You probably need vacuum advance to solve the problem but you can do a test by just adding 10 degrees of timing with your current setup. You won't be able to go WOT since you'll have too much timing for that but you can fire it up and take it for a cruise. Just don't open it up more than 1/2 throttle since you'll be running at 40 to 45 degrees of timing. MSD doesn't offer the E curve for big block engines so you would have to get the ready to run. Or switch over to a stock type distributor or switch to EFI to get complete control of the timing curve. But before you start spending money you should do some testing to make sure you know what the root cause of the problem is.

I have some of the same issue with locked out timing at 34. Not extreme though. I do have a retard device that will take a chip out (2-?) at 4,000 where my converter is at. I'm going to try your idea Andy and report what I find. I was thinking setting the timing at 40 and taking 4-6 out at WFO. I'll have to look what chips I have. This low budget/compression deal probably wants more like 44 at cruise...

50 at cruise

one thing that concerns me is your fan setup. in my opinion and experience over 50 years of playing with this junk, is decide right now what you want : mechanical fan or electric.
pusher fans can, and usually do, restrict airflow when the car is going down the road.
mechanical fans NEED a shroud, and have the underhood area sealed to the hood and ducted so that all the airflow is directed to, and flows through, the radiator core.
puller fans will out perform pusher fans.

with all that said, here is my opinion. [take this for what you will]
get an OEM electric fan setup that fits your radiator core. those setups out flow all the aftermarket setups by a TON, but need a charging system and wiring harness to match. fit the shroud of what you choose to fit your radiator. seal off everything you can in front of the radiator so it is directed through the radiator core. grab a fan sensor of your choice, set or adjustable, and go. this should help a bunch, provided your cooling system is set up properly and in good condition.
then, add in some cruising advance as the others have suggested.

remember, this is just MY opinion, and experience that has worked for ME in the past. your mileage may vary.

there are so many things that this could be. I would start with the basics. test using parts that you have on hand, or can borrow, or can get cheap, just to see if they work.
Usually if it overheats in traffic you do not have enough air flow.
If it overheats at highway cruise the radiator is to small or plugged up, or too little water flow.


Lack of a vacuum advance definitely will cause it to run hotter. If the cooling system is marginal, the advance will make a difference. If the cooling system is hopelessly small, the advance won't help. If you can borrow one, or test with a cheapie distributor, I would try a distributor with vacuum advance and see what difference it makes. I have a little story on this one. I did a fly-in drive home on a 68 Dodge crew cab truck. I asked the seller when I was buying the truck over the phone if I could drive it from Arizona to Minnesota. He said I don't think so, this is a 55 mph truck. I asked him if I could make the two-hour trip to my dad's house in Arizona. He said I wouldn't but maybe you could. When I got there to pick up the truck and inspect, I could see that the radiator hoses were new the fan belt was new, and the radiator had been re-cored. When I was leaving he handed me two 1 gallon jugs of water. I said has it been overheating? He said no. I said then why the water jugs? He said just in case. When I got out on the freeway, I learned that at 55 miles an hour it ran pretty warm. At 65 miles an hour it overheated pretty bad. When I got to my dad's I checked the distributor, and the diaphragm in the vacuum can was ruptured. I put in a new distributor with a new vacuum advance on it, and the truck ran cool-as-a-cucumber at any speed. So I could see that the previous owner had been trying to solve the overheating issue, but the real culprit was the vacuum advance can.
If you haven't already done so, you'll want to use a piston stop to verify top dead center on your ballancer. To make sure that the timing marks are correct so you are not inadvertently running it with retarded timing.
If you are running exhaust manifolds with a heat riser valve, make sure that that is not stuck shut. It also helps to block the heat crossover tube in the intake manifold if it has one.

You didn't say what you have for a water pump. You need a lot of flow. If you have some scrawny little drag race electric pump on there, get rid of it and put on something with a lot of flow, like a 55 GPM meziere, or a factory belt driven pump, or a flowkooler high flow. Check to make sure that your lower radiator hose is not collapsing.


Many flex fans and electric fans are useless, and some electric fans block flow on the highway. Do you see the potential problem with combining them? Try getting rid of the electric fans and put on a big 7 blade fan with a clutch. $25 at the boneyard, that's a cheap and easy test to make. See what that does for you. The next thing to look at is that AFCO radiator. It might just be too small for your application. Also if you have a high stall converter, and r using the transmission cooler in the radiator, the transmission can generate a lot of heat from slippage in the converter and actually transfer that heat into the cooling system. If this is the case you will want to use a separate transmission cooler and bypass the one in the radiator.

Good luck, let us know what you figure out, Joel

Many good reasons for vacuum advance on a cruiser, or street/strip car.
Mopar Action states longer ring and oil life as one.
I've always gotten better mileage with it hooked up.
I doubt you built this engine for MPG, but why give it away!

Reading Andy's post again,1,700 will burn it down to the ground! 1,200 in a street car? Good luck with that as well. I've towed with my diesel at short times seeing 1,100 and 1,200 exhaust temps. Let me tell you, that fan clutch kicks in quick! That's making way too much heat for really, any cooling system to battle in a sustained environment. I would expect 5-600 at cruise.

OP. your wagon is so sweet!!
What kind of pulleys are you running? Stock?
I tried running the 5 1/2" bottom pulley source sells, my temps would creep up on the highway.

I run a Moroso underdrive crank pulley.

I would like to see Holley make the Hyper Spark Ignition in a stand alone version for Carb guys. Since there isn't a E curve Dizzy for the BBs. That would make for a nice clean set up. Andy I see your seeing the benefits of step testing on the Dyno. Thats great..

One thing to mention regarding advance, you can adjust the msd pro billet advance bushings so you can get more initial advance and also maintain the appropriate total timing. I see FBO sells a 10 and 14* bushing kit so you can get 22-26 degrees initial without running your total timing too high. I'm looking into getting that kit myself. Also on a side note, your wagon is sooo nice. It might be my favorite car here. Good luck w the getting it all sorted out.

Yeah I think im gonna shoot FBO a Call next week. About setting up Vac Adv Dist. For my build.

I'm going to do the same thing using the Crane version for my HI-6 box.

Before Crane went through financial restructuring, they had come out with a really nice digital programmable distributor that included a vacuum advance option. The price scared me away at the time, but now they are nowhere to be found since they weren't in production for very long. I'd run one of those, if the opportunity came up to buy one again.

You also mentioned using the Moroso pulley... I had been told not to run one on the street because it would reduce cooling efficiency. Do you see any temp issues with your car, and what's the rest of your cooling system?

It goes down the highway at 180-190°, idles in traffic, No issues. Stock SB '65 radiator, Hayden Jag clutch on Mopar fan, 440Source WP and housing, no shroud and no thermostat. Warms up reasonably quick to 180 and stays there. Not supposed to work, but it does. The 3.54 rear gear helps, too.

One of those distributors would be awesome for us carb guys!

I sell those CNC bushings as well... not near as costly either.

JMO and agree with other, it likely needs to more timing under cruise situations. One problem with big cams is the low vacuum signal and finding a can that will activate with 10in or more vacuum. Lots of the cans won't do much of anything until 15in.

At idle you can clean it up with more initial timing in most every case.

Sounds good. Where do you sell the bushings?

Sent you a PM. Anyone else interested, send me a PM.

Thanks for the reply’s everyone.
Next few weeks I’ll be getting the car out.
I’ll go over the current timing first, and see where I’m at from there.
I know I have to come up with a shroud, and better fan arrangement.

I have a 22 inch radiator in my Coronet but it does have a shroud. I'm using a clutch fan setup and a mechanical water pump. The 512 inch stroker that I was running last year would cruise all day at 170 to 180 degrees with a 180 thermostat. Since I'm running a Sniper system I programmed in 45 degrees of ignition timing when cruising down the freeway and I know the extra timing really helped.

You could have multiple issues so if it was me I'd pull the cooling system apart first and double check everything. Have the radiator flushed out, check the lower hose to make sure it isn't sucking closed at speed. Put a shroud on there. Make sure your blade is in the correct position, make sure the belt is tight. Pull the water pump and verify how many vanes it has as well as the clearance to the housing, pull the thermostat and make sure it is working correctly. Lots of things can go wrong with a cooling system........