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Old 06-27-2021, 08:26 PM
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The Pontiac stuff was a work in progress that never got finished. As you can see David is a believer in tight LSA.

Stan
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  #42  
Old 06-27-2021, 09:02 PM
Steve C. Steve C. is offline
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The 6000 rpm number presumably came from the OPs first post, and probably reflects what Howard's states in a listing for the cam he was interested in which was 465/470, 223/235@.050, 110, 2-6k range..
Similar to "required" compression ratios often stated. Exactly why many catalog descriptions are useless !


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Old 06-27-2021, 09:23 PM
Steve C. Steve C. is offline
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However, a rhetorical question.... what about the peak power rpm with that cam in a 350 CID combo. 6000 rpm

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http://www.hotrod.com/articles/0712p...tiac-trans-am/

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5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE
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Old 06-27-2021, 09:34 PM
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Quote:
Originally Posted by Stan Weiss View Post
As you can see David is a believer in tight LSA.

Stan
And more valve lift and recommended cylinder flow than is seen for typical Pontiac applications.

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Old 06-27-2021, 09:45 PM
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Quote:
Originally Posted by Steve C. View Post
However, a rhetorical question.... what about the peak power rpm with that cam in a 350 CID combo. 6000 rpm
If I wanted to run a 350 Pontiac to 6000 RPM, dport 260 CFM intake / 210 CFM exhaust. 1.65 rockers. 2.11 intake valve.

Image.
This tool is conservative on LSA, depending on other analysis I might very well run tighter.

I did 350 cam specs with 1.5 rocker ratio in May 2019 using another tool at the link.
https://forums.maxperformanceinc.com...5&postcount=28
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  #46  
Old 06-27-2021, 10:02 PM
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JMHO,our pontiacs are intake challenged.I have taken a few diff engines and just changed intakes and could see peak HP jump many RPMs.Dual plane,than single 4 single plane and then2-4 tunnel rams.ALL increased with no other change except induction.The OP wants a good street engine and will be a 4 speed with tall gears.Tight LCs I have not found to be as street friendly against wider.Continue on.Tom

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Old 06-27-2021, 10:07 PM
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The OP wants a good street engine and will be a 4 speed with tall gears.Tight LCs I have not found to be as street friendly against wider.Continue on.Tom
Agree with Tom here.

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Old 06-27-2021, 11:30 PM
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You can not look at just one number like LSA and say it is good or bad. One thing widening LSA does is reduce overlap. If you look at the cam I posted it has 75.5 degree overlap @ 0.006" lifter raise. If you look at the cam Mike / Pastry_Chef posted it has 75 degrees overlap @ 0.006" lifter raise.

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  #49  
Old 06-27-2021, 11:56 PM
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Originally Posted by pastry_chef View Post
Yup, who said this exactly?

463 Pontiac target for 5300 RPM, so about an OF size cam. This is 2021 folks, I have a lot more than this.

Having less than optimal valve seat duration or area does not mean the engine won't pull the RPM. Seat duration needs to be close.

20 years ago I would just cam from what I'd seen on maybe 100 dyno sheets. It was never good enough in my mind.

This sheet shows a 239-243 cam, a far cry from the OPs 223-230 cam.
Its smaller than a RAIV which he would be better off with it and Rhoads lifters.
If this fellow puts his intended cam in a 455 with ported 62s with a giant dish he will not make the power he could with a proper cam and it will ping. Not good.
If you are going to have some iron heads ported for this application find some 96s, not hard to do and port them. Less chance of detonation.
His cam belongs on a 400. He needs at least .230 @ .050 on the intake. And I would go with more than that.
Crower 60919, 60211 are both better IMO.

Who ? Dan Whitmore taught me most of what I know. .223 was a puny street cam in a 455 to him. Pontiacs can take more cam, more carb than a given cid Chevy because of its high velocity port. Cam it up, single plane with a 850 and have some fun.
Oh, and because the RPM needle goes to 6K and you are shifting it does not mean its "pulling" to 6K. Shift at 5500 and your ET will go down. No way on the face of the earth will any 455 out pull mine with 62s,giant dish and a .223 cam, not happening, ever.
If I run a UD solid roller .264-.271 near .700 lift with HOs ported by Dan with 2" headers, HP 850, big fuel system and I can not "pull" to 6K there is ZERO chance this guy will. Slow down every single time I shift at 6000.


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Old 06-28-2021, 08:54 AM
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"...our Pontiacs are intake challenged."

Example. Rocky Rotella and Jim Hand have done flow bench testing on how much a intake manifold reduces the flow to the cylinder head. Jim reports that a stock intake will flow about 91.5 to 92 percent of a ported head at 250 cfm. A Performer RPM will flow about 93.5 percent. I presume these are as cast intakes and not modified. Rocky has tested a RPM intake on a stock 5C head that flowed an average of 208 cfm at .500" lift and stock SD-455 head that flowed an average of 237 cfm at .550" lift. The RPM was a just under 93 percent with the 5C head and just over 92 percent with the SD head. If the percentage stays true as flow goes up, you'll need head flow in the 260 cfm range to get 240 cfm into the engine. Rocky used a as cast RPM intake and not modified. He also reports the RPM intake flows about 2 percent more than the average unmodified iron intake.

In addition to this there is restriction with the carburetor. He measured a QJ with those intakes and found his Holley HP950 and a Cliff-modified QJ each reduced flow by another 5 percent. If the QJ is stock the reduction can be as much as 7 percent.

It's all about the total airflow delivered to the valves.


.

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Old information here:
http://www.hotrod.com/articles/0712p...tiac-trans-am/

Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine)
5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension
https://www.youtube.com/watch?v=qDoJnIP3HgE
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  #51  
Old 06-28-2021, 11:21 AM
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Vid, My builder(Gaydosh Performance/Baltimore) has been using his custom ground Howard's HFT cams in recent years. Myself and Mook on here have the same cam(I have D ports & he has round ports) and both dynoed 569/580hp and 630 tq so obviously a HFT can get it done. I think your 3.23s are a GREAT choice(get posi though).

Those are some big numbers! Thanks for the info. Is that with aluminum heads? I like the 3:23 too and yes a posi is on the master plan


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Old 06-28-2021, 11:54 AM
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However, a rhetorical question.... what about the peak power rpm with that cam in a 350 CID combo. 6000 rpm

The tired 350 I’m pulling out to make room for the 455 is the original motor (WU block) to the car and will also (eventually) get rebuilt. Maybe I’ll try the 223 Howard’s cam in that, sounds like a really good fit!

I don’t know that I’m planning to spin the 455 to 6000, but who knows what my right foot is going to do in the heat of the moment. However I am grateful that I learned the 223 was the WRONG cam for the 455 as far as detonation and overall performance. I’m taking all of this good advice to the bank you can bet your boots the cam I run will be no smaller than 230@.050”.


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Old 06-28-2021, 11:54 AM
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Vid, We both have aluminum heads/467" and we both put a lot of street miles on our cars. I have over 7k miles on mine and Mook definitely has more miles on his. Gaydosh has a few different custom grinds and usually has a few in stock.

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Old 06-28-2021, 02:09 PM
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OCMDGTO, looks like 245/251D .561/.594

I like it. Curious on the LSA and idle vacuum.

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Old 06-28-2021, 02:36 PM
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I would second the suggestion to reach out to Tim Goolsby at Bullet Racing Cams, if nothing else but for input/experiences. I pretty happy with the cam he recommended for my mild 400 rebuild (403hp/482trq) and he is super easy to work with.

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Old 06-28-2021, 09:58 PM
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I would second the suggestion to reach out to Tim Goolsby at Bullet Racing Cams, if nothing else but for input/experiences. I pretty happy with the cam he recommended for my mild 400 rebuild (403hp/482trq) and he is super easy to work with.

I filled out their online cam suggestion form last night and made it to Tim’s attention. Thanks


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Old 06-29-2021, 08:10 AM
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Not sure on LSA and no idea on vacuum. I have manual brakes but Mook has power brakes

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Old 06-29-2021, 09:51 AM
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I filled out their online cam suggestion form last night and made it to Tim’s attention. Thanks


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I would call him for quicker/personal service...he is really great and eager to help.

662-893-8022 (ext. 102)

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Old 06-29-2021, 12:42 PM
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I filled out their online cam suggestion form last night and made it to Tim’s attention. Thanks


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Let us know what you learn from Tim and what he rcommends. Thanks.

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Old 07-02-2021, 02:25 PM
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One other thing about Howards cams is that they ship them in a plastic tube rather than a cardboard box. Prevents UPS/FED-EX from dropping and chipping/bending the cam. FWIW

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