I am running a fresh rebuild 468 bbc with 10:1 compression. I pulled it apart because of a lifter failure. Once down, I decided to convert it to a Cam Motion recommended Hyd roller. After rebuild I lost 1000 rpm. The engine was barely getting in the low 4000's rpm. After beating my head against the wall all summer looking for the issue, per recommendation from Cam Motion, I retarded the cam 6%.with no real improvement, so then Bobby recommended I replace the new valve springs (that my local shop installed) with new valve springs again. This time going from 125 seat to 155 seat pressure. Well that did most of it. I am back to about 5000 rpm, however still short of the old flat tappet camshaft.

My question is, should I continue to run the 6 degree retarded camshaft and or go larger camshaft? When I pulled the flat tappet, it was 6 degree retarded as well. I guess this is telling me I am a little short on duration or ??

Original flat tappet camshaft Crower #01205, 220 - 232 108 LS .529 .527 (minor water reversion at low idle, Sniper did not like the LS angle)
New Hyd roller camshaft Cam Motion custom, 220 - 228 111 LS.553 .552 (smooth as butter idle, engine needs more?)

27 Excalibur Speedster
468 ci bbc
Edelbrock RPM O'port heads 110cc comb volume, 290 intake runners, 2.19 intake valve, 1.88 exhaust valve
Edelbrock RPM O'port intake
Holley Sniper EFI
Comp Pro Magnum steel full roller rockers
Imco exhaust

What RPM range are you looking for ? I'm not an engine builder, I don't sell camshafts but I've tried a few. I never saw much from retarding the cam except it made the motor lazy.

I currently have no problem getting on plane with the current cam retarded 6 degree. I am looking to spin the engine to 5300.

By looking at your numbers it looks like it's ground on a 111* intake cl. Are you saying that you have it in at 117*? That seems a bit much.

The new cam is ground at 107 intake centerline, now at 113

why dont you just buy a cam with a 114 split install it straight up and call is a day...........is this a mark 4 block ?

Yes Mark IV. What duration are you thinking? I know the carb HP500 was close to the cam I have but later Merc kept throwing bigger cams in the HP series.

Whats the max lift on the valve springs

Isky 9005 springs at 1.90 installed. Bind says 1.160

Who put in 125# springs!?
My head guy would chase me out of his shop if I suggested anything under 180#, granted I`m running a blower and my spring pressure is 225# but it`s obvious you had valve float .. to me 155 is still too low.