so wich are better 317's or 243's

 

243's! They flow slightly more than a 317 due to a slightly smoother cast and D shaped ports on the exhaust. Also, you'll gain 1 point in compression with the 243's. It will put you close to 10.5 on an Lq4.

 

If you can get a good price on 317's thats what I'd do then have them milled down. I don't think the difference in power gains is worth what people want for 243's these days. I bought mine supposedly as ZO6 take offs in perfect running order, and when I got them they where GTO heads and they had a bent valve. There is less chance someone is gonna be running an MS4 with factory 317 take offs then with 243's. If you do get 243's make sure you look em over real good before you install them. I was lapping in the valves when I found the bent one...

 

Actually, i agree with MPFD. Its retarded what you have to pay for a set of 243's these days! If you'd buy a set of 317's and mill them about .030 to .040 the performance difference would be very minimal between them and a set of 243's. And you would have saved your self a couple hundred dollars.

 

cool. thanx 4 the info guys

 

No prob!

 

https://www.performancetrucks.net/fo...d.php?t=464701

Make him an offer...

 

see that’s where these guys are wrong yes the 317 have better flow but compression is 9:4:1 u put 862 our 706 on it the compression goes to 10:4:1 which is more power with out doing anything else the 706 are same as 862 just little prone to cracking I have proven dyno numbers that the 243 head give u one our two more then the 862 not worth the price for them if it’s hp your looking for the 862 on a lq4 is better then the 317 all day every day I can send countless dyno numbers that prove that

 

LOL this is a 10 year old thread and that dude hasn't logged in since 2016.

You definitely told him!

 

I'd like to see the dyno proof because dyno numbers are cool.