Dartfreak75
Restore it, Dont part it!
So all the factory magnum stuff interesting. Are the 318 magnum heads any count ? I have a spare set of them I believe.
360 heads on a LA 318 vs Magnum heads on a LA 318
- Thread starter 318willrun
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magnum heads are the same, no matter 5.2 or 5.9. You cannot just drop magnum roller lifters and pushrods in a '76 LA motor and have it work. Depends if you are using a roller block or FT, the length the pushrod will vary.
Dartfreak75
Restore it, Dont part it!
I have a roller 86 318 block. The roller lifters from the magnum will work in it right?
should be just fine
If compression is equal, am I alone at liking open chamber heads ? (I shouldn't have asked... lol). I am attracted to the rocker arm shaft assembly of the LA. However, I have not had a bad experience with the magnum set up. To be honest, I think either head would be a nice improvement and work for the build.
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Dartfreak75
Restore it, Dont part it!
Im not a professional engine builder by no means and im still learning as i go but one conclusion that I have reached and I may be wrong but flow trumps compression imo. I wish I had the money to prove my theory but I believe a well breathing properly tuned 8.5-9:1 engine will out run a 10.5-11:1 constipated one.
flow does trump compression in a racing applications. However, flow with compression is ideal.
Yep. I'm no expert either and haven't experimented much like 318WR does but you need some compression. The Teens weren't high compression engines and if you bolt on a set of heads with a big ol' open chamber designed for 4" bores and use a thick ol' head gasket and throw in a big ol' cam with lots of duration (that bleeds off compression) you might have to spin it to 5 g's or better to make your big port heads to flow. Whew, that was one long sentence!
Dartfreak75
Restore it, Dont part it!
Yes I agree. The whole whole forced induction movement proved it to me. They can take low compression engines and make big power with forced induction and all forced induction does is increase flow in a forced manner lol I know it apples and oranges and alot will disagree but in a nutshell its the same thing if you increase flow whether it be with ported heads cam intake and exhaust or pushing/pulling boost down the engine its still increasing flow
PRH
Well-Known Member
For me, it’s a tough sell to have someone spend money on heads that are visibly cracked.
If you’re lucky enough to have a pair of them that don’t have the exhaust seats sunk down into no man’s land, and can get away with a very minimal amount of machine shop servicing........that’s great.
But if they’re cracked, and they need some seats and/or some guides installed........ do you really want to spend the money for that on castings that are already cracked?
I guess I’d(meaning you) have to assess the actual condition of the magnums you have on hand before I decided if they were a viable option or not.
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Generally cracks in Mag heads are easy to spot after a good wire brushing. You can also spray starting fluid on them and watch the area between the seats. It evaporates quickly, but will stay in the crack a might longer.
I've pressure checked a few Mag heads that were cracked and no leaks, but like PHR said, I wouldn't try to sell any work on them.
I've pressure checked a few Mag heads that were cracked and no leaks, but like PHR said, I wouldn't try to sell any work on them.
I would certainly take them apart and inspect them prior to use. I wouldn't put a bunch of money into them either. I do have all new valves for a stock magnum heads, springs too for that matter but they aren't the springs I'd be using anyways. I'd probably just buy new bare castings and put my new valves in them IF the magnum heads were the sure way I was going.
Yeah, I usually pour rubbing alcohol into the ports and see if any gets past the seats over the course of an hour. I sometimes I shine a flashlight in the port in a dark room and see if I can get a sliver of light around the valves.
To be perfectly honest, I'm leaning towards the LA 360 heads due to the fact I have 273 adjustable rockers/shafts and if I go solid roller, that would put me miles down the road cost wise.
Solid Roller! Now you got my interest!!
I agree IF the compression is the same, it is a toss up.
goldduster318
Overzealous Car Modifier
A lot more likely to get quench effect with the magnum chambers vs an open chamber. Less likely to detonate, more efficient combustion.
I'd like to go solid, and if I do, I'll most likely build my own solid roller lifters. First, most solid roller lifters are for non-roller blocks. 2nd, the price for solid roller lifters are incredible!.
Everyone always says "360 heads will kill your compression blah blah blah" but they fail to realize the only factory compression boosting heads for 318s were the 920 heads from 1967 and they well famous 302 heads. 360 heads all the way with a cheater cam (like the Comp 270) to build cylinder pressure and make up for the low compression.
Don't forget the industrial stuff!
water crossover instead of exhaust crossover so you don't end up with a couple of lower flowing exhaust ports, chambers cc'd at 62cc after a bit of de-shrouding around the valves and stock style valves with the dimples in the face. Aftermarket flat faced valves would get you to about 60cc I reckon. Not bad heads really but port volume was smaller than a standard 675 head.
Rat Bastid
Dunamis Metron
The magnum chamber is no more efficient than the open chamber. It’s also not less likely to detonate either.
dirty white boy
50 yr old Juvenal delinquent
what size solid roller you thunk'in????? would love to see details on "building" solid roller lifters,..im guessing from factory hydraulic roller lifters??
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