swirl port heads
- Thread starter gdwelch
- Start date
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Yes I have on a fairly recent 340 rebuild. "J" heads I had were trashed and I started looking around and it turns out that INDY recons these and sells them for a reasonable price with 2.10 and 1.65 stainless valves complete. I think I paid about $550 plus shipping and new head bolts. Car runs mid 13's with Holley carb, Edelbrock air gap intake, TTI headers and 3.55 rear end. From what I was able to find out these flow better then "X" and "J" heads. I don't remember the casting number series for these but believe they were used on mid-70s police cars. Might be info on www.allpar.com
PS: I believe we figured my final compression was about 10:1
PS: I believe we figured my final compression was about 10:1
mullinax95
Well-Known Member
Which ones do you have 302 or 308?
needsaresto
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Are you thinking of swapping to 308 castings? The main reason most do is because of the much improved exhaust port,predecessor to the magnum
dodge freak
Well-Known Member
However MP made some swill port heads based on the 308 castings but without the smog air hole drilled in the bottom of the exhaust ports and came with 2.02 intakes. Guess who found a pair on Ebay :cheers:
$350 bucks too and close enough to go in person to get them. (it was buy it now and I seen them 1 hour in to the listing. I did spend $300 more for Muscle motors to mill them .030 and redo the grinding a few valve seats but springs were in great shape and my little 318 revs to 6500 day after day and idles at 700 rpms in gear.
Those heads are my babies, lol.
$350 bucks too and close enough to go in person to get them. (it was buy it now and I seen them 1 hour in to the listing. I did spend $300 more for Muscle motors to mill them .030 and redo the grinding a few valve seats but springs were in great shape and my little 318 revs to 6500 day after day and idles at 700 rpms in gear.
Those heads are my babies, lol.
skybolt
Well-Known Member
You said you had j heads???? Better than your trashed j heads in your original post above?
mullinax95
Well-Known Member
He just asked swirl port. Could he not run 302s on his 340?
Locomotion
Well-Known Member
302's will bolt on. But if the pistons are near "0" deck or positive, they would likely hit the closed chamber part of the head.
302's would be a performance loss is stock form. Might help if ported right with bigger valves.
576 heads were the over-the-counter replacements for 308's and were available with 1.88" as well as 2.02" intake valves. Open chamber but are often called "swirl port" also.
I just saw your last post. It will work with OEM low compression pistons. Lots of torque will be available but don't expect the same performance as the original heads over 5000 or so. Might help fuel mileage especially if you experiment with the jetting.
302's would be a performance loss is stock form. Might help if ported right with bigger valves.
576 heads were the over-the-counter replacements for 308's and were available with 1.88" as well as 2.02" intake valves. Open chamber but are often called "swirl port" also.
I just saw your last post. It will work with OEM low compression pistons. Lots of torque will be available but don't expect the same performance as the original heads over 5000 or so. Might help fuel mileage especially if you experiment with the jetting.
needsaresto
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Magnums require a magnum intake,head bolts,hollow pushrods,amc lifters with oiling hole for pushrod. You can have them drilled for an la bolt pattern intake and use whatever intake you want. I do have a rebuilt set for sale here. They come with all the rocker gear and a pair of stock magnum valve covers. Shoot me a p.m if interested. These heads have been resurfaced,good 3 angle valve job with plunge cut,new seals and springs. I have a set of magnum porting templates I could use on them if you want,but if your runing a 318 theres no point in porting them.
Locomotion
Well-Known Member
The 576 heads were discontinued several years ago.
I've never messed with Magnum heads, but from what I've heard, they would perform well. The dowside is that you have to get all the conversion valvetrain stuff and intake manifold. And some Magnum heads were known to have crack issues between the valves.
I've never messed with Magnum heads, but from what I've heard, they would perform well. The dowside is that you have to get all the conversion valvetrain stuff and intake manifold. And some Magnum heads were known to have crack issues between the valves.
dodge freak
Well-Known Member
My 576 heads are not for sale (pm me in 20-25 years when I am an old man, lol).
I hear great things about those Magnum heads-expect for the cracks which is true. I do not like the non shaft rockers. Shaft rockers are best for higher rpm which is why there are kits to convert Chevy motors to the shaft style rockers.
I hear great things about those Magnum heads-expect for the cracks which is true. I do not like the non shaft rockers. Shaft rockers are best for higher rpm which is why there are kits to convert Chevy motors to the shaft style rockers.
mullinax95
Well-Known Member
I agree.
dodgetkboy78
EDELBROCK HEADS SUCK!
it will run better under 4K, it's over 4K that you will suffer with 302 heads. Be a compression bump, mild cam, compression bump, ping ping ping!
jimbo
Well-Known Member
#4323345 1985 318 police interceptor. Has a swirl port design with a high volume combustion chamber. Run with flat top pistons, no valve reliefs, and machined for roller lifters from the factory. I knew '85 was a good year for something. :glasses7:
1wild&crazyguy
Banned
Can somebody show the part of the port on one of these ''swirl port'' 308 heads that makes them swirl, and how it's different than all the other x,j,587,596, heads?
Also, can anybody show me the swirl inducing portion of the 302 int port and how it's different from the 675 318 heads?
It would be nice to know the info given has some proof to back it, thanks.
Also, can anybody show me the swirl inducing portion of the 302 int port and how it's different from the 675 318 heads?
It would be nice to know the info given has some proof to back it, thanks.
805moparkid
Slant and AFX Guy
im gonna play the stoop here and say i saw some x brand heads that were "swirl" port and the valves were moved around in the chambers....
The floor of the exhaust port is different (lower) on the 302/308 heads. Not sure if it really makes anything "swirl", but the gentleman that ported my 308's said that the exhaust port was very much improved compared to the earlier J heads. Most of the flow #'s I've seen for stock heads show the 308's flowing upwards of 10 cfm more on the exhaust side than the "587" 340 heads.
As far as putting 302's on a 340, I wouldn't. Especially if you have an early 340, since the pistons on the early 340's were above the deck, which makes it difficult to run closed chamber heads. And regardless, the 302's have the smaller 318 ports (and valves, although that can be fixed), so you'd be restricting a 340 with stock 302's compared to standard 340 heads.
I had a set of 308's set up for my 340 with 2.02/1.60 valves, and about a stage 2 port. They ended up flowing 264 cfm at .500" of lift, wish I had gotten the exhaust numbers. I went with the 308's because my 340's pistons are actually .018" proud of the block, just as the factory spec'd. Closed chamber heads would have to be clearanced for the pistons, so I used the open chamber 308's.
Also, be aware that the 302/308 heads have the same cracking problem as the magnum heads. It has to do with the induction hardening used for the valve seats, and the 302/308 heads are just as likely to do it as the later Magnums. The magnums are also closed chamber heads, with a smaller chamber than even the 302's. So, if you're pistons are above deck, they won't be the easiest to use either.
Here are some pictures of my 308's. Sorry, I don't have any pictures of stock X,J,587, etc heads to compare them too. But, here are the exhaust ports, before and after porting.
Yeah. Mopar. The 340s all came with swirl port heads. It's in the Mopar Engine book. Larry Shepard talks about the X and J head and how they found out (accidentally) that they were the first swirl port heads. So Mopar was ahead of the game even back then.
1wild&crazyguy
Banned
look at the floor on ALL 340/360 heads, look at the floor on ALL 318/273 heads
THEY ARE ALL THE SAME, SWIRL PORT EFFECT HAS NOTHING TO DO WITH THE EXHAUST BTW.
IF ANY ARE SWIRL PORT, THEY ALL ARE. LOL
THEY ARE ALL THE SAME, SWIRL PORT EFFECT HAS NOTHING TO DO WITH THE EXHAUST BTW.
IF ANY ARE SWIRL PORT, THEY ALL ARE. LOL
I actually think that was Larry Shepard's point as well.
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