BBC cam selection

[Scooby]

looking for some input as to what cam would work best with my setup.

have a 454 bored .060 over with forged crank, rods and pistons using stock 781 casting heads that will be ported and have the valves worked. getting a power plus dual plane intake and running a holley 850 DP and headers.

wanting this motor for street/strip more street than strip but still want to get the most out of the engine.

[74RAT]

the 71' LS-6 piston (right at .100 dome) with that head will give you right at 9.0:1. you said more street than strip,,, so a 270 or 280 comp cams kit with springs and also you will need rotater eliminators for under the exaust valve springs. some 3/8 pushrods/guideplates and some roller tipped rockers or full roller rockers to handle the increased fulcrum pressure of the valvesprings. (roller tipped rockers come with the grooved pivot balls for increased oiling of the fulcrum pivot). a 2500 converter and a set of 3.42 or 3.73 gears is a mean street screamer. the carb is a little bit big for that combo on the street. a 750 dbl pmpr. or an 800 dbl pmpr. with those cams would be better for each cam suggestion. 1 3/4 headers. that should get you deep in the 13's. it's a good pump gas combo. if you spin more than 6000rpms then you'll start doing more crank clearance and oiling system mods and want to step away from a hydraulic to a solid cam setup. that starts getting away from streetable for everyday driving and dependability. if your not very fimiliar with all that,, i'd keep it under 6000 for a street engine. those cams and carbs and small dome piston are a match for your dual plane intake on the street and very strong mid range torque.

[pdq67]

A good old CC 270S or 282S solid cam, imho!!

pdq67

[ZS10]

<font face="Arial,Verdana" size="2">Originally posted by 74RAT:
the 71' LS-6 piston (right at .100 dome) with that head will give you right at 9.0:1. you said more street than strip,,, so a 270 or 280 comp cams kit with springs and also you will need rotater eliminators for under the exaust valve springs. some 3/8 pushrods/guideplates and some roller tipped rockers or full roller rockers to handle the increased fulcrum pressure of the valvesprings. (roller tipped rockers come with the grooved pivot balls for increased oiling of the fulcrum pivot). a 2500 converter and a set of 3.42 or 3.73 gears is a mean street screamer. the carb is a little bit big for that combo on the street. a 750 dbl pmpr. or an 800 dbl pmpr. with those cams would be better for each cam suggestion. 1 3/4 headers. that should get you deep in the 13's. it's a good pump gas combo. if you spin more than 6000rpms then you'll start doing more crank clearance and oiling system mods and want to step away from a hydraulic to a solid cam setup. that starts getting away from streetable for everyday driving and dependability. if your not very fimiliar with all that,, i'd keep it under 6000 for a street engine. those cams and carbs and small dome piston are a match for your dual plane intake on the street and very strong mid range torque.</font>

My 427 is very similar to this. Other than my mistrust of Comp Cams, my 280H has been great. I'd recomend SRP pistons, much lighter and proving to be pretty tough. I also set my limiter to 6200, and use ported 781 heads with stock size SS valves, and stock type springs and rockers.
You won't belive how fast you'll butcher tires. Which is OK because you only need to run low grade gas. Mine's never seen anything better than 87 octane with 36* total timing.

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73RS/LT/427

[theflash]

Scooby, you rreally need more info on your compression before deciding on a cam. What pistons are you using? You could be anywhere from 8-1 to 9-1 with those heads.

[Scooby]

running ~ 9-1 CR with forged weisco pistons, was truly hoping to see much better than 13's already running that with a built 350 and 3.73 gears

[This message has been edited by Scooby (edited June 26, 2005).]

[Scooby]

spoke with my machinist again and he said my CR will be 9.8-1

playing with desktop dyno and thinking about going the the CC XR294HR, forgot to mention earlier i was getting the retro roller cam/lifter kit

[theflash]

Here's a really good calculator to figure your compression. I'm interested to see what cam you go with since that will most likely be my next purchase, and I'll be running 10-1 in a 454 as well. Oops see your going roller, I'm going hyd flat tappet.

http://www.rosspistons.com/calculator.php

[rscamaro73]

What head gaskets are you running to get the 9.0 w/ the 781's & the .100+ dome ??

[74RAT]

i had to cut .070 of my 049's to get down to 105cc and fit the intake manifold after that. i used the .030 over bore size .095 dome 71 ls6 gm forged piston (13.8cc dome volume) with a .039 fel-pro gasket with a .010 deck height for right at 10.1:1. i also used stock sized valves and a blue racer cam,,230@.050,,.550 lift. same specs as the 280h magnum comp cam. at a true elevation of 2700 feet i got some high 12's and solid low 13's as the day got hotter. all on 91 octane.

[Scooby]

from what I was told from the people I bought the rotating assembly from that CR was with a .039 head gasket, i thinking that the CR will be closer to 10-1 myself since http://www.pmeracing.com/wiseco.htm is showing my piston to have a 9.8-1 with a 119cc head

[This message has been edited by Scooby (edited July 01, 2005).]

[74RAT]

781's and 049's both cc out arround 118-120 depending on how much the valves have sunk.

the 71 gm .095 dome will give arround 8.84-8.9 with a .025 deck and .039 gasket and 119cc head.

scooby,, that must be the 20cc dome piston for 9.8:1,,,, that's cool!!! do it to it!!

[This message has been edited by 74RAT (edited July 01, 2005).]

[pdq67]

You cam always gain a schosh more compression using .020" steel shim headgaskets if you need/want it!!

pdq67

[rscamaro73]

<font face="Arial,Verdana" size="2">Originally posted by pdq67:
You cam always gain a schosh more compression using .020" steel shim headgaskets if you need/want it!!

pdq67</font>

So besides valve clearance, what the problems associated with useing them ?

[pdq67]

None!! GM used them stock on many motors through the years!

pdq67