[Jack T]

I have aftermarket chrome rocker arm covers on my 440 Magnum that are rusted and need replacing, so I'm wondering what kind came on the engine originally in a Challenger R/T SE. Does anyone know what really belongs on it?

[dave-r]

All mopar engines came with painted valve covers from the factory except for mid-'60s hemis and Formula S Barracudas etc which were chrome.

This is what a 1970 440 Six Pack looks like.

Just about the whole engine was painted in one go with all the major parts in place. The valve covers were painted with any rubber gromets or oil filler caps in place so they are painted as well. The covers were held in place with 1/4 inch bolts but in two holes each side they used studs and nuts. The placement of these is erratic but usually they were in the end locations.

[Jack T]

What is the oversize boring limit for a 440 block? I've heard about one that's for sale that has been bored 90 thousandths over and I'm wondering if it's been ruined or not. Thanks for the help on this one.

[dave-r]

The 440 is what is known as a 'thin wall' casting. This makes the block lighter and cheaper to cast. However that also makes the cylinder walls thinner. The less it is over-bored the stronger it is and the less distortion and flex you get in the cylinder walls. 40thou is normally considered the 'safe' limit. 60thou is pushing your luck a little but people seem to get away with it although some blocks and most later blocks will not like it. I have NEVER heard of a stock block being taken out to 90thou over. Maybe it has had special liners welded in or something?

[Frank V (Rtse)]

i think this question belongs here ...i was in a discussion w/another mopar nut and we started talking about engines and how they are balanced externally w/forged crank, internally-cast crank he then said he believed you could run a cast crank on the externally balanced ..say 440 - 383 engine without any problems up to 500hp i say you would have vibration in the engine and not good engine life even if the engine never got into the 500 hp range...why would a person want to do this? we agreed forged cranks are expensive and IF a guy(cheap one..lol)wanted to set up an engine this way it would be a way to do it...he did present some good points so i am not totally sure i am right....

[Dave-R (Roppa440)]

Every crank has to be balanced with the rods and pistons to be used. I am sure it is not true that all forged cranks were external balanced and all cast internal.

The external balanced forged 440 cranks were the ones with the six-pack rods. This is because of the weight of these rods. If you didn't have six-pack rods your engine was internally balanced.

At any rate. If you use the rods, harmonic balancer, and torque convertor type that came with the crank it makes no difference what engine you put it in.

[Tig (Cathtig)]

Hot rod did an article a few years back on a cast crank 440. They managed to get just under 700 hp out of it with no problems. I've heard of a 600 hp cast crank motor being reliable for seasons so I guess 700 hp might be possible. Personally at this level I'd go for a good steel one. So 500 hp should be a cinch for a cast crank. I used to run an 11 second cast crank motor and it was never any trouble.

[Frank V (Rtse)]

hmmm...my thinking was that the cast crank would throw the balance off. though you can compensate for any unbalance seems like alot of work! besides the strength of forged cranks i always thought that was why they ran externally balanced components w/it- to complement it, i did not even think about the 6 pac rods nor did it enter the conversation...thanks for your insight...

[Dave-R (Roppa440)]

When you get a crank balanced it is always balanced with everything that rotates with the crank. Or it should be.

Whenever you change pistons or rods you should always get the whole thing balanced.

[Frank V (Rtse)]

dave... i guess i was not clear w/the type of balance. i did not mean the balance of the rods or pistons what i was refering to was the harmonic balancer and flywheel i have always thought(not always the best thing for me..lol) the reason there are two different types of harmonic balancers and two different types of flywheels was BECAUSE of the differrent balanced cranks this was the topic we were talking about weather or not NOT changing to the right harmonic balancer/flywheel would cause the vibration he contended that this would not be a problem(engine lifewise) as long as the engine only made a maximum of 500hp....i think a person should not give a engine any chance of imbalance and though i am aware ANYTHING can be balanced it just doesnt seem right to me to use a part not designed for a certain application, this is my problem....

[Dave-R (Roppa440)]

What do you think is being balanced on the crank?

What on earth do you think the huge counter-weights on the crank are for?

The rods and pistons are part of the rotating mass. Remove them and you would not need the counter weights on the crank and it would not need balancing!

The mass of the counter-weights on the crank have to match the mass of the rods and pistons. It is not in practice as simple as that but we don't need to go into that.

For instance when you fit lighter after market pistons you also need to remove some weight from the counter-weights. This is balancing the crank!

In the cast crank the counter weights are not as heavy and so need some help with a harmonic balancer that has an offset weight built in. At the other end of the crank they also add weights to the torque convertor.

The six-pack rods are so heavy even the counter weights on the forged crank were not heavy enough. So they used external balancing on that as well.

I had my six pack crank and rods internally balanced. The guy that did it had never had to add so much mallory metal to a crank before. Mallory metal is a very heavy metal added to the counter weights to balance the crank. It would have been a lot easier to stick with the original external balanced harmonic damper.

Running an engine that has not been balanced or is well out of balance will cause bad vibrations and loose you power. Simple as that.

[Frank V (Rtse)]

hmmm.,,, we are still not addressing the fact that there are 2 different types of harmonic balancers and 2 different types of flywheeels these are used on 2 different types of cranks for what reason?... i have read back thru these posts and think i have been clear on what i am asking here its not how an engine is balanced, but if using a externally balanced harmonic balancer, cast crank, externally balanced flywheel, would cause vibration. i say it will because cast cranks are balanced internally,so my logic is they would throw each other out by trying to balance internally AND externally,how does this not make sense?

[Dave-R (Roppa440)]

Yep! I guess we are talking cross purposes here Frank and my reply above looks rude to me when I read it now. But that's not how it was written!

Let me try again. If you don't understand that is due to my inability to put accross what I mean in writing.

Cast cranks are balanced EXTERNALLY in the main Frank. Some forged are too. So using a cast crank with the external balance damper and flywheel is how it came from the factory anyway!

No wonder we are getting confused.

If your engine was originally externally balanced it is best to use the harmonic damper for that application. BUT YOU DON'T HAVE TO IF YOU ARE GETTING IT BALANCED ANYWAY! And you should ALWAYS get it balanced if you are putting together non-stock parts!!

Most if not all dampers built to race or NHRA spec are for internal balanced cranks.

If your forged crank is internally balanced and you use an external balanced crank you could still get it to work by lightening the crank.

Basically the answer is if you are swapping parts around in a non-stock way without getting the whole thing balanced you are madder than I am. Changing ANYTHING that alters the balance will cause vibration and stress on parts.

[Frank V (Rtse)]

ahh....ok this is what i thought your answer would be the first time....lmao, when i worked for a dyno company they put some HUGE weight on a certain type of drum to get it to balance so i have seen first hand the ability to get ANYTHING to be in balance ...it cost them alot to do it though