71 455 rocket

[my86442]

Ok i did a complete build to a 455 olds rocket about 4 1/2 years ago. Blueprinted and balanced and completely raw. Its got flat top pistons, bored 60 over on the crank and block. It does have the steel crank in it. the heads were redone with bigger valves, 2.05/1.90's. My biggest concern is the cam. Its got a comp 234, 244 duration with 480 lift i think. its enough to open it up but still has a pretty smooth idle. When its cold you hear it lope a little but when it warms up it runs smooth. Its also running the stock push rods and rockers.

My 1st question is What is the biggest cam i can go with with stock rockers and rods? I'd like it to have a pretty radicaL idle I would also like to leave it hydraulic as well.
2nd Im running an old school Edelbrok O4B performer intake and a jetted Holley. Its a 600 with 800 jet. I'd like to leave the carb but change the intake. Wat sugestions can i get with the Intake?

 

[83hurst-olds]

If you are wanting a more lumpy cam just for the sound, then you probably won't be happy with it. The 455's are known for thier great low end torque and if you cam it up too high, then it becomes a high-RPM engine and you move it out of the motors comfort zone.
What are the other specs of the car? Rear-end ratio? stall converter? Did they port and polish the heads while in there? What castings were the heads?

 

[RockSS]

That lopey lumpy thump idle comes from valve overlap the more you overlap the opening of the ex. and int. the more thump . that being said when you start get more overlap you start getting more rpm's to get to powerband.
Now I've been lookin at the comp cams THUMPER's they offer that hot rod sound and streetability, but I dont know how far you can go with the stock rockers .... but you can always just get stamped long slots there pretty cheap.

http://www.compperformancegroupstores.c ... de=THMSBC8

click this link the cam isnt much bigger than you run now (lift) .491

 

[my86442]

If you are wanting a more lumpy cam just for the sound, then you probably won't be happy with it. The 455's are known for thier great low end torque and if you cam it up too high, then it becomes a high-RPM engine and you move it out of the motors comfort zone.
What are the other specs of the car? Rear-end ratio? stall converter? Did they port and polish the heads while in there? What castings were the heads?

No, not at all for just the sound, i'm wanting more performance and a better sound out of it too. 😀 I want to keep it in one peice considering its been one of the best builds ive done but i'm still new to the whole master engine build category, ya know. Ive only done 4. Its already bored with flat tops, the intakes ported and polished but i dont think the heads are. i bought the motor in peices with receipts of what was already done to it. None of them show any other head work besides bigger valves. The heads are "J" heads and do have the egr ports but i have them blocked off. the trans is a 350 turbo with all new internals and bnm shift kit. I was told the convertor is a 2500 but it starts spinnin the rear wheels at at 1700 so i'm thinking stock is in right now. the rear end is a 10 bolt with strange 28 spline axels, a moser posi unit and richmond 4.11 gears. It gets out of the hole pretty quick packin the drivers front. currently my monte with the 455 will run 8.02 in the 1/8 and 13.66 in the 1/4.

 

[83hurst-olds]

Ok, that is good... I knew a guy that put a crazy cam in an otherwise nearly stock engine. He did that just because he liked the sound of it. The problem was that then everyone wanted to race him, and he had less power than before since the cam was really cut for more of a higher RPM power range and the engine still had stock small valve train.

I saw some C casting head recently on the local craigslist. I think they wanted $200 complete if that interests you.

 

[my86442]

Ok, that is good... I knew a guy that put a crazy cam in an otherwise nearly stock engine. He did that just because he liked the sound of it. The problem was that then everyone wanted to race him, and he had less power than before since the cam was really cut for more of a higher RPM power range and the engine still had stock small valve train.

I saw some C casting head recently on the local craigslist. I think they wanted $200 complete if that interests you.

Yea i'm interested but what would be the difference between the C and J heads. Yea the bottom end of my motor is built and ready and the heads are great. 500 ft burnouts are no problem but i would like more of a throaty sound to it ya know. And would you or anyone have any advice on an intake by chance?

 

[dogsht]

You did not give all your cam specs including valve overlap as RockSS says which would tell us more about what kind of lope or cam sound your existing 455 can produce. 234/244 duration if thats at 50 should be great for hot street and suggests some potential to sound mean without being an inappropriate race cam. Compression helps an honest measured and calculated 10-1 will help make the most of that cam, sound better that less compression, and can still work on pump premium.

Lastly there is also obviously the exhaust system itself. Everything matters to some degree in regards each component of the exhaust system and sound. Most for a wild sound out of even a stock engine like Flowmasters for their patented sound. Many other straight thru designs can flow better, restrict less power, and sound great without being as obnoxious sounding or the common drone as a big two chamber Flowmaster with dumps. Its a matter of what you want.

Any more detail gets too detailed unless you have a specific question.

 

[papabearxl]

If it was me, I would try different exhaust first, but that's just my $0.02...

 

[82cutty]

You can go up to about .500 lift with stock rockers and bridges. You can shim them but that gets shakey with bigger lift. I did the adjustabke rocker swap with BBC studs. I run a .505./.505 @.50 with a split duration of .226/.234 with a 108 centerline to bleed down my 10.25 to 1 compression..... I have a fair lope and fair idle and pulls real hard.....

 

[my86442]

You did not give all your cam specs including valve overlap as RockSS says which would tell us more about what kind of lope or cam sound your existing 455 can produce. 234/244 duration if thats at 50 should be great for hot street and suggests some potential to sound mean without being an inappropriate race cam. Compression helps an honest measured and calculated 10-1 will help make the most of that cam, sound better that less compression, and can still work on pump premium.

Lastly there is also obviously the exhaust system itself. Everything matters to some degree in regards each component of the exhaust system and sound. Most for a wild sound out of even a stock engine like Flowmasters for their patented sound. Many other straight thru designs can flow better, restrict less power, and sound great without being as obnoxious sounding or the common drone as a big two chamber Flowmaster with dumps. Its a matter of what you want.

Any more detail gets too detailed unless you have a specific question.

yea sorry bout that. the cam is at 50 with a 107 center line. At least thats wat the box says. My exhuast is 3 inch to 2.5 with 40 series flowmasters with dumps. Its a true dual exhaust too. No H or X piping. straight to the flows than dumped befor the rear end. Ive been told that it sounds mean as hell and its got great pull but it sounds stock :?: :?: :?: i mean when i start it when its cold, i can tell it has a cam in it because the whole car shakes and if i listen close enough i can hear the hits thru the exhaust but when shes warm after about the first 15 minutes, it levels off and sounds like its stock. Last summer i took it to London Dragway In London, Ky and it ran a 13.88 on old plugs. i put new in and it run a 13.12. but its run a 12.99 once. I dont know if the heads were shaved when i got it or not. my reciepts dont say, but with 30 inch hoosiers, that 455 packs the driver front, in my 71 monte, about 8-9 inches thru the 60 ft, sets down some than barks 2nd and chirps 3rd. I have a chain bolted to the motor and than to the frame to keep it from busting the driver side motor mount :!: i went thru that twice before i wised up. i noticed another post just after this says stock lifters can handle up .500 lift. could i do a 496 lift and up the duration? And is it duration or lift that gives the thump?