[Joog]

Hello, I was interested in 400 swapping a 55-57 chieftain. But I realized the motor mounts on a 400 are located on the passenger and driver side while a 55-57 are not set up like this.

Are there any motor mounts on the internet or someone else that makes them that will work for this application?

Is there any way I can custom make/weld motor mounts from a GTO, Firebird, or other factory 400 car to fit the 55-57 on the passenger and driver side?

[242177P]

Two examples of what the 55-57 Chevy guys use. SBC/BBC mounts are forward of where the 64-72 mounts are, but the later 400 blocks have other mounting options. You might be able to use a smog-era clamshell block mount with the Chebby pedestals? Dunno. If not, something like the late-to-early Pontiac motor mount adaptor plates might allow you infinitely more flexibility? Again, dunno. Hope this helps

[Joog]

I am using a 69 big body 400. Also, is that mount located on the crossmember or the frame rail? Because on my application the guy deleted the factory cross member and put a new bar further forward.

[Joog]

[QUOTE=242177P;6547396]Two examples of what the 55-57 Chevy guys use. SBC/BBC mounts are forward of where the 64-72 mounts are, but the later 400 blocks have other mounting options. You might be able to use a smog-era clamshell block mount with the Chebby pedestals? Dunno. If not, something like the late-to-early Pontiac motor mount adaptor plates might allow you infinitely more flexibility? Again, dunno. Hope this helps

I am using a 69 big body 400. Also, is that mount located on the crossmember or the frame rail? Because on my application the guy deleted the factory cross member and put a new bar further forward.

[Bill Hanlon]

Wait for Bill Eveland to check in. He'll know. Check out his Pontiac here:

https://forums.maxperformanceinc.com...r.php?u=137381

[Joog]

I’ve contacted him prior on the HAMB, but I was waiting for a response on a picture of how he put together those motor mounts!

[Tom63LeMans]

I copied the basic design of the Hurst 2nd design brackets for use in my ‘56. Since it’s a gasser and I was removing the factory crossover I moved the mount location back and inward from the Hurst design. They can be duplicated very easily with angle and flat steel. I will find a link that details measurements of the Hurst brackets.

[Tom63LeMans]

Here is the link to a Hamb post showing the mounts and also measurements of the brackets.
https://www.jalopyjournal.com/forum/...ontiac.998644/

[Joog]

Originally Posted by Tom63LeMans

Here is the link to a Hamb post showing the mounts and also measurements of the brackets.
https://www.jalopyjournal.com/forum/...ontiac.998644/

Thanks! Did you copy that design from the HAMB? I'm also doing a gasser build. And I think I saw your 56 at Pontiac nationals.

[Tom63LeMans]

Originally Posted by Joog

Thanks! Did you copy that design from the HAMB? I'm also doing a gasser build. And I think I saw your 56 at Pontiac nationals.

Yes that’s me. I used the Hamb post for some of the measurements and the basic idea. I didn’t care for how far forward the mounts were from the engine bolts but understood it was done that way to reach the original crossmember. I originally was not going to add a mid plate so I was concerned about stress on the bellhousing. I did end up adding a mid plate too.

[Joog]

Originally Posted by Tom63LeMans

Yes that’s me. I used the Hamb post for some of the measurements and the basic idea. I didn’t care for how far forward the mounts were from the engine bolts but understood it was done that way to reach the original crossmember. I originally was not going to add a mid plate so I was concerned about stress on the bellhousing. I did end up adding a mid plate too.

Alright, do you by chance have a photo of where and how you connected the bracket to the frame? And possibly a picture of the midplate.

[b-man]

The Chevy headers are your starting point.

You will have to finagle a way to weld them to Pontiac header flanges, above average fabrication and welding skills definitely required.

The only way Chevy headers can be used without modification is to use a Chevy engine.