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Well I think I decided to go with a ZZ4 motor. I have some questions regarding headers. I want to retain my stock sidepipes. Have any of you put headers on a ZZ4 motor with the "D" shaped ports? if so have any of you retained your stock 69 style side pipes?
I need to figure out who makes a shorter header for the heads used on the ZZ4's. I don't think mid length or long tubes will work with the side pipes.
Do you have stock exhaust manifolds on your car? If so then you can put them on a ZZ4, if you want headers then connecting them to stock side pipes it is a little harder, unless you use shorty headers. Either shorty headers or you'll have to come up with some creative "S" curves from the collectors to where the sidepipes come out from under the car.
Don't worry too much about the "raised D port" exhaust ports, they are only about .25-.30 higher than stock ports and really not shaped all that differently than stock heads. The difference in height on the ports doesn't really affect how the exhaust hooks up since you can pretty easily find that amount of play in the up and down movement of the stock exhaust.
I bought a set of "D" port headers from hedman for my 73,I have had them about 6 months and I like them,They were a bit hard to install but worth the trouble :)
Here are the Headman Headers with "D" shaped ports for the ZZ4. Since you have side exhaust then these will not work unless you go back to undercar exhaust. Everyone is probably correct when they talk about the performance loss over oval ports but if you were a serious racer and were looking for every advantage then port matching is one thing that can be done to squeeze out that extra 1 to 2 HP...which may make the difference between beating that Rustang or loosing to it.:D
From: Exiled to Richmond, VA - Finally sold my house in Murfreesboro, TN ?? Corner of "Bumf*&k and 'You've got a purdy mouth'."
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St. Jude Donor '06-'10, '13
Re: Question for ZZ4 owners (theandies)
In the GM manual for the ZZ4 they talk about the D ports. They say that testing with both D port headers and standard headers produced the same results. You are actually connecting to a larger area so there is no flow restriction.