Pontiac 455 cam recommendation

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Geoff2
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Re: Pontiac 455 cam recommendation

Post by Geoff2 » Wed Oct 26, 2016 4:55 pm

And the theories are......

And the results are......

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Re: Pontiac 455 cam recommendation

Post by tjs44 » Wed Oct 26, 2016 7:26 pm

WOW,6 pages devoted to a pontiac street 455!Tom

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Re: Pontiac 455 cam recommendation

Post by cstraub » Fri Apr 21, 2017 9:42 am

I have not heard from the customer yet. He did go flat tappet.
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Re: Pontiac 455 cam recommendation

Post by pmd400 » Fri Apr 06, 2018 5:13 pm

Cam I ended up going with was
Intake
270@.006
224@.050
.318 lobe lift

Exhaust
272@.006
222@.050
.295 lobe lift

108lsa, 105icl

Engine pings badly. Still pings with vac advance disconnected and full advance only at 30* all in by 3000rpm. Cranking compression test were 180-190psi for all cylinders.
Thoughts?

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John Wallace
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Re: Pontiac 455 cam recommendation

Post by John Wallace » Fri Apr 06, 2018 5:32 pm

Why not go with Camking's recommendation?
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 pmd400 » Fri Apr 06, 2018 5:38 pm

There’s on 1 camshaft in a 455 Pontiac, but several experts suggesting different cams

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Re: Pontiac 455 cam recommendation

Post by MadBill » Fri Apr 06, 2018 6:43 pm

I'm not a Pontiac guy, but sounds like something's out of whack. 9.4:1 CR & 180 psi cranking shouldn't be pinging on anything better than kerosene.
Does it ping at very low RPM, or only when the revs get up to xxxx?
If you lug the engine down at WOT via a hill or the brakes, at what RPM does the ping begin?
Is that 30° total mechanical, static included? (I believe a lot of Pontiac V8s run 34-36°.)
What's the piston/head squish clearance?
Has the timing pointer been verified?
Are you using 91 octane or??
What's the coolant temp?
Any chance the carb is way lean?
Can't compare exactly with the data at hand, but the Jones cam would probably have had ~ 5° later IVL and 10-15 psi less cranking compression.

You could try a slower spark curve and/or retard the cam a couple of degrees. If all else fails, https://boostane.com/ reviews put it several cuts above most octane improvers.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

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Re: Pontiac 455 cam recommendation

Post by pmd400 » Fri Apr 06, 2018 8:04 pm

Quench is .045
Comp ratio is actually 9.5
Engine pings whether total timing, mechanical + initial, is 30-36 degrees all in by 3000rpm.
Made it ping yesterday at 2500rpm by driving in 3rd gear, loading the engine by using the brake, throttle open but not WOT.
Fuel is 98 is Australia. Same as US 93

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Re: Pontiac 455 cam recommendation

Post by GARY C » Fri Apr 06, 2018 8:20 pm

pmd400 wrote:
Fri Apr 06, 2018 8:04 pm
Quench is .045
Comp ratio is actually 9.5
Engine pings whether total timing, mechanical + initial, is 30-36 degrees all in by 3000rpm.
Made it ping yesterday at 2500rpm by driving in 3rd gear, loading the engine by using the brake, throttle open but not WOT.
Fuel is 98 is Australia. Same as US 93
Do you have a heavier spring for dizzy to slow down the curve?

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Re: Pontiac 455 cam recommendation

Post by pmd400 » Fri Apr 06, 2018 8:24 pm

Iv put heavier springs in. Probably didn't get full advance until 3500. Afr gauge installed. Not running lean

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Re: Pontiac 455 cam recommendation

Post by GARY C » Fri Apr 06, 2018 8:33 pm

pmd400 wrote:
Fri Apr 06, 2018 8:24 pm
Iv put heavier springs in. Probably didn't get full advance until 3500. Afr gauge installed. Not running lean
If that stopped then it just advancing to fast, not every engine wants the same advance curve.

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Re: Pontiac 455 cam recommendation

Post by BadSS » Sat Apr 07, 2018 3:48 am

MadBill wrote:
Fri Apr 06, 2018 6:43 pm
Has the timing pointer been verified?
If you didn't build the engine, I'd definitely check that. Back when i used to tune cars all the time, a number of folks brought me their cars with "timing issues" only for me to find they had not set the pointer to zero during the build, put on an aftermarket pointer without "zeroing" it, replaced the balancer, etc.

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Re: Pontiac 455 cam recommendation

Post by mag2555 » Sat Apr 07, 2018 6:30 am

Well 1st off, you do not need a duel pattern Cam with a Intake to Exh ratio like that especially with the fast piston speed of that stroke being bigger then the Bore.
2nd, with that compression ( cylinder pressure ) and the high load of the 2.73 gears you want a minimum of 225 duration @ .050" .
Stock 6X heads without the Intake valve seal average a clearance between the top of the guide and the bottom of a stock retainer of .480" , so cutting down the tops of the guides will be needed , as will cutting the Exh guides for seals, Viton type seals by the way, NO Telfon!
With most any aftermarket spring do not attempt to use the stock oil shields.

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Re: Pontiac 455 cam recommendation

Post by rfoll » Sun Apr 08, 2018 11:37 am

rfoll wrote:
Thu Oct 13, 2016 1:08 pm
I have a 2.73 gear with a 27" tall tire. 70 MPH is around 2500 rpm with a stock turbo 350 converter. With a manual trans, you will need to pay attention to compression ratio. Bathtub chambers are not known for efficiency.
So much to do, so little time...

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Re: Pontiac 455 cam recommendation

Post by My427stang » Sun Apr 08, 2018 1:04 pm

That combo should be pretty tolerant on fuel.

Assuming the compression ratio is accurate, and the cam was degreed and in the right place

- Check TDC and make sure the balancer is correct
- Check initial afterward and total and report back.
- Make sure it's not running real hot
- Try a different fuel
- If it's still pinging bad, maybe the compression isn't what you think it is, you are lugging it too much, or the cam isn't what you ordered. Your cranking compression numbers seem to make sense, so I am banking on the ignition

BTW, I also like closing up the centers on a Poncho. We went with a 279/224 280/230 109 LSA and put it on 107 ICL for a 67 400 GTO. It runs REAL well for 4 barrel 400 HO in a 67 GTO 4 speed 3.55s. Car is a mild hot rod and blew the owner away from any cam he had in it before

As far as gear ratio for the crowd, remember, he has a Richmond 5 speed, so that 2.73 ratio acts like a OD, but the car should run like it has some gear out back in every other gear

SLR = 8.954, that'd be the same as a TKO-600 with a 3.25 gear in 1st or a Muncie with a 3.85 gear

OD = 2.73, same as a TKO-600 with a .64 and a 4.26 gear.

That car is set up pretty well, something must be not as expected. Cam is shorter, compression is higher, timing is wrong or quicker.
70 Mustang, 489 FE, TKO-600, Massflo SEFI, 4.11s
71 F100 SB 4x4, 445 FE, hot rod 4x4

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