Don Terrill’s Speed-Talk

The cam that really gets a lot use is the RA IV with rhodes lifters.I just never liked them.I have found the hyd roller cams to my liking and no breakin issue with FT lifters.Way more money though.Tom

pmd400 wrote:How would 276/268 adv. 233/227 at .050, .504/.489 lift with 1.5 rockers lunati voodoo sound.
I'm thinking 106lsa ground on a 102icl

I personally would not go negative on the exhaust unless I was going to dyno test it against something else. If it was me I would go with the 268 lobe on a 106 in at a 102, keep in mind that your 1.65 rocker will effectively add about 2 to 2.5 degrees to your .050 numbers.

I tend to er on the moderate side for a street cam, if it's a little small you might loose a little hp at the top of the rpm range but if it's to big you risk loosing both tq and hp everywhere except for the top part of the rpm range.

How about for the intake use an comp xe, 274 at 0.006, 230 at .050, .325 tappet lift.
Exhaust using comp magnum, 276 at .006, 226 at 050, .309 tappet lift.
According to comp both lobe families are asymmetrical. The xe is much steeper on the opening then closing ramp while the magnum is much closer to being equal

go back and reread the OP's first post
240 or 270 gear
under 5500 rpm
what makes you think a 230 degree cam would be any fun?

pmd400 wrote:How about for the intake use an comp xe, 274 at 0.006, 230 at .050, .325 tappet lift.
Exhaust using comp magnum, 276 at .006, 226 at 050, .309 tappet lift.
According to comp both lobe families are asymmetrical. The xe is much steeper on the opening then closing ramp while the magnum is much closer to being equal

I like that one, fast intake with slow exhaust. It may be worth while to pay a little extra for the treated core...I never have but everyone says it's good insurance. I did groove my lifter bores on my Pontiac with Comps grooving tool, I don't know how much it helps but I did it anyway.
I ran a Comps XE 284/240 in a 9.5:1 468 BBC in my 77 T/A with a set of well worked over oval ports a performer rpm with an old holley 800 dp I wished I had chose the 274 because the 284 was a bit much at idle due to a very tight 11" converter only 1000 over stock stall but it was stupid fast even with a 3.08 gear and a 295-50-15-tire it was traction limited even rolling at a good pace.
MAKE SURE! you have sub frame connectors! I have seen guys twist these cars bad enough that the door will not close, also as well as a quality slapper bar like Competition Engineering or Cal Tracks. Big Block tq will find any weak links.

Yes, Pontiac 14* heads have a 135* sweeping bend in the exh port. I do not see this as being so bad... Whether by accident or design, it positions the exh port exit interface with headers at a less sharp/more favourable angle. Compare the Pontiac port to Mopar Wedge, SBC exh ports, that have upward pointing exh port exits & a sharper angle entering the header.

I don't have the cam card in front of me.
Mike Jones (jones cams) made me Hyd roller cams that has worked well in pontiac street applications.

It's around 226/226, 525/525 on 108 or 110. Different lobes int and exhaust. I think you would be happy with that.

Your not going to do as well picking and choosing lobes as working with the cam designer. I would avoid comp, esp a flat Hyd or street roller. Much better off working with Mike jones (or Chris Straub etc...) for a little more, you'll get something made for you and good quality.

The only reason is I have driven a lot of 455s with 230s duration.The long arm likes them.The 3 3/4 stroke 400s dont.Tom

Looks to me like you want a cost effective camshaft. I have had great tire blowing,very strong pull to 5500 on 455 9 to 1 motors with these two camshafts. Ether one will more than fit your engine combo and make you smile without hurting your wallet.
Crower 60916 278-289-221-229 460 470 112 in @108
Summit 2802 282-292-224-234 470 490 114 in @ 109

Pontiac/Olds/Buicks.. My personal experience with OEM Heads.. Wider seat Duration and Wider Center has given me the best results. Plus they don't rattle like a sold roller:)

Kenny

Kenny M wrote:Looks to me like you want a cost effective camshaft. I have had great tire blowing,very strong pull to 5500 on 455 9 to 1 motors with these two camshafts. Ether one will more than fit your engine combo and make you smile without hurting your wallet.
Crower 60916 278-289-221-229 460 470 112 in @108
Summit 2802 282-292-224-234 470 490 114 in @ 109

Pontiac/Olds/Buicks.. My personal experience with OEM Heads.. Wider seat Duration and Wider Center has given me the best results. Plus they don't rattle like a sold roller:)

Kenny

What did you experience when you compared a tight LSA cam against a wide LSA cam?

427dart wrote:Compared to all the "new" way to design a cam for a particular engine...were all the factory engineers just guessing when developing a cam for engines back in the late 60's? Pontiac had Malcom McKellar design their factory race and street cams...one of the best back then.

Surprisingly, the answer is at least partly "yes"! I read an article many years ago re a race cam development approach Pontiac tried using the "Cuban Square" (or some similar name) They created some kind of geometric figure and used it to guide them in shifting around open/close events in search of the optimum combo.

I never worked with KcKeller who had an excellent reputation but Chrysler's cam guy- in the South did his by hand- I've been trying to come up with his name but am embarrassed to say it does not come up-- Camcraft?
that said
OP would be well ahead to use a HR, the Jones HR but maybe one size smaller due to the compression and axle
even that Hot Rod article shows the difference
With a MOPAR size lifter you can come close to HR profile but with all the durability problems, with the chevy size lifter there is no comparison HR all the way

230-236 on a 108 lsa 104 icl .536-.540 this would be a custom grind using comps XE lobes. 455's really like a 108, monster torque and really good power, anything tighter and vacuum becomes a problem and anything wider you give up torque and power. you won;t have to worry about to tall a gear or a heavy car.
Len C

Len,I know they like the 108 for HP but IMO with a street stick shift car they suck to drive.Been there done that.Tom

MadBill wrote:

427dart wrote:Compared to all the "new" way to design a cam for a particular engine...were all the factory engineers just guessing when developing a cam for engines back in the late 60's? Pontiac had Malcom McKellar design their factory race and street cams...one of the best back then.

Surprisingly, the answer is at least partly "yes"! I read an article many years ago re a race cam development approach Pontiac tried using the "Cuban Square" (or some similar name) They created some kind of geometric figure and used it to guide them in shifting around open/close events in search of the optimum combo.

Bill,
A few of their cams seem to have some dwell. It almost looks like a Cycloidal type curve was used.

Stan