327/300HP: Modify..or leave it alone?

[Kenneth B.]

Hello, folks,

I am in the process of re-assembling my 327/300HP (bored .030 over w/ new L2165 flat top pistons, Edelbrock Performer intake, stock AFB, Hooker headers & sidepipes) NOM for my 63 convertible (4-speed, 3:70 posi). A few years back, when gathering parts, I purchased a Crane Blueprint series 350HP cam for use this engine. However, after reviewing many posts in the NCRS archives, I am leaning strongly towards going back to the 929 300HP cam instead.

Agree? Disagree? Any reason to consider keeping the 350HP cam in this engine?

Also, Duke, if you're out there, thanks for all of your contributions to this forum - your posts made a very good case for sticking with the 300HP cam. You recommended pocket porting and port matching the heads with a multiangle valve job, plus retarding the OE 929 cam four degrees.

My heads are freshly reconditioned with a three-angle valve job ( but no pocket-porting or port matching) - should I still consider retarding the cam
four degrees?

Thanks in advance to all.

[Duke W.]

Re: 327/300HP: Modify..or leave it alone?

If the heads are not yet installed, consider diassembling them and doing the pocket porting/port matching/chamber relieving. That's where most of the benefit is, and without the head work, the better flowing manifold won't have much effect.

Retarding the cam shifts the torque curve up the rev scale a few hundred revs, so you gain a little at the top end, but loose a little on the bottom end, but it works best with massaged heads. The 350 HP cam further shifts the torque curve up the rev scale. It's a matter of matching the torque curve to your gearing and driving habits. For most of us geesers the 300 HP with tall gears is probably best for our current use of vintage Corvettes, but the "Special 300 HP" cam with massaged heads makes the engine act like a 300 HP at idle and the low end with more top end power than an OE 350 HP - the best of both worlds.

With a thick gasket those pistons won't make much compression. I hope you make the requisite measurements, run them through a CR calculator and select a gasket that will give between 9.5 and 9.75:1.

Duke

[Gary B.]

Re: 327/300HP: Modify..or leave it alone?

Since you are looking to improve flow, I used a vendor in Wisconsin who will machine out your exhaust manifolds, referred to me by an engine builder. At least he use to for the circle track racers. He has an NC machine. I did it and the job looked great. If you are interested, let me know and I will look for the info this weekend.