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poly 318 with LA heads. #1652273 07/29/14 01:02 AM 07/29/14 01:02 AM
Joined: Sep 2006 Posts: 515 New Richmond, WI K kams OP mopar
kams OP mopar K Joined: Sep 2006 Posts: 515 New Richmond, WI	Can you put LA style small block heads on a 318 poly motor? I was thinking of boring it out to 4.04 and using 915 340 J heads 2.02 1.60 valves. Any ideas.

Re: poly 318 with LA heads. [Re: kams] #1652274 07/29/14 01:20 AM 07/29/14 01:20 AM
Joined: Jan 2003 Posts: 1,018 Here and now J jeebis44 super stock
jeebis44 super stock J Joined: Jan 2003 Posts: 1,018 Here and now	I'm pretty sure the geometry's all wrong on many levels

Re: poly 318 with LA heads. [Re: jeebis44] #1652275 07/29/14 06:22 AM 07/29/14 06:22 AM
Joined: Sep 2003 Posts: 1,295 Hawley, Texas shinnery super street
shinnery super street Joined: Sep 2003 Posts: 1,295 Hawley, Texas	I think if you lay a LA head gasket on the poly block you will find no way to put intake pushrods in it. Bryce Every electronic device is manufactured with smoke stored deep inside... only a true genius can find a way to set it free. The most terrifying words in the English language are: "I'm from the government and I am here to help!"

Re: poly 318 with LA heads. [Re: shinnery] #1652276 07/29/14 10:14 AM 07/29/14 10:14 AM
Joined: Jan 2003 Posts: 21,065 Niles , Ohio T therocks oh wait.but hey.lets see.oh yeah.
therocks oh wait.but hey.lets see.oh yeah. T Joined: Jan 2003 Posts: 21,065 Niles , Ohio	I agree they are different.Rocky Chrysler Firepower

Re: poly 318 with LA heads. [Re: therocks] #1652277 07/29/14 12:33 PM 07/29/14 12:33 PM
Joined: Feb 2003 Posts: 8,671 A Andrewh master
Andrewh master A Joined: Feb 2003 Posts: 8,671	someone here or maybe another board used to say it would work, but I don't recall actually seeing pictures, or anyone else trying.

Re: poly 318 with LA heads. [Re: therocks] #1652278 07/29/14 12:34 PM 07/29/14 12:34 PM
Joined: May 2003 Posts: 6,561 Downtown Roebuck Ont Twostick Still wishing...
Twostick Still wishing... Joined: May 2003 Posts: 6,561 Downtown Roebuck Ont	I was always told the reason push rod angles suck on an LA is because they never changed the lifter angle from a poly. Kevin

Re: poly 318 with LA heads. [Re: Twostick] #1652279 07/29/14 02:06 PM 07/29/14 02:06 PM
Joined: Jan 2005 Posts: 12,419 Kalispell Mt. H HotRodDave I Live Here
HotRodDave I Live Here H Joined: Jan 2005 Posts: 12,419 Kalispell Mt.	LAs go on a poly easy enough, it is the other way around you don't want ot get involved in They have the same deck height, rods, crank, pistons, timing cover, timing set, lifter angle, oil pump... just the poly block has clearance for the intake PR to go at a weird angle and the LA does not, if you try to notch you LA block for poly PR angles you will hit water. I am not causing global warming, I am just trying to hold off a impending Ice Age!

Re: poly 318 with LA heads. [Re: Twostick] #1652280 07/29/14 09:26 PM 07/29/14 09:26 PM
Joined: Jan 2004 Posts: 8,241 fredericksburg,va C cudaman1969 master
cudaman1969 master C Joined: Jan 2004 Posts: 8,241 fredericksburg,va	Quote: I was always told the reason push rod angles suck on an LA is because they never changed the lifter angle from a poly. Kevin Correct, Chrysler was saving a dime from retooling. The pushrod angle was designed for the polyhead and they needed a smaller v8 package for the new a-bodys so a smaller head was designed for the block they had. The block had proven to be very good, all about money. I think the poly head would have been a better perfprmance head in the long run(canted valves).

Re: poly 318 with LA heads. [Re: cudaman1969] #1652281 07/29/14 09:42 PM 07/29/14 09:42 PM
Joined: Jan 2011 Posts: 137 Daytona Beach, FL C cknight member
cknight member C Joined: Jan 2011 Posts: 137 Daytona Beach, FL	Don't forget to use an LA camshaft, as the valve layout on the LA heads is different than on the poly. Regards, Chase

Re: poly 318 with LA heads. [Re: kams] #1652282 07/29/14 09:55 PM 07/29/14 09:55 PM
Joined: Sep 2006 Posts: 515 New Richmond, WI K kams OP mopar
kams OP mopar K Joined: Sep 2006 Posts: 515 New Richmond, WI	I just want to use the poly block so I can bore it out to a 340 size and make a cheap motor.

Re: poly 318 with LA heads. [Re: kams] #1652283 07/29/14 11:12 PM 07/29/14 11:12 PM
Joined: Jan 2003 Posts: 9,826 las vegas 70AARcuda master
70AARcuda master Joined: Jan 2003 Posts: 9,826 las vegas	Are you sure that the Poly 318 3.91 bore can go .130 to a 4.04 bore...? Tony 70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)

Re: poly 318 with LA heads. [Re: 70AARcuda] #1652284 07/30/14 02:19 PM 07/30/14 02:19 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	UT is your friend. There is no guarantee that any 3.91 block will go to 4.040. Yes, the LA (Light A) block is lighter than the Poly, but where did the weight change come from? Hasn't been researched, AFAIK. Mopar castings were all over the map, early or late. R.

Re: poly 318 with LA heads. [Re: dogdays] #1652285 07/30/14 02:48 PM 07/30/14 02:48 PM
Joined: Jan 2005 Posts: 12,419 Kalispell Mt. H HotRodDave I Live Here
HotRodDave I Live Here H Joined: Jan 2005 Posts: 12,419 Kalispell Mt.	They were way thicker in general but core shift was worse so the odds are better but still not good, especially considering 60 years of corrosion from not being serviced properly... BTW I have a 71 318 block in the shop right now that is 4.070 bored and was a running motor with 12.5 compression, no block filler and was being dirt track raced till it developed a rod knock... I am scared to reassemble it I am not causing global warming, I am just trying to hold off a impending Ice Age!

Re: poly 318 with LA heads. [Re: HotRodDave] #1652286 07/30/14 03:28 PM 07/30/14 03:28 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	It'd be interesting to sonic check it. R.

Re: poly 318 with LA heads. [Re: dogdays] #1652287 07/30/14 03:53 PM 07/30/14 03:53 PM
Joined: Jan 2005 Posts: 12,419 Kalispell Mt. H HotRodDave I Live Here
HotRodDave I Live Here H Joined: Jan 2005 Posts: 12,419 Kalispell Mt.	I sonic tested it by tapping the bores with a screw driver and they sound like glass, the block weighs 122# and a 68 std bore block (same casting number) weighs 165# on the same scale I am not causing global warming, I am just trying to hold off a impending Ice Age!

Re: poly 318 with LA heads. [Re: HotRodDave] #1652288 07/30/14 07:51 PM 07/30/14 07:51 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	43 lb is 43 / 0.258 = 167 cubic inches of material. Calculating a 6" high cylinder 4.040 inches diameter, subtracting a 3.91" cylinder 6" high I get around 48 cubic inches, so your numbers work out. I bet you don't have any cylinder wall with more than 0.100" thickness. R.

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