Smallest non-Magnum head chambers?

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NWDave

NWDave

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I have a 1971 Valiant, with a stock 318 2brl engine, that was rebuilt by the previous owner. I would like to add some performance, via headers, cam, intake & carb, and want to get some better flowing heads.

What heads can I add, that have a small enough combustion chamber to keep the comp ratio up, and give me some boost in power?
 
DO you have something against magnum heads? They could work pretty well on a 318 with the other things you want to do.
 
1986-1991 318 2-bbl. heads, a.k.a. #302 castings (casting number ends with 302). They have small, closed chambers and swirl ports that will increase low-end torque and gas mileage. They don't flow too much better (in stock form) overall than earlier 318 heads but they take very well to porting. Just make sure if you pull a pair off of a junkyard engine you have it checked for cracks between the valve seats, as it's a very common issue on heads from these years.
 
I have a 1995 Jeep Grand Cherokee, with the 5.2 Magnum engine, and really like the power it has. I was wanting to stick to a stock type setup with the heads on the 1971 318, but the Magnum heads do have a lot of advantages.
 
Magnum heads flow so good. I pulled a set for $75 at the local salvage. They can be found for cheap. Take them to your machine guy. Install GM beehive springs and retainers. Moderate cam. Good intake, carb and headers. Bam. 300 hp easy
 
You can pick them up pretty cheap too. I sold a set for 150 a few weeks ago that had a fresh valve job, head bolts, and valve covers too. If i were gonna build a 318 tomorrow I'd zero deck it and use magnums. A nice comp cam over .500 lift, single plane Edde intake, and surprise the hell out of a lot of people. Especially in that 71 valiant 4 door!!!
 
Just went to the Pull-A-Part junk yard yesterday, and saw 3 sets of Magnum heads. They all had fairly high miles on them though, and would be in need of a rebuild before I'd go through the time and effort of installing them on the car.
 
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