jeffbant

I was forced to remove the vacuum adv as distributor timing could not be set with original 300 distributor as new high rise aluminum intake interfered. I fixed the position of the platform that was normally controlled by the vac adv. I set timing @12-14 degrees and the engine seemed to start and run fine. Runs cool at all speeds but when idling it gets hotter and hotter. New aluminum rad, hoses, pistons, valves, springs, reworked heads to be L79 + standard L79 cam.

Removed thermostat no effect.

Do I need to find a vac adv for the 350 that avoids the high rise? Dist is original 300HP with probably 300K miles on it. Ran fine as a 300HP. Using same Holly carb that was on the 300HP which also ran fine.

Will check vac this week as several posts point to vac as a possible problem. tks

p.s. I have owned the car for 46 years. I did a frame off this past winter and found spec sheet on top of gas tank stating the original engine as 350....therfore the change.

Randy G.

From my experience the idle timing all in needs to be 26* or so to not overheat at idle, which is where a properly operating vacuum advance would put it. Just for fun you could try to move the timing temporarily there at idle only and see if it still tries to overheat. Don't drive it that way, though.

DansYellow66

To operate in low speed traffic and stay cool you need the vacuum advance hooked up. The distributor needs to be move around a tooth or two so the vacuum canister clears and the wires moved on the cap to match.

Westlotorn

You said you have new pistons, does that mean you now have the domed OE style L79 pistons bumping your compression to 10.5 - 11.0:1?

kobi67

Make sure the distributor gear is indexed correctly on the distributor shaft, if not it will cause the distributor to be out of position and the advance unit may hit the manifold then timing the engine. The gear has a dimple in it, it needs to be lined up with the rotor tip. You need to run vacuum advance for best all around performance.

plaidside

I helped a friend a few years ago who built a 327-350 and he had the same problem with the advance hitting the intake runner.
I removed the distributor and re-positioned the gear 180 degrees so the dimple was opposite the rotor tip.
I put it back in and was able to set the timing correctly and hook up the vacuum advance.
Joe

MikeM

[QUOTE=jeffbant;1595620929

Runs cool at all speeds but when idling it gets hotter and hotter. [/QUOTE]

Can you quantify "hotter and hotter"?

For those that are beating the timing thing to death......................

Some '67's (including 350's) idled with no mechanical advance/retarded timing at idle and no vacuum advance and didn't seem to overheat.

That's not to imply that retarding the timing won't increase exhaust temperature. It will but in the case of '67 GM California cars, not enough to use the term, "overheat".

Maybe you just need to top off the cooling system?

jeffbant

Pistons are domed and engine is now close to 11:1 compression.

I didn't change the gear position on dist. I may do that to try and get the vac adv to clear the intake. ( I thought that gear was pined and would only go on one of 2 ways. Not sure how putting it on 180 out helps position vac adv?) I can see moving a tooth and then changing wires to restore original timing. I will give that a try.
Rad is topped off and not thermostat installed

I saw a dist shaft listed in a Paragon cat that was only for a 350. Not sure of why the difference? Also saw a vac adv for a 350 only. Might there be parts that I should have added? tks, jb

jeffbant

oops forgot one..

I don't have actual temp levels at idle. I just noticed that temp gauge increases as the car idles. est: after 10-15 min idling, gauge is reading on approx 3/4 across temp gauge. Currently when car runs, temp gauge is approx 1/4 up the temp scale with thermostat removed.

dmaxx3500

is the rad clean/clear inside and out?
,does the car have a fan shroud?
,does it have the biggest fan that fits?

LB66383

Put the thermostat back in. The system needs that restriction to slow down the flow. Otherwise, the coolant can flow through the radiator too fast to be cooled down much.

Are you using the factory-style thermostatic fan clutch? Is it working properly? After shutting down the engine after it has gotten really warm, try turning the fan. It should be somewhat hard to turn. If it turns easily, the fan clutch is bad.

jeffbant

Car has a new aluminum radiator. Shroud is standard and in good condition. Fan is standard size and the fan clutch is a couple years old. I'll check out clutch as you describe.

I'll put thermostat back in on Monday and attempt to move dist position and wires to re-accommodate the vac adv.

tks, jb

MikeM

If you insist.....................

Put the wires on the cap where they belong, not just jump them around to cover some other malfunction.

Turning the gear 180* will give you a half tooth adjustment instead of you moving the distributor a whole tooth which will throw you off in the other direction.

Before you do any of this, verify your fan is working correctly and the actual temperature of your engine coolant.

Westlotorn

Thermostat is removed. most likely he has been fighting overheat prior to removal but I agree you need to install a good 160 thermostat and start tracking from there.
Get a infra red thermometer and start shooting the engine temps at the thermostat housing and at the upper and lower radiator hoses to isolate your problem. Then with facts in hand start fixing the car.

jeffbant

Engine has been overheating since rebuild. Removed thermostat to eliminate it as a problem. I tested it's function on the stove, and will follow advice and reinstall on Monday.

IGO200

Have you actually checked the timing. Sounds retarded. (The timing, not you)

jeffbant

Timing is set 14*

Randy G.

No vacuum advance. Not enough timing.

jeffbant

Just a personal comment about vac adv.

I drove this car as a 327/300 many many years (probably 10-15) unknowingly with a frozen vac adv. I just found the car ran better at 12*-14*. Last year I bumped into the problem by accident. I replaced the vac adv and now run it at 8* which is spec. During that period I had no issue with overheating. It was hard starting at times, but that was the only apparent drawback. So when the vac adv didn't fit with the high rise manifold I was comfortable removing it, given my experience. I will work on reinstalling it this week to see if has some effect on overheating. I understand the logic being presented in the above posts and will proceed with the recommendations offered. tks, jb

JohnZ

It makes a difference because the distributor drive gear and the gear on the cam that drives it both have 13 teeth, and the hole for the roll pin that orients and secures the driven gear on the distributor shaft aligns with a gear tooth at one end and with a valley between teeth at the other end, That half a tooth change provides 13-1/2* of movement, which is all you need to get the VAC off the #8 intake runner.

Like MikeM said, don't screw around with the wires and do a "Bubba" fix - do it right; we've been through this specific issue hundreds of times on this board over the last 15 years.