[barebase57]

First off I hope every one had a great Thanksgiving, now down to business, I was a industrial diesel mech for 50 years so I'm well aware of the difficulty in diagnosing with out being there. here are tune up specs, MSD dis. without vacuum advance and a 6AL box, timing set at 34 deg. max advance, it was 10 or 12 at idle remember no vacume advance, plugs are RN10Y .040 gap. valve set .022 int. and .024 ex.. carb is a holley 4160, originally primary jets where 73 and where changed to 68 and plugs look like they could go smaller. Cooling system, CSi elec. high volumm water pump, original instructions said to drill 2 1/4 inch holes in thermostat,I also tried a high volumm ther.both of those things didn't work, currently there is a OEm therm. with 1 small hole in it. Rad. is a aluminum griffin with 2 10 in. high volumm fans. Heres the funny part, I took her for a ride the other day 50 degr. ambient temp. engine ran hotter at highway speed. both fans run constantly.

 

[hotrodg726]

First off I hope every one had a great Thanksgiving, now down to business, I was a industrial diesel mech for 50 years so I'm well aware of the difficulty in diagnosing with out being there. here are tune up specs, MSD dis. without vacuum advance and a 6AL box, timing set at 34 deg. max advance, it was 10 or 12 at idle remember no vacume advance, plugs are RN10Y .040 gap. valve set .022 int. and .024 ex.. carb is a holley 4160, originally primary jets where 73 and where changed to 68 and plugs look like they could go smaller. Cooling system, CSi elec. high volumm water pump, original instructions said to drill 2 1/4 inch holes in thermostat,I also tried a high volumm ther.both of those things didn't work, currently there is a OEm therm. with 1 small hole in it. Rad. is a aluminum griffin with 2 10 in. high volumm fans. Heres the funny part, I took her for a ride the other day 50 degr. ambient temp. engine ran hotter at highway speed. both fans run constantly.

I would bet you could use more initial timing, also a fast advance curve would be helpful to get it to 34 sooner like 2400 rpm. a vacuum advance would help on the highway. BBC engines like a lot of timing early. the 10" fans are not helping either as they do not permit enough airflow at highway speed and if they are on the actually reduce airflow at say 60 mpg. I run dual 12" and they rarely come on at highway speeds.

 

[Roadsterdave]

Just a shot in the dark. I had the same issues with an LS engine that would run at cool temperatures in town and then overheat on the highway. Found that the headers were heating the temp sending unit. Put a dam up between the headers and the sending unit and problem fixed.

 

[Rick_L]

This talk about too much airflow, too much water flow, needing restrictions, etc. is just plain wrong. More flow = more cooling = lower temperatures.

I agree on the possibility of 2 10" fans not being enough. 2 11" fans is a big step up.

But the real culprit is the electric water pump. Doesn't flow enough at speed.

Vacuum advance might help too, and might help it drive better at part throttle.

 

[barebase57]

Thanks for all the input and you've given me a few things to try. Timing could be a factor I don't have a remote tach so I really don't know when the timing comes in, and my fans run all the time I'll try hooking them up to a thermostatic control. I have thought about going to a real water pump but that will be a major repair, not enough room between engine and fan shroud for water pump and pulley. Some of the stuff done to this car was done a long time ago, I bough it 50 years ago, built the engine 40 years ago and drove it under its own power for the first time last year

 

[hotrodg726]

I have thought about going to a real water pump but that will be a major repair, not enough room between engine and fan shroud for water pump and pulley. Some of the stuff done to this car was done a long time ago, I bough it 50 years ago, built the engine 40 years ago and drove it under its own power for the first time last year

a short bbc pump and pulley is no longer than an electric water pump. the csr pump is 6.0-6.5" depending on which one you have and the edelbrock aluminum pump is 5.75", 1/4-3/4" shorter than the electric. the edelbrock flows the same at idle as the electric and way more at highway speed

 

[barebase57]

Sounds like a plan, I'll give that a try. Thanks