HP potential for a 9.2:1 360???

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swinger340

swinger340

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Eddy closed chamber heads, stock cast crank, pistons, and rods (15K mi. engine) super clean was running good. Quick hone new rings and bearings. W thin head gaskets 9.2:1 can be achieved. Is there any potential power that can be made on 9.2:1? This is a low budget engine for my brother to put jn his 69 notch back barracuda. What would be a good cam if this is the route he wants to go? I would like to see some flat tops and free floating rods, but he dont want to spend much and is only looking for more hp then his stock 318, and im doing my best to help him out. I have already donated the engine, some 273 rockers and push rods.
 
No reason why it cannot see 400 plus.
 
you mention low budget....if that is your desire...stay with a hydraulic cam...other wise you need to buy adjustable rockers and new pushrods......the old rockers and pushrods can be used with the eddy heads.
 
70aarcuda said:
you mention low budget....if that is your desire...stay with a hydraulic cam...other wise you need to buy adjustable rockers and new pushrods......the old rockers and pushrods can be used with the eddy heads.
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I gave him some 273 adjustable rockers w 3/8 push rods that came off my 340 before installing the comp rockers. Adjustables not an issue.
 
Is it really possible to achieve 9.2:1 with stock pistons? I was playing around with a CR calculator and I think you would need .055 or less deck clearance, .039 head gaskets, and 65cc head volume to get there.
I also have a low mile 360 roller LA. I guess I should pull the heads and measure the deck. Always counted on around .080 with stock slugs. If this works out for you I may be following in your footsteps.
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67Baccaruda said:
Is it really possible to achieve 9.2:1 with stock pistons? I was playing around with a CR calculator and I think you would need .055 or less deck clearance, .039 head gaskets, and 65cc head volume to get there.
I also have a low mile 360 roller LA. I guess I should pull the heads and measure the deck. Always counted on around .080 with stock slugs. If this works out for you I may be following in your footsteps.
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I figured it out with 62cc heads and a thin .024 head gasket. Came up w 9.18:1
 
I have the same combo. dyno numbers were at 423hp. 4 valve relief speed pros, stock rods and crank, 63cc ede heads, comp xe284 cam, ede air gap intake, 750 holley street hp.
 
Are those copper headgaskets?
If I could get even 8.5 to 1 with my combo, I would run a cam similar to the hughes Wiplash roller.
 
skep419 said:
I have the same combo. dyno numbers were at 423hp. 4 valve relief speed pros, stock rods and crank, 63cc ede heads, comp xe284 cam, ede air gap intake, 750 holley street hp.
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Very nice.... I dont want him to have that much HP. Id feel awful if the low budget 360 was rite up there with my not so cheap 340. LOL!! JK
 
67Baccaruda said:
Are those copper headgaskets?
If I could get even 8.5 to 1 with my combo, I would run a cam similar to the hughes Wiplash roller.
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No. detroit gasket. White composition. They are blue like fel pro. No sealant required. 4.125 bore .024 compressed thickness. I found them on e-bay. Have never seen them before, but it does state that they are a new item. Not sure how they hold up, but an easy way to up compression half a point.
 
You want to use the gasket with the pre-flattened fire ring with those heads or they may work themselves into the head surface and start leaking over time. You should be running the FelPros. Also, with the aluminum, I think you've got a compression problem and the lack of static will be felt. I doubt it will make 400hp without some larger cam and rpm which makes it less streetable. I'd lose the RPMs for a set of EQ Magnums. They aren't big coin and will retain more heat in the chamber, and can be run with any gasket.
 
If he has adjustable rockers, stay open to a solid flat tappet. It will always make more with a solid....all across the board.
 
70aarcuda said:
http://www.monicattichrysler.com/comersus/store/comersus_viewItem.asp?idProduct=247

they are bluish/white....

your mopar thin head gaskets...got several sets in use with eddy heads with over 11 to 1 compression...
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There's reasons why Edelbrock says to use the Felpro 1008s. You can run any gasket you want, but the fire ring will brinnel the head over time.
This is a privately done article but google brinneling and you'll see a bunch come up.

http://www.pbase.com/image/25091801

It doesnt take much time and if this is a "place holder" it means that when the heads are "given back" they'll need to be surfaced before using again.
 
I could run the 1008s. Would lower the compression closer to 9:1
 
Remember with the aluminum the affect or "feel" the engine sees due to the thermal characteristics is the same as having iron heads and 8:1 at that point. So cam accordingly (small). That's why I think the 400hp level is pushing it. If you can get it up to 9.5 or 10:1 static, you can run a cam that has a good chance of making those numbers without it feeling doggy and having plug fowling and carbon issues.
 
moper said:
Remember with the aluminum the affect or "feel" the engine sees due to the thermal characteristics is the same as having iron heads and 8:1 at that point. So cam accordingly (small). That's why I think the 400hp level is pushing it. If you can get it up to 9.5 or 10:1 static, you can run a cam that has a good chance of making those numbers without it feeling doggy and having plug fowling and carbon issues.
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Probably best if I can talk him into just putting a set of flat tops in it and be done with it. What would be a descent inexpensive flat top? KB or speed pro?
 
Talked brother into going w some KB107s. Now we are talking a whole new ball game. 10.5:1 compression is alot better. Thinking pretty hard on a vodoo cam as well. Sad thing will be, if he stomps on my 340. Then ill have to build a stroker.....
 
Pistons are like 30G each -/+ your have to balance.
 
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