Hi Ed . . .

I am atleast a year from being on the road as well. It's taken alot of patience to research, locate and acquire the parts I wanted.

I am doing an early 50's hop up on an outwardly stock '49 Chevy Fastback. I am following the guidelines set forth by Roger Huntington and Bill Fisher to modify the 216 that's in the car. An antique hot rod built from antique speed manuals. I am doing most of what's in those books - except converting to full pressure oiling.

I think that this type of grind has lots of promise for a street engine. I have studied the specs on alot of I6 cams. The problem with 'symetrical' long duration cams - like what California Bill describes as a Super Grind:
---------Timing----Adv Duration
Intake----35-73--------288
Exhaust---31-74--------285
is that you get killed at low RPM by early/late valve events and extreme overlap:

1) Opening the exhaust valve so early during the power stroke is a killer on low RPM lugging abilility. One needs to provide alot of additonal compression ratio, displacement or both to over come this low RPM loss of power.

2) Opening the intake valve so early causes exhaust to backup into the intake manifold. This kills vacuum, which impacts low end throttle response, and dilutes the intake charge effecting voumetric efficiency.

3) Keeping the intake valve open so long after BDC causes the intake charge to backup. This reversion further kills intake plane vacuum - so throttle response suffers further still.

These 'late closing dual pattern' grinds we're talking about try to address these three low RPM issues. They do this by only lengthening the exhaust duration to one extreme. This is accomplished by shifting/retarding the lobe center. Which means that the exhaust valve stays closed during more of the power stroke (not opening so early - addressing issue 1). But stays open longer providing exhaust scavenging during the overlap (which helps volumetric efficiency). While the comparitively shorter intake duration and valve events provide a good idle (Issues 2 & 3).

It's a 3/4 race on the intake - and a rumpy full race on the exhaust . . . that's what sold me.

You may want to give the guys at Delta Cams a call. They did right by me Delta Cams Posting on Inliners BB

regards,
stock49

[Linked Image from 49fastback.com]