SB head question..

Posted By: valiantboy

SB head question.. - 06/18/10 10:54 PM

well, times are tight. ive decided to change directions with my a100 due to cash flow. i was going to turbo it. now im going to build a 390" motor on a 318 platform. ive got a pre-magnum block to use for the base. ive also got a pair of newer 360 iron heads off of a dakota r/t. ive done some bowl cleaning, gasket matching (to LA intake), and chamber polishing. will be useing stock valves as well. i dont want anything too radical, it will be mostly a street dweller. ive found a cam that should work quite well from hughes engines. hyd roller, 208/214@.50 .512/.520

my question: will these heads be enough for this motor? i know they flow better than the x heads. i was going to use them on the turbo motor, only at 318ci. im kinda limited on budget or id just use a set of edelbrock aluminum heads.

any input?

in advance

Posted By: Dakota542

Re: SB head question.. - 06/18/10 11:22 PM

So the heads are 5.9L magnum heads? I've read that the magnum heads are very good. It was an article about a 400 hp 318, and they used magnum heads. If the heads don't have a 2.02" valve, you can always put in a set of new SS valves. Cam sounds very streetable.

Posted By: Kern Dog

Re: SB head question.. - 06/19/10 12:18 AM

These heads are the basis for the iron headed Magnum crate 360 motors using similar cam specs. Good decision. You may have stumbled into some good luck here. Time to buy a lottery ticket before the luck wears off.

Posted By: GO_Fish

Re: SB head question.. - 06/19/10 04:19 AM

Ported OEM magnum heads should handle 390 c.i. very well. The factory magnum valve sizes should also be fine unless you plan on running the engine at high rpm's. No need for 2.02 intakes on most street applications. With lift above .500 you will probably need to cut down the top of the valve guides or you will have carnage. Check carefully.

Posted By: ademon

Re: SB head question.. - 06/19/10 05:31 AM

sounds good but i would up the duration at .050

Posted By: POS Dakota

Re: SB head question.. - 06/19/10 05:51 AM

Quote:

sounds good but i would up the duration at .050

I agree. But it depends on what his compression ends up at.

9.5:1 with a 236/242 cam would be really nice for the street. The longer stroke really wants more duration and you shouldnt be afraid to go with more.

Posted By: 80arrow

Re: SB head question.. - 06/19/10 01:33 PM

Quote:

So the heads are 5.9L magnum heads? I've read that the magnum heads are very good. It was an article about a 400 hp 318, and they used magnum heads. If the heads don't have a 2.02" valve, you can always put in a set of new SS valves. Cam sounds very streetable.

Are Magnum heads off a 318 the same as the magnums off a 360? Is there any years that are better or are they all the same?

Posted By: valiantboy

Re: SB head question.. - 06/19/10 03:01 PM

the comp will stay 10:1 or under. as close to that as possible. theres not very many pistons for this so ill have to fudge with headgasket thickness. itll have a beefed 904 behind it with 3.55's probly out back. the 904 will have a low gear set. im useing a999 internals so im kinda stuck with the low gears. im thinking around 3000 for the converter. think thats too much with the low gear set?

i also thought of more duration. lift will stay around .520 because of the heads. maybe talk to scott brown about a cam?

Posted By: patrick

Re: SB head question.. - 06/19/10 07:53 PM

Quote:

Quote:

So the heads are 5.9L magnum heads? I've read that the magnum heads are very good. It was an article about a 400 hp 318, and they used magnum heads. If the heads don't have a 2.02" valve, you can always put in a set of new SS valves. Cam sounds very streetable.

Are Magnum heads off a 318 the same as the magnums off a 360? Is there any years that are better or are they all the same?

they're all the same essentially.

that duration would work great for a torquey, idle-5000 RPM motor. I'd look at the hughes HER1828, I think...

Posted By: valiantboy

Re: SB head question.. - 06/20/10 05:14 PM

id definately have to have the guides cut for that cam. if i did that then id go ahead with 2.02 valves. thered be no reason not too...

Posted By: patrick

Re: SB head question.. - 06/21/10 01:21 PM

Quote:

id definately have to have the guides cut for that cam. if i did that then id go ahead with 2.02 valves. thered be no reason not too...

yeah there is, you'd be spending another $150 for valves, you'd need new guides, or at least hone the existing ones out if you use SBC valves.

you could drop down to 1.5 chevy rockers if you're concerned about the lift, or if your mag heads need a valve job, just sink the valves .030 to get that little bit of installed height.

another option would be to look at bullet cams hydraulic roller profiles and have them regrind your stock magnum cam. it's $150+ round trip shipping. I went with their HR259/316 lobe for both intake and exhaust.

I'd see if they could fit the HR272/340 lobe on the regrind, or the HR274/325. either should work good with hughes #1110 springs. use the same lobe for intake and exhaust, the magnum heads, especially if you do a little port clean up, flow good enough on the exhaust you don't need a split pattern cam.

only downside with the 904 is the small converter hub. my comp XE262 cammed 360 cracked the hub in my 5th ave....

Posted By: valiantboy

Re: SB head question.. - 06/21/10 02:25 PM

just found out that a friend has all the equipment for cutting guides/seats. all id need are parts. ill check out bullet cams. anything to help save $$ is ALWAYS in best intrest. fortunately i have a kick ass converter. stainless snout, anti-balooning.. the whole works. BUT its 3600 stall... probly need to swap that for somthing in the 2800-3200 range.