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 455 build advice needed
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Cfd2bc
Tribal Scout

5 Posts

Posted - 03 Aug 2017 :  2:59:01 PM  Show Profile  Visit Cfd2bc's Homepage  Reply with Quote
Hello all. I have looked through about all of the cam topics and while they are all good reading, I'm having trouble finding one that will answer some questions of my set up. I am building a Pontiac 455.I drive the car a lot so I would want good street manners but also the get up and go throughout the rpm's. Here's what I'm looking at doing.
79 Trans Am=3800 lbs
Power brakes
ST-10 4 speed
3:42 posi
headers through Fowmasters
Dual plane with 700 Holley DP Mech secondaries

Bore .030 over
forged flat tops, recondition stock rods
Deck block to .005
6X-4 heads. Stock 2 piece valves 1.5 rockers

I come up with 9.8:1.

I am looking at a number of different cams.
Crower 60919, 60243, Comp xe274h, 041H

Which cam do you think would work the best for my set up, if any of these? Are these good with just regular lifters for vacuum? Would I need Rhodes? Not sure I'd like the noise I hear they make.
Since I am using stock heads and valves, what are your suggestions for springs? Should I go with a set of RPM forged OE replacement rods?

Thanks in advance everyone. It looks like there are some very knowledgeable folks on here so looking forward to the feedback!

Jeff


Edited by - Cfd2bc on 03 Aug 2017 3:54:27 PM

cortcomp
Coyote

USA
5335 Posts

Posted - 03 Aug 2017 :  5:21:49 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Go with springs mated to the cam you end up choosing (or good ones rated the same.) I would never hesitate to upgrade the rods if you're in that far, simply because you can't easily do so later. I can put a better radiator, or intake, or carb, or exhaust on later if i have the money. Can't swap the rods out later. If you're not going that far into the motor, and you know you're going to keep it under around 5200, i wouldn't worry about it, i just wouldn't get too froggy too often on the high end of the rpms.

As far as cams, i liked my couple XE cams in 9.0-9.5ish motors, but i hated the clack in the XE284. It was minor but those kind of noises grate on me. So, when i did a 9.0ish 327 for my other car, i decided to get a lunati grind as i heard they were softed on the let down. I found an older forum discussion by harold who designed the lobes and went with the lunati cam he recommended, although the thread was old. Car is as quiet as a church mouse and i like them that way.

Were i to do another pontiac, i'd call lunati and say hey, i want one of your cams that's about the same as the XEwhatevercam, and take what they recommended. It didn't have great vacuum though, if you want that you have to compromise some power. With a 455, there's plenty of power to sacrifice for manners, and it will smooth out a cam for a smaller motor anyways.

I also hear good things about the summit cams in these setups? 2802 i think?
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Blued and Painted
Chief PONTIAC

USA
3406 Posts

Posted - 04 Aug 2017 :  11:31:42 AM  Show Profile  Reply with Quote
Anything over .460 or.470 lift, you could run into clearance/interference issues. You dont want the spring retainer crashing into the top of the valve guide. Or the spring coils to bind. Or the rocker to contact the edge if the retainer. Aftermarket cams may have a different base circle diameter. Moving to a fully adjustable valve train is a must in my opinion.
You dont want the welded two piece valves to become two piece again.
Contact one of the pontiac specific head builders and get the heads set up for the cam U select. Butler Performance, SD Performance, and there are a few others around the country.

Im running the crower 60243 in a 455 @ 9.5 compression and like it. Its mild enough so in a good state of tune (carb and ignition) any one could jump in the seat and drive it. And has a serious mid range and top end charge.
Agree with Cort, the summit 2802 is run with success in many builds. Race guys would say both cams are undersized for the 455. But for a street car with a decent compression ratio like yours, either is a good choice.



Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 04 Aug 2017 11:33:39 AM
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Blued and Painted
Chief PONTIAC

USA
3406 Posts

Posted - 04 Aug 2017 :  11:45:35 AM  Show Profile  Reply with Quote
Push Rod Geometry

- https://www.youtube.com/watch?v=o5is9BsH5OU -


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 04 Aug 2017 11:47:26 AM
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