Getting my credit card# ready for a ZZ4 with the fast burn heads, rated at 425hp/460 lbs torque.....those numbers were achieved with a single plane manifold, 750 cfm carb and 1 3/4" primary tube headers....How much performance would this engine lose if a dual plane manifold and 1 5/8" headers is used. You always hear about single plane not being an ideal street application. Any input from any body would be greatly appreciated.

JR

jredding38688.3897916667

I'm not sure but I believe you might have to change the intake regardless due to the ZZ4 intake being taller and would likely make for hood clearance problems without going to a hi-rise hood. Intake height has traditonally been a problem for Corvettes without hood modifications or use of dropped base air cleaners or custom air cleaner configurations.

That being said, going with a dual plane intake would provide somewhat better idle characteristics and low end performance at the expense of some to end. The same could be said of the 1 5/8" headers as opposed to 1 3/4". Of course, a lot depends on the make and design characteristics of the intake and headers...short-tube vs. long tube headers, etc. All can make a difference.     

What you might do is call Summit Racing or Jegs and talk to their techs. Tell them your plans and what kind of driving you do and what you want out of the car and they will give you good recommendations. They each carry many brands and will give you good advice.

Thanks for the quick response, Bruce.....You just answered my question about dual-plane vs. single. Streetability is important. I replaced the original hood with an L88 one......that wouldn't be an issue.  You're right, those tech guys would be a big help.

JR

The ZZ4 in my '78 came with an intake and HEI distributor and it fit under my '78 L-82 hood with the Q-jet in place.. Nice power plant!!