[General Z]

Seeking opinions:

My oil pan and rear main seal are leaking. So, I was going to pull the engine. I’ll need a new pan, one piece gasket and was going to do the one piece rear main seal.

While the engine is out, I was curious about making upgrades. Personally, I feel like the car is a dog for the size of the engine and the combination of parts and drivetrain. I understand that this is subjective. On my little quarter mile test tool, it will do mid 14 seconds. I feel like the car should be quite a bit faster.

I’m curious if a different cam would give me more power, without sacrificing street manners? The car currently has perfect street manners. It drives like any modern car. But, when I punch it, I’d like it to be faster. I don’t have a big desire to switch to a roller cam.

The springs are pretty old and I was thinking of going to the Crower 68404.

Also, the last time the engine was out, I feel like the timing chain had quite a bit of slack in it. Seeing as how the block has been line honed at least once, I was thinking maybe I should run one of the undersized chains?

Looking for any advice on cam, lifters, pushrods, timing chain, if there is more power to be had, without sacrificing street manners.


The car is a 67 Firebird convertible.

The engine is a 1970 455, bored .060. It’s been line honed as well.

It has a factory crank ground .010 on rods and mains.

Forged pistons and rods.

The heads are 1971 Pontiac 400 heads, Code 96. Mildly ported, stainless valves. I’ve got Comp Cams roller rockers, ration 1.52. I think they are Magnum. The springs are some tired Comp 988 springs. I was thinking of switching to the Crower 68404.

Compression Ratio should be 9.53:1.

Intake is Edlebrock Performer, port matched.

Car is a Holley 750 with vacuum secondary.

Distributer is Performance Distributors HEI, custom curved.

Trans is a 700R4 with a 2600 stall lock up converter.

Rear end is 3.73 Chevy 12 bolt.

It’s got headers and dual exhaust.

The cam is a Summit 2802.
Cam Style:Hydraulic flat tappet
Basic Operating RPM Range:2,200-5,500
Intake Duration at 050 inch Lift:224
Exhaust Duration at 050 inch Lift:234
Duration at 050 inch Lift:224 int./234 exh.
Advertised Intake Duration:298
Advertised Exhaust Duration:303
Advertised Duration:298 int./303 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.466 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.488 in.
Valve Lift with Factory Rocker Arm Ratio:0.466 int./0.488 exh.
Lobe Separation (degrees):114

Thanks in advance