Mill my 317's or get some 243's?
08-06-2012, 01:36 AM
#41
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Well I have the 317's that have been ported. I was just wondering if milling them too now that I have them would be the right way to go. I understand 243/799 are what most people go to. But since I have these would I be able to mill some material off or would I want to spend the extra money elsewhere. I'm getting confused some say yes others say no.
08-06-2012, 01:51 AM
#42
Well I have the 317's that have been ported. I was just wondering if milling them too now that I have them would be the right way to go. I understand 243/799 are what most people go to. But since I have these would I be able to mill some material off or would I want to spend the extra money elsewhere. I'm getting confused some say yes others say no.
08-06-2012, 02:22 AM
#43
TECH Fanatic
yes you can mill the 317's, but the problem you run into is PtV clearance depending on your cam. Factory 317's are 71cc, 243's are 64cc.
I would say measure the PtV with your current setup, that will tell you how much you can safely mill. Also if you flycut the pistons, or change to aftermarket pistons with valve reliefs, you can pick up another .125" or so of PtV.
I would say measure the PtV with your current setup, that will tell you how much you can safely mill. Also if you flycut the pistons, or change to aftermarket pistons with valve reliefs, you can pick up another .125" or so of PtV.
08-06-2012, 06:01 AM
#44
It's ultimately upto u, no brains involved in throwing 243/799's onto your combo , and you can run a plastic intake with no issues , if you plan on running a aluminum manifold such as a Vic jr etc and don't mind some extra time in setting it up then mill them a bit and enjoy.. Ultimately upto, you..
08-06-2012, 08:07 AM
#45
TECH Enthusiast
If you want to put the money into 317's you can make them identical to 243's. The reason that they are lower compression is the shape of the combustion chamber. There is more quench area on the 243. You can have the chambers welded to almost the same shape, actually add a little more material than necessary, then get the chambers CNC cut by one of the sponsor head porters like AI or TEA etc. They actually cut an improved 243 chamber as part of thier porting process, as they would do on a 243 head. While they were there I had a valve job and a full port job done on both the intake and exhaust.
The only reason I did this was because I had the 317's free, from a 30K mile 6.0 pull out I bought out of a truck, for a few hundred bucks. I bought the pullout for the 6.0 short block, and incidently had the heads. They were low milage, and there were in great shape, the guides were like new etc. I ran the numbers both ways, and the additional work of converting my 317's dimensionally identical to 243's was cheaper than finding a set of used 243's and starting from there. I would have been putting at least a $1000 dollars worth of work into the 243's anyhow, for a full port job.
All said and done I had a 317 head with a 60.5 CC chamber, with the same PTV as a 243, and my runners and chamber were cut to exactly the same profile a ported 243 would be. They were cut using the AI 226 CC CNC program for the 243 heads and chamber. Total cost was $1149. So a head identical to an AI ported 243 for this price I thought was a good deal. I've not seen anyone disapointed in the performance of the AI ported head. If you had to buy the cores for $150, you would still only have $1300 in them plus the cost of springs. If you can buy good 243 cores for $300 or less, that would be the way to go, but I've not had much luck finding them for a deal like that, I know they are out there and some people get them.
I'm not saying this is the way to go for everyone, but I think it worked out well for me.
PS. Don't get your chambers welded by anyone who has not got alot of experience welding and repairing cylinderheads. If they get them too hot core shift can occur. Welding cylinder heads is common place in the professional racing world, to create unique shapes and profiles, I would bet that on any given Sunday every sprint cup car has had some material added to thier heads and intakes in strategic places, to create a profile that thier team engine builders feels gives them an advantage. If it is done right it is not of any concern, its just as if more material was added when the head was cast.
The only reason I did this was because I had the 317's free, from a 30K mile 6.0 pull out I bought out of a truck, for a few hundred bucks. I bought the pullout for the 6.0 short block, and incidently had the heads. They were low milage, and there were in great shape, the guides were like new etc. I ran the numbers both ways, and the additional work of converting my 317's dimensionally identical to 243's was cheaper than finding a set of used 243's and starting from there. I would have been putting at least a $1000 dollars worth of work into the 243's anyhow, for a full port job.
All said and done I had a 317 head with a 60.5 CC chamber, with the same PTV as a 243, and my runners and chamber were cut to exactly the same profile a ported 243 would be. They were cut using the AI 226 CC CNC program for the 243 heads and chamber. Total cost was $1149. So a head identical to an AI ported 243 for this price I thought was a good deal. I've not seen anyone disapointed in the performance of the AI ported head. If you had to buy the cores for $150, you would still only have $1300 in them plus the cost of springs. If you can buy good 243 cores for $300 or less, that would be the way to go, but I've not had much luck finding them for a deal like that, I know they are out there and some people get them.
I'm not saying this is the way to go for everyone, but I think it worked out well for me.
PS. Don't get your chambers welded by anyone who has not got alot of experience welding and repairing cylinderheads. If they get them too hot core shift can occur. Welding cylinder heads is common place in the professional racing world, to create unique shapes and profiles, I would bet that on any given Sunday every sprint cup car has had some material added to thier heads and intakes in strategic places, to create a profile that thier team engine builders feels gives them an advantage. If it is done right it is not of any concern, its just as if more material was added when the head was cast.
08-06-2012, 10:26 AM
#46
TECH Senior Member
If you want to put the money into 317's you can make them identical to 243's. The reason that they are lower compression is the shape of the combustion chamber. There is more quench area on the 243. You can have the chambers welded to almost the same shape, actually add a little more material than necessary, then get the chambers CNC cut by one of the sponsor head porters like AI or TEA etc. They actually cut an improved 243 chamber as part of thier porting process, as they would do on a 243 head. While they were there I had a valve job and a full port job done on both the intake and exhaust.
The only reason I did this was because I had the 317's free, from a 30K mile 6.0 pull out I bought out of a truck, for a few hundred bucks. I bought the pullout for the 6.0 short block, and incidently had the heads. They were low milage, and there were in great shape, the guides were like new etc. I ran the numbers both ways, and the additional work of converting my 317's dimensionally identical to 243's was cheaper than finding a set of used 243's and starting from there. I would have been putting at least a $1000 dollars worth of work into the 243's anyhow, for a full port job.
All said and done I had a 317 head with a 60.5 CC chamber, with the same PTV as a 243, and my runners and chamber were cut to exactly the same profile a ported 243 would be. They were cut using the AI 226 CC CNC program for the 243 heads and chamber. Total cost was $1149. So a head identical to an AI ported 243 for this price I thought was a good deal. I've not seen anyone disapointed in the performance of the AI ported head. If you had to buy the cores for $150, you would still only have $1300 in them plus the cost of springs. If you can buy good 243 cores for $300 or less, that would be the way to go, but I've not had much luck finding them for a deal like that, I know they are out there and some people get them.
I'm not saying this is the way to go for everyone, but I think it worked out well for me.
PS. Don't get your chambers welded by anyone who has not got alot of experience welding and repairing cylinderheads. If they get them too hot core shift can occur. Welding cylinder heads is common place in the professional racing world, to create unique shapes and profiles, I would bet that on any given Sunday every sprint cup car has had some material added to thier heads and intakes in strategic places, to create a profile that thier team engine builders feels gives them an advantage. If it is done right it is not of any concern, its just as if more material was added when the head was cast.
The only reason I did this was because I had the 317's free, from a 30K mile 6.0 pull out I bought out of a truck, for a few hundred bucks. I bought the pullout for the 6.0 short block, and incidently had the heads. They were low milage, and there were in great shape, the guides were like new etc. I ran the numbers both ways, and the additional work of converting my 317's dimensionally identical to 243's was cheaper than finding a set of used 243's and starting from there. I would have been putting at least a $1000 dollars worth of work into the 243's anyhow, for a full port job.
All said and done I had a 317 head with a 60.5 CC chamber, with the same PTV as a 243, and my runners and chamber were cut to exactly the same profile a ported 243 would be. They were cut using the AI 226 CC CNC program for the 243 heads and chamber. Total cost was $1149. So a head identical to an AI ported 243 for this price I thought was a good deal. I've not seen anyone disapointed in the performance of the AI ported head. If you had to buy the cores for $150, you would still only have $1300 in them plus the cost of springs. If you can buy good 243 cores for $300 or less, that would be the way to go, but I've not had much luck finding them for a deal like that, I know they are out there and some people get them.
I'm not saying this is the way to go for everyone, but I think it worked out well for me.
PS. Don't get your chambers welded by anyone who has not got alot of experience welding and repairing cylinderheads. If they get them too hot core shift can occur. Welding cylinder heads is common place in the professional racing world, to create unique shapes and profiles, I would bet that on any given Sunday every sprint cup car has had some material added to thier heads and intakes in strategic places, to create a profile that thier team engine builders feels gives them an advantage. If it is done right it is not of any concern, its just as if more material was added when the head was cast.
08-13-2012, 09:48 AM
#48
im in a similar situation I got a set of 317s for free with LS6 valve springs I was planning on sending them to AI to convert them to 243 specs (no other port job just yet) i have not picked out a cam for this set up if possible does anyone know the specs of a cam i could run without running into ptv clearance problems? just a side note i have no plans of forced induction
08-16-2012, 01:24 AM
#50
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Y'all are some very smart folks no joke but could could I also convert my 806s identical to 243s? The 317s are 150$ help. The cam I will use is a 220/220 .525or.515lift. What's pvt? I'm a newb for initial keywords sorry
08-17-2012, 07:12 PM
#52
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Thanks for the vital info, ill just buy some aftermarket afrs heads used
08-17-2012, 09:17 PM
#54
I've used 317s on an ls1 ported and polished milled .100, worked great and ran a best of 11.7 @118 in a trans am. They flow good and yes u can get away with milling them but don't run a big cam till u flycut. A 224 230 581 591 @ 112 is the cam with 7.375 pushrods and ls7 lifters 
Last edited by anheuserbusch08; 08-17-2012 at 09:22 PM.
08-17-2012, 10:10 PM
#55
I've used 317s on an ls1 ported and polished milled .100, worked great and ran a best of 11.7 @118 in a trans am. They flow good and yes u can get away with milling them but don't run a big cam till u flycut. A 224 230 581 591 @ 112 is the cam with 7.375 pushrods and ls7 lifters
08-18-2012, 04:52 AM
#56
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To be honest . Porting polishing the milled 806s heads for 350 would hang in there similar in performance hp gain with the 317s? Or id be better off buying the 317s for 150$ and pay extra 350 for port&polish?
Would it be big difference? Or meh :/
Would it be big difference? Or meh :/
08-18-2012, 10:44 AM
#57
But does that mean it looses power? Depending what else is done with the valves, valvejob, port work, etc I don't think you can know for certain. I know people have had problems on the flowbench from making the chambers to large too.
For about the price of a set of used 243/799 heads, you can have a set of 317 heads with a fresh valve job and freshly machined deck that could very well outperform the 243/799 heads, depending on how good the valvejob is. What it comes down to is how much P-V is needed?
For about the price of a set of used 243/799 heads, you can have a set of 317 heads with a fresh valve job and freshly machined deck that could very well outperform the 243/799 heads, depending on how good the valvejob is. What it comes down to is how much P-V is needed?
08-18-2012, 11:18 AM
#58
Mine with untouched 317's just milled .100 made pretty good power for what was done.. And minimal outlay in money, would I suggest everyone go out and lop off .100, no... But if you have a 1/2 a brain you can have a hard running car for minimal $$.. I have a large cam (250/250 .648/.648) but that's to go with the fact it's a race car with a 5200 stall You can have a solid 400+whp all day long if done properly.. 50 diff ways to skin a cat
