Engine/Transmission Part Selection

[carfreak6970]

Hello Folks,

This really isnt an "issue" per-say, but I need some help determining cam, pistons, torque converter, and various other trans part for a vehicle:

The vehicle is a 70 charger. This is an original 440 6 pack car, with the original drive tran long gone. It has a 440 and a 727 from an early 70's imperial, so that is what we are working with. We have what we think is the original intake with all the 6 pack induction stuff. The car currently has a 3.23 sure-grip 8 3/4, but we may change that to 3.55's. The transmission is currently apart and awaiting new parts to be reassembled. The engine is also apart and being dropped off at the machine shop this weekend with the crank, main caps, and piston/rods. It will most likely need a bore and a decking. It will get all new bearings. It is going to a shop that builds race engines where the owner of the car cousin is married to a guy that works there.

So with keeping the 3.55 and 3.23 in mind, we would like to make the car a good cruiser with some stop light pulls and entrance ramps romp. The car would be located in the state college PA area with making runs to Altoona PA for work. So that is about 50-70 miles round trip (hence wanting to keep the 3.23 and maybe the switch to 3.55's) on interstates that really do not get that crowded.

We would like to keep the iron heads since they were redone before the car was taken off the road in the early 90's (I may try to influence him to get them looked at again just in case). Now I do not know what casting they are... I will try and get that information so we can get a rough idea of combustion chamber volume. But what would be a good piston/cam selection for running premium fuel on the street for a street car that would maybe see the track once in its life time with the occasional right foot abuse from a hot headed almost 30 year old like me? One stipulation is that the owner doesnt want the "thumpity-thump" at idle... I find that to be lame, but hey his car and I am more than happy to help him put this important piece back on the road with him

Second would be converter. I know my old man always used the stock ones, but seeing how this came out of a C-body, Im sure the converter really isnt matched properly for a car with slightly more power and lighter. So what would be a good converter choice for this car given the intended purpose?

Thirdly, what would need to be done to the transmission? From my research there were a couple internal differences between the "high performance" 727 and the "standard duty" 727. To my understanding that would be the amount of pinions and the amount of clutches and springs. I want to at least make the transmission the high performance variant of the 727. Would there be anything else I should spec out for the trans? I am not to sure a shift kit is needed, but the owner does not want to break his neck during shifts, he is use to the shifting in his 70 383 Polara. But he does realize that the shifting should be a little crisper with a vehicle like a 70 6 pack B body.

Again this is just going to be a cruiser. It will be driven in the summer on nice days. Im sure if there is a 40% chance or greater of precipitation it wont come out.

I appreciate all of the help. thank you

 

[turbodart68]

I like the sound of this build. I own a six pack car myself and I have found a few things that six pack cars like. One thing for sure and especially if he is looking for a cruiser and occasional bruiser, I would build it mostly stock. So lets start from the top. Six pack induction is fine. The heads I would talk him into the 440 source aluminum heads because its hard to redo a set of stock heads for the money and they flow half way decent plus they look stock. If he insists on using the head he already has then thats fine too. Just know aside from valve size pretty much all the big block heads are esentially the same. Cam, I would use a comp XE270 myself but it will have a little lope to it as the factory 6 pack cam will too. You really can't go wrong with the 6 pack report cam but the comp 270 will make another 20-25 hp. The bottom end will be stock everything except the pistons, I would use KB zero deck flat tops KB237. I would use the .041 thick gel pro gasket and with the stock open chamber head it'll be around 9.8 to 1 compression. The problem with a steel head small cam and almost 10 to 1 compression is that it will want to detonate on a hot day but you can take a little timing out of it and it'll do just fine. Thats where the 440 source aluminum head is good it does away with that because of aluminums ability to absorb heat. So converter, you will want to spend a good amount of money here because its not just about stall speed. I would go with a tight 10 inch converter with 2800-3000 or so of stall speed. You will get better torque multiplication out of it and it'll soften the hit at the shift at part throttle plus it'll wake it up with the highway gear. These motors really only have a 1500-2000 rpm power band and its nice for it to flash into its power band when you floor it. The trans, most 727s are the same with the Hemi and some 6 packs having the four gear planetary. He doesn't really need that and a stock rebuild with a 4.2 kick down lever and a trans go 2 stage shift kit would do great. I would go with the 3.55 rear gear over the 3.23 because at the end of the day there is about 200rpm difference of rpm at highway speed but it really helps in the torque multiplication. It sounds like a fun car and was this your dads car or another Charger R/T?

 

[carfreak6970]

The 6 pack car is the friends car. He had this car since the mid 80's. The old man picked up his in the early 2000's. Funny thing is that we got the old man's charger on the road way before our friend even started on his 6 pack charger. So Id like to think it was the ride in the old mans charger that woke the friend up to finally get working on his 6 pack car.

But thank you for the suggestions! and the tid bit of information about detonation on hot days. The old mans charger pinged a little bit under load over the summer and I thought it had to deal with timing being off, but I really couldnt replicate it in the fall. So I will keep that in mind when I start to really dive into tuning that car.