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-   67-69 Firebird TECH (https://forums.maxperformanceinc.com/forums/forumdisplay.php?f=432)
-   -   '67 400 4 speed conversion - crossmember and cam (https://forums.maxperformanceinc.com/forums/showthread.php?t=845294)

bobzdar 10-27-2020 10:37 PM

'67 400 4 speed conversion - crossmember and cam
 
Converting my '67 400 from th400 to m22 4 speed - do I need a new crossmember? Iirc I need the th350/pg x-member to work but it's been about 10 years since I last looked into it.

Also looking to upgrade from the stock cam to a 744 style, but not sure what the modern equivalent would be, or what's new these days on that front. I had a wg1028 in my '78 400/4spd 3.23 geared t/a and it was a great match, so this car will be similar just with slightly shorter gears (3.36) but taller 1st (2.20 vs 2.40). Car has otherwise stock 400, new long branch manifolds and og ram air pans (dealer installed in 67), so basically an RA1 clone. Looking for similar power range - basically came in strong around 2500rpm and pulled to 6k. The '77 had headers and a torker 1 intake but about 2 points lower compression, so figure it'll be a wash and I'll get similar power with a little fatter low end but less top end pull due to the higher compression but less air flow.

stich 10-29-2020 10:30 AM

Crossmember works but needs to move forward about 6". You may have the holes in your frame already there. Mine is a convertible, so it is fully boxed and I had to fab up the frame bracket to accept the crossmember. I used the same driveshaft but had to change out the front yoke.
https://i.imgur.com/civITFj.jpg

tom s 10-29-2020 10:38 AM

IMO a 2.20 first gear 4 speed in our pontiacs suck unless a 3.90-4.10 gear with a 400 engine.With 455 and maybe a 3.42ish rear maybe.New M22s are avil with a lower 1st gear ratio.Tom

grandam1979 10-30-2020 07:11 PM

If it’s a Firebird you need the other cross member if it’s a A body you move it.

bobzdar 11-09-2020 01:30 AM

Ok, grabbed the th350 x- member. Iirc, the Muncie and st10 slip yoke is the same as th400 - is the driveshaft the same length?

Any thoughts on cam selection or should I just grab a melling spc3?


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