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Later Pontiac motor in 55-57 Chassis
I know there is some threads on the board here about this, but much of the information is scattered about and hidden. I have a few questions about the install. I know some of the guys here have done it. I have been doing research on putting a later Pontiac motor (post 1959) into an earlier chassis (55-57 Pontiac). I know about fabricating side mounts and a later trans mount. Got that.
My questions are about installing an early timing cover on later motors and using the factory style front mount (chin mount). Okay: Please let me know if I have this right: 1960 cover was the first year of "normal" cooling and earlier timing covers are for the "reverse flow" cooling. The 1960 timing cover is not aluminum and has the mounting surfaces necessary - I think. Crank diameter is smaller on the 1960 cover (and earlier) and the best mod is to bore out the crank hole and install a newer seal as stated in this: http://www.pontiacsafari.com/L1Garag...ealUpgrade.pdf ===== Questions: ===== 1. I appears that later covers (later motors) have the same mounting surfaces to use a "chin mount". Are these covers not used because of the material used or in fact do these cover not have the mounting surfaces? 2. If using the 1960 cover on later motor, what must be done with some of the smaller water passages? I would seem there is holes that do not mate up. 3. Is there any block modifications that need to be done? Ie, drill/tap any holes in the block or cover? 4. What year gasket is recommended? Thanks for reading and I hope to get some responses :D PS: I am asking these same questions on other boards also just in case you read it there..... |
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NOT MY CAR:
I found this picture on the internet.... This looks like using a later motor (cover) and simply bolting it to the cross member. Is this wrong? Or at least bad? :confused: |
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. I appears that later covers (later motors) have the same mounting surfaces to use a "chin mount". Are these covers not used because of the material used or in fact do these cover not have the mounting surfaces? the alum covers that started to be used in '61 cannot be as strong as the earlier cast covers that were designed to hold the weight of the engine. 2. If using the 1960 cover on later motor, what must be done with some of the smaller water passages? I would seem there is holes that do not mate up. Not sure there is a problem with that but. remember, things got 'better' as time went on and Pontiac designed better and more efficient water pumps and routing for the larger engines that came out. Not sure how well an early cover/pump would work on a later, larger engine. Of course the application is an important factor when asking questions and trying to provide answers. You have not shared your intentions with us. 3. Is there any block modifications that need to be done? Ie, drill/tap any holes in the block or cover? I take this question is specific to the timing cover mount? If so, the answer is no. 4. What year gasket is recommended? I would use the gasket for the year t cover. But, check both the block and the cover you use with the gasket to make sure it seals properly. Thanks for reading and I hope to get some responses you are welcome You mention using a 'post '59 block'. I think you mean t o say 'post '58 block'? '59s were the first year with side mounts. Another very important factor you do not mention is your trans choice. If , for example you plan to use your stock trans, then swapping in a '59 or '60 389 is quite simple and effective. '61 and later engines will require more work to fit primarily because of the bellhousing change. Again, without knowing your intentions and what you want to do for a trans, I can only half guess here. One reason why the trans type is so important to know is the earlier trans mounted at the bell, the later trans mounted at the tail. If you use a later tail mounted trans with an earlier engine mounted t cover, You are putting a lot of stress on the assembly as nothing is supporting the eng/trans in the middle. |
Okay, what I am trying to understand is:
If I wanted to use, say a 1969 400, bolt it into a 1957 chassis. What would be needed to do? I understand about fabricating side mounts and the rear trans mount if I wanted to go that route... What if I were to use a 1960 timing cover? From what I have learned the 1960 is the first year of "normal" coolant flow and the last year of the iron cover that is strong enough for a "chin" mount. I have heard of others do this. I just don't have all the little details. I get the rear (bell housing mount) thing. I have a TH400 and I have the capability to fabricate such a mount to make a "mid mount". I could also make up a crossmember to use the normal TH400 mount also. I would NOT just do the "chin mount" and the normal TH400 mount. I think that would be too far apart for the mounts. :) |
Oh, when I referred to the "post 59" block.... I was thinking in reference to the coolant flow and not the side mounts that appeared in 1959. I think I have that right:
1959 - First year of side mounts, last year of "gusher/reverse" coolant flow 1960 - First year of "normal" coolant flow. Has side mounts, but timing cover is strong enough and has mounting surfaces (I think, if different than later years) to use as "chin mount". Do I have that right? :) |
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And... what about that mounting in the picture I found? That appears to be a late model motor using the timing cover as a mount. Is that smart considering I have read about the 1960 covering being the last one made of iron and having the strength to do that?
THE BELOW PICTURE IS NOT MY CAR |
Thru a couple of my threads I've posted about using a 60 cover on a 66 389 and the flat area of the front of the block sealed up with just using the 60 gasket and no changes were needed to the block. There was a change not sure when about the front of the block not being flat all the way up to seal the unused holes. This hole on the cover was pretty rough and would need machined to be able to seal up with a freeze plug. I tried with just sealer on the freeze plug and it didn't hold.
What year block are you trying to use? There are some pics of this on my Hurst mount thread . |
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Any input from anyone is greatly appreciated. I will be using a 1969 400. I wanted an idea before I tear the cover off to see what is needed and get a better idea what to expect. Question: If Pontiac no longer used the "chin mount", why is it that the newer (1960 and up) still have the mounting holes in them? Or am I just not seeing it right?:confused: Thanks |
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One thing about using the front cover mount is it should have side mounts at the trans like the original setup.
The 60 cover lower holes for the bracket use 7/16" bolts, the later aluminum covers the holes are 5/16 . Can't really say why there still there , maybe something used at the factory for assembly? So whoever did that set up in your pic is relying on 5/16 bolts in aluminum to support the front of the engine, it might be ok but not something I would recommend. |
Okay, thanks... good information.
With reference to the pictures... You have confirmed my thoughts on that install. I wasn't planning on that. As far as actually using a 1960 timing cover on a later motor... it looks like the only concerns are the coolant bypass routing for quick warm up as you did on your early motor and machining/freeze plug the unused port in the back of the 1960 cover. Then it is the crank seal mod. Is there issues with using a later vibration dampener with the older timing cover? |
Thanks Bill!
I really appreciate you knowledge. THANKS for answering the same questions on both web boards!! :D |
One main difference is the early cover only has a pointer on the cover, whereas the later have the numbers on the cover. I transferred the spacing and numbers onto the damper .
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Thanks again for all the info!
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I was going to ask some of the same for a 56 I'm contemplating buying and doing a
TH400 and later engine swap to. |
If all of this gets too hairy, I have installed a v8 in a 55 and a 50 pontiac, It was fairly easy to make a set of side mounts, One thing I would recommend is to use a 70 and later block that has provisions for mounting later year firebird motot mounts, the fire bird mounts are further forward, Its not an issue on the passenger side but on the driver side the steering box is in the way so using the more forward mounts gives you a bit of wiggle room to weld up a frame mount in front of the steering box.
also use a long shaft th400, that way the tail shaft will extend through the X brace, if you use the short shaft u joints have very little clearance and the normal up and down motion of the drive shaft wil cause it to contact the x brace, cutting enough clearance for the drive shaft weakens the x brace to the point of it being useless,. better to use the long shaft that extends through the x brace and out the back. |
56 Pontiac
Have you got any answers to your questions? I have a 56 that I’m building. Managed to find a bell housing on this blog so I can at least go to a Muncie or other trans for my 316. I talked to a guy in KS that said he uses the aluminum timing cover and front motor mount. With 600 hp engine. Not sure I believe that but I’m going to try it. If it works with the 316 I’m looking for a 389 and try that.
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front cover lower holes
On the later engines with auto trans the factory bolted brackets to the lower holes in the timing cover for the trans fluid cooling tubes.
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"On the later engines with auto trans the factory bolted brackets to the lower holes in the timing cover for the trans fluid cooling tubes."
Good info! I did not know. |
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