243 head/valve question
Thread Starter
Racer
Joined: Oct 2004
Posts: 480
Likes: 16
From: chicago il
243 head/valve question
I have a set of 243 heads off an 05 vette. I also have a set of cnc ported 241heads that are junk( ported into the water jackets) But the 241s have rev 2.02 1.57 stainless valves.. comp double springs titanium retainers and all that good stuff .. Im really on a tight budget ....
So the plan was to just have the 243 heads milled a little to bump up the compression. and run them with the stock valves.. My machine shop said they could also do the valve job and swap the larger valves in and do a little bowl blending for a nice gain in flow..
Its going on a 2000 c5 m/6 stock bottom comp 228/232 588/595 on a 112 installed straight up
So the question being will there be a big advantage to swapping the bigger valves in or just stay with the plan and run the stock valves just swapping the double comp springs on??
So the plan was to just have the 243 heads milled a little to bump up the compression. and run them with the stock valves.. My machine shop said they could also do the valve job and swap the larger valves in and do a little bowl blending for a nice gain in flow..
Its going on a 2000 c5 m/6 stock bottom comp 228/232 588/595 on a 112 installed straight up
So the question being will there be a big advantage to swapping the bigger valves in or just stay with the plan and run the stock valves just swapping the double comp springs on??
Last edited by fst85vtt; Nov 10, 2008 at 07:33 PM.
Pro
Joined: Aug 2007
Posts: 619
Likes: 1
From: ATLANTA GA
Bump for interest, Im on a budget also and have milled 243's(59cc) Wondering what ill gain..
While they are disassembled I was wondering that also if i could have a shop do the bowls correctly, then just LIGHTLY Massage the runners myself with sandpaper rolls to smooth it out some
While they are disassembled I was wondering that also if i could have a shop do the bowls correctly, then just LIGHTLY Massage the runners myself with sandpaper rolls to smooth it out some
Pro
Joined: Aug 2007
Posts: 619
Likes: 1
From: ATLANTA GA
Im on the same budget you are right now,
Im flycut .080 on both sides when I rebuilt the motor.
Im running a 239/242 .649 . 609 111LSA This particular cam clears a stock deck LS1 dot to dot with .060 clearance- The absolute bottom line safe clearance for these motors.
The current LS1 heads on my car were cut .025 so I had .030 taken off these heads since they start at 64 That puts me at 59. (.06 for every cc)
Im also going to run a .040 compressed thickness cometic gasket. Shaves another .013 also provides better quench.
Factoring the compression loss with the flycuts I should be arround mid 11:1 depending on what calculator im using. According to all my information this should all go together without a problem but I do intend on doing a quick clay test to double check. I Know I can run the milled heads without a problem because im running the ls1 heads with the same clearance. The gasket will be the only deciding feature so if it doesnt give good clearance ill just use stock gaskets.
How much is your shop charging for the bowl work? Honestly thats the major part with a port job that scares me, I think i could lightly massage the runners to smooth out the casting marks and have a budget bang.
Im flycut .080 on both sides when I rebuilt the motor.
Im running a 239/242 .649 . 609 111LSA This particular cam clears a stock deck LS1 dot to dot with .060 clearance- The absolute bottom line safe clearance for these motors.
The current LS1 heads on my car were cut .025 so I had .030 taken off these heads since they start at 64 That puts me at 59. (.06 for every cc)
Im also going to run a .040 compressed thickness cometic gasket. Shaves another .013 also provides better quench.
Factoring the compression loss with the flycuts I should be arround mid 11:1 depending on what calculator im using. According to all my information this should all go together without a problem but I do intend on doing a quick clay test to double check. I Know I can run the milled heads without a problem because im running the ls1 heads with the same clearance. The gasket will be the only deciding feature so if it doesnt give good clearance ill just use stock gaskets.
How much is your shop charging for the bowl work? Honestly thats the major part with a port job that scares me, I think i could lightly massage the runners to smooth out the casting marks and have a budget bang.
