I have a 69' Coupe with a ZZ3 small block and a M-20 4-speed with a 3.70 axle (manual steering/brakes, no A/C).
Being accustomed to driving big-block vehicles most of my life, I am somewhat disappointed with the level of performance of my ZZ3- Mainly low end torque.

I have recently aquired a 400 CI small block from a 71' Chevrolet (4-bolt main) that I am considering using for the basis for the C3. Tentatively, I am thinking about using the 400 short block (with the low comp dished pistons) and putting on the 58cc aluminum ZZ3 heads to bump compression to around 9.5, along with the ZZ3 aluminum intake/carb.
The questions I have are:
Has anyone done this before and what was the result?

What would be the best cam selection for this combination (I want great low and mid range torque- The motor would never go above 5500 rpm)?
A hydraulic roller cam would be trick but too expensive for what I really need. I've been toying with the old Duntov 30-30 mechanical cam idea as well just because I love the sound- But I'm not sure that is a wise decision either.

Does GM or anyone else make a 153 tooth flywheel for the 400 small block (externally balanced)?
I just put a new 10.5 clutch in about 300 miles ago and would like to avoid having to convert clutch/bellhousing/starter for the 168 tooth flywheel.

Any tips or advice would be GREATLY apprecited!
Thanks,
Elm

 

If you're using the internal components of the 400 and it came with an automatic, you should be able to cheat and use the original flex-plate from the 400 to modify your flywheel.

Just take the flex-plate (with the additional spot-welded weight) and your flywheel to a good machine shop and ask them to transfer the weight to the flywheel.

When the 400's first came out, they weren't offered with a stick transmission. If you wanted to use one in something with a stick you were out of luck… unless you transferred that weight… It worked beautifully on an old Chevy 4-wheel drive pickup for many years…

GUSTO

 

Try calling Howards Cams aka Competition Products in Oshkosh WI 1-800-233-0199. They have a "Bolt On Balance Plate" ... it may be that their P/N 4161 is correct [it's for 350 Flywheel (not flexplate) with 400 crank ... about $20. Let us know what you end up with. Also, you can buy a brand new cast iron 400 crank that is INTERNAL/NEUTRAL BALANCE for about $200. If that ZZ3 motor is later & has a later "one piece rear main seal" ... the flywheel-crank bolt pattern is different than earlier 2 piece seal motor ... so your new flywheel may not even bolt to old 400 crank. I'd check those bolt patterns first.

 

Jack, good catch, I forgot about the ZZ3 flywheel being different...

GUSTO

 

No way is a "30-30" cam going to give you good low to midrange torque in anything. That is the last cam I would choose for that application. I run it in my 302 and it is strictly a top end cam, not a very good one at that but it is correct and works well with a stock valvetrain to ridiculous RPM.

Pick one with narrower lobe centers to work with the longer stroke would be my choice. You can't beat a street roller if you have the bucks and are OK with the rest of the issues.

-Mark.