LSX454 BTR Stage 4 Cam opinions
08-25-2020, 04:04 PM
#81
The cam grinder will have specs when the cam is at TDC (intake/exhaust over lap period) say in this case .100 tappet lift (when engine is at TDC again it is 0 tappet lift). This .100 will fluctuate on where cam is installed the ICL etc. You would then multiply by say the 1.7 rocker arm ratio so the cam is at .170 lift during the overlap period. So if you were to drop the valve as mention above and say you come up with .300 you would have .130 (.300-.170) piston to valve clearance at TDC. Now what they will say is they want an additional cushion of say .20-.30 to cover issue that the piston is kind of up there in limbo for a few degrees not going anywhere (before heading down the bore) but the cam is still opening. So lets say they like a .030 factor so at end of day you PTV clearance would be .100 (.130-.030). The comp cam lobe book has the TDC measurements on their cam lobes.
08-25-2020, 06:11 PM
#82
I made contact with the tech department of GMPP today and they put out a question for the engineer department for dish size on the LSX 4.185 piston they use. It’s a dish of 11.1 and valve relief of 0.3cc
Hope this helps somebody else in the future! Will move forward with the Mast 285’s with Ti valves on both sides, milled to 65cc yielding a 12.3:1 compression ratio. Will install roller tip rockers and shoot for some big lift, why not. Should be happy in the 25X/26X range with the Mast heads producing impressive velocity and flow clean past 700 lift.
Excited to see how much power will be gained and how responsive it will be with the 285’s.
Hope this helps somebody else in the future! Will move forward with the Mast 285’s with Ti valves on both sides, milled to 65cc yielding a 12.3:1 compression ratio. Will install roller tip rockers and shoot for some big lift, why not. Should be happy in the 25X/26X range with the Mast heads producing impressive velocity and flow clean past 700 lift.
Excited to see how much power will be gained and how responsive it will be with the 285’s.
08-25-2020, 06:17 PM
#83
ModSquad
iTrader: (6)
I made contact with the tech department of GMPP today and they put out a question for the engineer department for dish size on the LSX 4.185 piston they use. It’s a dish of 11.1 and valve relief of 0.3cc
Hope this helps somebody else in the future! Will move forward with the Mast 285’s with Ti valves on both sides, milled to 65cc yielding a 12.3:1 compression ratio. Will install roller tip rockers and shoot for some big lift, why not. Should be happy in the 25X/26X range with the Mast heads producing impressive velocity and flow clean past 700 lift.
Excited to see how much power will be gained and how responsive it will be with the 285’s.
Hope this helps somebody else in the future! Will move forward with the Mast 285’s with Ti valves on both sides, milled to 65cc yielding a 12.3:1 compression ratio. Will install roller tip rockers and shoot for some big lift, why not. Should be happy in the 25X/26X range with the Mast heads producing impressive velocity and flow clean past 700 lift.
Excited to see how much power will be gained and how responsive it will be with the 285’s.
08-26-2020, 05:21 AM
#85
Jesel Shaft mount-Sportsman series.
Have those heads checked out n gone thru. I would not 100% trust that guys second hand info. They didn't look like they were "gone thru" in the pics of the for sale thread you sent me. Does titanium rust? Those valves looked kinda shytty. Maybe post up the pics I saw here for others to see. Along with his description. For that price, id still be interested too. But your new set from Mast wasnt all that more and you ll know exactly what your gettn. If I was selling a set of heads thst nice, I sure would have spent some time cleaning them up, etc. I dunno. Ask if he has a reciept of them being "gone thru".
Have those heads checked out n gone thru. I would not 100% trust that guys second hand info. They didn't look like they were "gone thru" in the pics of the for sale thread you sent me. Does titanium rust? Those valves looked kinda shytty. Maybe post up the pics I saw here for others to see. Along with his description. For that price, id still be interested too. But your new set from Mast wasnt all that more and you ll know exactly what your gettn. If I was selling a set of heads thst nice, I sure would have spent some time cleaning them up, etc. I dunno. Ask if he has a reciept of them being "gone thru".
08-26-2020, 05:23 AM
#86
I made contact with the tech department of GMPP today and they put out a question for the engineer department for dish size on the LSX 4.185 piston they use. It’s a dish of 11.1 and valve relief of 0.3cc
Hope this helps somebody else in the future! Will move forward with the Mast 285’s with Ti valves on both sides, milled to 65cc yielding a 12.3:1 compression ratio. Will install roller tip rockers and shoot for some big lift, why not. Should be happy in the 25X/26X range with the Mast heads producing impressive velocity and flow clean past 700 lift.
Excited to see how much power will be gained and how responsive it will be with the 285’s.
Hope this helps somebody else in the future! Will move forward with the Mast 285’s with Ti valves on both sides, milled to 65cc yielding a 12.3:1 compression ratio. Will install roller tip rockers and shoot for some big lift, why not. Should be happy in the 25X/26X range with the Mast heads producing impressive velocity and flow clean past 700 lift.
Excited to see how much power will be gained and how responsive it will be with the 285’s.
08-26-2020, 08:15 AM
#87
Jesel Shaft mount-Sportsman series.
Have those heads checked out n gone thru. I would not 100% trust that guys second hand info. They didn't look like they were "gone thru" in the pics of the for sale thread you sent me. Does titanium rust? Those valves looked kinda shytty. Maybe post up the pics I saw here for others to see. Along with his description. For that price, id still be interested too. But your new set from Mast wasnt all that more and you ll know exactly what your gettn. If I was selling a set of heads thst nice, I sure would have spent some time cleaning them up, etc. I dunno. Ask if he has a reciept of them being "gone thru".
Have those heads checked out n gone thru. I would not 100% trust that guys second hand info. They didn't look like they were "gone thru" in the pics of the for sale thread you sent me. Does titanium rust? Those valves looked kinda shytty. Maybe post up the pics I saw here for others to see. Along with his description. For that price, id still be interested too. But your new set from Mast wasnt all that more and you ll know exactly what your gettn. If I was selling a set of heads thst nice, I sure would have spent some time cleaning them up, etc. I dunno. Ask if he has a reciept of them being "gone thru".
