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LA 915 heads on top a 318 #755620 07/23/10 12:37 AM 07/23/10 12:37 AM
Joined: Jun 2006 Posts: 3,075 Eastern Ohio mopowergtx OP master
mopowergtx OP master Joined: Jun 2006 Posts: 3,075 Eastern Ohio	How much would I have to shave off a stock LA 915 casting head to get the combustion chamber volume down to where if they were bolted to the top of a bone stock 1978 318 with Felpro .040 head gaskets I wouldnt lose ANY of my already anemic 8.4 to 1 comp ratio? And I dont want to hear how I should put a set of Magnum heads on there thats not going to happen. LA heads only on a LA motor here. Now I've never had a set of the infamous 302's; I hear they have a low cc chamber but are they LA style or Magnum style? What I'm doing is putting a stock pattern 340 cam in this along with a stock 1978 cast iron spread bore intake with the factory choke and a 1975 Thermoquad. I'm retaining my stock exhaust manifolds and stock Y-pipe which feeds into an already installed 2 1/2" single exhaust system running all the way to the back. The exhaust system came from Summit Racing, it was one half of a dual kit for a A-body with headers. The 7 1/4 rear end with 2.4 gears will be exchanged for a complete with 11" drums 8 1/4 sure grip setup with 2.94 gears out of a Dippy cop car. I'm still not sure what I will do with the 904 yet. I'd think this combo would like about a 2000 stall but its a lock-up unit so that rules out a cheapo converter from Mancini for it. Not only is this an El-Stocko swap out its also El-cheapo. I have had the new stock 340 cam kit for years sitting in the box for a long lost project. I got lots of 915's sitting around along with the 8 1/4 2.94 sure grip rear. The stock intake has been collecting dust and the Thermo quad was rebuilt a couple years ago put in a large plastic zip lock bag and shoved in a box waiting to be put on something. I know I'm going to probably get alot of "hate" responses to this post saying how this wont make any real power, this is not the way we do it now, Magnum head it and put a Vodoo cam in there get you a Eddie Air Gap RPM intake, and on and on. Thats not what I'm after. I'm after putting together a solid turn key stock looking stock sounding stock apperance all Mopar slight hop up with parts I already have and would like to see get used to an already super running completely reliable motor and car. Let the begin....

Re: LA 915 heads on top a 318 [Re: mopowergtx] #755621 07/23/10 12:47 AM 07/23/10 12:47 AM
Joined: Feb 2004 Posts: 4,501 Gainesville,FL G goldmember master
goldmember master G Joined: Feb 2004 Posts: 4,501 Gainesville,FL	I'd leave it alone,build a 360,or 408. Sorry I'm not any help.

Re: LA 915 heads on top a 318 [Re: mopowergtx] #755622 07/23/10 01:15 AM 07/23/10 01:15 AM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	Quote: How much would I have to shave off a stock LA 915 casting head? Now I've never had a set of the infamous 302's; I hear they have a low cc chamber but are they LA style or Magnum style? (1) I'd see if the archives have the CC's of your 318 heads to compare w the 915's and may have how much to mill to loose a certain amt. (2) 302's are LA live every 24 hour block of time like it's your last day on earth

Re: LA 915 heads on top a 318 [Re: RapidRobert] #755623 07/23/10 03:58 AM 07/23/10 03:58 AM
Joined: Aug 2003 Posts: 12,291 Kent, Wa 340SHORTY Truck Nut
340SHORTY Truck Nut Joined: Aug 2003 Posts: 12,291 Kent, Wa	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 I am truckless..

Re: LA 915 heads on top a 318 [Re: 340SHORTY] #755624 07/23/10 07:22 AM 07/23/10 07:22 AM
Joined: Jan 2003 Posts: 25,200 Upper Midwest M MoparforLife Too Many Posts
MoparforLife Too Many Posts M Joined: Jan 2003 Posts: 25,200 Upper Midwest	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. Clean it, if it's Dirty. Oil it, if it Squeaks. But: Don't fix it, if it Works!

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
mopowergtx 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: MoparforLife] #755626 07/23/10 10:17 AM 07/23/10 10:17 AM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	Quote: Best to mock up before cutting the intake side. X2. 2 seperate trips to the machine shop live every 24 hour block of time like it's your last day on earth

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
mopowergtx 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: mopowergtx] #755628 07/23/10 02:35 PM 07/23/10 02:35 PM
Joined: Jan 2003 Posts: 6,816 Alton, IL D Dakota_Don master
Dakota_Don master D Joined: Jan 2003 Posts: 6,816 Alton, IL	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..

Re: LA 915 heads on top a 318 [Re: MoparforLife] #755629 07/23/10 02:37 PM 07/23/10 02:37 PM
Joined: Jan 2003 Posts: 6,816 Alton, IL D Dakota_Don master
Dakota_Don master D Joined: Jan 2003 Posts: 6,816 Alton, IL	then after shaving the heads, you will most ikely need custom push rods..

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
mopowergtx 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: mopowergtx] #755631 07/23/10 04:14 PM 07/23/10 04:14 PM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	Quote: 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? I hear what you are saying. I want my head port/intake port alignment dead on & that's why I have the deck(s) milled then mock it up & figure how much the head intake face needs milled & since it is on an angle it's harder to figure & I want to eliminate as many error possibilities as I can and since I am making regular trips to the shop anyway it is not an inconvenience. live every 24 hour block of time like it's your last day on earth

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: 4,444 Michigan MarkZ Worthy
MarkZ Worthy Joined: Jan 2005 Posts: 4,444 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: Dakota_Don] #755633 07/23/10 06:01 PM 07/23/10 06:01 PM
Joined: Sep 2004 Posts: 6,906 IL, Aurora A ademon master
ademon master A Joined: Sep 2004 Posts: 6,906 IL, Aurora	Not going to be cheap to cut the heads / intake surface, i would use any 318 head and use the 1.88 valve with a little porting. Your setup is super mild

Re: LA 915 heads on top a 318 [Re: mopowergtx] #755634 07/23/10 06:30 PM 07/23/10 06:30 PM
Joined: Apr 2010 Posts: 1,216 Under My Car Mopar_Country pro stock
Mopar_Country pro stock Joined: Apr 2010 Posts: 1,216 Under My Car	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.

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
T2R9 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: mopowergtx] #755636 07/23/10 07:05 PM 07/23/10 07:05 PM
Joined: Nov 2006 Posts: 1,459 oklahoma F forphorty pro stock
forphorty pro stock F Joined: Nov 2006 Posts: 1,459 oklahoma	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

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 M MoparforLife Too Many Posts
MoparforLife Too Many Posts M 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.

Re: LA 915 heads on top a 318 [Re: MoparforLife] #755638 07/24/10 10:17 AM 07/24/10 10:17 AM
Joined: Jun 2006 Posts: 3,075 Eastern Ohio mopowergtx OP master
mopowergtx OP master Joined: Jun 2006 Posts: 3,075 Eastern Ohio	Yeah it just seems to me to gain anything from the 4 bbl intake and Thermoquad a set of 360 heads have to go on there. The mismatch between the 318 intake ports on my stock heads versus the 360 intake would be a real bad scenario. Leaving the stock heads on there would be WAY easier for sure but would it negate any gains from the Thermoquad and intake? When Chrysler put this combo together(360 heads 360 intake) on the 318 cop cars did they have different pistons in the 318's versus what I'm running? I was just out checking out the stock 1979 spreadbore intake versus where my A/C brackets land. Looks like I'm good on the passenger side but I am missing what I need on the drivers side. My 2bbl intake has a squared up stat housing where the 360 intake is off towards the drivers side and canted. Its right where the drivers side gusset mount is running right now on my intake.

Re: LA 915 heads on top a 318 [Re: mopowergtx] #755639 07/24/10 10:25 AM 07/24/10 10:25 AM
Joined: Jun 2006 Posts: 3,075 Eastern Ohio mopowergtx OP master
mopowergtx OP master Joined: Jun 2006 Posts: 3,075 Eastern Ohio	Looks like this Eddie intake has the mounting boss right in the drivers side front between the first two intake mount bolts for what I need for my A/C gusset bracket. Chrysler must have used different brackets between the 318 2bbl and 360 4bbl A/C setups. Dang.

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