Small block heads

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svitaks

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Ok i need to get things straight. My buddy has a 318 out of a 84 truck would putting 340 2.02 heads on this stock bottom end motor kill the compression. I thought i read that all small block heads had a 70cc chamber but different valves and runner sizes. Also what years did they make the closed chamber heads? We were curious if it would be worth it to switch back to the stock heads. By the way the pistons are stock.

Also what do you guys w/ small blocks run for total advance w/ out the vacume advance?

Thanks to all who can help
 
Swap back to the 318 heads. You killed compression. Reduced flow velocity and made a engine run worse. Your better off pocket porting the stock heads. If your looking to get the car to go fast, 360 (1.88/1.60) valves are the way to go.
Closed chambered heads came along in the late 80's. Look for the heads with the casting numbers ending in "302" for the 318.
Advance wise, I tune the car for highest vaccum. Once I get there, you will notice theres a few degrees where it will stay high on the gauge. Back of the timing until the vaccum gauges drops, then go back (advancing) till it reads highest, not a smidge more. Run and tune with the gas you'll use. Test drive. Make sure it doesn't ping. If it does, you know what to do. Back it off a tad until it stops and then 2*'s.
 
The earily heads can take as much as 35* and the close chanbers can only take 30* due to chamber shape, after this the engine will start to loose power and torque. The 302 heads are the right way to go with the 318 engine and bore.


BJR Racing
 
I have some milled 2.02 J-heads on my 318. My chambers are now 56cc's and let me have a 9.7:1 compression ratio on the .030 'teen. The 2.02 isn't the best choice for the small bore, but since I got the heads for free I wasn't about to buy another pair for smaller valves. It may give a bit of a soggy bottom end with the bigger valves...but it depends on your combo.

My motor has the rest of the drivetrain working with it to overcome any lack of power/bottom end from the bigger valves. 3000rpm converter, low gear set in the trans and a set of 3.91s out back help it get out of the hole and rev, hopefully into the high 13s on my next outing.

Hope i could help some
-Mike
 
Thanks for the replys, so do the 340/360 heads have bigger chambers or no? We really want the car to go fast. So who's in favor of the stock heads? Also i've been reading about these eddy heads, i've been around mopars my whole life but never heard of them. Who sells eddy? I may be interested. But ya my buddys car has a lunati cam, hooker headers, edelbrock carb and intake, thats about it. He never decked the block or milled the heads and has stock pistons. about what would his comp. ratio be at roughly? just curious about were he's sitting at right now. Thanks again to everyone. I appriciate it.
 
Swap back to the 318 heads. You killed compression.
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Yes, the 360 heads have a larger chamber.
Depending on your year 318, it's a 8.5-1 ratio engine. Adding the 360 heads dropped your ratio by a half point. Useing a thicker than stock head gasket drops it further and into the 7's for the ratio.

S
o who's in favor of the stock heads?
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Go back and read the replies. All of them.
Also i've been reading about these eddy heads, i've been around mopars my whole life but never heard of them.
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If you have not heard or seen Edelbrock heads, your going to have to get out from under that rock you live under. These have been out for a long while now and have made many many appearances over the entirer world.
Go to jegs or sumitt, mancini,racing. Even local auto parts stores like advanced auto, auto zone and the pep boys sell them
A switch to the Edelbrock heads will do nothing to the compresion ratio. But they'll more than likely help in a lose of powqer on a stock bottom end 318.
 
I say dont mill. If you really want to use the 340 heads get taller pistons and a thinner head gasket. Take about .010" off the heads to get the chambers down to 69cc, a piston that sits about .011" in the hole and mopar gaskets that compress .024"-.026" with a 4.060" bore and you'll get about 9.5:1 compression. that's if you really, really want to use the 340 heads.
 
stroker416 said:
I say dont mill. If you really want to use the 340 heads get taller pistons and a thinner head gasket. Take about .010" off the heads to get the chambers down to 69cc, a piston that sits about .011" in the hole and mopar gaskets that compress .024"-.026" with a 4.060" bore and you'll get about 9.5:1 compression. that's if you really, really want to use the 340 heads.
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I agree on that. My heads were milled when i got them so i ran with them like that. I'm one for the 340/360 heads. But make sure your combo is well rounded and it all works together.

My motor isnt much more than a 318 - .030, a decent cam, the stock (but milled) j-heads, alum intake and a pair of headers...I'm lookin at likely high 13s on my next outing so it's doing well for being what it is. They can put out some decent power.

Good luck!
-Mike
 
In terms of bolting on stuff, I'd say a set of 302s would be a decent help. The 340/360/318 4bbl heads have huge chambers. It's bad in a bunch of ways if there is no other work being done, we'll just shorten it to "try not to use them unless you do some homework". If he's thinking of spending the bucks on Edelbrock heads, he should spend the money on getting a shortblock that will be able to take advantage of the capabilities thye have. In your case, it's a waste of effort and money just bolting them on.
 
Thanks so far i have heard of edelbrock just never refered to them as eddys but it fits. I was curious about the eddy heads. My buddy just wants to bolt some different heads on. He's got and 86 318 truck, would it have the 302's? Or we'll just put the 84 318's back on. Guys thanks alot i knew you all would know.
 
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