Engine and transmission questions from a newbie

[40plyrod]

Hi, I'm a newbie to this and not very smart with a computer so let me know if I do anything wrong. This is a great resource for the hobbist I have used the search many times so Thanks! I'm building a 40 plymouth sedan and have some questions. I was going for a mild custom look and was going to cut the front suspension out and replace it with a mustang II but after searching the forums I decided to keep it with upgrades to disc brakes and moving the upper shock mount(thanks again) My question or two or ten is about the transmission and engine. I've always wanted to keep the flathead six in it and seeing pictures of some of the ones built up here has reinforced that but what are the differences between the american and canadian motors(mines canadian)? Also what is a spitfire head I've never seen one, What were they on? About the transmission, my car is a factory overdrive car but I was thinking about switching to a t5 because I'm scared that the old overdrive won't be up to the task and parts my be hard to find what are your thoughts? George asche is too far away for a rebuild and t5s are fairly easy to get. What am I looking for with regards to a t5? The wilcap adapter is a little pricey but is that the easiest way to adapt one? I'll stop asking questions now I'm sure you've heard enough. Thanks

[Reg Evans]

Here's what a 25" long Spitfire head looks like. I think most if not all Canadian cars had the 25" engine.

Edited January 23, 2010 by Reg Evans

[greg g]

If your car already has ad OD, you basically have the same advantage that the 5 speed will give you with parts that are designed to work to gether. The transmission is virtually bullet proof and the OD is a simple planetary set up. There are two basic types in the MOPAR the R7 and the R10. Fos some reason they were abandonded by PLymouth from 42 till 50 or so. and then they went to the R10's. I believe the r7 is the simpler and fussey unit. it will allow split shifts in 2nd third, essentialy giving you a 5 speed.

There are folks more versed than I on the OD units and their experience with them, but no one who has one that is working as designed has anything bad to say about them.

Try a search for "R7" on this forum and check All Par and do the same search.

I don't want to talk you out of the 5 speed but a OD working as designed will give you basically the same result except fo the floor shift.

Welcome to the forum, hope you get your ????'s answered.

[Don Coatney]

Welcome to the forum.

The Spitfire head was a Crashler only thing and as far as I know it was only a boost for advertising as no additional horse power gains are supported by this head.

As Greg said the Mopar overdrive transmission is almost bulletproof. Of all who have installed one I only know of two folks who have had a problem. The T-5 is also a good option if you have the skills to do the install. I have instralled a T-5 in my car and it works great. Follow the Photobucket link below and go to the T-5 album for pictures of how I did it.

[40plyrod]

How hard is it to drive the stock od? I basically saved this car from the crusher the floor had to be replaced from firewall to trunk lid as well as the rockers so I never got to drive it. There's a cable going to the transmission with a big chrome button on it that says OD. I don't see any switch or solenoid. Also is there a transmission yoke that would change it to a more modern driveshaft to mate to 10bolt posi rearend I want to install

[Captain Neon]

If you do decide to install a T5, there is a ready market for your R7. I lean towards the R10 for its ease of installation in my '46 P15S four door, but since I have no OD yet, I am keeping my options open whether it is an R7, R10, or T5. There is definitely something to be said for a transmission that I can armstrong engage versus relying on solenoids, wires, and a switch. All three are excellent choices to mate to a MoPar L6.

[Frank Elder]

Captain what is your opinion on adapters for automatics, do you think our sixes can push them, or will they be too weak?

[kencombs]

I did do some research while trying to decide whether or not to install an automatic. Aside from the cost, I think that is a very good combo. I think acceleration should be better with the auto, as the torque converter will improve 'power' from a standing start, and with a lockup circuit installed there is no slippage at speed.

The pump in the trans should only use mimimal HP, maybe 3-5 would be my estimate. My trans of choice would have been a GM 200 4R. Small and effcient with a good overdrive ratio. My next choice would be the Chrysler corp 904 or its' overdrive version, the model escapes me at the moment.

If you can reconcile the adapter, trans and incidental cost it should be a great driver.

I opted for an A933 4 speed, OD version from an early 80s slant six van. They are super strong, come with a factory Hurst shifter, and in the van the shifter was moved forward and up, great for my use in a 56 pickup w/flathead.

[Captain Neon]

My 230 L6 came mated to a pushbutton automatic out of a '56 Dodge Coronet. I didn't see any power problems with that set-up when it was in the Dodge. I simply do not know the logistics of making such an installation in a P15.

For me personally, given a choice, I always prefer a manual transmission. That is part of the reason why the T5 and R7 maintain some appeal for me. The ease of installation of the R10 appeals to me more. Having just rebuilt my standard three-speed tranny just two years ago, the installation of any OD tranny is low on my to-do list.

[Frank Elder]

I can shift as good as the next guy, for a while, but my left leg is kinda weak over the years from a F-4 incedent, just curious.

[blueskies]

...change it to a more modern driveshaft...

Here's the modern driveshaft info that I have, made the swap on my '50.

Pete

[40plyrod]

If your car already has ad OD, you basically have the same advantage that the 5 speed will give you with parts that are designed to work to gether. The transmission is virtually bullet proof and the OD is a simple planetary set up. There are two basic types in the MOPAR the R7 and the R10. Fos some reason they were abandonded by PLymouth from 42 till 50 or so. and then they went to the R10's. I believe the r7 is the simpler and fussey unit.

Thanks to all. What makes the r7 fussier? I read on blueskies website that he too had a r7 but got rid of it because it wasn't very user friendly. In what way?

[RobertKB]

Here's the modern driveshaft info that I have, made the swap on my '50.

Pete

Or get a driveshaft out of a Canadian D25 or P15 that already has modern style joints. The pictured one is on my '48 Dodge D25 and I have a parts car with the same. It would require the yokes from the tranny and differential as well. It was a Chrysler option apparently and many of the post war cars had it although my '53 Plymouth is back to the ball and trunnion type u joint.