Max Flow From 670 Heads?
 

Saw an ad on marketplace from a guy claiming 670 heads on his 1969 something-or-other Pontiac had been ported to "flow 300 cfm."

My B.S. alarm went off but I started wondering what flow numbers are possible from a 670 head with professional CNC porting?

Max Flow From 670 Heads?
 

I think the highest number I’ve seen is 275. And that highest I heard of is 295. But I don’t know if that’s accurate. And neither was a 670.


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Marty P had a set of 455 HO heads that were severely ported, several holes in the ports,
(many years ago) and they leaked at 290 cfm. A very accurate flow bench was used.

I can believe 275.

Tom V.

Without welding or epoxy work a true 270 to 275 cfm@28” is it with a 2.11” valve and a maxed out throat size.
And that 275 number hinges on if the casting has any appreciable core shift!

The 670 casting just does not have enough short turn height to make for instance the 285 plus cfm that you can get from all out porting work on all the other D port castings from 1968 to 70.

Unrealistically Manipulating the side to side position of a wedge type head like a Pontiac on the bore adapter when doing a flow test can bring in another 5 to 8 intake cfm that will not be had in use when the head is bolted onto the motor with the intake valve up on one side of the bore.

Thanks to all who replied.

Paul C. down in Tucson finished up a set of 7F6's for a 455 I built a while back. They were initially ported by Dan Barton and after Paul was done with them, improving the flow by changing the valve job angles around, they flowed 282 CFM. They didn't appear to be massively ported either, just a very nice job, all done by hand, no CNC program. Paul noted that he flowed several ports and they were all within a couple CFM of each other.

Paul was working on his own set of 670's at the time and experimenting with different things. I don't remember the flow numbers exactly but I remember them being similarly impressive.

Not overly difficult to reach these numbers with iron Pontiac heads but it's not cheap.

He is going to get my HO heads for a freshen up-port work. Might used some custom valves like the 5.7 Hemi valves he used but longer. If he can get 300cfm out of them that would be something.
Thats the plan after I run my High Port a season or two. Going to see how much power I can make with a 9-1 461.

Here’s some info / detail for you folks.

On all of these heads I cover here I am talking about flow numbers that can be and actually still have it be safe to run the heads with water pressure applied to them.

If you want to go to completely unsafe paper thin port walls then you can get greater flow numbers out of these heads if your just looking for what amounts to flow bench bragging rights!

High comp D port heads of less then 80 CC of chamber volume start life on average with 154 CCs of port volume.

If you have a set that has not yet had a valve job that has sunk the intake valve mote then .030”, and if this set of heads has little cord shift then 285 to 290 cfm can be had by very labor intensive porting work.

On heads ported like this your raising the the roof so much that your exposing a lot of the rocker stud hole as seen here in my photo of a number 13 casting.

Next are the round port 455 HO heads that start life at some 172 CCs of port volume or some 12% larger then the high compression D port heads.

All I will say about these heads is that if you are max porting then and you can’t attain the same or greater flow numbers then max ported D port heads then you do not know the proper way and procedures needed to port these 14 degree valve inclination heads properly!

Next up the 69 and 70 RA4 heads that show up out of the factory with between 182 to 184 CCs of port volume, or about 18% greater port area then the D port heads .
These heads will max port out to well over 325 cfm , but not with out raising up the roof so high at the flange that a high port type Intake is a must.

These heads then are better left for most folks being reworked to flow 295 to 300 cfm.

I will not talk about the SD 455 heads and there slightly larger port volume then the RA4 heads because there deeper low compression chambers and resultant lower short turn height means that in fully port form they can hardly beat out the potted flow numbers of the ported D port heads!

With all of these heads I have covered here that flow over 285 cfm where talking about them having been converted over to 45 degree seats, but still only running a 2.11” Intake valve.

In regards to the comment in post number 6 here where it’s stated that it’s not overly difficult to port heads to this level then you need to try hand porting just one D port Intake port into the 280 cfm range, since that’s 3 hours of work to get the port to finish level !!

It's not overly difficult in the sense that one knows what they are doing.

Is that better Steve? Geez I figured that went without saying :rolleyes:

The time involved also goes along the same lines as being pretty expensive, which is what I meant, I thought people could figure that out, LOL In other words I try to give these guys around here a little more credit without the need to spell everything out.

:thumbup: That' sounds cool. I'd love to hear more about it.

Good info Steve25 but that seems like out dated information. Accurate to a point but a lot of those "max" numbers have been surpassed.

Maybe you can ask Paul if these numbers are correct for a head he did sometime ago. 670 head 2.08" 7mm stem intake valve 288 cfm. I only have intake numbers.

Stan

For all you head flow experts, & guys who know how to calculate power related to ET, here's a question.

I assume Randi Lyn Shipp's '67 Bird Stocker runs 670 heads.

The car has run quicker than 10.50, on several occasions.

So, although the NHRA Stock rules call for no porting, how much head flow is required for that car to run 10.50 ?

These old school Stocker combos that can run low 10's & high 9's & are quicker than the same combo was in SS form, back in the '70's, are very interesting to me. I know the unlimited valve spring pressure & cam duration play a big part. But, I don't think that MOST "as cast" factory heads will flow enuff to run the big numbers some are running today. Assume some form of "porting", which would have been illegal back in the old days.

Have read all sorts of methods that have been used to increase flow, such as acid porting, inducing rust, & even hand porting, and then covering it up, in various ways, so that it's hard to detect. Assuming that NHRA finally just gave up & decided to let it go. Have read that "Heads-Up" builds some of the very best flowing Stocker heads. There WAS a section on their site, vaguely describing their Stocker head port enlarging modification. But, that section disappeared, as of the last few times I tried to find it. The Stock section just says "Under Construction".

https://www.headsupcylinderheads.com...der-heads.html

Every last cfm it can flow for as long as the valve can stay open and at a very high rpm.

Equals square lobe cams ;) Keeping the lift per rules but duration is unlimited. Not great for longevity but doesn't matter in class racing where tear downs are part of the game.

Since all any of us can do is guess. I would say around 220 CFM for the intake.

Stan

You rally can’t answer the question as to how much hp is being made to run a 10.5 ET, you have to look at MPH.

In these these types of racing classes the motors are set up to make there best power, but in a very narrow rpm band.
The cars are then geared to run in that narrow band which allows the most average power to be used throughout the run, and also every spec of power is applied to the track!
The last time I messed around with the intake valve job on a stock 670 head I got it to flow 225 to 228 cfm@28”.
If you go by the 225 cfm number then a motor could make 57.8 hp per cylinder at 100 percent VE.
This would come to 463 hp out of 8 cylinders.

In a 3500 lb car this will go 11.3 to near 11 flat in the 1/4 mile at about 120 mph.
And increase of VE by just 5 percent gets you to 485 hp, and now your darn close to running a 10.80 ET.

LOL !

Yeah, it runs good.

But aprox how many cfm do you suppose the heads flow ? :confused:

Will a 400 Stocker engine make that much power @ 240cfm flow ? 250cfm ? 260cfm ? OR ??? :confused:

"... on a stock 670 head I got it to flow 225 to 228 cfm..."

So, you think Randi Lyn's '67 Stocker can run 10.50 or quicker, with no more flow than that ? :confused:

OR, do you think the heads have been "massaged" to flow more ? IF so, how much more ?

I understand about Stocker "tricks" & "set-up" to run quick. BUT, the engine still has to make a certain amount of power to run the big numbers.

SO, since this thread is about 670 head flow, there's no better place to include the 670 heads on an NHRA Stocker.

Aprox how much would heads have to flow in order for a 400 Pontiac engine to turn 8000 rpm ? Is that something you guys can calculate ?

Bryan Phillips also has a 10 sec '67 Bird Stocker. So, I assume his 670 heads also flow more than a non-ported factory stock set.

There is no set answer. The more the heads flow the less cam that is needed. The less the heads flow the more cam that is needed.

I will set the over under on HP @ 530 and take the under to run 10.50 with a DA of zero.

Stan

I have one for you; how fast do you think Mrs. Shipp's 400 would run in a stock 67 Firebird? Maybe assume a TH400 and the performance gear ratio.

"...what flow numbers are possible from a 670 head with professional CNC porting? "

When I went back I read this, I decided to check on the SD CNC porting deal.

To my surprise, SD no longer fools with iron heads. I suppose I'm the last to know.

http://www.sdperformance.com/listPro...?categoryID=53

I suppose he has much more than he can do, with just alum heads.

So, who now has the best CNC program for iron Pontiac heads ? :confused:

Butler says they do more Pontiac heads than anybody else in the world.

https://butlerperformance.com/i-2445...tegory:1234782

I suppose there are several members here who do hand porting. I assume most members know who these guys are. Any who wish to advertise their porting services can. Don't know who now does a lot of CNC Pontiac iron head porting.

KRE shows lots of alum head CNC porting. But there is no mention, specifically, of porting iron heads.

http://www.krepower.com/Pontiac%20Cylinder%20Heads.htm

Nitemare shows Pontiac iron head porting services. Not a recommendation. Just a possible source.

http://www.nitemareperformance.com/cylinderheads.html

Got this from a Google search.

https://headsandmanifolds.wordpress....-head-porting/

In a rules restricted class like NHRA Stock, you just have to work within them. The heads are so limited in flow, all you can do is open the valve as quickly as possible and keep it open as long as possible. Any duration allowed. You end up with rectangular cam lobes and hope for the best. Valve springs become super important. Lifters and cams don't last long.

Yeah, some of that's true.

BUT, those things alone won't produce the quick times SOME cars are posting.

Therefore, SOME Stocker heads fudge on the rules, therefore producing much more flow than the stock, as produced, ports will flow.

What I'm saying is NOT a secret. It's a well known fact that Stocker guys have been modifying head ports, for a long time, to increase flow.

My guess is that some of these guys got caught, back in the old days. But, I'm thinkin that nowadays, you'd have to have a really big, obviously enlarged or otherwise modified port, in order to provoke a DQ at an NHRA race.

I suppose they COULD check the ports really close & DQ a Stocker. But, somehow, at this point, I don't think they will. Could be wrong tho.

To me, it would be REAL interesting to get a good close up look at a stock, as cast, 670 head, right beside a head off Randi Lyn & Bryan Phillips' '67 Stockers. Might be rather "eye opening", especially to you guys who have done lots of Pontiac head porting, & are very familiar with 670 heads.

On the other hand, it might actually surprise me, if I could see no difference in the ports, at all. I'll never get that chance, & probably nobody else will, except those involved with the cars and/or head prep.

Lot's of the current Stock racers spend many thousands of dollars for heads that will flow enuff to produce the big numbers needed for class wins & nat records. As long as there are those willing to spend the big bucks, there will probably be guys who will build those heads.

BUT, thankfully, due to the breakout rules used for the rounds which are not same-class heads-up runs, maybe Stock Eliminator will survive for a while longer. Many of the Stock/SS guys HATE it when anyone likens their form of racin to bracket racing. Some will get downright nasty with anyone who even suggests a similarity. BUT, in spite of that, without the breakout rules, Stock/SS would probably not exist today. Only the super rich could win.

All the slower, really soft combinations would eventually disappear, & Stock/SS would become more of a "pro" class. NHRA could make most any combo completely non-competitive, with one hp factor hit.

But, as long as the breakout rule is in effect, any car that will pass tech & teardown, & can run it's index or quicker, it can win a race.

i’m not sure he always gets my sense of humor, but if i had a set of iron heads that i wanted ported I would PM steve25 and ask him if we could port them or, if not, who he would recommend. the guy seems to know his stuff.

Quicker than that same car with absolutely "as cast" ports, on otherwise identical heads, is my guess.

So, are you saying that the heads on her engine have absolutely "as cast" ports ? Hey, I'm asking. I don't know. There's no possible way I could know.

It's just my thinkin that these 1st gen Pontiac Stockers couldn't run low 10's with D-port heads, which have untouched, "as cast" ports.

Don't it take around 500hp or more to run these times/speeds ? Will a legal '67 Pontiac 400 Stocker engine make 500hp ? More ? How much ?

To me, these are legitimate questions. I don't have a clue how to calculate the answers. But, I assume that some here can.

Randi Lyn's Bird
 

Since I brought it up, I feel obligated to post a little more info about Randi Lyn & her '67 Bird Stocker. Here are some quotes from the article, linked below the quote.

"...Running at 3,210 lbs. (with driver) in D/SA (11.55 index), the Pontiac has run 10.40 at 124 mph. And when set up lighter for C/SA, it's run a best of 10.31 at over 125 mph...

Amazingly, the Poncho sings to 6,800 before she clicks the gears, and it buzzes across the stripe where no Pontiac should go—revving to 7,800-8,000 rpm!...

rated by Pontiac at 325 hp and factored to 338 hp by NHRA. It's meticulously prepared to take full advantage of the Stock Eliminator guidelines and produces north of 500 hp..."

https://www.motortrend.com/features/...1967-firebird/

The article was published back when she only had 4 nat event wins. I think she now has 7. But, I don't think she's married yet. So, she's still "Miss" Shipp, & has never been "Mrs. Shipp". LOL

There are lots of pics in the article. One of 'em shows that the engine does indeed have 670 heads. And I assume she revealed the 500+ hp number, because she's seen the dyno numbers.

So, bottom line is that she shifts @ 6800, crosses @, or very near 8000, makes over 500hp, & has run quicker than 10.50's.

She even provided the ET, top speed, & total weight numbers, so you guys who know how to calculate stuff can do your thang.

Randi Lyn seems like a real nice lady, and their whole racing operation seems to be 1st class. So, she & her Pontiac are a couple of my favorites. :)

But, with all that said, I still don't have a clue if those 670 ports are "as cast", or not. :D

Here's another article, with less technical info.

https://dragchamp.com/2020/nhra/stoc...ndi-lyn-shipp/

https://dragchamp.com/2019/nhra/stoc...-66-nationals/

https://www.facebook.com/rlshipp

My exp with my stk parts SD455,35 yrs ago. Car weighs approx 3740. Heads were done by AHines Racing out of Lawrence burg Ind. He was doing engines for different Pontiac guys. Anyways I had some input from John Herslow.John said to run 4.56 gears. I tried them with basic slapper bars. Car was spinning,i tried adjusting shocks ex.just couldnt get good consistent times. So I put 4.10s in got car to 12teens at 110. Still not good. He had gone 11.70s. So we talked. He gave me a cam that he said went the fastest with,however he said car was popping through carb. I have cam but was afraid to use it. My point being you need all the dyno time, testing in car to find what works.Another you could estimate hp, work backwards car weight,mph get ball park figure for required hp. I do think heads are modified with acid to get the flow for the hp. I'm satisfied at my age if I was younger I would test different ideas. Automatic trans are in the $5k range I've been told,gulp! for me. Testing ,more testing.i will tell you for my SD that the qjet 2nd metering rods are very very thin,I picked up when I did that the engine wants fuel.

My mistake I though she was married to Bo.

What you are asking in regards to the CFM it would take to run mid tens in her car is going to be tough to figure out. There is a whole lot more going on with the rest of the car than just what's under the valve covers (as you know). If you knew what the engine would run in a stock Firebird or known chassis it'd be easier to base line the power their engine is making.

I don't know enough about their combo to venture a guess. I'm certain, based on my past experiences is a lot of "class" racers seem to think ten horsepower that they paid $5k for is a better than ten horsepower they can buy for $500.... Regardless they do manage to squeeze a lot of ET out of their combinations. I'm glad a handful of them are flying the Pontiac banner with success after all these years.

Easy to figure. If it only weighs 3210 with the driver, that's pretty friggin light, then it only needs a little over 500hp to run mid 10's. That's a pretty light car so it doesn't surprise me to run those times with a 400 and 670 heads considering all the other tricks they do. Don't need a dyno to figure that out, but it's a rough guess. One thing for sure as Paul has already said, they know how to use every bit of power the engine puts out.

The rules state they aren't supposed to play around with the ports, but nothing about what they can do with valve jobs, seat angles, and valves.

I already stated how Paul improved the flow of the heads I sent him with just his valve job tricks. The flow sheets showed as much as a 30 cfm gain. I'm sure other engine builders that do a lot of NHRA builds have figured that out too. Work within the rules.

So for conversation sake, if a 670 head flows 220 cfm stock, theoretically you might find another 30 cfm just playing with certain valves and valve angles if you know what you're doing.

With the low lift cam having tons of duration (square lobes I mentioned earlier) to take advantage, I could see the engine making some decent HP, and HP is just a math equation of torque production. With that said, even more interesting is that I'd bet torque production would be better than most other engines of that size and that's what helps move the car down track.
Boy this kinda got way off subject, lol. But interesting.

There is also a reason why you'll see that Pontiac combo more often in stock NHRA type racing than most other Pontiac combos. Seems those 670 heads have something better about them than most other castings. I've heard that from a couple of Pontiac stock eliminator guys.

Now, there's something else that's real interesting.

I have only known of 2 Stockers & 1 Super Stocker that are running 670 heads, in recent history.

LOTS more Stockers running a '68 Bird, especially in this century. The NHRA hp factor for the '68 D-port head 330hp engine has always been very similar to the '67 hp factor, as far as I know. So, I'd say maybe the open chamber #16 & #62 heads might have just as much potential as the 670 heads. Is there info proving that the 670's are better ? :confused:

There have also been lots of 4X head '74's & 6X head '77/'78's, that have run strong in Stock & SS. Many more than '67's.

"...I've heard that from a couple of Pontiac stock eliminator guys."

Just out of curiosity, were those guys running 670 head Stockers ? Unless one of 'em was Bryan Phillips, I'd don't know of any other guy who has run a 670 head Stocker, in the last 10 years. If there is one or more, I'd like to have that info.

About forty years ago I sold a virgin pair of 670 heads to a gentleman from another State. He seemed all hot and bothered to get them. He had me send them to Ellison Race Engines, which if I remember correctly were in Cincinnati. About three weeks after sending them I get a call back from the gentleman wanting to know if I had interest in buying them back. He told me Ellison said they were nothing special.

If Shipp’s car is set up down to the minimum weight for C/SA the car and driver weight should be 9 x 352 HP = 3168 lbs. It mph’s at about 120 mph. That indicates closer to 460 HP by the et calculators I use. Ball park number…Working the old super flow HP equation backward that is 221 cfm @28”. What that car does exceptionally well is that first 1/8 mile, that is usually where S and SS are quick, the quarter et is mostly made in the first 1/8th. That 10.50 ish et is quick for a 120 mph blast.

300 cfm shouldn’t be that difficult of number to hit if someone put in the work on a d port. I am not sure how easy it would be on a 670, IRC they are known to be stronger flowing at the lower lifts versus other d ports. Without flow numbers at all the lifts it is really really difficult to judge how well and how long they would work for racing or on the street. Maybe it flows 300 but it is at .8” lift, 300 sounds awesome but if the cam doesn’t even have .5” lift the car would likely be faster with stock heads. Lots of people have went over 300 cfm with d ports. But they look something like this photo of these D ports of a friends, ran deep into the 9s NA in a 3200 lb car….bad azzzz set of d port heads.

"...9 x 352 HP = 3168 lbs..."

Not sure where you got those numbers.

According to the Class Racer Info site, it looks like the current hp factor is 338hp.

http://www.classracerinfo.com/Engine...4&MAKE=Pontiac

9 x 338 = 3042 + 170(for driver) = 3212 lbs min weight for C class, if I punched in all the correct numbers.

She said that in C/SA it ran a "...10.31 at over 125 mph..."

She said that in D/SA it ran "...10.40 at 124 mph..."

9.5 x 338 = 3211 + 170 = 3381 lbs min weight for D class

So, maybe 124 mph @ 3380 lbs will give you guys the numbers you need to make a closer estimate of power ? :confused:

Guessing they probably ran at least 20 lbs or more heavy, to be on the safe side. So, I'd use an even 3400 lbs for the D/SA min weight, when punching in the numbers.

When I punched in 10.40 @ 124 mph @ 3400 lbs, the Wallace hp calculator shows somewhere between 596 & 506 hp. That's quite a range, so I don't know how accurate it could be. What online 1/4 mile hp calculators do you guys think may be fairly accurate ? :confused:

http://wallaceracing.com/hpcalculatorquarter.php

This calculator says it'll take 506hp to run 124 mph in a 3400 lb car.

https://racingcalcs.com/quarter-mile-calculator/

This one also says 506hp.

https://www.tciauto.com/racing-calculators

Same for this one. Apparently, several of these are using the same formula, which, according to this site, must be "HP = (MPH ÷ 234)³ × Weight".

https://www.gregraven.org/hotwater/c...p-from-qm.html

IF this formula is close to accurate, Randi Lyn's engine has to be makin a little over 500hp, minimum.

I agree with Steve on using ET to figure H.P. with NHRA cars.Use MPH.Tom

You are correct Don, I was using the 67 400 RA rating and forgot to add the 170 lbs on for the driver and min rating weights. But the 120 mph was from when I watched the car go down the track, 120 to 121 was what I watched. From those better numbers you listed I come up with 528 hp, recalculating that is likely at most a 253 cfm head using the .26 super flow number. I doubt though that the .26 is correct, likely .28 or more on a stocker, I am guessing the head flow in the 230s. Can’t really compare stock and SS to other porting that does not have to meet port volume criteria for class rules.

X3 on using mph and not et

"... the 120 mph was from when I watched the car go down the track, 120 to 121 was what I watched..."

Yeah, with the NHRA hp police being on duty, at most big races, most of the quick cars sand bag, so their combo won't get a horsepower hit.

A quick search turned up a D/SA speed of 124.06 mph, for Randi Lyn, @ Indy, in August. She was more than a sec under, but had to settle for D/SA class RU. The D/SA winner was more than 1.2 under, which would have earned a hit from NHRA, this year. The US Nats race has been exempt in recent years, but not this year.

https://www.dragracecentral.com/DRCS...r2019#indextop

Look how even the quick cars were very careful to NOT go 1.2 under, this year.

https://www.dragracecentral.com/DRCS...r2021#indextop

At most races, a time of 1.20 or more under the index will get the combo an automatic hp hit.

I've read that some just add a bunch of weight. Some short shift. Some let off early. Some detune. Some use some combination of 2 or more of these methods.

So, Randi Lyn will not be running near as quick as the car is capable of, at MOST races.

Same goes for all the Stock/SS cars that can run 1.20 or more under.

It is hard to say what HP the car is showing because there are a number of things about the car we don't know. Based on my assuming somethings I get this using less than 500 HP. Shifting at 6800 RPM and 7997 RPM @ 1320 feet.

60 Foot ET = 1.2845
330 Foot ET = 4.0715
1/8 Mile ET = 6.5046
1/8 Mile MPH = 101.1140
1000 Foot ET = 8.6110
1/4 Mile ET = 10.4082
1/4 Mile MPH = 125.3550

Stan

I picked up a pair of Butler ported 670 from a forum member here and took them in for new bronze guides and a valve job. The intake port shape is the same on my heads and looks a little square.

The machine shop indicated they flow a lot better than the 250cfm that I thought and called them a race head. Combustion chamber has been modified to an open back-woods modern version as well. The cc was 172 on the intake ports.

The 670 heads are pretty popular with guys so while they are just a normal D-port they can be a good head once modified. Something about the later cast heads have the larger combustion chambers that intrudes into the port turn.

Ellison
 

"...Ellison said they were nothing special."

He should have known. For any here who don't know, Ellison did engine work for lots of Pontiac Stock/SS racers back in the day.

The 1st time I saw an Ellison decal on a Pontiac was on Truman Fields '68 Bird, after it won Stock @ Indy '73.

I recently saw both the Ellison & Fields names on an Angeles & McCarthy SS/IA '68 Bird. There was also an Ellison decal on the gold 2nd gen SS Bird which I think belonged to Bob Michael. It had Golden United Life on the side. IIRC, he said either his brother or brother-n-law sold that insurance.

When Truman got the '72 GTO SS sponsored deal, that car also had Ellison decals. That car was also a record holder. I assume that he used Ellison for all his Pontiac machine work, at least when he lived in that area.

The couple that I talked to were running 670 head combo's in later model pontiacs so different class but same idea. Have to look at other classes to find them. That type of class where a classic engine is run in a 3rd gen Firebird for example, they could run any model year engine/cylinder head package they want but choose the 670's, which I thought was interesting.

I'm familiar with Ellison, they were a big name decades ago around the Cinci area. They mainly seemed to build Chevrolets from what I remember and some good running Chevy engines came out of there back in the day. But like any shop they dabbled in everything. Saw a lot of their stuff running at Edgewater back then.

OK, that makes all the difference. That's why I wasn't aware of their cars. Those are "GT" Super Stock class cars.

Those engines go by Super Stock rules. More head mods allowed, plus unlimited roller cams & aftermarket intakes. IIRC, a GT racer posted that the ports in SS heads can be reshaped.

So, I won't even consider SS heads in this discussion.

BUT, I'd really like to know what cars those engines are in. I try to post info about all Pontiac powered SS cars that are entered in big races. BUT, for the GT cars, most lists do not post what engine is in each car. I've discovered several Pontiac powered GT cars, which I'd missed.

Pete McCartney used to like the 670s. He had a 67 goat SSer and a green early bird. Don't know what happened to those cars.

We sent them home one year at Butlers bracket race, with our junkyard 670 400...

It still begs the question.....with the rules more laxy dazy, why are they still choosing 670 heads with all the other options that are out there available to them?

That's why I brought it into the discussion.

I only know of 1 SS '67 GTO & 1 SS '67 Bird that have been active in the last 20 years or so. The Bird is green. I suppose it's possible that one or both those cars were the Pete McCarthy cars.

Joel Larkin has been running the Bird. The driver of the GTO was Jay Cason. He's #49 on this list.

https://www.dragracecentral.com/DRCS...r1998#indextop

I have pics of '67 SS Birds from the early years, sponsored by Stan Long Pontiac, Gay Pontiac, & Myrtle Motors. They're what I call "small tire Super Stockers". The Stan Long Bird was a nat record holder.

I figure that one reason why the '68 Birds have been so much more popular for class racing is because of the larger head choice. NHRA allows the much more common #16 & #62 D-ports, as well as the RA2's.

That's a good question. Why don't you try to contact them, ask that question, & post their answer on this thread.

High compression 400 engines are not popular for SS racing. Mike McKinney did OK with one. But that's been a few years now. It seems that the lower compression engines have been much more competitive, in recent years. And that includes 350's, 400's & 455's. I suppose that's because the lower CR engines have softer NHRA hp factors. Seems that the 428 has become the most competitive Pontiac SS engine. 2 428 powered Cobalts have run in the 8's, & both are Indy class winners. But, I think they both have Eddy alum heads. So, I'm WAY off the subject of this thread.

While the stock head rules do not allow you to do very much. They do allow any valve job. Exactly what that means and how far that can be pushed I don't know. The question is which casting after a "creative valve job" flows the best?

GT / SS is a totally different animal. You can do all of the porting and filling on the ports you want. They only have to measure under the max port volume cc's listed.

Stan

That's exactly what I was talking about earlier, and gave an example of how Paul used different valves and valve angles to pick up 30 cfm on the 7F6 heads he did for an engine I built without touching the ports or bowls at all.

I did something similar with the 12 heads on my 400 for PS racing. No porting allowed, but that doesn't mean you can't change the valves and play with valve job angles. :)