what to do with 317 heads??
what to do with 317 heads?? so i just picked up a set of 317 heads. in good shape, but need a good cleaning. now i also picked up a cam specs : 228/230 .585"/.585" 112 lsa. i will also eventually have a 100 shot to add to the mix. should i have work done to them or sell them and pick up 243s or something else? My thought was since i already have these to just have them milled and p/p to get closer to the 243s (so i have read, i think). but as you can probably tell im kind of a noob at head machining and matching heads with a cam(or vise versa).
thanks everyone for all the help,
Bruce
thanks everyone for all the help,
Bruce
TECH Senior Member
Joined: Mar 2004
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From: BFE
317 runners are very similar to 243/799 (internally). Milling a bit is the cheapest way BUT then you have to watch for PTV clearance. 317 are 71cc and .006/.007 off for every cc you loose that much in PTV distance.
Another way of doing this is to find a good aluminum welder and filling the chamber to desired compression. Critical is GOOD welder. Then PTV remains constant while chamber gets smaller.
You'll need to mill chamber 6.5cc to get to 64.5 (243/799 size). That translates in .040 mill at least and that reduces your PTV distance by that much.
Measure PTV on your cam with stock 317 chambers and based on that you will be able to determine if removing .040 keeps you in the .080/.100 safe distance or not.
Another way of doing this is to find a good aluminum welder and filling the chamber to desired compression. Critical is GOOD welder. Then PTV remains constant while chamber gets smaller.
You'll need to mill chamber 6.5cc to get to 64.5 (243/799 size). That translates in .040 mill at least and that reduces your PTV distance by that much.
Measure PTV on your cam with stock 317 chambers and based on that you will be able to determine if removing .040 keeps you in the .080/.100 safe distance or not.
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Some shops charge 60-70 to surface heads to make them flat(.008-.010)mill
Many shops charge shop time after that since they can only mill .003-.005
per pass after that. Again you'ld have more PTV clearance if you sold those
317s for $100-$200 then secured some 243s for $300-$400 which would only
need a .008" to seal, rather than .040" to get compression back.
Many shops charge shop time after that since they can only mill .003-.005
per pass after that. Again you'ld have more PTV clearance if you sold those
317s for $100-$200 then secured some 243s for $300-$400 which would only
need a .008" to seal, rather than .040" to get compression back.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Hand ported and pretty well done, they flowed very similar (average 297cfm intake with very little variance). Darn good for hand porting. The guy that bought my 05 C6 (procharged), ended up slapping 2 hair dryers on it and is still running them today.
Last edited by PREDATOR-Z; May 23, 2012 at 01:06 AM.
Send them to AI (advanced induction). The ports are the same as the LS6/243 heads and AI will weld some metal in to them to reshape the chamber that will be as good or better than LS6's. They do the same to regular 241/LS1 heads with the "High Compression" option, and I got great results. No problems at all running on today's crap gas with 11.5:1 and a mild cam.
Jason
Jason
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Send them to AI (advanced induction). The ports are the same as the LS6/243 heads and AI will weld some metal in to them to reshape the chamber that will be as good or better than LS6's. They do the same to regular 241/LS1 heads with the "High Compression" option, and I got great results. No problems at all running on today's crap gas with 11.5:1 and a mild cam.
Jason
Jason
