[68WarDog]

Was the intake tried with a spacer? A Wilson 1" taper may have added 15-20 hp.

[pastry_chef]

Originally Posted by johnta1

Maybe borrow a different intake for higher RPM/flow?

Torker 2

Can you provide the lobe numbers?

Here is a 243°/251° Voodoo hyd roller and 265/190 CFM heads.
http://forums.maxperformanceinc.com/...d.php?t=809537

[Formulajones]

Originally Posted by 68WarDog

Was the intake tried with a spacer? A Wilson 1" taper may have added 15-20 hp.

Do you have any experience with the Wilson taper spacer on an rpm dual plane? I ask because I haven't known this to work well on a dual plane. They flat Rock on the single planes though.

[65nss4spdGTO]

Originally Posted by Dragncar

For SD heads to only go 260 they were not ported much. Get that RPM off that thing. SD heads, put a Warrior on it, period correct. A 496 will have plenty of low end with a single plane.
At any rate, for the cam had head flow the numbers don't seem too far off to me.

So a 30cfm to 35cfm is “not ported much”? You obviously have never ported a set of iron Pontiac heads.

Calvin Hill
Hill Performance
708-250-7420

[Formulajones]

Originally Posted by pastry_chef

Torker 2

Can you provide the lobe numbers?

Here is a 243°/251° Voodoo hyd roller and 265/190 CFM heads.
http://forums.maxperformanceinc.com/...d.php?t=809537

Paul did that engine. Another excellent example of voodoo lobes that Paul spec'd.

I wouldn't be surprised if the 242/248 lobes are similar to mine. That seemed to be a popular choice for a lot of years.
Our lift is similar. Mine is .612/.638 with a 1.7 rocker.

[65nss4spdGTO]

Originally Posted by napster

Forgot to mention...these are uncorrected numbers,

Cam is small and I would change the intake, an easy 30 to 40 still on the table.

Calvin Hill
Hill Performance
708-250-7420

[Dragncar]

Originally Posted by 65nss4spdGTO

So a 30cfm to 35cfm is “not ported much”? You obviously have never ported a set of iron Pontiac heads.

Calvin Hill
Hill Performance
708-250-7420

Coming from the guy who got accused (like others) of having SD do their iron heads and claiming them as there own, well, why you bringing this up ?

I said what I said because I have more than just a little bit of experience running that style of head on pump gas and a 455.
His cam is puny. Put a real cam and single plane on it and it will make real good power.
My HOs "might" go 260-265cfm. SD heads are a better head than HOs.Ports are the best PMD ever did. My 455 is junk, TRWs and only 9.3 CR.(10.84) He has better heads, higher CR, better internals and over 1/4" more stroke. It should RIP.
If I put my cam, intake and carb on that thing it makes 600. But it would be more race.
Change the cam, Northwind and he will be happy.

[Steve C.]

NAPSTER,
You mention formula involved to help determine your power. With no specifics mentioned did it involve cylinder head flow as tested on a flow bench or the total intake-system air flow as delivered at the valve.

Note my comments within post #15 and #56 in this thread that might relate:

https://forums.maxperformanceinc.com...low+Research**


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[Cliff R]

The cam is just a tad on the small side for what you are doing. That's pretty easy to spot as the power quits at 5200rpms. Changing intakes and adding spacers will move power around a bit and you might see a bit more peak power, but it really needs more cam if you want a broader/stronger power curve.

Even with that said I wouldn't worry much about it, dyno's just help us nail down the basic tune and provide some run time for the engine before placed in the vehicle. I'll bet it makes enough power to but a big smile on your face and nearly impossible to hold with any type of street tire.

For the big CID engines on pump gas with iron heads we've done very well with pretty "hefty" cams in them pushed out on 114LSA. Not trying to start another LSA debate, but take a look at the dyno runs below and you can clearly see how going to much bigger lobes, more seat timing, and wider LSA works in these engines.

The engine builder consulted with a tech at Comp for the first cam choice, it was not only a "turd" for power production it pinged hard enough on the dyno to require rod bearing replacement. I got the call because everyone right down to the guy taking out the trash was blaming the Q-jet (built by the engine builder with my rebuild/tuning parts). So other than sending them some parts I really had no dog in that fight.

After some Q-jet bad mouthing over the phone I asked about the engine details and when he told me that the heads were professionally ported and flowed at 250cfm (#96) and 9.3 to 1 compression I told him to remove the Comp XR276HR cam and provided the new cam specs. The engine builder did so and only made ONE change.

He called back after the dyno runs and said that the engine now idled better, improved throttle response, no pinging whatsoever and they were able to bump up the timing and make quite a bit more power with it.

For what you are doing another 10 degrees of camshaft and bigger lobes would really pick the power up.........Cliff

[blueghoast]

I would listen to Cliff. The man knows his stuff.

GT.

[TCSGTO]

Try to get the corrected numbers since they could be quite a bit different. Without that it’s hard to compare it to any other results. The torque should be up close to 600 when corrected to standard conditions, especially with an RPM intake. The op said the dyno is known to be a bit stingy also. Put it in the car and see how it runs, that’s the real test.

[77 TRASHCAN]

You mentioned the Dyno shop is know for smallish power numbers. There are different types of numbers as mentioned in posts before me.
My engine builder only spoke of "Net" numbers, not corrected, no frictional HP added, etc.
He built a simple Chevy SB 400 for a friend of mine, pump gas, very user friendly. The 5000 pound 66 C10 pickup truck that the engine went into was incredible to drive/ride in. It was only 300 HP/400FtLb engine.

Cliff has done this! Don't let any corn eaters influence you!!!

[Cliff R]

Agree on the corrected numbers. It also helps to get track numbers if you race the car, they show the true power the engine makes and how well you are using it. If you can find good traction and make a hard run engine power is pretty easy to calculate based on vehicle weight and DA that day at the track.

If it's street only I can't imagine you could find any fault with a 496 build with SD heads on it and a 240 something @ .050" roller camshaft. Intake, exhaust and everything else would be small players in the big plan if you were just evaluating the power with full throttle blasts......IMHO......Cliff

[Formulajones]

A small cam for the size was my first thought. 500 cubes is getting up there for a 242/248 cam.

I'd bet that thing has a really flat torque curve that'll be a total blast on the street, and stealthy in appearance.

[Steve C.]

Remember Lou Rotella's 495 designed to maintain good idle and superb low-rpm street manners. Small cam with 219/229 duration and a Performer RPM intake. 474 hp at 5,000 rpm and 594 lb-ft at 3,700 rpm.
He was pleased.

https://www.hotrod.com/articles/474-...-inch-pontiac/


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[pastry_chef]

Originally Posted by Formulajones

A small cam for the size was my first thought. 500 cubes is getting up there for a 242/248 cam.

Also that 496 trying to breath through a 260 CFM head. A popular SBC head the AFR195 street goes 275 CFM at .500 lift.
A 350 with only 214 @ .050 cam / 2200 stall converter dropped the ET more than a half second swapping from 882 castings.
Entry level BBC heads are 340 CFM and up.

[Steve C.]

Trying to breath. Grab a bicycle tire pump sometime, and first try to operate it as quickly as you can. Then, slow down the pumping action. You will notice that it is far easier to move the pump handle slowly. Reminds me of the engine sensitive to under-flowing heads. High piston speed.


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[TheGrudge]

I’m very interested in this thread - my saga (rather than build as it has taken so long)
is very similar, although .035 over, 290cfm early E heads 87cc & 268/276 .620/.640 110 SFT.
Hopefully on the dyno first quarter of next year. Jim Butler spec’d out the cam; said something like “the longer stroke will absorb the extra duration” as it seemed a real big cam to me. FWIW.
JP

[pastry_chef]

Originally Posted by TheGrudge

.035 over, 290cfm early E heads 87cc & 268/276 .620/.640 110 SFT.

Required valve seat duration is based from mean piston speed at peak power.
Required valve lift and the curve are figured from displacement, RPM and induction efficiency.
Without having the lobe numbers and other engine specs it looks like a good cam for 1/4 mile. 10s with a good combination.
Ideally I'd want more head flow and a solid roller cam.

[68WarDog]

Originally Posted by Formulajones

Do you have any experience with the Wilson taper spacer on an rpm dual plane? I ask because I haven't known this to work well on a dual plane. They flat Rock on the single planes though.

Yes, almost 20 years ago,, 1" wood 4 holes amd RPM intake, 750 holley. Although I also did a gear change too, it was more responsive and picked up in the 1/8 mile. But specifically how much the spacer helped, I can't say.