[gavin]

I am going to try to mount a late engine to 55-60 trans the same method may work up to 64 but i'm not sure as I have no access to a 61-64 trans.The first thing to do is machine up this hub adaptor.If this works I will put up a drawing but in the mean time the hub mounts the flex plate/flywheel 1/2" further back as the post 60 blocks are 1/4" longer than 55-60 blocks and the block adaptor plate is 1/4" thick as well. When you get the hub machined up make sure they put the pcd mark on the hub so when you put your flex plate on it you can mark the holes.Note the holes are not evenly spaced so you must mark them off the plate.

[gavin]

For some reason the pics did not load so I will try to add here

[gavin]

This the hub mounted to a 455 and the 56 flex plate is mounted on the hub.I will get some longer bolts tomorrow and bolt it up .The other photo is of our about to be released adaptor plate.You will be able to down load this plate on to a usb to take to your local laser cutter.Tomorrow I will show you how to modify it for this project.For manual trans the input bearing must be moved 1/2" II think we will just add a spigot to this hub design to press fit the bearing in.Back in twelve hours.

[Stuart]

Good stuff! It's great to see people providing parts and knowledge for vintage Pontiacs.

[Jack Gifford]

'56 flex plate? You'll be putting a 455 in front of a Dual-Coupling HydraMatic?

[gavin]

Its just the only complete engine on a stand that I can get at the others are on engine stands that tie up the bell housing.Please understand this is for my amusement and others education.I think the most practical engine to use is 61-62-63 and some 64 due to the starter.When I mount the starter I will bolt it all to a 62 block.Please do keep commenting if you see some thing as I have not done this before.It may be it will all go bad but it does stave off boredom.

[gavin]

This is a adaptor plate we must first cut the starter mount off it.When this done we must look at drilling the holes that match the late block out to suit a 3/8" bolt.Note the 2nd hole up is wrong its the one beside it.Alcohol induced mistake.

[gavin]

These were supposed to be drilled and tapped after the drilled round bar was welded.No real harm done you just lose 1/4" of thread.You then drill and tap for the 3/8"studs in the laser cut holes at bottom and c/sink the two holes shown.You can use a bolt in the top hole if you mod the bellhousing I prefer bolts myself.Also weld the dowels in the plate.The dowels in the block need cutting to 1/4" sticking out or again you could relieve the bell housing.When you bolt on the plate and then present the bell you will see the bell fouls the crank hub.This is fixed with some careful grinding and while you are at it you need to drill bottom bell holes out to allow the studs to go though.

[gavin]

The bell is now back on with the hub area mods done.If you look at the arrows you can see with some work you could use bolts here.The studs and nuts need to be as short as possible as they get very close to the flex plate.Its a miss but not by much.Next we look at the starter I think it will foul the 65 and later blocks unless you grind the starter pad.We will see tomorrow.I just need to get the flex plate studs lined up and I think it will bolt together.

[BruceWilkie]

Hey Gavin... it should clear. The thicker 55-60 stater adapter I made is still rectangular and adapter clears pan rail by @ 1/16" . The starter flange is below that. (I have bolts clocked at 57 deg not 60 like stock 55-60)

Hydramatic and early flywheels are 14.625" vs 13.98" of t400 and later stick cars. The upper starter bolt on the 55-60's is @ .625" above pan rail and bolt/stud goes thru housing.

Not sure its the same on 61-64... larger radius bolt pattern of 61-64 starter leads me to think the upper starter bolt may have still gone thru or into housing. My sons 64 BonnieBrougham 389 (4brl single exhaust)had the superhydramatic, the "upside down""421" starter(which was original to the car). The 64 block did have holes drilled and tapped for the "modern" delco. I saw that when I rebuilt the starter around 2001. Wish he hadnt sold it. I cant recall all the details that far back lol!

In 64 the blocks were made to accomodate the new style starter used on A body.

[gavin]

Well.The whole assembly bolted together perfectly and would work very well.Now the bad news the starter is going to be a problem.I knew it would foul on the later blocks but was hoping it would be ok on the 62 block.The starter flange seats on the mounting but you cant rotate it around enough to get the bolts in.On a drill press you could redrill the holes and maybe relieve the cage around the pinion gear and it would probably work.As the g/box is not mine I cant really play with it too much.As I was trying to do something so any one could easily do it I guess its a fail.The real tragedy is I wasted a day that I could have been in the pool drinking.Any way here are some more pics.Kids don't try this at home.

[59safaricat]

WHOA! A 455 mounted to a dual coupling hydro is gonna be a crazy wicked setup. Getting traction in that monster low 3.97 first gear will be a fun challenge to take on.

Any plans to rebuild the hydro for maximum durability?

I'll be eagerly following this thread

[Bill Hanlon]

Don't know if it would help, but somewhere in the garage attic I think I still have a starter nose for a Pontiac starter that was used on V8 GMC (Pontiac) starters that clocked the solenoid to about the 5 o'clock position. If it could help, let me know and I'll dig it out.

[gavin]

Bill a photo would be very welcome as it happens a buddy of mine is working on a 56 GMC But because now I am back at work on the island it will be four weeks before I can take a look.While I did it just to see if it could be done I dont like failing so it would nice to finish it.It does sound like a likely item that starter nose. 69 Its on the 455 because the 455 is on a stand that I could get at Im really just playing.However if I get it working and someone is really going use it pay the postage for the hub and plate and they can have it the catch is with my work it might be a while.That stater is as I think about it maybe the answer for another problem.When the plate is used as an adapter on 61-64 to turbo it might work well there.Yes please send a photo.

[Bill Hanlon]

Just spent an hour in the garage attic with no luck. I've sold off most of the good stuff I had up there over the last 2 years and that GMC end bell must have gone with it. Sorry. Take a look at your buddy's GMC starter when you get a chance and see if it will help. Basically, it just moves the solenoid from the top around to about the 4-5 o'clock position.

[gavin]

Thanks bill I gave my buddy with the GMC a ring and he is going send a pic to me.Good info we will see if it works.

[ClassicDriverMan]

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[Rocky 389]

Don't know if this grainy photo helps but it's of a 57 GMC bell housing and starter I use to own. The solenoid was on the bottom of the starter when installed. I don't have any more photos of the starter, sorry.
I can tell you the starter for my 1959 car stick bellhousing [different from GMC] requires a shorter nose than the same year automatic starters.

[gavin]

Thanks for the info rocky It does look like the starter would work.I will try to track one down.The starter nose info is interesting to.Perhaps the solenoid position was changed to avoid heat soak in a heavy duty application.

[59safaricat]

Any progress thus far? My curiosity is still piquing.