62Ranchero200
Famous Member
The new combo for my AL head 250:
Head milled .056, 47 cc chambers, SCR ~10.5, DCR ~8.5, mild porting, valve guides cut down .100
Clay Smith / Vintage Inlines 280H cam (280/280/110) - .512 lift with 1.6:1 rocker arms, 231 duration @ .050 (.032 higher lift than previous 274H cam)
These are no longer available on either web site, but Clay Smith / Vintage Inlines CSC-200-STY springs (single spring with damper);
Clay Smith / Vintage Inlines 1.6:1 adjustable rocker arms
Machine shop has verified that in regard to both coil bind and valve guide interference, I should be OK up to nearly .600 lift. Have not degreed the cam yet, but do not expect piston to valve clearance to be an issue (at least, barring timing chain failure, at which time cam to conrod clearance may be more of a concern). My sole concern with this setup is high RPM valve float. I intend to break this combo in gradually, and initially keep the 5,500 RPM rev limiter on my MSD 6-AL. If all appears well, will definitely increase the rev limiter setting to 6,000 RPM.
Do any of you know anyone who ran the 280H cam on the single springs with dampers? Never had any issues with the 274H cam, even on all-out efforts like dyno pulls, limited to 5,500 RPM, with the same springs. On disassembly, valve train was in perfect condition after 10,000 miles, except for camshaft dowel pin, which was loose enough to fall out once cam gear was removed.
If I detect valve float, the next step is to move up to the dual valve springs (CSC-200-TOY), which are still on the Clay Smith web site.
If I ever upgrade the cam again, it will be to a solid lifter cam and I will definitely need the dual springs and will probably also get longer valves.
Thanks
Bob
Head milled .056, 47 cc chambers, SCR ~10.5, DCR ~8.5, mild porting, valve guides cut down .100
Clay Smith / Vintage Inlines 280H cam (280/280/110) - .512 lift with 1.6:1 rocker arms, 231 duration @ .050 (.032 higher lift than previous 274H cam)
These are no longer available on either web site, but Clay Smith / Vintage Inlines CSC-200-STY springs (single spring with damper);
Clay Smith / Vintage Inlines 1.6:1 adjustable rocker arms
Machine shop has verified that in regard to both coil bind and valve guide interference, I should be OK up to nearly .600 lift. Have not degreed the cam yet, but do not expect piston to valve clearance to be an issue (at least, barring timing chain failure, at which time cam to conrod clearance may be more of a concern). My sole concern with this setup is high RPM valve float. I intend to break this combo in gradually, and initially keep the 5,500 RPM rev limiter on my MSD 6-AL. If all appears well, will definitely increase the rev limiter setting to 6,000 RPM.
Do any of you know anyone who ran the 280H cam on the single springs with dampers? Never had any issues with the 274H cam, even on all-out efforts like dyno pulls, limited to 5,500 RPM, with the same springs. On disassembly, valve train was in perfect condition after 10,000 miles, except for camshaft dowel pin, which was loose enough to fall out once cam gear was removed.
If I detect valve float, the next step is to move up to the dual valve springs (CSC-200-TOY), which are still on the Clay Smith web site.
If I ever upgrade the cam again, it will be to a solid lifter cam and I will definitely need the dual springs and will probably also get longer valves.
Thanks
Bob
