[David Jones]

What are reasonable limits to observe when modifying a factory stock (non-SD) 1973 455? By modifying I'm referring to changing the cam and heads for a bit more performance. I have a set of lightly ported (225-230 intake) 6X heads that I could use. I'm not interested in a lot of rpm.....5000 to 5500 and have always thought that the "stump puller" from SD Performance would be about right.

Would a cam similar to the stump puller, my 6X heads, headers and the P4B-QJ/quadrajet (correctly tuned) combo I currently run on my 400 be a recipe for certain factory 455 shortblock death?

[boater bill]

Based on my recent 461 build, I would fill the exhaust cross overs on your 6X heads since you are using your old Doug's headers I'm guessing. use your Hyd roller cam and Qjet and get an RPM or larger plenum intake. It will be tons of torque and fun! Has the block been bored and will it need to be bored again? I hear rumors that some of the cylinders can have core shift causing thin cylinder walls.
I would replace the rods with the low priced forged rods for insurance. I might also stud the main bearing caps. Good forged pistons, Moly rings, standard quality good rebuild parts will make it reliable and easy to use. Pontiac Dude prepped oil pump is also a very good thing.
Torque is easy to build reliably with the 4.21 stroke.

Good luck!

[ta man]

Originally Posted by David Jones

What are reasonable limits to observe when modifying a factory stock (non-SD) 1973 455? By modifying I'm referring to changing the cam and heads for a bit more performance. I have a set of lightly ported (225-230 intake) 6X heads that I could use. I'm not interested in a lot of rpm.....5000 to 5500 and have always thought that the "stump puller" from SD Performance would be about right.

Would a cam similar to the stump puller, my 6X heads, headers and the P4B-QJ/quadrajet (correctly tuned) combo I currently run on my 400 be a recipe for certain factory 455 shortblock death?

I've been running a basic 455 rebuilt bottom end for a few years now..with the Old Faithful Cam and SD KRE 290cfm heads into the mid 11's.If I was racing every weekend I would upgrade my bottom end for sure but for my 4 or 5 track outings a year and keeping shiftpoints under 5500..no problems.

[72blackbird]

Anything worth doing is worth doing right. You got a good block, the last thing you want to do is cheap out and run the stock bottom end- stick good forged pistons and rods in it, and use ARP studs on the main caps. Now you can put good heads on it make 550-600 hp and not worry about tossing a rod. Yeah, it costs more, but the piece of mind is priceless when you're punching it and you got your foot to the firewall.

Let the guys with the stock bottom ends worry about their rods when you pass them- I'm not worried about my 455.

Geno

[66bonne]

David-For the combo you are putting together and with the RPM limit you'll impose I think you'll be fine with a stock bottom end in the 455. I've had similar combos in 455s and beat the dog snot out of them on the street and track without issue. I say go for it.

Just my 2 cents on the cam:https://sites.google.com/site/ksmsinc/
Give P-Dude Ken Keefer a call and talk to him about the "Butcher Special" hyd roller cam.
It is by far the best cam I have had in any motor, regardless of make. Nice lope at idle, cruises terrifically on the street, plenty of vacuum for the brakes and accessories.
Purrs like a kitty on the street and growls like a tiger at the strip. With this cam and lightly ported 6X-8s we were running low 12s in full street trim in our obese [4100 pounds] Catalina.

Have fun, Jim
Your results may vary !!

[b-man]

David, you're good.

My 455 bracket engine, original-never rebuilt lower end:
http://forums.maxperformanceinc.com/...5&postcount=19

[grivera]

Originally Posted by b-man

David, you're good.

My 455 bracket engine, original-never rebuilt lower end:
http://forums.maxperformanceinc.com/...5&postcount=19

That's a bad-a$$ sleeper...I'm sure you've surprised more than a few at the light

[Thomasmoto]

Yeah I used ARP main studs, forged pistons and H-beam rods. I used my orig crank because of all the service that Jim Hand wrote about with those cranks. They are pretty darn tuff. I've put a lot of miles on this 455 and hit it with the spray often as well. Of all the things I worry about with this car the bottom end of the engine isn't one of them.

[David Jones]

Thank you gents. All of you.
The purpose of finding a good bottom end was to NOT have to swap the rods/pistons/bore it etc. I really hate the thought of the hyd roller expense (and I haven't bought one yet...) but the hyd roller I have in my 400 (220/224 with .513/.528 lift) made a huge difference in that engine. And Jim, I got it from P Dude about 6-7 years ago after giving him the same parameters....5000-5500 rpm with a broad middle. He nailed it. What I'd like is a 455 version of my 400. Bumping the cam up 10 pts (220 to 230, 224 to 234-6) should get me there.
I've still got to pull this 455 down and have a look. It's got a bit of crap on it and I want to give it a bath before I take the heads and pan off. Long term project.

[lust4speed]

Most important speed part is a rev limiter - especially with a stock 455 bottom end. I'd shift at no more than 5,200 with stock rod bolts, and have the limiter set for 5,400 RPM. It should live a nice long life.

[Thomasmoto]

Originally Posted by lust4speed

Most important speed part is a rev limiter - especially with a stock 455 bottom end. I'd shift at no more than 5,200 with stock rod bolts, and have the limiter set for 5,400 RPM. It should live a nice long life.

I agree. I'm shifting my 462 @ 6,000 but I have a forged bottom end. Its the rods and bolts that are limiting you. Believe it or not the crank is pretty tough.

[David Jones]

When I order the cam, part of the discussion will be rpm related.

[Cliff R]

"I really hate the thought of the hyd roller expense (and I haven't bought one yet...)"

An alternative to the HR would be the Crower 60919 cam, high ratio rocker arms and Rhoad's lifters. It will make nearly the power of the roller at less than half the price.

We back to back dyno'd that deal a few years ago on my old 455 engine.

That engine made 455.4hp with 230cfm 6X-4 heads, and 494hp with KRE heads.

Swapping in a 230/242/112 HR gained 3hp/4ft lbs torque, no other changes.

That cam did run over a tenth quicker at the track, as the dyno is unable to show the loss in drag from the flat cam (revs quicker).

Best ET with the flat cam set-up was 11.64 @ 116mph, the HR went 11.52 @ 118mph, and the air was actually a tad better when the flat cam runs were made compared to the HR runs.....Cliff

[ta man]

Originally Posted by lust4speed

Most important speed part is a rev limiter - especially with a stock 455 bottom end. I'd shift at no more than 5,200 with stock rod bolts, and have the limiter set for 5,400 RPM. It should live a nice long life.

Especially when you add over 100hp like I did a few years ago with a head/cam swap..I never knew a 455 street engine could rev like that ..my Rev Limiter has saved my engine quite a few times.