB.
Here is an excellent article that will answer all your questions about engine overheating written by John Hinkley. Suggest you read it and then work through your set up and you will solve your problem WITHOUT resorting to an electric fan.
http://www.lbfun.com/warehouse/tech_...em/cooling.pdf

And, don't pay any attention to Joe's point 3. above. He owns a roadster same as we do, and he knows it. He just likes to jerk on your chain. Our roadsters have rollup windows, and we call them roadsters. If it is not Merriam Webster correct, well that is just tough.

[Brian D.]

Re: 65 Vette

It has never boiled over. I have installed a second temp gauge & sending unit to confirm readings. What I find puzzling is why running hot at 70-75 MPHI will check temp with IR temp gun. I stand corrected, no plastic curtains.

[William C.]

Re: 65 Vette

Non oem temp sending units are notoriously unreliable...

[Brian D.]

Re: 65 Vette

excellent article on cooling systems, thanks

[Patrick H.]

Re: 65 Vette

Repro radiator caps are notoriously unreliable, so think about that if it ever boils over.

I searched for an overheating issue for a few years on a 72, and it turned out to be the timing. Once I figured that out and ran full time vacuum to the distributor the car ran great. Along the same lines, be sure your vacuum advance actually works.

[Robert K.]

Re: 65 Vette

Many years ago driving home from Williamsburg, my 62's temperature started to rise at highway speeds. I figured it was the fan clutch. I stopped at a parts store and changed it out. It is still in there today and no overheating problems.

Years before that my 62 with a newly rebuilt motor over heated at idle and more recently my son's Rallye 350 did. Both of these were solved with increased initial timing.

As to the Roadster thing, I think more people will call it a roadster than not. Joe's strict definition originates in 1916 and coined by the Society of Automobile Enginneers (SAE). It has since been relaxed to include all 2 seater open air cars. I have also seen it referred to a convertible were the top disappears under a panel.

[Joe C.]

Re: 65 Vette

Brian,

Since the engine "overheats" at highway speeds, then that rules out the fan clutch and spark timing. I would VERIFY coolant temp with an IR gun before I did anything else. If the coolant temp is indeed elevated, then that would point to radiator capacity or a closed/partially closed thermostat, or a collapsed lower radiator hose. Much less likely would be a severely corroded/ineffective water pump impeller. GROSSLY retarded timing could cause your issue, and normal spark advance should be between 48-52 degrees with full vacuum and centrifugal advance at a steady 65 MPH cruise. Some people report having an "air bubble", or partially filled system, but I have NEVER seen that with my cars.

Don't get into any bad habit by calling your convertible a roadster. People here do that because they think it gives their car more panache'. It's pretentious and just plain wrong. I call my car a convertible, and when I want to use the vernacular I call it a ragtop. By the same token, I never refer to my Mustang GT coupe as a "saloon".

[Robert K.]

Re: 65 Vette

Brian,

Since the engine "overheats" at highway speeds, then that rules out the fan clutch and spark timing.

Not true! As I stated above the fan clutch caused my bone stock 62 to overheat at highway speeds. I change it, it fixed it while on the road. Not many variables there. That was 20 years ago and it is still fixed.

As little a 4 degrees too retarted initial timing can cause over heating at an idle. It is possible you have 2 problems. Advance the timing 4 degrees at an idle and see if your overheating disappears at an idle. It's quick, easy and it don't cost a dime.

[William C.]

Re: 65 Vette

And at Hwy speeds, the spark timing is very much affected by the vacuum advance can...

[Carl N.]

Re: 65 Vette

if your top radiator hose is several years old check and see if it is "soft" it could be collapsing at speed and restricting flow, also if your still running solid lifters (365 hp) check your valve lash hot - this can affect timing just as vacuum advance does. sometimes it is something very simple

[Mike E.]

Re: 65 Vette

By the same token, I never refer to my Mustang GT coupe as a "saloon".

Mike

[Jim T.]

Re: 65 Vette

Repro radiator caps are notoriously unreliable, so think about that if it ever boils over.

I searched for an overheating issue for a few years on a 72, and it turned out to be the timing. Once I figured that out and ran full time vacuum to the distributor the car ran great. Along the same lines, be sure your vacuum advance actually works.

Patrick it will be 44 years come SEP that my new 1970 Corvette would run cooler with full time vacuum from the carb directly to the distributors vacuum advance. Another advantage of 100% full time vacuum to the vacuum advance was better gas mileage in city driving.