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Stroked and Supercharged 440 Timing Help

Eric Johnson

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Hey guys,
I've been having a lot of overheating issues on my 440 that is stroked to about 500 cubic inches and has a procharger on it. The engine very rapidly overheats at low speeds which I why I thought it was a radiator problem but my radiator guy said he's sure my radiator is big enough to handle my engine and I've had a few people tell me they think its timing. So I finally started messing around with the engine and the first thing I did was remove the intake tubing and check the timing like it was just carbureted. Its running around 15 degrees advanced at idle and around 35 degrees total. (I need a better timing light because it was hard to be exact) From what I can find online, being too far advanced can cause overheating. So I was wondering if anyone has any advice on supercharged Mopar engines. My Ignition is all MSD, mechanical distributor, 6AL box with an additional MSD boost timing controller. I'm thinking I should time it with no supercharger equipment then if I can resolve the overheating then I'll add the supercharger. What are your guys thoughts on this?

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wedg2go

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That is an impressive set-up you have there!

Timing, 15 degrees I would think, should not be an issue to over heating at low speeds. For every degree of initial timing, the combustion chamber temp will go up a few hundred, but your cooling system should compensate for that increase. Depending on the springs and bushings you are running in the MSD distributor to achieve 35 (36) total, you are most likely ok at 15 degrees at said rpm. It also will depend on hearing detonation on load or after running when the engine is switched off. Especially, after it "warms up"!

My two cents?

Not enough air movement across the radiator. "Low speed" or "idle" is the given clue for lack or air movement across the radiator (Does it do "Ok" at higher speeds?). All of course can relate to fan(s), shrouds or direction to move that air thru the radiator and not diverted to flow over or under the radiator.
 

Eric Johnson

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That is an impressive set-up you have there!

Timing, 15 degrees I would think, should not be an issue to over heating at low speeds. For every degree of initial timing, the combustion chamber temp will go up a few hundred, but your cooling system should compensate for that increase. Depending on the springs and bushings you are running in the MSD distributor to achieve 35 (36) total, you are most likely ok at 15 degrees at said rpm. It also will depend on hearing detonation on load or after running when the engine is switched off. Especially, after it "warms up"!

My two cents?

Not enough air movement across the radiator. "Low speed" or "idle" is the given clue for lack or air movement across the radiator (Does it do "Ok" at higher speeds?). All of course can relate to fan(s), shrouds or direction to move that air thru the radiator and not diverted to flow over or under the radiator.

I thought the same thing but the problem is the car will heat up extremely fast from a cold start, before the coolant even starts to flow through the radiator. You can honestly visibly watch the temp gauge rise from a cold start. The engine seems to run fine at higher speeds once theres air flow through the radiator. But thats the strange thing is the engine itself runs great, it just gets wayy too hot.
 

Chryco Psycho

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I assume you are running electric fans , a clutch fan & shroud work far better .
runnin lean will also make a ton of extra temp , make sure you ave adequate fuel supply
 
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gzig5

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I don't know about BBM's but I know that some engines can get an air bubble in the block that significantly affects the flow and cooling capability. Are you sure it is properly "burped"?
 

fasjac

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I don't know about BBM's but I know that some engines can get an air bubble in the block that significantly affects the flow and cooling capability. Are you sure it is properly "burped"?
When I first built my recent stroker, I couldn’t get it to clear out without having the front end on ramps. Can’t say that was the reason but, it burped a couple good ones in a few minutes and been fine ever since. And heater core is capped. Ha
 

Dodgeboy

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My 2 cents: if its heating up way to fast from a cold start it maybe a lean condition. I myself don't have a blower (not yet anyways) or a choke on the carb. My idle afm is at 18:1 - 20:1afm on a cold start. It settles at 13.5 once the motor is warm. Could this be your issue? Does it still idle super hot once the engine has reached operating temp.? Your base timing sounds good, but have you tried dropping it down to 10° just to see if the issue is still there?
 

Ernies

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what is your boost timing control box set at ? depending on how many pounds of boost will take out timing over all ?
 

Eric Johnson

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My 2 cents: if its heating up way to fast from a cold start it maybe a lean condition. I myself don't have a blower (not yet anyways) or a choke on the carb. My idle afm is at 18:1 - 20:1afm on a cold start. It settles at 13.5 once the motor is warm. Could this be your issue? Does it still idle super hot once the engine has reached operating temp.? Your base timing sounds good, but have you tried dropping it down to 10° just to see if the issue is still there?

I replaced my electric temp gauge with a mechanical gauge and it seems to be sitting at 180 were its supposed to be. I spent 2 days burping the system to make sure I didn't make and simple mistakes this time. I haven't driven it yet because I want to make sure I get it right first. I did find a stretched advance spring inside the distributor so I went and bought an MSD spring kit to replace that. I'm going to go try to time it again. I'm running the light advance springs that were on it since I don't know how to figure out what kind of mechanical advance curve is perfect and it seemed to like them. I tried to look in my Chilton's manual for timing specs but they're super low, like under centrifugal advance which i believe is mechanical advance it says .5 to 4 degrees initial and 10.5-12.5 degrees final? I know my engines not stock but 36 degrees final compared to 12.5 degrees final is an enormous jump. So you think running 36 degrees total and 10 degrees initial is a good start, and use the spring and stop bushing kit to achieve that amount of curve?

Dist_Spring.jpg


ManualSpecs.jpg
 

Eric Johnson

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what is your boost timing control box set at ? depending on how many pounds of boost will take out timing over all ?
I don't fully trust my boost controller. It has an adjustable dial you can adjust the amount of retard per pound of boost and it goes from 0 to 5 degrees and no matter where I turn it the car runs the same, at least as far as I can tell. The engine doesn't seem to run hot or ping at the higher rpms where the boost comes in so... That's why I'm taking a step back and disconnecting the supercharger all together and making sure the engine runs perfect carbureted first, then add the supercharger. But overall, I'm only running between 5-8 psi total. I'm not trying to go crazy with the engine, just give it a little extra.
 

craigbred

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I too had overheating problems. I have a new 440/505 stroker with 10.9:1 and alum. heads, and a 160 thermostat. Before the changes, with 90F air temp., it would creep up to around 190 going slow around town, around 180 on the highway. Since the new motor, I have been running a full shroud, Chrysler's big 7 blade fan on a fan clutch (all the blades had to be cut off to fit my factory shroud though). The fan clutch was working good because at idle with the hood open, when it was up at 190 deg, the fan was blowing a lot of air.
I tried Amsoil coolant boost (similar to Water Wetter) and only 15% Antifreeze (down from 50/50). That helped a little, maybe 5 deg or so, but it would still overrun the thermostat.

Finally I bought a new aluminum radiator, a Cold Case (to replace my old original, but re-cored factory copper rad). The problem solved!!! Earlier this week it was around 90 deg, and I was driving for about 1 hr, and it did not go over 165 deg.

At one time I had an electric fan. It could not even keep my old 440 with lower compression from overrunning the thermostat in the summer.

Also, I drilled a little hole in my thermostat to help let any bubbles back to the rad, when the thermostat is closed.
 

Dodgeboy

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The blue advance bushing should give you 21° total so if you start at 10°,you'll get 31° total. Which i would think is not enough but if the overheating is still there (not effected by the base timing) then you could adjust for 15° inital (36° total) without having to change the advance bushing. The 2 light silver springs will bring it all in by 1800-2000rpms. I don't think i'd want anymore then 36° with boost, but I am curiuos where you end up. Even the factory settings with 23° total (mech + vac) sounds low, but 8°-10° idle sounds normal for stock
 

Steve340

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It sounds like your water bypass could be blocked. All engines should have a bypass to allow (small amount) of water to flow through the cooling system while the thermostat is closed.
 
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