Pontiac 455 cam recommendation

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Re: Pontiac 455 cam recommendation

Post by LCaverly » Mon Oct 17, 2016 9:21 pm

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.
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Re: Pontiac 455 cam recommendation

Post by tjs44 » Tue Oct 18, 2016 12:33 pm

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

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Re: Pontiac 455 cam recommendation

Post by Stan Weiss » Tue Oct 18, 2016 1:11 pm

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.

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Re: Pontiac 455 cam recommendation

Post by wyrmrider » Tue Oct 18, 2016 1:14 pm

with the short little valve springs some dwell was necessary if there was any duration
best to step back and look at the flow demand, cylinder heads, compression, etc
then develop timing points-- duration and lca will fll into place

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Re: Pontiac 455 cam recommendation

Post by GARY C » Tue Oct 18, 2016 1:18 pm

tjs44 wrote: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
tjs44 wrote:With a 250-250 on a 108 with a 3.90 rear gear it did not like being under 1800 rpms around town in 5th gear and had to be pulled back
They would suck with that much duration @.050, way to much overlap for that rpm.

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Re: Pontiac 455 cam recommendation

Post by LCaverly » Tue Oct 18, 2016 4:02 pm

TJS thats a relatively short duration for a 455 and a 108 will hardly be noticeable. I agree on the street with a 250 250 it would be quite noticeable. Advertised duration is what has the most affect on idle and low speed characteristics and if you compare a RA4 cam to the XE 274 you can see why the XE is more street able , advertised for the RA4 was 308, 320 while the XE274 is only 274, 280. The aggressiveness of the profile makes a big difference in drive ability. An off the shelf XE274 would work fine for this application but a custom grind with a 108 would work even better.
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Re: Pontiac 455 cam recommendation

Post by wyrmrider » Tue Oct 18, 2016 9:45 pm

I was thinking back to the Winternationals CA 1962?
Micky Thompson had the Tempests with the 421's installed and solid rear ends instead of the transaxle
one of them had heads with the sparkplugs like an FE Ford- I know cuz I changed them
wish I could find the pictures- never saw those heads again
anyone else seen them?

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Re: Pontiac 455 cam recommendation

Post by wyrmrider » Tue Oct 18, 2016 9:49 pm

custom grind...would work even better
heads with different flows
tall gears
your best shot
http://jonescams.com/street-performance/
I would think there is more experience with gears and converter, maybe more compression and heads with less exhaust flow
but that's not OP's build

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Re: Pontiac 455 cam recommendation

Post by Walter R. Malik » Fri Oct 21, 2016 11:36 am

Walter R. Malik wrote:
pmd400 wrote:Hi
Iv read plenty of articles, books and forum threads on cams. Iv studied a couple of vizards books, Jim hands Pontiac book as well as several articles and forum threads. Old school Pontiac says to go wide lsa and dual pattern cam. Vizard books tell me tight lsa and single pattern cam. Iv read recently on this forum that lower exhaust lift and less aggressive exhaust lobe is beneficial. So anyway, I'll get to the engine specs
Pontiac 461 - bore 4.18, stroke 4.21
Rods length 6.625
9.4:1 compression
Edelbrock p65 dual quad/dual plane intake
2 edelbrock 600 carbs
1 5/8 diameter/unequal length primary headers
2.5 x pipe exhaust. Mufflers to be used but not yet purchased
6x heads. Flow as follows
Lift Intake Exhaust E/I ratio
.100 76 54 72%
.200 134 117 88%
.300 181 154 85%
.400 219 178 81%
.500 229 194 85%
.600 229 202 88%

Car is a '72 firebird, 3500lbs
Rear is 2.41 or 2.73(have both)
Trans is a Richmond 5 speed, ratios are
1st - 3.28
2nd - 2.13
3rd - 1.57
4th - 1.24
5th - 1.00

Car is a street car. Power brakes are a must. Engine will never go above 5500rpm.
Any recommendations will be much appreciated.
Thanks
I called an acquaintance who has a very similar combination to yours but, a Tri-power and 480 cubic inches in a mid 70's Firebird with a Tremic and 2.56/1 rear gear.

He had a camshaft ground by Lunati ...
hydraulic roller ...
single pattern #62009 profile ...
268@.006"; 215@.050"; 134@.200"; .326" lobe lift; 108 separation +2; .538" valve lift with 1.65/1 rockers.
I would like to comment that this vehicle idles with a slight lope, pulls hard and is all done at 5,400 RPM but, revs to 6,000 RPM easily, pulls out of a city 90 degree turn in third gear, at around a 1,000 RPM with no detonation and driving on the interstate is perfect in 5th.

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Re: Pontiac 455 cam recommendation

Post by wyrmrider » Fri Oct 21, 2016 12:24 pm

Excellent reminder Walter
much different than a 4 speed and 390 gears
few have experience with that combo
I think 230 type cams would be no fun at all in HIS build

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Re: Pontiac 455 cam recommendation

Post by CamKing » Fri Oct 21, 2016 12:38 pm

pmd400 wrote:Thanks for the replies. I probably should have mentioned that I'm after a hyd flat cam. Lifter diameter in 0.842. Valves are about .120 longer then stock. Also Iv already got 1.65 rockers
With that 4.21" stroke, you need some duration.
This cam will peak @ 5,100rpm, have plenty of vacuum, and a smooth idle. I would not go any smaller
Cam# P455, H71330-110
228/228 @.050"
.330"/.330" Lobe Lift
.544"/.54" Valve lift w/1.65 rockers
110 LSA
107 ICL
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Re: Pontiac 455 cam recommendation

Post by wyrmrider » Fri Oct 21, 2016 1:05 pm

Mike- is that not a mid 280 seat duration flat tappet
I think he is looking for an HR
OP- which is it?

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Re: Pontiac 455 cam recommendation

Post by CamKing » Fri Oct 21, 2016 1:09 pm

wyrmrider wrote:Mike- is that not a mid 280 seat duration flat tappet
I think he is looking for an HR
OP- which is it?
Look at his post I quoted. Hydraulic Flat Tappet
Yes, it's 284 seat duration.
With his stroke, that'll act like a 260 seat duration would in a 350 SBC.
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Re: Pontiac 455 cam recommendation

Post by Walter R. Malik » Fri Oct 21, 2016 7:18 pm

Everybody's attention and priority seems to be with Wide Open Throttle so, I guess that is the only important thing and all that matters here ... have at it. :roll:
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Re: Pontiac 455 cam recommendation

Post by tjs44 » Fri Oct 21, 2016 8:11 pm

im not and never have been.I actually drive these engines virtually every day in a stick shift cars and have been trying everything from 108s to 113s and from 218s to 260s Intake for 20 years.Have found wider is better(112)a little bigger(230s)split better(6 more or so on E) have better manners(power brakes),have less detonation issue with 9.5 iron heads on CA 91 gas.Continue on.Tom

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