The truth on milled 317s....?
10-02-2011, 10:23 PM
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The truth on milled 317s....? Awhile ago i made a trade for a set of 317 heads that were milled to 63ccs. The person i acquired them off of told me that it would be the same as a set of 241/243 at the same cc and that i should be with ptv clearance.
The issue is i have a few people telling me that they are not the same and that I will most def. have issues with piston to valve.... so the big question is.. will these work with my current setup (torquer v2) and if not, is there anything that i can do to make them work.
If they do work, what kind of results can i expect to see from them?(over my 806 heads, which im under the assumption are the least favorable out of the years) 7.42 at 92 in the 1/8 with a 1.59 60ft. Just out of curiosity.
Thanks for the responses in advance!
The issue is i have a few people telling me that they are not the same and that I will most def. have issues with piston to valve.... so the big question is.. will these work with my current setup (torquer v2) and if not, is there anything that i can do to make them work.
If they do work, what kind of results can i expect to see from them?(over my 806 heads, which im under the assumption are the least favorable out of the years) 7.42 at 92 in the 1/8 with a 1.59 60ft. Just out of curiosity.
Thanks for the responses in advance!
10-02-2011, 11:26 PM
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Your post is a little confusing but to maybe give some insight a 317 head has the same ports as a 243/799 the only difference is they have 70 cc combustion chambers which will lower compression if unmilled. But since yours are milled to the same chamber as a 243 they are effectively a 243 except for now the valves and head surface are closer to the deck of the block/pistons so they could very well have some PTV issues. Your best bet is to use the clay method and measure the PTV clearance
10-02-2011, 11:32 PM
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Thankyou. I was under the assumption that the valves for 317s at 70cc were the same distance as 243s at 64 cc or whatever they are factory from the deck. I was thinking that 63the on a 317 would be like 58 or 59 cc on a 243 milled the same amount.... if that makes sense.. lol. So 63cc on these should be the same ptv. Clearance as 243s? Correct? Sorry for the confusing post
10-03-2011, 12:35 AM
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When you mill the head you will have less PTV than a head that is left alone. The 243 and 317 have the same overall thickness but but the 317 has a larger bowl (70cc). If you mill the heads down to a 63cc chamber you will have less PTV than a stock 243 or stock 317 head.
10-03-2011, 12:41 AM
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Ok...... let me re-phrase this.. lol.. a 243 at 63cc and a 317 at 63cc will have the exact same amount of ptv clearance, correct? That's the question boiled down.
10-03-2011, 12:50 AM
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Ok, I didn't read into his post deep enough. So are these heads pretty much useless? (Aka, too much material removed to fit my cam?) I know I would need to measure but if its not even in the same ball park I wont bother. Thankyou everyone for ur responses so far
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10-03-2011, 12:59 AM
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Haha. Also known as... useless to me... correct my math if im wrong.... mine are milled for 7 less cc on compared to stock. 243 is 64cc stock. (64-7=57). So comparably... I have a set of heads with similar ptv as a set of 243s at 57cc.... not good. Lol
10-03-2011, 08:32 AM
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not really a good way to do it since the different chambers mill out different. But effectively maybe since I understand what youre getting at. Bottom line is your valves will now be closer to the piston which will cause some potential issue if you dont flycut. If it were me I would just rent the tools and flycut
10-03-2011, 10:08 AM
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No its quite simple just a little time consuming. Rent the tools id say from another member on here and you put the tool in your head and use the head to guide the cutting tool down to the piston. There are in depth write ups. Basically its a valve with cutting teeth on them. Some people have even used stock valves and stuck 40 grit sand paper on them and done it.
