Looking to boost the power of my 318

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Rockerdude

Rockerdude

Rock n' Roll and A-bodies
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Hey guys, I have a nice fresh .030 over 318 in my station wagon and I think it might be suffering from low compression. It has a set of fresh 915 j heads on it and the pistons in it are the trw forged units. Looking at the specs of the pistons themselves, they are supposed to come out to 8.2 compression with 68cc heads and I know for a fact my heads have bigger chambers than that. So I was considering swapping the slugs to a set of kb 399s, which are supposed to have 10.4 compression with 68cc heads.

Anyone have any input?
 
Oh yea, you have a low ratio issue. Knowing the cc amount of the heads (Both heads) would be of great help before we continue.
 
rumblefish360 said:
Oh yea, you have a low ratio issue. Knowing the cc amount of the heads (Both heads) would be of great help before we continue.
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thats what he said, but if your heads have not been surfaced a bunch you could reasonably expect them to be around 72-73 cc's. Only way to know for sure is to measure but those numbers tend to be fairly close for guestimating purposes.
 
I think you would benefit more from a cylinder head change.
 
I was considering going to a set of magnums, but Im torn in all different directions. Im not s big fan of 302 casting heads, small valve and ports to begin with.
 
To have a set of 302s done, I may as well buy a set of magnums that are already done.
 
Remember, you have a different intake bolt pattern on the Magnum heads. Unless you have the chicom knockoff intake you'll have to have the intake machined too.
 
I'd go with a magnum type head, do you know if your engines piston are zero to the deck?
 
This is always the dilemma. Your going to have to pick your poison. Weigh it out. Going the Magnum head route will cost more in extra parts to make it work, but the 1.6 ratio is a perk. I myself would look at the after market heads. The head flow is much better for what you get vs. what you pay for.

Sorry to see you short sell the 302 head. Do not think the head doesn't flow enuff to do well. It does and ported it'll do much better than you think. They port out very well and are capable.
 
rumblefish360 said:
This is always the dilemma. Your going to have to pick your poison. Weigh it out. Going the Magnum head route will cost more in extra parts to make it work, but the 1.6 ratio is a perk. I myself would look at the after market heads. The head flow is much better for what you get vs. what you pay for.

Sorry to see you short sell the 302 head. Do not think the head doesn't flow enuff to do well. It does and ported it'll do much better than you think. They port out very well and are capable.
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wasn't Wild's head porting thread on 302's?
 
By magnum type I mainly mean aftermarket, 302's are good choice if you only want to make 300hp or port them for more hp. But I think most people don't want to port or pay to have them ported so magnum make more sense in the long run and can be ported later for more power.
 
If I had a grand to drop into this swap I would go aftermarket, I don't see the point of having a set of 302s completely done when I could go for a set of rhs heads for around the same money. But since I don't, I thought it would make more sense buying a set of magnums and selling my j heads and intake to fund the rest. Or just buy a set of the kb399s and call it done.
 
Rockerdude said:
If I had a grand to drop into this swap I would go aftermarket, I don't see the point of having a set of 302s completely done when I could go for a set of rhs heads for around the same money. But since I don't, I thought it would make more sense buying a set of magnums and selling my j heads and intake to fund the rest. Or just buy a set of the kb399s and call it done.
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I can't see having a set of heads ported to the time of a grand
Unless there in need of a total rebuild. While new and larger. Albers to replace the small ones already in the head would be a added cost, did you speak to a head porter on pricing at all?

I understand you on price vs. head flow and valve size surplied.
 
Well if I found a set of old 302s out in a junk yard somewhere, and had them gone through completely to actually make some decent power, I may have well should have bought a set of new better heads. I know for a fact that porting and having heads machined costs a ton because of all the time and work involved. I was quotted $1000-1500 for a slant six head a while ago..
 
Yea, a total rebuild plus porting is pricey and a look at RHS heads is a option worthy of a look.
 
What about the Engine Quest Magnum Heads? I thought you could get them with an LA Intake and valve cover pattern?
 
Like I said earlier, I'm not looking to drop a grand into this. Just bring the compression up the most cost effective way possible.
 
Well, I ended up picking up a magnum 5.2 for a good deal from a friend. It is fresh, but I'm going to freshen it up again to make sure gasket wise and such. It's 100% stock, but I plan for a crosswind intake and my 4 barrel, and possibly a cam later. It also has the rear facing magnum exhaust manifolds (flow much better than my early-a 273 manifolds) anyone know if they will fit on my car with this motor?
 
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