Topic: 400f tranny in 350f cases?

[Jay B]

I'm sitting here with to much time on my hands nursing broken ribs. I've got my 350f rebuilt and running great, but I'm thinking ahead to next winter. I know a 350f and 400f are very  similar beasts. I'm wondering if a 6 speed from a 400f would go into a 350f's cases without mods to the case. You see them on eBay once in a while, and that 6th gear would sure be nice.....

[heffay]

with no mods to the case?... don't believe so.

[GroovieGhoulie]

Could you drop a 400 engine into a 350 frame and bolt up the 350 exhaust for the right look?

Might give you a little more oomph.

[heffay]

groovie... i'm pretty sure that's an option but, why chose the 350 exhaust over the beautifully swoopy 400f's?   i mean, if you've already got a non-stock motor why try to keep it stock?  you see what i mean?

[GroovieGhoulie]

I agree with the 400F exhaust looking better, but if you're trying to make a "sleeper", then 350 exhausts might be the way to go.  The cases are immediately recognizable as 400F cases, especially the clutch, but the 350 seat, bars and tank all combine for a certain image and the 4-into-4 350 exhaust ties into that image perfectly.  The 400F exhaust, while superior in look and function, would seem out of place, to me at least.

If I were making a shamless hybrid, I wouldn't hesitate to use the 400 exhaust, but since the 400 is a punched out 350 with better heads, it would be like a "factory" big-bore upgrade on a 350.

[Jay B]

If I would've come across a 400f motor I'd have put it in there in a heartbeat, but I've got this one all rebuilt now. So what's better about 400 heads, bigger valves, higher CR or what? Damn, the wheels are turning again.

[GroovieGhoulie]

They fit the bigger bore and are larger so they have bigger valves and breathe a little better.

It's not much as the valve angle in the heads didn't lend itself to much increased duration or lift.  Yoshimura and the others did what they could with cams, but it wasn't much.

Also the 400's CR was higher by a point: 9.4:1 versus 9.3:1.

You MAY be able to drop 400 jugs and pistons and head onto a 350 bottom end as the crank and rods were the same, but I would leave it as is.  The 350 is great as it is.  You would spend more money to 400-ize your 350 than it would cost to get a 400.

[heffay]

yes... ghoolie, i agree.  i picked up a 350 motor not long ago for 50 bucks... supposedly runs although i've never tested it.  just an example of how cheap you might be able to pick up a complete motor.

also, i agree about the 350 being great "as it is".