As cast or mildly ported Eddy’s are recommended for a stock/ mild 318 many times over. And yet a cnc ported is not recommended for a stock/mild 340 or 360. The biggest excuse is the ports are too big and the engine can’t use that much flow. Why is that? Is that about it or am I missing something? Kim
Alum Heads
- Thread starter oldkimmer
- Start date
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A 318 head is different than a 340/360 head. Is this what you are talking about?
I think it’s a load of ****. As cast for a teen should be able to carry you very far in performance. A CNC’d set just raises the bar higher. I don’t see a problem anywhere with a set CNC ported on ether engine.
It would have to be a disastrous mismatch to be bad. IMO of course.
Actually I didn’t know that. I assumed it was the same head. My mistake.
Well wouldn’t a cnc head be a disastrous mismatch on a basically stock 340/360?
I don't if that is exactly true but if so, probably 340/360 comes with decent heads so depends how much power your looking for, stock especially with a little work can make pretty good power. 318 heads are good for about 300 hp so if you want more then that could go 340/360 head but there's the compression problem then if start putting an good amount of money into them might as well go with new heads, 318/340/360 all can benefit from a good set of aluminum heads.
For mild 318/340/360 I wouldn't go cnc, speedmaster or edelbrock aren't that huge of a port they flow like a decently ported stock 340/360 head, problem with edelbrock is there the same price as trick flow I'd have hard not going with them so to me the choice is cheaper speedmasters or trick flow.
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The reason people build 318 engines are they can’t handle the bigger motors. lol!
Or their wives won’t let them have a bigger motor. LMAO!
Shall I keep going?
Sorry OP - needed a good laugh Back to you olekimmer.
Or their wives won’t let them have a bigger motor. LMAO!
Shall I keep going?
Sorry OP - needed a good laugh Back to you olekimmer.
Sure it would as I’m sure the CNC work would open up the ports to gasket size if possible. But…. Would you use a mismatched set up like below? Of course not and basically it’s stupid. Bringing it up when I know you know better is a weird question I didn’t think I’d see.
Below is an Edelbrock gasket laying on a stock steel 318 gasket.
Those look nice, but just curious how much do you have into them total when done?
My machinist is a small block Mopar guy so I traded some stuff that I had. The heads were my Dad’s.
Honest answer is , “IDK”.
Good deal then
Like mine, a mis matched pair of 273 heads and I traded porting, surfacing and set up for a few electric grinders they use to do the work.
moper
Well-Known Member
Way oversimplified, but if the goal is power, and you are talking Mopar small block head choices, put the biggest port volume on it you can and cam it properly for your goal. There’s some subtleties to that but it’s a solid rule to go by if you done need to sweat initial investment and have a specific goal or set of goals to achieve. Mopar small blocks suffer from not having enough port or flow in applications beyond 1.25-1.5/cid.once you need more than that yu gave to spend a lot to get there. It’s a market/business thing, not a design or performance thing.
I wouldn't hesitate to use a set of Trick Flow CNC heads on a any low compression small block with some thin head gaskets. You're going to see some improvement just on account of the smaller 60cc chamber. I'd much rather risk having a cylinder head that's oversize for the application with 9 plus something to one compression with some actual head flow than a smog head with 8.4:1 as a starting point for a "real" performance build. IMHO, you need all the cylinder head you can get when you're depending on atmospheric pressure to fill the cylinders...
That's exactly what i'm doing... '85 318 roller LA, with trick flows.. pistons were .055 in the hole and i used a .028 head gasket.. The math cam to (i think) 9.6:1.. haven't fired it yet though
What
Nice! What intake and cam are you going to use and what are you dropping it into?
I have a roller block too. I haven't done any math nor have I done much homework, but I was thinking zero deck and the Speedmasters I have in the basement. With the right head gasket 10.5-11 to 1 should work without detonation. Just thinking out loud. 350 horse?
10.5 with good heads and cam.. at x1.25 that's 397.. 350 should be easy
intake is a RPM cause i was worried bout hood clearance the cam is a howards roller .525 227/235 on 109 that is completely wrong.. car has 2.89 gears when i started, now it has 4.57s, cam will run out at 5800or so.. which is fine this is a temp motor to get the car mobile.. oh and a FTI 9.5" 3400 converter..
I was just building a granny cruiser but it got out of hand.. 62 belvedere btw.. it's in my sig
Nice! No doubt it would like a lot more cam with the converters and gearing, but at least you had the right mindset and optimized the drivetrain for the 318 incher. I’ve always liked the ‘62 Belvedere. If this is the temporary motor, what does the future hold?
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