Hi All, My friend and I are just about to order the parts for the engine in his Top Flight 63 Roadster, HP 340, Decked and restamped block. I'd appreciate some feedback as to everybody's opinion of what they would put into it. Pistons to be Forged, Rods to be heavier than original, (Sportsman are too costly), and what Cam do we like? Brand names etc. The Heads for this rebuild are done as original. Thanks!

 

The cam and components that will probably give you the best all around performance and satisfaction would be from the 1970 LT1 engine.

 

If you haven't already done so, the first thing I'd recommend are some critical measurements.

A. Cylinder head CC
B. piston/deck clearance - hopefully you did this before the teardown and can simply subtract the amount of deck that was removed. If not, I recommend creating a mock-up and taking measurements.

W/o these measurements your new compression ratio will be a shot in the dark.

On another note, SCAT makes a nice set of small journal press fit rods for about $230. They are not as nice as the Crowers but they are way better than the early and late OE rods.

I went with the LT1 CAM but sometimes wish I went with the 30-30. The LT1 is better when you consider torque bandwidth but the 30-30 supposedly has a nastier idle lope and explodes into the top end. It may lose at the track but the sensation would be much better.


Brian

 

If you think Crower Sportmans are too expensive then you should rebuild it with a 300 HP cam and limit revs to 5000. The OE rods are seriously WEAK! I nearly lost my 340 HP engine based on a magnaflux inspection that showed a very bad crack adjactent to a bolt seat on #7. The later design small bearing rods are better, but still marginal for a 6500 RPM engine. The Crower Sportsmans are cheap insurance and you will never have to worry about taking it to redline as long as you have a full oil sump.

The LT-1 cam is the way to go. It will idle like the Duntov cam but make more top end power. Also, more top end power is available by pocket porting/port matching the 461X heads and finishing them with a muliangle valve job; .040" wide inlet seats are okay for street and will provide good longevity; .060" on the exhaust side.

Spend your budget on Crower Sportsman rods and head work including the best available guide rebuild and seals. Use OE or equivalent parts everywhere else including the forged pistons. Before you disassemble the block measure deck clearance so you can get a head start on computing CR. With a .040" compostion gasket and typical OE deck clearance it should come in at no more than 10.5 with the OE replacement domed, forged pistons. Have the crank magnafluxed and checked for straightness and journals polished. Do not grind it unless ABSOLUTELY necessary. Grinding removes the surface Tufftride treatment. The entire bottom end should also be balanced along with the torsional damper and flywheel.

If it still has the OE or a OE replacement vacuum can, replace it with a NAPA/Echlin VC 1810.

Duke

 

I've seen this advice twice, "do not grind the crank because you will remove the tufftride treatment".

Well if the crank is in need of grinding then you have no choice. You can have the process re-applied to the crank. I worked for a shop that made cranks from GM raw forgings, we ground the crank to .010 above finish size then sent the cranks out for heat treating and Tufftride. After they came back they all were bent, took care of that then ground to customer spec. The process turned the cranks black.

I have a fully counter weighted 454 crank the is nearly 20 years old that is still standard.

I've bought a lot of cranks from Crower and don't remember anything about tufftriding on those, maybe I missed it.