underhood heat

[Glenwood]

Problem #1 is you need a shroud! Without the shroud all your fan is doing is blowing air here and there and not pulling air through the radiator to cool the engine and not putting air directly on the engine.

I don't disagree, however this is not the root cause. The issue was certainly magnified by this fact on a hot day. For two months without a shroud, no issue. And that while the engine was breaking in.
I believe the problem lies within the ignition and possibly fuel system. A shroud will help for sure, but i need to get the other components set up properly to minimize the heat that the engine is producing. That is what I've learned from this thread anyway.
Besides i like doing tests and analyzing the results. I find it very interesting. Glad it is at the end of the season here though and not the beginning!

 

[Glenwood]

Just to update this thread...

Playing with the timing and idle mixture did not seem to eliminate the stumble when the engine reached operating temperature. The plugs continue to have soot, now heavy soot, so way too rich. Idling too long isn't helping either, and found I'm going through a lot fuel during this adventure.

Bought a new timing light from innova that has a tach which helps. Now I can read the timing marks properly. Time to retire the 35 year old light.
Tried a new flame thrower 2 coil, that has a primary impedance of 0.6 ohms and no ballast resistor. Stumble gone! However, plugs still rich. I turned my attention to the carb.
Picked up a calibration kit and changed the metering springs to match my 15" of vacuum, along with new jets and metering rods to lean it out some, according to edelbrock's chart. Gave the carb a good cleaning and I noticed that the electric choke was set too rich. That is likely contributing to the rich condition, although the choke plate always opens up fully. Set the choke to much leaner so that it opens sooner, installed it and fired up. Plugs still looked a bit rich afterwards, but better.

I set up a fuel pressure gauge and noticed that the carter mechanical pump is putting out too much pressure. About 8lbs at idle and 6lbs at 2000 rpm. So I picked up a regulator and set it for 5.5 as per edelbrock's manual. Seems much better. I took it out for a cruise and it is running way better. The car now has loads of power, laying down rubber like it never could before. No stumble, but some pinging at higher rpm. I plan to install the original distributor with the recurved mechanical advance and orange box to see how it performs. I think I will have to put the BR back into the circuit as the new coil will probably burn out the ecu.

Long term plan is to either pick up the FBO kit or replace the reluctor with the pertronics 2 module. I've read mixed reviews about pertronics, so I'm not sure yet. I also plan to rebuild the holley 750DP and try it out, hopefully before the snow flies!

As far as underhood heat goes, it is hovering above freezing outside in the mornings now and seldom gets above 60* during the day, so I'll get a shroud over the winter and see how it performs next summer.

 

[JimKueneman]

a few pics from my bulkhead connector. the engine harness was new!

I think you agreed with me on another thread. No one will agree with me but I think putting this big alternators on without rewiring a lot of the harness is a bad idea. The most of the factory connectors are rated at about 50A max under ideal conditions. I bet you had the exactly problem I covered. You were working on the car and running the battery down to the point where the big alternator was running wide open (75A) with a quality battery which is WAY to much for most of the Packard connectors.

 

[JimKueneman]

You don't you use one of these, quick, easy and deadly accurateView attachment 525218

Don does this work on old SB Mopar point distributors?

Jim

 

[threewood]

Glen, I'm glad you about got it licked. If your plugs are still sooty, you may go a step hotter heat range on your plugs to see.

Eddy carbs are simple to tune and pressure is critical so I think you are on the right track regulating the flow.

If you are pinging, retard the ignition until it stops. What grades of gas do you have available?

I am a big proponent of the Pertronix II and III. Have one of each and run them without issue. As long as the coil is matched, BR bypassed, it is a great ignition. If you go III, do not get rid of that old timing light as it is a multispark ignition and will cause an advance light to go wonky.

 

[miller]

If your plugs are still sooty, you may go a step hotter heat range on your plugs to see.

Another thing that might be worth looking at, is your plug wires...actually the spark the plugs are giving. Just pulling a spark plug, arrange it where it's resting on ground, and fire off the motor. To watch the plug spark, should be fairly crisp.

Happened to me. Kept getting fouled plugs, so started checking things. My 'new' plug wires were junk, only getting a weak spark. Changed plug wires...all good to go.

 

[Glenwood]

I think you agreed with me on another thread. No one will agree with me but I think putting this big alternators on without rewiring a lot of the harness is a bad idea. The most of the factory connectors are rated at about 50A max under ideal conditions. I bet you had the exactly problem I covered. You were working on the car and running the battery down to the point where the big alternator was running wide open (75A) with a quality battery which is WAY to much for most of the Packard connectors.

Couldn't agree more Jim. There's a reason the alternator wires were separated and isolated in the multi-wire bulkheads in later mopars. I feel that the problem is more than just the amount of current though. Despite my efforts to use a new engine harness and mate it to the original dash harness, these wires likely still had a loose fit even after thoroughly cleaning up the dash side. Previous issues may have pitted the terminals and went unnoticed. At least I caught it before it did more damage.

It is hard to say how much current a low battery will draw, but I think I saw in excess of 30A with the lights on. I agree, if you're going to upsize the alternator, the wiring should be upsized as well and reroute it away from the bulkhead. Even if the theoretical demand of current should never reach the alternator's capacity, all it takes is a shorting circuit to permit a high draw of current and resulting fire.

 

[Glenwood]

Glen, I'm glad you about got it licked. If your plugs are still sooty, you may go a step hotter heat range on your plugs to see.

Eddy carbs are simple to tune and pressure is critical so I think you are on the right track regulating the flow.

If you are pinging, retard the ignition until it stops. What grades of gas do you have available?

I am a big proponent of the Pertronix II and III. Have one of each and run them without issue. As long as the coil is matched, BR bypassed, it is a great ignition. If you go III, do not get rid of that old timing light as it is a multispark ignition and will cause an advance light to go wonky.

Thanks Mark. I'm much closer to resolving the problem(s) and learned a lot about tuning so far. More testing is needed still, along with upgrades. The pinging is slight at higher rpms on 93 non-e. It wouldn't surprise me if I have some thick layers of carbon on the heads/valves causing a slight increase in cr, which may contribute. Anyone use seafoam for carbon removal?
I still have to inspect the plugs after my last run. I'm knee deep in the kid's civic engine swap atm.

 

[Dennis H]

For gas additive, I use Amsoil PI in once a year for maintenance. Modern Hemis too.

 

[threewood]

Carbon removal? Use good old water. Dribble it down the carb as you gentle rev the motor.

 

[hoover]

You don't you use one of these, quick, easy and deadly accurateView attachment 525218

where can I buy these???

 

[threewood]

where can I buy these???

http://4secondsflat.com/Mopar Mechanical timing limiter plate.htm

 

[JimKueneman]

where can I buy these???

I ordered it and new springs in their kit. Will be here Tuesday