[e3pres]

I took delivery of a 1958 Chieftain today! Much to my surprise, when it was delivered, I found that it had a 1964 389 installed... very poorly. New motor mounts had been welded to the crossmember to bolt to the block. I'm assuming that the bell housing has been swapped as I believe the trans is the original Hydramatic unit. I need to get it on a lift to find out for sure (P is all the way down... does anyone have a link to trans ID info?). Can someone post some pictures of what the stock rear motor mounts look like and how they bolt up? I guess at this point, I'll have to decided if I should rebuild the mounts and fix the problems with them (the exhaust manifolds are touching the upper a-arms, I'm sure that the driveshaft angles must be all wrong, etc.), or find a 370 with a bell housing and brackets to put the car back as it should be.

Ideas? Any help would be appreciated.


Thanks,

Adam

[BVR421]

Adam sorry no pics, but a few thoughts about one of my favorite year Pontiacs.
Havent had a 58 since I was a kid. Recall the 2 rear bellhousing motor mounts and the front center mount under the cast iron timing cover. Put a GTO cam in my Chieftain coupe when I was 16. Be glad you didnt watch.
P (park) is all the way down? actually? or only on the indicator? My 63 indicator still has original marks but the actual th400 detent pattern on trans is far different.
A 58 Hydramatic would have an all cast iron bellhousing and trans case. Might have the 64 trans to match motor as the bellhousing bolt pattern is different than the 58, either 3sp Roto Hydramatic (very small diameter trans overall) or the last year in 64, 4sp aluminum hydro. Roto sort of sucks, 4sp Hydro is sweet. Either 64 automatic will have the starter that bolts to the bellhousing. Most, not all 64 engine blocks had the holes drilled in the block for the then new for 64 block mount starter used on GTO s and B bodies with 4sp manual trans.
If the 64 motor runs well Id clean up the install and use it. Much less trouble prone in the valve train oiling area. 58 heads oiled thru the hollow rocker stud instead of the pushrod. an elegant solution but prone to plugging the rocker stud pinhole with sludge as the early oil filter was not that great and the PCV road draft tube was not very effective at clearing sludge producing acid vapors from the crankcase.
Original 58 parts should be available from Steve at Pontiac Heaven.

[e3pres]

Sorry, I meant Reverse was all the way down.

[Stuart]

I can't comment on the motor mount situation, but reverse all the way down is how all those old Hydramatics (1964 and earlier) were configured. The one in your car could be the original transmission or it could be the mate to the 1964 engine; they were different transmissions, Steve P is our resident transmission expert and can tell you how to tell which one you have.

[Bill Eveland]

55-58 used the front mount . Up to 60 is still a steel cover. After that like yours is aluminum and I would not recommend the front mount under that cover. I have mounted a 60 cover on my 66 389 so it's possible to get a 60 cover and go back to the front mount deal. 55-59 is reverse cooling so I wouldn't use an early cover. 60 is pretty much the only one to work for these reasons. But this requires some type of side support, either similar to the rear 2 side mounts or some type of midplate or support so the tailshaft of the trans doesn't break. I built side mounts for my 55 but have since went back to the front mount set up with the 60 cover.

I built these to go along with my front mount since my th400 doesn't have any side mounts, only the rear tailshaft mount.



Or redo your side mounts , the 2 rear mounts are on the side of the trans. But if your keeping your engine/trans configuration and don't have these mounts on your trans than I probably wouldn't worry about it and fix what you have.

[e3pres]

Okay, so I can swap the front cover on my '64 389 for a '60 front cover with the early style front mount and add side mounts like yours between the bell housing and frame?

That seems easy enough.

[Bill Eveland]

There are 2 pieces under the cover, a bracket than the mount. And depending on you accesories, and the 60 cover does not mate directly to the front of the intake, a pipe and hose are used. It's never that easy! At least for me anyway, there are always bumps in the road along the way.

I would try to fix what you have now if possible.

[Jack Gifford]

Nice work on those rear mounts, Bill.

[Bill Eveland]

Thanks, I got those engine brackets from Speedway. You can see the top unused bolt hole for the Chevy trans it was designed for, the middle hole is for the dowel pins if you mount these between the engine and trans. I had to cut away part of the bracket than refill in with the welder to get the top bolt hole there. The frame master cylinder is in the place on the other side (i'm mounting it on the firewall anyway, but that area sticks out on the frame) and I had to extend the other bracket downward. If it wasn't for my headers in the way (which really should be fenderwell headers), I would have used the original trans cross member to tie into.

[PRC]

Bill,
Those mounts look nice but here is a word of caution. My '57 had a similar setup to mount a '59 engine and a 4 speed trans. The original crossmember was not used, just mounts from the bellhousing to each framerail like you have. This setup was in place for at least 30 years. Over that time the weight of the engine and trans actually caused the framerails to bow outward slightly. I would hate to see the same thing happen to your car. Just make sure that you have something tying the framerails together. My car now has the original crossmember at the bellhousing and an added crossmember at the tail of the trans.

[Bill Eveland]

PRC, thanks for the info. If it matters The front engine crossmember is also removed and the front radiator crossmember is boxed in with 1/4" plate, and i'm running a Hurst mount. More pics are in my 55 Pontiac progress thread. I was thinking about adding in a bar between my front leaf spring mounts for support.