Big Block Perches

[66_C20]

I’m working on getting some fitment issues worked out with cramming a 454 into my 66 C20. I have the motor itself bolted in using the original motor mounts and perches that were in the truck and everything seems to fit pretty well, had to massage the firewall a little for the valve covers but I expected that. The main issue and big hurdle I have right now is gettin the headers to fit. I have a set of Doug’s shorty headers with a 3/8” flange and 1 and 3/4” primaries and they just aren’t fitting inside the frame rails very well. I expected to maybe need to trim a little of the top of the frame rail but even that wouldn’t get it done. Then I came across these big block motor mount perches from classic parts and the motor mounts they suggest using with the perches and was wanting your opinions on whether it might be worth it to spend the coin on them.

https://www.classicparts.com/1963-72...nfo/79%2D065/#

I’d gladly spend the money on them if it’ll fix the issue but I’d hate to shell out the cash for it to make no difference on header fitment. The only other idea I have is to move the motor up and forward but I don’t want to run into clearance issues with the radiator/fan and water pump pulley. So any and all help is welcomed and appreciated.

[Chevy Fleetside]

http://www.67-72chevytrucks.com/vboa...d.php?t=259536 I used the tubular mounts. Some will use the 67-72 BB mounts but I didn't want to spend the $300+ for them. These have been in my truck for 4 years+ now with no problems.

[shortstep60]

I have 68-72 big block mounts on mine did not have to do nothing to the firewall. You can buy them from Jegs for $125.00

[The Rocknrod]

Originally Posted by Chevy Fleetside

http://www.67-72chevytrucks.com/vboa...d.php?t=259536 I used the tubular mounts. Some will use the 67-72 BB mounts but I didn't want to spend the $300+ for them. These have been in my truck for 4 years+ now with no problems.

Weird, those are the exact ones I fit my small block with. Even had to trim the rails like yours. POL sells them. They look great.

[66_C20]

Originally Posted by Chevy Fleetside

http://www.67-72chevytrucks.com/vboa...d.php?t=259536 I used the tubular mounts. Some will use the 67-72 BB mounts but I didn't want to spend the $300+ for them. These have been in my truck for 4 years+ now with no problems.

Are these the ones you used and would recommend?

https://westernchassisinc.com/1963-6...-Brackets-V-8/

I’m also going to be doing a front end swap from a square body C20 for front discs/better suspension. I’m not sure if that will affect how the perches bolt to the newer model crossmember.

[Chevy Fleetside]

Originally Posted by 66_C20

Are these the ones you used and would recommend?

https://westernchassisinc.com/1963-6...-Brackets-V-8/

I’m also going to be doing a front end swap from a square body C20 for front discs/better suspension. I’m not sure if that will affect how the perches bolt to the newer model crossmember.

You can just use the engine mounts from the newer cross member. If you don't want to use the then these should bolt up no problem.

[Captainfab]

I would use either the '68-'71 factory big block brackets and mounts, or a set of brackets and mounts from a '73-'87 C20 or C30. I have no idea about fitment of your headers., Are they supposed to be for a '63-'72 truck with a big block? On my Suburban I just used Hedman headers for a '73-'87. Of course they are long tubes. When installing a big block in the '63-'67 trucks, it is advantageous to trim the top flange of the frame as was done '68+ to clear the manifolds/headers.

[shortstep60]

If you go on ebay and put in 67-72 chevy big block frame mounts you will see them for $125.00 Its getting hard to find a set off of a 67-71 chevy truck.

[66_C20]

So it looks like we have three options listed here that would work, ordering a tubular set like what I linked earlier, the motor mount perches from a square body crossmember used for disc brake swaps(they look completely different but I’ll roll with it), or perches from a 68-72 big block truck. Would it be accurate to say that all three of these options should work?

Originally Posted by Captainfab

I would use either the '68-'71 factory big block brackets and mounts, or a set of brackets and mounts from a '73-'87 C20 or C30. I have no idea about fitment of your headers., Are they supposed to be for a '63-'72 truck with a big block? On my Suburban I just used Hedman headers for a '73-'87. Of course they are long tubes. When installing a big block in the '63-'67 trucks, it is advantageous to trim the top flange of the frame as was done '68+ to clear the manifolds/headers.

The headers I have are shorties and I tried to get the smallest primaries I could to help with clearance because I knew it was going to be an issue. I don’t mind trimming the top flange of the frame but it’ll be a whole lot of trimming. So maybe using big block perches will at least help with header clearance I’m hoping so I can actually trim the top flange of the frame instead of having to hack it up.

[The Rocknrod]

On the tubular mounts you have to trim the top of the frame also. So maybe it's a common issue.

[Captainfab]

I can not speak for the aftermarket mounts, but either of the factory options I mentioned will work. If you have headers made for a big block in a truck, you shouldn't have to trim more than 1/2-3/4" off of the top flange of the frame. On my '66 Suburban, I just used a '73+ frame as a guide and trimmed accordingly. I also used headers for a '73+ with a big block.

Originally Posted by 66_C20

So it looks like we have three options listed here that would work, ordering a tubular set like what I linked earlier, the motor mount perches from a square body crossmember used for disc brake swaps(they look completely different but I’ll roll with it), or perches from a 68-72 big block truck. Would it be accurate to say that all three of these options should work?




The headers I have are shorties and I tried to get the smallest primaries I could to help with clearance because I knew it was going to be an issue. I don’t mind trimming the top flange of the frame but it’ll be a whole lot of trimming. So maybe using big block perches will at least help with header clearance I’m hoping so I can actually trim the top flange of the frame instead of having to hack it up.

[shortstep60]

I used 68-72 chevelle headers big tube they fit nice

[Captainfab]

The Chevelle headers will only work if the bellhousing crossmember is not being used.

[shortstep60]

Mine has a 700r4 with a cpp crossmember everything fits nice.

[66_C20]

Yeah I was originally going to try to use the 3OTT that came in the truck but it presents too many issues, one of which being header fitment. So I’m swapping in a turbo 400 and will be using an aftermarket tubular crossmember with it that will hopefully help with fitment/routing of the headers and the rest of the exhaust.

[Chevy Fleetside]

Mine has a 700R4 with a stock Automatic cross member. I have long tube header though.