How can I tell if the Heads are Closed Chamber

[Plum_Crazy_Purp]

So I have a 1970 dodge dart...A 318 with 360 heads so im running at about 7 to 1 so im looking for closed chamber heads...How can I tell if the heads are closed chamber other than casting numbers and what type of closed chambers for my 318 do you think is best?

[70AARCuda]

none of the LA 360 heads are close chamber....

the 302 heads for a 318 are close chamber and that is it...

casting number will tell you what kind of head you have...

magnum heads are close chambers....

[DonCarr]

Cheapest way to go may be to mill the open chambers right off those 360 heads (+ mill intake).

It's a lot of milling, over 1/10"

Maybe someone here has experience with this?

[adodgemann]

old 273 heads are closed chamber, found a set off a 318 motorhome that were too.

[hotroddave40]

315 and 920 are 273 closed chamber heads, I thinnk there is one more 273 head casting number that is closed but the 920 is the one you want, it is from a 67 273. 302 and 920 are 318 closed chamber heads. The 920 heads are 67 only heads for both the 273 and 318. The early 273 heads have a little bit of a funky intake bolt pattern, you can wallow out the holes in your intake to use them though. The 302 would be my second choice, they have a larger chamber but higher swirl and smaller ports with a tad less flow, you probably wouldn't really notice a differance in the 920 and 302 castings.

If you are a little more adventourous then the magnum head would be a very good choice, more flow great swirl, better sealing, higher ratio rockers and way better chambers. You would need to get the intake bolt holes redrilled to work with your intake and you would need all the rocker gear from them and if you run a flat tappet cam you need to make sure they have a PR oiling hole in the lifter(most do) and you would need mopars conversion pushrod, they make them in 7.625 length just for this swap.

[passing you]

the best 318 heads IMO are the 234' closed chamber with blind heat cross over that water flows through, block it, so there are no cross overs in the exhaust ports.

I would rather have these then 302's

[70AARCuda]

magnun heads would be your best bet, especially if you are looking for a performance gain...

[dave5711]

Originally Posted by DonCarr

Cheapest way to go may be to mill the open chambers right off those 360 heads (+ mill intake).

It's a lot of milling, over 1/10"

Maybe someone here has experience with this?

I've got some experience with this, and it doesn't turn out cheap. The valve train becomes and issue, (pushrod length etc..)and a lot of smaller machine shops don't machine intakes.

It can be done, but given the availability of heads like 302's, then why set your money on fire?

[TK]

Me?

Change the pistons!

However, building a big port 318 will mean you have a gas sucking dog for the street.

The best 318 head, for performance in stock form, (Done this too many times) is the 68-72 ish head, (Cant remember the casting# off hand, 615? Or something. The are open chamber, but work great.
Best bolt on head, is the 302, by far, the older heads, may be great, but todays gas will kill them without seats.

[MOPEkid]

Originally Posted by TK

Best bolt on head, is the 302, by far, the older heads, may be great, but todays gas will kill them without seats.

I agree. When I got the original heads off my '70 318 one of the exhaust valves had receded into the seat over 1/8"!!! If I recall compression in that cylinder was down around 50-60 psi before I pulled the engine.

[Plum_Crazy_Purp]

Ya I have a pair of 69 open heads lying around but if i used the closed chamber heads it should give a little more compression right?

[TK]

No, not if cc's are the same, and open you can raise compression faster with shaving.

[rampage_82]

hey guys sorry for hi-jacking this thread, but are there any internet shops out there that specialize in LA's / Magnums like there are for the big blocks. I know of Hughes engines, but am wondering if there is like a one stop place for info and parts, like 440source... it would be nice if there was a 360source...lol .... sorry I'm a bit tipsy right now

[TK]

Maybe I should move to Seattle and open up a 318 source......

Couldn't make any less than I do now..... haha

[Plum_Crazy_Purp]

If I get a pair of 302s which came from a 2brl then can I still use a 4brl intake or would port holes not match up?

[passing you]

Originally Posted by TK

Maybe I should move to Seattle and open up a 318 source......

Couldn't make any less than I do now..... haha

sounds like a plan to me, someone's gotta do it and get rich hopefully.

[passing you]

Originally Posted by Plum_Crazy_Purp

If I get a pair of 302s which came from a 2brl then can I still use a 4brl intake or would port holes not match up?

You should buy a performer intake, it has 318 port windows.

[DonCarr]

Are people suggesting unported 318 heads are a better power producer than unported 360 heads given compression ends up the same ?

Never even occurred to me, maybe it's true.

302 casting heads are heavily shrouded around the valve to force the air/fuel mix past the spark plug. Great swirl but poor flow.

I'm lost on this one. I know the old single plane 318's were rated at 230HP with that tiny 2 barrel and a larger 2 barrel 360 was only 255HP. Pretty close output.

[TK]

In mild applications, yes, the 318 loses a of of low end from the 360 heads.

[Plum_Crazy_Purp]

wait so can i use a 4brl for heads that came off of a 2brl?

[TK]

Yes.

Use the offey dual port 273/318 manifold, the Holley streetmaster. Sp2P. or the performer... (Performer is my last choice) For a mild-ish 318, with small port heads.

OR

Open the head to match the 360 port gasket, and use big port dual planes.....

But, you have to go wild with the 302's to make it worth while, and might as well go X or J heads, or the better of all the big port heads, the mighty 308.

How smooth is it going to idle?

[Plum_Crazy_Purp]

not too bad but has a lopie cam in it, i got this car with no info on the frankenstein motor so dnt knw the lift of the cam or anything.

[TK]

Skip, lope, or chop?

post a clip of it!

Or have you already disected it?

[Plum_Crazy_Purp]

lope and ill try to record it

[Dart 360]

360's compression are not that high, putting them on a motor 42 CI smaller will lower the compression even more, 302's are off a 318 but you will need to get the right manifold to match the ports or modify them.

[TK]

Or, if you have a big port manifold, just slap it on, don't be skerd....

[Plum_Crazy_Purp]

Ya the 360s are shit. So the ports of an open chambered 318 is dif. than the closed chamber?

[TK]

No, same ports...

What is shit?

[Cudafever]

I thing you might be getting a little confused here.

ports(= intake ports) is the part of the head that the intake is bolts on too.........and as far as i know they are all the same size on a 318.

the comment about the 360 lowering you compression has to do with a larger combustion chamber(the part of the head that surround the piston.

The combustion chamber, and the intake port are larger on the 360, compared to the 318.'s combustion chambers and intake ports.

[DonCarr]

Though 318 ports may be the same volumes I think the 302 casting has updated intake port, taller with flat floor. Taller because of increased pushrod pinch and flat floor for some reason ?? Exhaust port is revised too.

This article has 318 results with stock 318 heads.
http://www.compcams.com/Community/Ar...?ID=1968181674

This article has 318 results with pocket ported 318 heads verses ported 360 heads. I assume compression remains same, but who knows.
http://www.compcams.com/Community/Ar...?ID=1826270359

Maybe they can help decide which way to go?