I changed the fan clutch and wp pulley to the correct parts. I checked on the vac advance can I purchased 3 years ago and believe it may be the wrong one. Here is what I got.
http://www.zip-corvette.com/ProductD...GR-SR&CTitle=&
I think this is the correct one. Am I right? And could this be the cause of overheating while in traffic or sitting idiling? Shemp
http://www.zip-corvette.com/ProductD...GR-SR&CTitle=&

 

Check the idle timing w. the VAC connected (idle timing = initial timing + advance provided by the VAC usually about 16*)

If the VAC is functioning correctly you should see about 24*-26*advance BTDC. Below 20* there is a problem with the VAC or vacuum source.

 

Is it boiling over?

 

Shemp:

Check replies given to your earlier questions on this subject in ffas23 post "Radiator Problem with 1967 Coupe" (yesterday)

Also, you need to check to see if the vacuum source to your distributor vacuum advance can is "full time vacuum" or "ported vacuum". It came from the factory as ported, but should be changed/converted to full time source for best operation.

Larry

 

Just took this pic of the way it is set up now. If I'm understanding correctly that it is hooked up to ported vac now and it should be hooked to the nipple on the base plate of the carb to be manifold vac (full time). Is that right?
Do I just switch it and put the cap on the one it is on now,and will I have to adjust timing afterwards? Shemp

 

That's a later re-issue carburetor, and most of them had the metering block vacuum source changed to "ported" for emissions reasons. Cap that one off and either use the other angled nipple on the front of the baseplate, or tee into the hose going to the choke pull-off diaphragm - both should be full manifold vacuum sources - you can verify with your vacuum gauge. You won't have to change the timing, but you'll need to re-set your idle rpm (it will increase when you change from "ported" to full manifold vacuum to the distributor).

 

John, just so I'm clear here, are you stating that later issue Holley's with the barb in the metering block like his, instead of the original threaded hole, have ported vacuum go that barb instead of full vacuum?

If so that affects a lot of cars, likely right in our own forum.

 

I can't speak for all of them, but many of the later re-issues used a later metering block with different passages that connected to an orifice in the main body just above the throttle plate ("ported" source). The correct primary metering block for a '67 427/390 with a LIST 3811 carburetor is stamped "4796" on top; if it's stamped with a different number, it may provide "ported" vacuum. Easy to check the source with a vacuum gauge - if there's no vacuum at idle, it's a "ported" source.

 

John I just went and checked w/ a vac guage. The carb is a new 6210 650 Holley. The one I had it on is ported and I switched it to the full one. I do not have a mighty vac as powershift suggested to check if I have the right can though. I have a friend I just spoke with that has one, so I'll do that tomorrow. Shemp

 

Are you sure the engine is full of coolant and doesn't have an air pocket? I have seen this problem when guys replace the stock radiator with an aftermarket radiator that doesn't use the pressurized coolant tank reservoir. Sometimes the radiator cap is lower than the cylinder heads, which means that you can't completely fill the engine block using the radiator filler. Remember, water seeks its own level, and if the radiator cap is lower than the highest point of the coolant passages on the cylinder heads, they won't fill completely.

 

My new replacement Holley on the Chevelle SS has the ported vacuum in that same location...

 

Latest update: I just got back from a 10 min. cruise, got it up to temp then let it sit in the driveway for about 10 min. idiling. The temp guage got to about 212* so I checked w/ a temp gun at the thermo housing it read 198*- 203* and got no higher. Before it would have hit the redline. So I think I'm on the right track here. I think that 200* is a little high right? Shemp

 

Shemp you can check with me if you ever need anything. I'm right in Davidsonville.

 

a lot of guys will tell you that 200º is too high but personally I see no problem with the temps as long as they stay under 210-215º. Definately no harm to the motor at that range. Remember, a few years after your car was built and they started dealing with emission requirements that factory even upped the minimum operating temps of the motor to about 200º by replacing the standard 180º tstat with a 195º tstat, lowering the initial timing setting and switching to ported vacuum - all in the goal of RAISING the operating temps to help burn off more hydrocarbons and reduce emission outputs. So, there is nothing at all wrong with running at 200-215º. Besides, it took 10 minutes of idleing in the driveway, with no airflow from moving, (in a big block motor yet!) to get the temps to come up to 200º - not something you normally encounter in a normal drive.
If it stays at or 200º while driving than you should be just fine

Now that you switched to the correct manifold vacuum source and saw the temps lower, I'd just now double check your dwell (30º) and timing settings to make sure they are correct (36º total timing with vac can disc and plugged, all in by about 3000rpm, and with the initial timing falling around 12-15º. Than replug in the vac adv can and it should be adding about another 16º timing at idle).
Than go out and enjoy the car without worrying about it anymore.

 

I think you have some other factor in your cooling system that you haven't discovered yet that is causing your engine to heat up like that.

It is true that just a couple years after your car was manufactured, the OEM's raised the normal operating temperature of their engines but they didn't do it without some difficulties.

The extra heat caused hardening of wiring insulation and deterioration of rubber underhood hoses. Also, vapor lock problems. One reason, if not the only reason the fuel return line from the fuel pump was included in the design.

The extra heat also adds some discomfort to occupants of the car in hot weather.

Some guys have BB's and don't even use the vacuum advance and they do it without running hot.

I'm not saying I'd fix it, just that I believe something else is amiss.

 

Mike, I'm with ya. I am still not happy w/ 200* at idle. I will have to do some more checking, but I'm getting there. It is no where near as bad as it was. Shemp

 

Have you flushed out the block, pull the side plugs and see how much junk/rust you get out of it.

 

The motor only has 4000 mi. on it. Shemp

 

You said you changed the fan clutch. I'm not familiar with these new replacements but I hear people talking about re-clocking the spring so the fan will start pulling air at a lower temperature than the pre-set higher temperature of the replacement clutches.

That may be the missing link here.

 

yes, i believe the new fan clutches are pre-set for a higher temp - around 195º or so but you can adjust the spring setting to move it down to about 180º or so.
I don't remember the details of which way to move the spring but you may be able to find it in a forum search