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Are those the old truck heads that Hemi Performance used to sell?
360 heads on a LA 318 vs Magnum heads on a LA 318
- Thread starter 318willrun
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Are those the old truck heads that Hemi Performance used to sell?
making solids out of hyd has been done before...
dirty white boy
50 yr old Juvenal delinquent
not much info to be found on it, none that id put much faith in! id like to see how you would do it!
Slantsix64
Well-Known Member
I have a 1988 Roller block with magnum heads the motor runs really strong, i went from 302 heads to magnum heads i pulled at the junkyard and holy **** i picked up some Balls. Plus that 1.6 rocker ratio added lift to my camshaft. It pulls to 6k very easy and quick im running the stock springs as well. 264/266 duration with 0.453/.437 regrind
Slantsix64
Well-Known Member
360 heads on a stock 318 equals really low compression probably in the 7:2:1 range, pretty much loss of low end but you gain high end.
but keep in mind the roller La 318 had taller pistons and actually were 0.040 in the hole. In the ones i took a part, those 360 heads are like 72CC mill them down .040 probably get you in the 68cc area Advance that camshaft 4 degrees or more to build up some pressure run a thin *** head gasket you might be alright, then again depends on your camshaft and rear gears also.
but keep in mind the roller La 318 had taller pistons and actually were 0.040 in the hole. In the ones i took a part, those 360 heads are like 72CC mill them down .040 probably get you in the 68cc area Advance that camshaft 4 degrees or more to build up some pressure run a thin *** head gasket you might be alright, then again depends on your camshaft and rear gears also.
Dan the man
Well-Known Member
I don't have any knowledge of the magnum heads, but I've heard that they are prone to cracking next to the valve seats, my question is if they crack next to the valve seats won't this only get worse? Will the cracking cause the valve seats to come out? Also I just looked up what edelbrock performer rpm heads for a sbm would cost and was surprised to see that they are around $200 a pair cheaper than promaxx heads.
Dan the man
Well-Known Member
I'm sure that this has been brought up before, isn't there a formula to follow when you mill the heads? Also would milling the heads and the deck surface along with thinner head gaskets affect port alignment, intake manifold bolt holes lining up, also push rod length? I know that I asked several questions here it's that I've never seen this item's brought up when guy's say to have the cylinder heads milled. Thanks everyone, I'm trying to learn, don't mean to be a pest.
Dan the man
Well-Known Member
Do you have a part number for those pistons? I've heard that before about the LA roller block's having a taller piston but when I try to look them up they always list the 318 pistons with the same short compression height
Those ones came off a 318-3 Truck engine - casting #277.
Hemi performance did have a bunch of nos bare heads they were selling at one point, i should have grabbed a set while I had the chance. Great heads for a stock replacement or mild motor with a bit of a clean up.
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I got a set when they were $400 a pair. They are getting the special treatment from a friend as we speak and should go 240's+ with ease.
Slantsix64
Well-Known Member
ive heard that the later magnum heads had this problem fixed im not sure if that is true or not but all i did was pull the heads and run a razor blade between the seats and if there were no cracks i ran them.
PRH
Well-Known Member
It’s a bit hard to make the determination of which is the “better” head without some specifics regarding the targeted goals(hp, rpm range, etc).
Looking for a hot little 318 on pump gas. Looking at solid roller cam, 10 to 1 compression, something that may like 6500 rpms... Basically finding use for the parts I have laying around, including the '85 roller 318 that's on the stand. It came out of DT, so we've been running/beating on it for a year.
Post up a thread when they're done, 240cfm might be a bit tricky with a intake port that small. And a 1.88 intake valve is probably about as big as you will get in there. Mine ended up around the 130cc mark after porting.
I would be interested to see the results.
"WHICH" 360 heads? I think the 308 heads can be made to flow like Niagara Falls, for instance.
I have just the typical 360 heads from the '70's. I'd have to look again and see "which" casting number
I think the 308s are about the best. See what @MOPAROFFICIAL says.
I like 308's, but I will use the set I already have between the magnums and 360 LA heads. I have most of what I need for this build, besides the pistons I'm going to use and the camshaft.
thesiren74
Well-Known Member
I did the same thing but had a 292 erson cam with stock converter and stock 2.45 gears and a 28" tire wow! It was horrible!! After 3,000 it pulled pretty good.
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I might. My 302's went 240's with 140 cc port so it shouldn't be too hard.
What did yours flow?
I used to think this also. Then read this at Moparchat. Any validity to this?
"Magnum Heads (5.2 vs. 5.9)
There ARE actually two different castings for production Magnum heads, Apparently the 5.9 heads made in Mexico (machined at Toluca) and the 5.2 head made in the USA (machined at Mound RD). I donÂ’t know when these changes were made or if they have been there since the Magnum engines were introduced.
The major differences are listed below:
1) The intake port volume is 10cc larger on the 5.9 head (about 162-163cc).
2) The intake port is about .100 taller on the 5.9 head.
3) The valve guide boss in the intake looks smaller on the 5.9 head.
4) There are several minor differences in the physical appearance of the castings, most obvious is a little “hump” between the exhaust ports on the 5.2 head, this “hump” is not seen on the 5.9 casting.
SPECIFICATIONS
5.9 CASTING
Casting # 53006671
Machined Part Number 53021139
Intake Port Volume 162-3cc
Castings made at Cifunsa in Mexico/Machined at Toluca
Included on all production 5.9 engines built at Toluca
Mopar never sold this cylinder head separately as a service part
Mopar Performance Magnum crate motors are equipped with this casting on all Arrow Racing built/reworked engines
Mopar Performance crate motors now built/reworked by Cummins include these heads (since the Mound Road heads are no longer available) Earlier motors built/reworked by Cummins up to mid 2001 included Mound Road heads.
Mopar Performance Cylinder Heads P4876257 and P5007086 are now made from this casting (but there may be mixed stock in the depots since the 5.2 head was used up until the Mound Road Plant built-out).
5.2 CASTING
Casting # 53020466
Machined Part Number 53021137
Intake Port Volume 152-3cc
Castings made at New Haven, MI/Machined at Mound Road Engine Plant
Included on all production 5.2 engines built at Mound Road Engine Plant
Mopar sold this casting at dealers to service both 5.2 and 5.9 engines from ’92 to ‘01
Mopar now sells this a Re-Man cylinder head since these heads are no longer available from Mound Road.
Mopar Performance Crate Motors included these heads when Cummins started building them (up to mid 2001).
This head is no longer available from Mopar and has been “ruled” to a Re-Man head R5852426 (since mid 2001)
Mopar Performance Cylinder Head P4876256, when it was available was the same as this cylinder head."
that is all news to me. If it's accurate, I believe it would be due to the foundry, not any intent on Chrysler.
Probably. I just found it interesting and wondered if, for whatever the reason, we could say we are comparing apples to apples if all OE magnum heads are not the same. Since we are in the process of putting Magnum heads on my son's 318 la. Very interested in this post and will be watching. Thanks again for your informative posts!
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