No, both are cathedral port heads, 243's probably flow better than the 799's. another option would be a 317, they have about the same flow as a 243 but have a larger combustion chamber so it will drop your compression to 8.5-1 I believe.

 

To my knowledge 799's and 243 are basically the same thing. These are the most sought after heads as well (best flowing cath.) and are usually fairly expensive. ($250-300+) They will out flow a set of 317's.

I run the 317's on my setup because they were cheap. Picked mine up for $100 complete. Comp. calculator I used put me at at 8.6:1 with ls9 head gasket on a dished piston 5.3.

Wouldn't sweat it to much the 862 castings are a dime a dozen and will still make decent power. Sold my spare set for $25...

Heres some good info...

http://www.performancetrucks.net/fo...ns-158/tech-only-gm-head-casting-info-434396/

 

Great build, hanging to see it start

 

http://texas-speed.com/p-4-prc-stage-25-ls6-cnc-ported-heads.aspx

 

243s off of a ls6 have hollow valves. All other 243s/799s have solid valves. There is no difference in flow between a 243 and 799.

Cheapest Ive ever seen a complete set go for was $385 shipped. I just sold my set complete with springs for $400 cash. Going rate is $400-$500 for a shipped complete set.

The 317s flow better than the ls1 heads, not as good as the 243s, but are better for a turbo because of the compression drop. I got rid of my 243 heads in favor of L92 heads for the same reason... Flow increase and compression drop.

 

Update?

 

Ugh.... No good updates. Haven't touched it in weeks. I DID score a replacement head after finding one cracked badly. I still have to put it in the parts washer and scrub it up and swap springs, then I can get the engine back together. I am getting married this saturday so that has slowed this project down a lot with all the planning and BS that goes with that.

 

Sucker! Lol congrats man

 

Congrats! What's his name?

 

Wedding in the books. Back to work!!!

Got a new head for $free.50. Got it cleaned up last night. Turns out on the outside, the new head was dirtier. On the inside, much cleaner. That was good. I got the springs swapped out too. Then I wen ahead and took the port-o-band to the manifolds and cut the flanges off. Gotta get the V-bands welded on this weekend. Rough goal is to have the engine back together this weekend and maybe fired back up. We'll see....

 

Get it did! I want to see some burn out videos by the end of the weekend.

 

Excellent project. Congrats on your wedding too.

Keep the spanners busy so we can see the finished product!

 

Two steps forward, three steps back.

Got the "new" head ready to go on. Was looking over the deck to make sure it was clean (it wasn't) and ready for the head. That's when I noticed one of the pistons was in backwards. FML. The shortblock was the ONLY thing left that the previous owner touched that I hadn't had to go through and re-do/fix/change. That shit went out the window.

Got the motor pulled last night. The reason the piston was in backwards is that he was supposed to have gapped the rings. That shit didn't happen. The top ring is at .018". I am going to get some new rings for it (ANY RECOMMENDATIONS?), maybe a new oil pump just because I hear tales of these having problems, and maybe a new timing chain since this one is still original. Thoughts?

 

Thanks! She's a super lucky girl!

Spanners.... Are you from across the pond?

 

Three dots forward, one backward.

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I wonder if they put the piston on the rod backwards or the whole rod and piston backwards.....

 

Doh! The prev. owner sounds like too much of a tool to have managed to remove a pressed piston pin. (guessing it’s pressed anyway)

I’d look close and make sure they got all the cracked caps on correctly and see if the bearings are trashed. If the rings look good and were installed properly, I’d just run them. Sounds like OEM gap to me. Re-gap them to whatever your comfortable with and go to town. The original rings should already me “married” to the cylinders. Swapping in new ones will require a hone…then break-in… etc.

 

Whole thing was in backward. All the others look ok but i've got the one out now.

I think I want to hone it anyways since the cyl look so bad. Like they sat for a year with water in them.

 

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Not the worst one.

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Wow, thats crazy!!