Jul 5th, 00, 03:12 PM
I have a 69Z with stock 302 dz motor. Previous owner has installed headers, not sure of the brand. I am looking to replace the headers later this year with ceramic coated hooker super comps. What is the best choice of header size and collector with the 186 heads and dz302 motor. 1 5/8 or 1 3/4. Right now I am running 2 inch duals thru flowmaster 40 series, I also plan to order the chambered exhaust reproduction from Gardner exhaust, and have the chambered modified to weld up to the headers. Thanks
Jul 5th, 00, 06:19 PM
I'd go with 1 5/8" for a street car with stock type iron heads. If you were drag racing with steep gears, roller cam, ported heads, and open headers, maybe 1 3/4".
Just my guess.
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Jul 5th, 00, 06:39 PM
I have a beefed up 302 and I went with the stainless headers through summit racing (borla makes them). They are 1 5/8, but with the 302 the smaller tube headers should help the bottom end power alittle. I havn't put them in yet, heard they fit well (dave).
Jul 5th, 00, 08:16 PM
What about Doug Thorley Tri-Y's. These headers are designed to increase low end torque, which the 302 tend to lack. They will also provide plenty of top end air flow especially since you only have a 302. I have a set of these on my Camaro, they have great ground clearance. I would consider these for any project I build in the future.
Jul 6th, 00, 06:26 AM
Forget about trying to increase the low end torque with your 302. It can be done but you will suffer on the big end. I'm running 1 7/8 Hooker Super Comps on my 302 into a full 3in exhaust with Flowmaster 2 chamber mufflers, runs great. The thing to rember is that the 302 is an RPM motor that was designed for road racing not drag racing. If you want a 302 to come out of the hole hard you have to do it through rear end gearing (running 4.56 myself). My motor is 302cid but not stock as far as intake, valve train and heads go. If your going to run your motor in a more stock configuration I would go with the 1 3/4 and let it breath, they need it at 8000+ rpm. Good luck and happy motoring.
Bob 69 302 Z
Jul 6th, 00, 10:38 AM
Ed from Hedders by Ed recommends 1-5/8" tubing if the car is going to be driven on the street. 1-3/4" is only for true race cars since street cars spend 99% of their time below the rpm range where the 1-3/4" becomes useful. I plan on running the crossram with ported 492 heads and 1-3/4" factory style headers just to make the car look like a factory race car.
Jeff H - 93 Indy 500 Pace Car, Hugger Orange 69 Z28 with JL8 brakes
Jul 6th, 00, 06:20 PM
I would run the 1 5/8 unless you run your motor over 7000 rpm. I have raced and built several 302 ford engines that ran 11-12 sec. 1/4 mile times with 1 5/8 headers. Yes I said Ford, but the principles are the same. It will hurt your torque curve if you run bigger headers. You are much better off to replace your exhaust:get a 2 1/2 inch mandrel bent exhaust with a crossover and 2 1/2 mufflers, if you are running tailpipes make sure they are mandrel bent as well. There are so many people running headers and then shooting themselvs in the foot by having a kinked up poor flowing exhaust. Doug Thorley and Flowmaster are some of the many who make complete kits.