Re: LA 915 heads on top a 318
[Re: MoparforLife]
#755625
07/23/10 08:51 AM
07/23/10 08:51 AM
|
Joined: Jun 2006
Posts: 3,075 Eastern Ohio
mopowergtx
OP
master
|
OP
master
Joined: Jun 2006
Posts: 3,075
Eastern Ohio
|
Quote:
Quote:
IIRC a .050 cut results in a .5 raise in comp. so you need .100 cut to get 1 point. a .100 cut is abour 3/32 of an inch. you do the math... you ruined a set of heads
Seen them cut .140 basically turned into closed chamber but had like 48 CC's. Personally have cut .070 off and gotten down to 60 CC's. Remember that anything over about .020 off you more than likely will have to cut the intake side of the head .0095. Best to mock up before cutting the intake side.
I wonder what my stock 78 318's are running for CC's? Looks like they are 593 castings. I have found when I've checked stock 915's anywhere from 68-72cc on them. Yeah I figured to match cut the intake side for what ever I need to take off the deck side. Last set of 915's I cut like .020 or .030 off them to get them cleaned up and they match cut that spec to the intake side which was actually quite useful in making a nice smooth flat surface for the intake gasket. It went to together super and sealed right up. Its amazing the porosity and casting flaws those cuts cleaned up.
|
|
|
Re: LA 915 heads on top a 318
[Re: RapidRobert]
#755627
07/23/10 01:33 PM
07/23/10 01:33 PM
|
Joined: Jun 2006
Posts: 3,075 Eastern Ohio
mopowergtx
OP
master
|
OP
master
Joined: Jun 2006
Posts: 3,075
Eastern Ohio
|
Quote:
Quote:
Best to mock up before cutting the intake side.
X2. 2 seperate trips to the machine shop
Why wouldnt you just cut the intake face the same time you shave the deck mating surface?
|
|
|
Re: LA 915 heads on top a 318
[Re: Dakota_Don]
#755630
07/23/10 03:02 PM
07/23/10 03:02 PM
|
Joined: Jun 2006
Posts: 3,075 Eastern Ohio
mopowergtx
OP
master
|
OP
master
Joined: Jun 2006
Posts: 3,075
Eastern Ohio
|
Quote:
the 302 is a LA head, my stock 68 318 had the 302s with a 340 cam lifters and springs..i did port the intke side of the head just enough to match the 360 intake gasket, pluss i used a TQ carb and 360 exh maifolds, the engine ran great, but the small valves hurt it a bit on top end..
Finally I'm not the only person out there thinking like this. Yeah the only other thing I got for heads is a set of closed chamber 1967 318 heads which would probably bump up the squeeze but they sure look restrictive without some port work. Plus no hardened seats for the unleaded gas. Anybody got any idea what cc's my stock '78 heads are? My plan is to get the heads done before I tear it apart so I can do this swap out over a weekend thrash. But I need to know how much I got to cut the 915's to keep a 8.5 to 1 squeeze.
|
|
|
Re: LA 915 heads on top a 318
[Re: RapidRobert]
#755632
07/23/10 05:38 PM
07/23/10 05:38 PM
|
Joined: Jan 2005
Posts: 4,463 Michigan
MarkZ
Worthy
|
Worthy
Joined: Jan 2005
Posts: 4,463
Michigan
|
Are 915 heads open chamber? If not, and if you haven't had any work done to them yet, hit up a couple local yards and look for 302 castings. They're a closed chamber, LA head with 273/318 runners. You can find them in any 85'-'89 M body with a 2bbl carb (4bbl cop packages had 360 heads).
For some reason, shaving a ton off of a set of heads never sat right with me. Closed chamber is what you want.
1987 Fifth Avenue - 512/518/D60
|
|
|
Re: LA 915 heads on top a 318
[Re: Mopar_Country]
#755635
07/23/10 07:02 PM
07/23/10 07:02 PM
|
Joined: Aug 2007
Posts: 2,754 Conway, SC
T2R9
master
|
master
Joined: Aug 2007
Posts: 2,754
Conway, SC
|
Quote:
If I were doing the build I would stay with the stock 318 heads. No worry's about dropping compression. With the 340 cam stock intake and the TQ with a set of headers should put you in the 300 HP range. When installing the cam be certain to swap the valve springs and I would throw a double roller timing chain in there as well. The 318 heads are about 62 cc's so your not gaining a lot with the money spent and the extra work. I would also throw a valley pan in there too. IF you decide to run the 302's check them carefully they can be prone to cracking in the valve area. That 318 when tuned right will run very good. Ask me how I know.
Stick with the original heads and save your money. My combo is a stock 318 long block, Small Summit cam, (slightly smaller than a 340 spec) Good t-chain, Performer Intake, and a 73 340 TQ. Early 340 exhaust manifolds with 2 1/4 duals. This engine pulls hard right up to 5300 rpm and was CHEAP to build.
|
|
|
Re: LA 915 heads on top a 318
[Re: forphorty]
#755637
07/24/10 08:22 AM
07/24/10 08:22 AM
|
Joined: Jan 2003
Posts: 25,200 Upper Midwest
MoparforLife
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
|
Quote:
I think a swap to 360 heads would be a waste of time and money, especially with that 2.5 single exhaust. http://www.dippy.org/forum2/index.php/topic,242.0.html
well the 318 cop engines were pretty dang healthy running and that is what they were is 360 heads & intake on a 318. You don't like it don't do it.
|
|
|
|
|