Topic: 455 build plan with questions

[gixxer711]

Some new decision edits below.

I have a 75 Trans Am, Turbo 350 and 3.23 rear, set up pro touring style, subframe connectors and solid bushings. Stock manifolds with full 2.5" Pypes exhaust with x-pipe, planning to upgrade to Ram Air manifolds.

I want a fun all around street car, not a drag car. I want to have good vacuum for power brakes, be able to run AC and run as minimal of a stall as possible. Below is the recipe I came up with to hopefully make over 400 horsepower. We drive our car and plan to do the full Power Tour next year (did half this year) which will probably be a 4000 mile round trip. It has been over 20 years since I have built a Pontiac, so comments and suggestions are welcome.

455 with targeted 9.5 compression
- zero deck
- stock crank
- RPM rods >> H-beams floating pin
- Speed Pro forged pistons >> ICON pistons (dished for 9to1 or flat for 9.5to1 is the new question for safe gas use)

6X-4 heads rebuilt no porting >> might attempt a gasket match
- one piece valves
- Crower 68404 springs
- PC seals
- 1.77 exhaust
- BBC studs
- Stock rockers >> PRW roller tips 1.52
- Poly locks

Crower 60243 cam >> Cam is still up in the air trying to figure out if it will work with my needs above
Crower camsaver lifters
Performer RPM (plan to upgrade to EFI later so need square flange) >> going with factory intake, possibly modified by SD performance
Quadrajet using Cliff's kit and book


I have a few questions.

1. What length valves should I use? Stock or should I go longer for later expansion? Which intake seat angle, 30 or 45? >> going with stock length
2. Can I use stock length pushrods, with stock length valves?
3. Crower suggests the 68404 springs above for the cam listed unless running 1.65 rockers. Should I go to the 68405 springs instead, in case I choose to go up in rocker later? Plus I also read some people using the 68405s later with smaller roller cams by shimming them. >> sticking with 68404 springs if i go with a Crower cam that calls for them, will not be doing 1.65 rockers.
4. Can I use the stock retainers and locks with either of these springs? >> changing both out
5. Torque converter recommendation?
6. Which rear main seal? One piece or?
7. What gasket set to use? Is the Butler set good?
8. What length rocker studs do I need?

[gixxer711]

Made some edits above. Could still use some opinions on whether my combo sounds well thought out and if it works with my criteria, especially the vacuum for power brakes.

[gixxer711]

Made some more edits to the original posting. Looking for some feedback on a final couple things.

The biggest thing I am trying to decide on now is which cam to use and what compression, 9to1 or 9.5to1. I can get to 9to1 with the dished pistons or 9.5to1 with the flat tops. The motor will need to be able to run on 91, although we have 93 here. AC, vaccum for power brakes and minimal to no additional stall while making the most power within my parts and budget constraints.

[rad400]

the crower 60243 is a good cam in the 455 also the 60919 is good as well i would get the bowls blended refering to under the valves on the heads.