dougal

I have a custom RV where the front end is a 1965 Dodge Coronet and I just had the following work done:

• Rebuild Heads
• New water pump
• New thermostat
• New fuel filter and line from fuel pump
• Petronics Ignitor II
• Mallory Distributor Cap
• New Plugs and wires
• Flame Thrower II
• Edelbrock Intake
• EDELBROCK PERFORMER SERIES 600 CFM, STREET LEGAL ELECTRIC CHOKE CARBURETORS
• Power Brakes
• Transmission Rebuild
• New Differential and Axles
• Front Disc Brakes
• 4 core Radiator
• 140A Alternator

When I got the car back, it ran fine except it overheated. Mechanic says it was an air bubble.

When I got it back again, it ran fine until the fan trashed the radiator. (Note: you should not install a 4 core rad in a 65 coronet. 3-core maximum.

I put the old radiator in with the electric fans I was expecting to return and it overheated again. I read the trick of elevating the front end to bleed the cooling system and did that and it still overheated. I noticed bubbles in coolant reservoir and saw white smoke out one side. I suspected a blown head gasket.

The mechanic says that doesn't see the bubbles or white smoke. When driving away from the mechanics on city streets, everything was fine. When I got the highway and punched it on the on-ramp, I lost almost all power and started surging down the highway and my speed kept dropping to nothing. It stalled when I stopped. I re-started, heard some backfiring for a while then everything smoothed out. Drove normally to my next destination.

Stopped for about 20 minutes and had trouble restarting. Once I got it started, it seemed to idle very low and I had to two-foot it when stopped at intersection to keep it running.

After 10 minutes of driving, the surge came back and I couldn't keep driving it in the stop and go traffic. I pulled the air cleaner off and revved the engine at the carb and sometimes it would be smooth and other-times it would backfire through the carb.

Some additional details that might be pertinent.

• I live in denver (mile high) and everything carb related is stock from edelbrock
• The carb linkage was modified to get the automatic transmission kickdown to work.
• The ballast resistor is part of the coil circuit.

I've put a lot of money into this beast and it could travel further when I picked it off the farmers field where it had been laying for 15 years.

I'm new to all this so any help would be appreciated.

Silverick

I'd have a few more words with the mechanic! (I think it was the radiator part of your story that swayed my opinion!)

This is a shot in the dark...
But, it almost sounds like the timing chain jumped a tooth or if it's the original timing gear and it's one of the nylon toothed gears, you may have lost a tooth or couple of teeth....

What engine do you have? Big block or a small (poly?) block?

I'm sure that someone else will get on board here.....

Rick

dougal

Once the new radiator get's installed, I won't be seeing that mechanic again. Got a lead on a good one here is Denver.

Sorry for not mentioning:

It's a 361, 8 cylinder, Auto transmission, with 3.55 gear ratio. (Thinking of going back to 323.)

TVLynn

Have you looked to see the plugs ?? a 600 on 361 may be too lean. Up in mile high Denver I would keep the 3.55 gears . If the budget allows at a later date get an overdrive trans

dougal

The plugs are brand new and it will run perfectly and then not and then run perfectly so I don't see how the plugs would change characteristics unless they was cracked.

My working theory is that the ballast resistor drops the the voltage to the coil and when it gets hot under the hood, the resistance increases and the coil voltage decreases. But I come from an electrical background and may be looking for a solution inside my wheelhouse.

The Petronics manual says that I can run with the ballast resistor but doesn't recommend it. I'll take it out this weekend and see what happens.

dougal

Regarding the gear change. Because this is an RV, the majority of driving will be highway miles. It had a 323 when I bought it and the mechanic convinced me to up to a 355. The rpm's seem perfect at 55 with the 355 but a little high at 65.

I'm not lacking in power, so I'm thinking that the $600 to change back to 323 will pay for itself pretty quickly in gas mileage.

I looked into overdrive and the parts alone were $3,300. That's a lot of driving to pay for itself.

dougal

I did take out the ballast resister this weekend and took it out on the highway. After about 5 miles the temperature rose to the high side of normal and decided to turn back before it was too late. I idled at a gas station for a couple of minutes and then hit the highway back.

Halfway back, the engine started surging again. It was if I was pressing and releasing the gas pedal and the speed dropped between 40-55 mph depending where I was in the surge.

Once I hit city streets, the problem disappeared.

Question 1: What would cause the engine to overheat so quickly other than a blown head gasket?
Question 2: What could cause the surging? Vapor lock maybe? The rubber gas line runs up the front of the engine to the carb with a metal fuel filter and I've been meaning to move it.

Any help would be appreciated.

99dakota440

I think tvlynn was saying, check your spark plugs to see if your running lean, if its leanit might look something like this one

dougal

I expected it to be rich because the carb was tuned at sea level and I'm at 5280 ft. I ordered the high-altitude jets recommended by Edelbrock. Should I not install them?

Here is a random spark plug. It is a new plug replaced less than 1000 miles ago.

TVLynn

IF it was the correct carb application you would no have had to modify the linkage. They make a special linkage arm the bolts to the carb to adapt the kickdown I would check into getting one. THE kickdown adjustment is VERY important.
If it surges maybe check the distributor

dougal

It is the correct carb and the correct linkage is installed. (Called Edelbrock this morning to be sure) The throttle cable was short and the mechanic customized a 1/2" link to extend it. I don't see how the kick down could have attached to the linkage either and they modified it by added a nut and bolt to keep the linkage in the correct position. The kick down seems to work well 90% of the time and I'll get the new mechanic to look at it to be sure.

However, I just finished watching the Edelbrock installation videos and the mechanic connected the vacuum advance to the manifold vacuum port instead of the advance port.

Could that really be the answer to all my problems? Could the manifold vacuum damage the vacuum advance? How can I check?

Thanks for your help!

dougal

Went to Mopower Masters in Denver and they spent 5 minutes adjusting the timing and 90% of my problems are gone. They say that have to work on the distributor vacuum advance next week and that will fix the other 10%.

TVLynn

Yes the distributor needs to be hooked up to ported vacuum NOT full time manifold vacuum.
Sometimes fixing problems can be very simple

Chryco Psycho

Absolutly , connecting the vacuum advance to manifold gives it full advance at idle & reduces the advance with increased RPM so it works backwards , this will cause overheating & a lot of drivability problems . There is a allen screw inside the vacuum canister , to adjust the amount of advance the vacuum moves as well so you can turn the screw counterclockwise to reduce the total advance so it will not overadvance at higher RPM
If you want to use a clutch fan Flex-A-lite has an 18 6 blade fan , get a Jaguar fan clutch , it is very short & will clear betwen the rad easily on the early B body cars

dougal

They actually adjusted the counterweights and springs in my distributor for altitude.

Still had the overheating problem afterwards and we finally found out that the fan shroud worked perfectly during city driving but blocked airflow and possibly stalled the fans at highway speeds. We cut out all of the metal down to fan support and I could drive on the highway reliably.

However, it still ran very hot, partially because I now know that the engine will run 20 degrees hotter at altitude. The main problem, however, was that my new 3-core champion radiator couldn't keep up once the transmission got to temp.

We created a new cooling system for the transmission and now everything appears to be working like it should.

Chryco Psycho

Excellent