[JOE ALLAN]

I have seen posted on here a number of 287 cfm! Was that at 28" ?

[JOE ALLAN]

I have seen posted on here a number of 287 cfm! Was that at 28" ?

[SupergasDil]

Dave Allreds 62's flowed 275 @ 25" from Butler
so they're a bit higher at 28".But I don't have that figure right now.

[JOE ALLAN]

Thank You. I looked on pontiac dude's page and if i'm read'n it rite it states a factor of 1.06 to convert 25" to 28".....So: 275 x 1.06 = 291.5 cfm........This sure don't look rite! Sounds like a bit much! I guess with all his experience he's ahead of most.

[thirdgen455]

using the same math no P-dudes site and using the head flow #'s from Pete M's artical on http://www.pontiacpower.org/ultimateflow.htm

1973-74 No. 46 (1973 350 D-port)
Date cast: K132 Grade: 2 (worn guides)
Valve sizes: 1.96 (45° seat)/1.66
Intake port volume (2 ports): 152.4, 152.2
Intake(D) Flow (cfm) Exhaust(S) Flow (cfm) Exh./Int.
.100 54 63 .100 41 .70
.200 99 108 .200 81 .78
.300 145 150 .300 105 .71
.400 170 172 .400 118 .69
.500 181 181 .500 125 .69

go from 12 inches to 28 inches =1.53
so 181 X 1.53= 276.93cfm

sounds damn good from a stock head

[Rob]

I got 303 on a head with water in three places!

-Rob

[Will]

I'd trust those Pete M. flow numbers about as far as I could throw them. There's no way a '73 #46 head with small valves outflows large valve heads by 15-20% at .500".

My 061s flowed 273 cfm @ .28" at .550" lift and Dave B. said it was pretty easy to get that out of them and that they could probably go another 15-20 cfm with more work. He attributes this to the excellent intake port design (same as 670s) and the shallow, wide chamber that offers very little shrouding of the valves.


----------------------------
'72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car!
'73 Firebird 400/4-speed Black on Black, mix & match.

[Tom Vaught]

Quote:

"Thank You. I looked on pontiac dude's page and if i'm read'n it rite it states a factor of 1.06 to convert 25" to 28".....So: 275 x 1.06 = 291.5 cfm........This sure don't look rite! Sounds like a bit much! I guess with all his experience he's ahead of most."

The factor is correct.

As far as the 275 Pete McCarthy head testing/
12" to 28" deal you forgot to subtract out the
"dead mouse" factor in the laminar element which
"soiled" all of Pete's data.

Pete's testing was done many years ago on a laminar type bench (owned by SMS engineering) that had several major testing issues at the time.

One was the dead mouse, a second was the low test
pressure the heads were run at 12" water (Pete
in his part I stated the heads were tested at 12"
Mercury! (Even Ford does not test at 12" mercury)

But back to the best D-port head.

Marty Palbykin I believe got around 290 with a
set at 25" h20 but the ports were so thin he had
water in the cylinders on the dyno. That would be
a 307 head at 28" water. With the heads sealed with "water glass" it was a small pin hole, he
made around 735 hp on a 473 type engine with D
port heads.

Tom V.

[thirdgen455]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Tom Vaught:
Quote:

As far as the 275 Pete McCarthy head testing/
12" to 28" deal you forgot to subtract out the
"dead mouse" factor in the laminar element which
"soiled" all of Pete's data.

http://kurtsplates.homestead.com/files/UR2SLO.jpg <HR></BLOCKQUOTE>

LMAO thats the funniest thing I have ever heard of!

no wonder when I asked Pete McCarthy about this at the last PSN he really had nothing to say.

so really someone needs to take the time again and do a REAL test and get REAL data. man I thought my math has been wrong all this time.

thanks for pointing that out maybe John needs to put a dead mouse disclaimer on the site

[Tom Vaught]

First off I want to say that there have been a few very good things to happen to Pontiacs over the years.

When H.O. Came out with their first articles on pontiacs. (Not all of the info was accurate but it was really neat to read about a pontiac).

When Pete McCarthy's first book (he wrote by himself) came out. It has a tremendous amount of
SD pontiac info in it and a lot of great general
knowledge photos and part numbers.

When Nunzi and Mike McKenny etc picked up the flag
of the pontiacs after it was ripped out of the hands of people like Bert Straus, Truman Fields,
Jim Mino, etc because their cars were TOO FAST.

When Marty Palbykin proved the GM engineers wrong
by making well over a 1000 hp when the factory
said the block would crack at 1000 hp, Marty made
1600 hp.

Along the way we had several great writers come along. Pete, Paul Z, Chuck Roberts, Don Keefe, etc.

So back to Pete's head test.

The fact that Pete tried his best to accurately
test of every head he could find is a great thing.

He had no way of knowing that the bench was screwed up when he ran his tests! The guys who ran his tests had been porting heads for him for years and many other guys too.

The specific type bench used had an effect due to the fact that the bench worked by reading a difference in pressure from one side of the element to the other side. When the mouse died it blocked part of the element which increased the delta P across the device and therefore the flow
numbers were artificially high but the difference
in flow between the heads is still valid.

As usual you try and do a good thing and it turns
to ***** on you. Pete has always been embarassed
about the mouse deal. But it was not his fault.

I still say he tried very hard to write an full
and accurate comparison of the pontiac heads.
I respect him for that.

Tom V.

[Will]

Tom, not bagging on Pete at all, have a lot of respect for the work he's done for all of us in the Pontiac hobby.

But (always a but, no?), if <BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> the difference in flow between the heads is still valid <HR></BLOCKQUOTE> is a true statement, then we should be acquiring all of the '73 #46 heads we can find because the flow through them is far superior to any of the large valve heads, no need for porting.

Funny, but the 428 I'm working on now has a set of '73 #46 heads going onto it prepped by SD Performance. They have been modified to accept the larger valves. Someone should tell Dave that's not necessary with these heads.


----------------------------
'72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car!
'73 Firebird 400/4-speed Black on Black, mix & match.

[Skip Fix]

The main thing Pete's article is good as there is for any flow numbers, and that is comparing different heads on the same bench, same time. I think the article Pete did was great for all the heads he found and had comparable data to each other.

As I'm sure Tom the engineer can tell you comparing two different flow benches is often apples to oranges, is it a true Superflow, same model number, or a laminar flow, is it calibrated for every flow range as some Superflows have to be or were they lazy and just the first range? Corrected for temp and humidity? Then to sell heads/port jobs was the data "tweaked" like dyno numbers?

[Rob]

Flow Bench numbers get shared a lot because they sound good, but after you doing a decent amount of flow bench testing that max CFM, or CFM under the curve, or CFM at .700 inches of lift is just sales pitch. You can reverse the math and see how many hp you should make per cfm you find on a flow bench but rarely do you ever get it.

A Ram IV head will always outpower a D-port, even if they flow the same numbers. A Ram V will outpower a Ram IV even if they flow the same numbers. And the rockershafted stuff of today will make the most power, a little because of the size and shape of runner, a little because of nice small combustion chambers, but mostly because of the size of valve and how far it's lifted from the seat.

For D-ports you're best bet for most TQ and HP is to get the compression up with the smallest chamber possible and run the big valves. Super stockers may have some feelings on what D design is better, but to me 62, 16, 48, 670s all perform the same.

-Rob

[Rob]

Hey Tom, tell us about the Engine Combination of that 473cid engine 735hp is up there.

-Rob

[JOE ALLAN]

So at 28" 265-270 cfm would be great for a #16 head for a bracket motor! This is the highest i can go and still be "SAFE"! Rite..I want something that will go all season with out trouble and just normal maintenance and common sense. Thanks for the info and insite on past stories.

[Steve C.]

I have a set of D-ports (#16 castings) that produced 291 cfm at .600" lift. They were tested at 28" on our SF600 bench. Also the combustion chambers were modified for swirl similar to the McCarthy material published in High Performance Pontiac magazine Dec '91 and in the Feb '92 issue.
They were done by Jerry Goodale many, many years ago ...and developed on tested on his bench without the mouse nest

[This message was edited by Steve Coombes on October 25, 2003 at 12:38 PM.]

[Tom Vaught]

Quote:

"I have a set of D-ports (#16 castings) that produced 291 cfm at .600" lift. They were tested at 28" on our SF600 bench. Also the combustion chambers were modified for swirl similar to the McCarthy material published in High Performance Pontiac magazine Dec '91 and in the Feb '92 issue.
They were done by Jerry Goodale many, many years ago ...and tested on his bench without the mouse nest stuck in the bench"

First off Steve, I firmly believe the 291 cfm flow
number off your SF 600 bench at 28" h20.

I am not saying that Jerry was not a good porter
but how many years ago are we talking here?

When Pete did his flow testing (with the mouse,
and the nest?) Jerry's bench had motors that would
only pull 12" of water test pressure. I sent him
better motors so that he could test at higher test pressures (like 28"). By the way I have not
helped him since due to the fact that he ripped me off on the motors and the UPS insurance costs.

This is before he "got religion" but it still pi$$es me off every time I think about it.

So if you say he tested your heads at 28" water
I would like to know how he did it. Would not
respond except this discussion is something that
I personally was involved in.

Thanks. Tom V.

ps As far as how Marty's 735 hp engine was built
I can tell you it was a stroker motor and had EFI
but Marty will have to tell you the rest.

[Steve C.]

Tom- This was back in late '94 or early '95.
I was under the impression he was using a 25" test pressure on his bench at the time, but not sure. My machine shop here in Austin uses a SF600 bench and we re-tested at 28".
Damn good set of heads, 560hp on my 400 combo and 600+ on the 462. The chambers are 68.8cc's otherwise I'd be using them today. But I'm bound and determined to stay off race gas

[Ken K]

Why doesen't someone do another test minus the mouse? Do you have any idea how much misinformation has been spread because of the original test?

[Rob]

Joe, for the best D-port, do three angle valve job, cut the intake as high as you can, open up to the pushrod wall at the pushrod till it's as thin as paper or go through it and put in tubes for your pushrods, clean the bowl(actually never seen that make any power, but looks neat) Gasket match to your intake. Try not to get so thin that your gasket doesn't have anything to be sandwiched by.

You will find the extra hp from the work at pushrod buldge.


Tom,

So what if the dude found God, he still should pay his bills. Hey, is Ford doing any neat wet flow benching stuff with pictures or heat imaging?

-Rob