[Half-Inch Stud]

CLIFF's Post 97 matches why i picked the tame cam. CLIFF may be spot-on.

Two cases:
HIGH Compression; I woul argue & recommend the cam in my 11.0-12.0 ET Signature for ANYBODY looking for the best of the breed performance and manners (smart sounding idle, suspension limited 60foots, low ping, great MPG, etc) Sliderule indicates 550HP with the Wensler. Notice the LSA is not 104, but more toward CLIFF's window of acceptablility. My 104 LSA experience didn't get the track data and it's tough to beat 550 HP with low RPM, so the LSA arguement seems moot. I enjoyed tuning the Hi-Compression engines because it seemed i knew what i was doing.

LOW Compression; think i'm lost, think in the woods, can only see the treeline with my 12.2 ET Signature, and that Tomahawk TC-02HF cam result was a great sounding stinky idle that could make a diesel mechanic cry, pig rich carb setting for performance, and terrible MPG. Yet the recent cam (Comp 280h-10 232/236 110LSA) is all good, itsa Winter, and will need to get track time in the Spring to see if it reaches 12.2 or exceeds (some porting was done). Yet similar cams huh. The 104 LSA Case remains Open for Low Compression, except CLIFF data-laden experience says low LSA is a bad deal for low compression.

I loath tuning the Low Compression engine regardless of the cam, because it seems tuned-up. i got no 'next step', no skill', no game to get above 400 HP, well until track data reveals the performance. Long Winter for me huh.


the 406 sbc is kinda cute, manual clutch and all. The 455 Pontiac inside 3850lbs will remove the Muncie countershaft teeth in low 12's and 11's. So, itsa TQ converter and TH400 to Reliably handle the Twist & Shout.

[Half-Inch Stud]

I got to find the money to afford HYD Roller Lifters, Springs, Dizzy gear, Lifter Bore brace, pushrods?, Stud brace? What is that $2000?

[Formulajones]

Originally Posted by Half-Inch Stud

the 406 sbc is kinda cute, manual clutch and all. The 455 Pontiac inside 3850lbs will remove the Muncie countershaft teeth in low 12's and 11's. So, itsa TQ converter and TH400 to Reliably handle the Twist & Shout.

If that was the road I'd take, I'd just put a crush box in it that would handle the abuse. One thing I won't do is take a factory stick car and convert to an auto. I already have a particular car with an auto to make big power with.

[tom s]

Hyd roller cams dont need the lifter bore brace or a stud brace,saves a little!Tom

[tom s]

and a lot of labor!Tom

[Half-Inch Stud]

@ Formulajones, yez, i converted my Stick car to an auto for the reasons of TH400 merits, and inability to afford the rugged Manual clutch and gearbox. Someday i will put the manual 4L80 in with clutched converter. If that plays well, then i'll afford a high stall dual clutch converter, and be done. I think.

@Tom, I'd skip the stud brace & consider skipping the Lifter bore brace. But Holy Von Mises! that #2 lifter bore scares me.

*Von Mises hoop stress, not the glorified idiot.

[Formulajones]

Originally Posted by Half-Inch Stud

@ Formulajones, yez, i converted my Stick car to an auto for the reasons of TH400 merits, and inability to afford the rugged Manual clutch and gearbox. Someday i will put the manual 4L80 in with clutched converter. If that plays well, then i'll afford a high stall dual clutch converter, and be done. I think.

@Tom, I'd consider skipping the Lifter bore brace. But Holy Von Mises! that #2 lifter bore scares me.

I understand all that and know the reasons why. I have a couple of 400 turbo cars here, one I throw all the power I can afford at it so the reliability of the drivetrain certainly comes into play.
That car I linked a video of wasn't about any of that at all. It's simply a fun street car with a stick and a tight LSA cam that's an absolute blast to drive. It behaves rather nicely on the street considering that cam is supposed to be a complete mess, lol.

[tom s]

HIS,I have run 400 lobe lift hyd roller cams with 1.65 rockers for years with solid rollers with 200 on the seats and 600 open without either with NO issues.Kind of rule of thumb is if the duration at 200 lift get to 200 duration the lifter bore brace should be used.Tom

[pastry_chef]

Originally Posted by Cliff R

Right to start with, IF you pick a cam big enough to make big HP, it's going to be a complete TURD in a relatively low compression 455 build with really tight LSA. (The engine I was quoted on above had over 11 to 1 compression with the huge 108LSA cam, and still very rough idle and poor street manners at low rpm's, in case anyone is taking notes here.) Idle quality will be horrible, really stinky exhaust, and not user friendly anyplace. With high compression you can start pulling the LSA down with less negatives, as the added static compression trumps the increased overlap.

Here is a low compression combo - 108 LSA flat solid
11.01@119 in a 3800 lb 66 GTO

Originally Posted by Mike Davis

11.50's with a 428 is easy. Here is a combo I ran about 7 years ago. 421 bored .060, Ross Pistons, Eagle Std length rods. Used a factory 428 4" stroke crank for 433 cid. Ported #62 heads That flowed 262 cfm, Ferrera Stainless Valves, Comp 995 Springs. Ultradyne Solid Cam 288/296 adv 255/263@ .050 with .540/.556 lift on a 108LSA/102ICL. 6qt Milodon Baffled Pan, Pontiac Dudes Crank Scraper, Factory Windage Tray. Victor Intake port matched to the heads with a Barry Grant 750 Race Demon. Hooker 1 3/4 Super Comps, 3" mandrel bent pipes to a 3" x-pipe into 2 chamber Flowmasters. 10" 3500 Converter, TH400 trans, 3.73 gear. This set-up with street tires, stock mounting location suspension ran 11.01@119 in a 3800 lb 66 GTO and was very streetable.

I doubt it Cliff!

[Cliff R]

Keep digging up "old" information if it fits what you are looking for. I'm not sure at this point what point you are trying to make here? Seems like you're just looking for an example that goes against what I'm putting up here...IMHO

I'll also bet you don't know Mike Davis, or his car, or anything about any of it. That example is NOT 4.21 or longer stroke either, those engines are a completely different animal, but if you had any first hand experience with one you'd know that.

Even the 428 we built and dyno'd a few years back used a custom ground HR cam on a 110LSA, and it made great power for the combination of parts......FWIW.....Cliff

[pastry_chef]

I call discrepancy and nonsense when I see it. In every area of life.
Sometimes BS I read here.. creates laughter, sadness and often anger.

FACTS
There is NO reason lower compression would prefer more LSA in a cam.
NO reason smaller stroke would respond better to less LSA.

You don't know me.. and you have NO CLUE about my knowledge and resources.
A minor tidbit.. often spend hours a day with motorsports equations - Masters degree level.
It has been a passion for decades.
I've learned from some of the very top in the industry.
Near genius IQ (doesn't matter)
People tell me I should move to South Carolina all the time.

I quote notable others as it helps readers make a connection.

[Cliff R]

Maybe instead of calling anything about anything you should tell the readers here about your great accomplishments with Pontiac street engine builds, dyno numbers, track numbers, and just as important how well they worked in actual use.

When it comes to these engines a couple of things are certain. Low compression absolutely KILLS engine efficiency as it reduces cylinder pressure and the heat production required to effectively burn a lean mixture. Combine that with installing a cam on a tighter LSA with additional overlap and you reduce the efficiency even further....but since you are an "expert" you should have already known that.

Anyhow, two things are certain here, I probably spent more time on the crapper last week than all of your total direct experience combined with this topic.......and second, and absolutely for sure I am NOT going to waste one more second of my time responding to your useless posts that are nothing more than copy/pasting and regurgitating old information because it seems to agree with your line of thinking.......FWIW......Cliff

[Half-Inch Stud]

Originally Posted by pastry_chef

Here is a low compression combo - 108 LSA flat solid
11.01@119 in a 3800 lb 66 GTO .....

What was the duration at .050? That seems important.

[pastry_chef]

Originally Posted by Half-Inch Stud

What was the duration at .050? That seems important.

255/263@ .050 with .540/.556 lift

Ultradyne solid flat - a bit important as well.

------------------------------------------------------------

How about:

403 Cubic inches with 10.4 compression and 106 LSA
3.763 stroke

Made 474 ft.lbs at 2,500 RPM for BMEP of 177
Torq hit a high of 581 ft.lbs

---------------------

A 455 at the same "efficiency" would have 534 ft.lbs at only 2500 RPM

Just saying reduced LSA does not necessarily mean low end "TURD"

[Formulas]

That's pretty close to the Comp 290B6 camshaft.. I have one in a 440 short block 10.8 compression E'heads.. need to finish assembly of that after I get my 360 broke in..

[pastry_chef]

Originally Posted by Formulas

That's pretty close to the Comp 290B6 camshaft.. I have one in a 440 short block 10.8 compression E'heads.. need to finish assembly of that after I get my 360 broke in..

Close yup. 290B6 is pretty good.
The Ultradyne has an advantage
Dur at .200 is 166 degs vs 160.

[Half-Inch Stud]

Originally Posted by pastry_chef

255/263@ .050 with .540/.556 lift
Ultradyne solid flat - a bit important as well.

------------------------------------------------------------

How about:

403 Cubic inches with 10.4 compression and 106 LSA
3.763 stroke

Made 474 ft.lbs at 2,500 RPM for BMEP of 177
Torq hit a high of 581 ft.lbs
---------------------
A 455 at the same "efficiency" would have 534 ft.lbs at only 2500 RPM
Just saying reduced LSA does not necessarily mean low end "TURD"

Ah, sounds like the E & F lobes. I had UD make both D & E, and E & F lobes on 104 LCs, and they behaved great with 11.5:1. These days, i'm scared to try such cams on low compression. Really skeptical if that much .050 duration would run on my 9.0:1 low compression.

[pastry_chef]

Originally Posted by Half-Inch Stud

Ah, sounds like the E & F lobes. I had UD make both D & E, and E & F lobes on 104 LCs, and they behaved great with 11.5:1. These days, i'm scared to try such cams on low compression. Really skeptical if that much .050 duration would run on my 9.0:1 low compression.

Is this for the 469
4.21 stroke?

If looking at a solid flat. Say 5600 RPM.
A guess would be 73 degrees of overlap (.020 tappet)

The 288/296 on 108 has 76
I'd go down one size.

----------------------------------------------------------------------
Here is wonderful scientific explanation from Vizard.
Should make clear sense to most.

In an analysis of compression ratio versus LCA remember that the exhaust needs to
scavenge just a little more than the volume contained in the combustion chamber. Overscavenging impacts fuel efficiency, and this is a concern for a street engine. On the other hand, a certain amount of over-scavenging is good for an all-out drag race engine in which fuel economy is not a concern. For a 17:1 CR 500-ci Pro Stock engine the total combustion chamber volume is 63 cc. For a 10:1 556-ci engine the chamber volume is 128 cc. That is a big difference. As a result, to scavenge a chamber of 128 cc the overlap area needs to be substantially greater in proportion to the overall duration. This means that a lower compression engine must have a tighter LCA.

[pastry_chef]

HIS, consider contacting twperformanceparts.com about COS-CAM
I think its $100 for the analysis if you buy a cam from them.
It can take everything down to valve job angle into consideration.

Another member here did for his 433, it spec'd a single pattern cam around 230 @ .050 on a 106 LSA.

[slowbird]

So what is considered low compression and what would be a cam too big for that compression?
I ran a cam that was 276-286 @ .050 in an engine that had a hair under 11:1 compression. It seemed to work pretty good.