[Mcronk]

I guess when it comes to race cars racers will do anything they can to gain an advantage if they think they can get away with it.

According to research I found the factory originally used plastic valence panels on 72-73 cars. However they were replaced with steel ones due to so many issues with the plastic ones being easily damaged. 73 bumpers had additional support structures and were heavier than earlier bumpers. Later in 74 the 5 mph federal impact standard was in effect and bumpers with their support structure got even heavier.

[unruhjonny]

iirc the 1973 bumpers passed the front end 5mph standard.
I believe that the rear bumperettes became standard to make the car pass the 5mph rear impact test too.

[ponyakr]

Originally Posted by Mcronk

I guess when it comes to race cars racers will do anything they can to gain an advantage if they think they can get away with it.

According to research I found the factory originally used plastic valence panels on 72-73 cars. However they were replaced with steel ones due to so many issues with the plastic ones being easily damaged. 73 bumpers had additional support structures and were heavier than earlier bumpers. Later in 74 the 5 mph federal impact standard was in effect and bumpers with their support structure got even heavier.

Seems I remember having an early 2nd gen which had a plastic piece in the rear between the taillights. Had others with a metal piece there. Didn't know any were made of plastic 'til I bought a car which had a piece busted out of the plastic tail panel. Ya'll will just have to excuse me. I have no idea of the exact correct name for that piece.

So, for you experts, exactly what year or years were those pieces metal & what years plastic ?

[unruhjonny]

those pot metal tail panel parts are early 1970-only.
They were used on some early cars, but not a regular production item.
The regular production piece was fiberglass - like the Formula hoods.

[ponyakr]

Here's the Bird that had a metal tail panel & a factory 12-bolt rear end. It also had a Formula hood on it. I reckin it had to be a '70 model.

I was gonna make a bracket car out of it. But, I found a '71 Esprit body that was in much better shape, requiring less work. I did eventually use the 12-bolt out of the Formy, in the Esprit.

[johnta1]

Do you have any info on the Formula? VIN or PHS etc?
The metal tail panel was very rare, from very early Bird.

Any other pics of it?

[ponyakr]

Originally Posted by johnta1

Do you have any info on the Formula? VIN or PHS etc?
The metal tail panel was very rare, from very early Bird.

Any other pics of it?

Nope. Sorry. That was back in the late '70's or more likely the early '80's.

Picked it up in Northeast Louisiana. Most likely had bought from the Monroe LA Pontiac dealer, since it was the biggest dealer in the area. But, @ 10 or more years of age, it could have come from most anywhere.

That's the only pic I have.

If I hadn't run across it, I'd probably never have known any metal panels ever existed.

Only other things I can remember about it was that the front fenders had the Formula400 emblems on 'em, and that some of the "fingers" in the rear of the FG hood were broken/missing.

https://www.classicindustries.com/pr...rts/fb056.html

Only bought 2 other Formulas. IIRC, 1 was a '72 & 1 was a '73. The one I think was a '72 was blue & had tilt steering. The only reason I remember that is because the guy I sold the car to had problems with the tilt, & brought it back to me to fix. I didn't have a clue how to fix it. I was NOT a very good mechanic. Could only do the very basic stuff. Mostly just bracket racing stuff.

[sdbob]

I have a 70 Esprit,350. That had the original tailight panel in fibreglas . Replaced it with nos,fibreglas if I remember. Car was originally orange!
Talking about weight reduction. The 73 F body core supports to fender straps are thicker than 74s. John Herslow told me they made them out of aluminum then somehow sprayed them with steel so magnet would stick, to lose front end weight. He also said the fastest he went with stocker was with 4.56 gears! I tried them just couldnt get tires at local strip to hook. Seems counter to what is known now.

[ponyakr]

"...He also said the fastest he went with stocker was with 4.56 gears! I tried them just couldnt get tires at local strip to hook.,,:

Sorry, but I don't understand that.

Assuming he ran slicks. So, are you saying that you couldn't get your car to hook, even with slicks, when running 4.56 gears ? Or, was it hard street tires that wouldn't hook ?

"...Seems counter to what is known now."

To what is that referring ? What is it that is "known now".

This reminded me. I have 3 of what I assume are early pics of the H&M T/A, when it was running G/SA, therefore obviously was not running an SD455, at the time. Also, didn't have SD-455 on the shaker. NHRA Nat Rec Holder was on the side, while still running G/SA.

In pics 4 & 5, it was running E/SA. Therefore, I ASSUME it was NOT an SD455 car from the factory, but was switched over to SD455 power later, by the Herslow & Morlock team. Did it also set the E/SA nat record ?

This sound reasonable to me, because John Clegg's original '73 SD455 Formy ran D/S @ Indy, & Ray Hunt's SD455 Formy ran D/SA @ Indy. Since the Formy would be a little lighter, it makes sense that the heavier T/A might run 1 class lower.

So, do you know all the details of the car's race history, assuming it WAS the same car. For all I know, the G/SA car & the E/SA car may not have been the same car. But, I assume there was only one car, which ran G/SA, with a D-port 455 for a while, then ran E/SA for a while, with an SD455, then was switched over to SS.

[Mcronk]

If I remember correctly the old HO performance book recommended gearing that would allow a rpm 10% over peak HP rpm going through traps.

There are so many variables comparing todays ETs and those 30 or 40 years ago. Better tire technology, suspension technology, etc. I have a complete set of the old HO newsletters. I do recall reading about a lot of the cars and they ran very steep gears back then. I think there were even a few class cars featured. Back in those days a lot of folks geared their Pontiacs like BB Chevys.

I would think heavier cars would require more gear multiplication (providing tire will hook and engine would stay together) for optimum ET. You also have to consider peak torque and HP of specific engine. The 400s could use more gear and survive. Larger displacement with longer stroke and large main journals would make peak torque and HP at lower RPM and did not survive well at higher rpm. Also tire height and for automatics convertor slippage will affect trap rpm. I never raced class cars but noticed they would spin their motors higher. I figured when every .01 mattered they would run on the extreme edge to gain an advantage.

[Stan Weiss]

Originally Posted by Mcronk

If I remember correctly the old HO performance book recommended gearing that would allow a rpm 10% over peak HP rpm going through traps.

There are so many variables comparing todays ETs and those 30 or 40 years ago. Better tire technology, suspension technology, etc. I have a complete set of the old HO newsletters. I do recall reading about a lot of the cars and they ran very steep gears back then. I think there were even a few class cars featured. Back in those days a lot of folks geared their Pontiacs like BB Chevys.

I would think heavier cars would require more gear multiplication (providing tire will hook and engine would stay together) for optimum ET. You also have to consider peak torque and HP of specific engine. The 400s could use more gear and survive. Larger displacement with longer stroke and large main journals would make peak torque and HP at lower RPM and did not survive well at higher rpm. Also tire height and for automatics convertor slippage will affect trap rpm. I never raced class cars but noticed they would spin their motors higher. I figured when every .01 mattered they would run on the extreme edge to gain an advantage.

Yes you would set the rear end gear ratio for the finish line RPM. Back in the day you did not have much choice in trans gear ratios. Today you have all kinds of choices. So you adjust you SLR (Starting Line Ratio) by which trans gear set you get.

Stan

[ponyakr]

I'll mention a couple of things that MIGHT affect the rear gear used.

Back then, aftermarket rods were NOT allowed.

Therefore, all non-SD 455's had to run cast factory rods, in order to be legal.

BUT, as we all know, the SD455 had nice forged rods & pistons. Therefore, the SD455 could live @ a higher rpm than a D-port 455.

Also, the SD455 came with 744 spec cam lobes, which was the biggest cam that came in any Pontiac 455. Therefore, a Lunati "cheater" cam from that time period would have allowed the SD455 to make power @ a higher RPM than the smaller D-port cam would have.

Then too, the superior flow rate of the SD455 heads would allow more top end power.

Also, a legal '73 T/A was NOT light. Would have weighed around 3800lbs, or more, depending on driver weight.

http://www.classracerinfo.com/Engine...px?ENGINE=2080

So, these factors should have allowed an SD455 car to run more gear than a D-port 455 car, or a lighter car. 4.56 sounds about right, to me. That's my opinion & I'm stickin to it !

So, does anybody know exactly which Stock records the H&M car set, when, & the exact ET of each record ? Class wins ? Stock event wins ?

Here's an E/SA record of 11.89, set in '75.

https://www.classracer.com/classforu...8&postcount=10

But, the car already had lettering on the side saying it was a rec holder, when it was still running G/SA. Don't know when that rec was set, or how quick it was.

[Mcronk]

I am not much help when it comes to class cars. I started bracket racing in the 80s but always was impressed with performance of stock class cars. Had thoughts of going in that direction but class racing is not a part time effort and requires a big investment for the ET achieved. Easier to go faster in brackets but I tipped my hat to those who ran fast in stock.

The only achilles heel I could see with 455 SD was the 3.25" main journal. Lots of surface area to create friction. A lot of the 455s I saw break were either rods (non SD) or spun main bearings. Superior oiling mods can help but those cranks are heavy.

When I get some time I will dig through my old HO newsletters and gather info on any class cars they featured. These are mostly from the 70s.

[sdbob]

My local track was slippy. I tried initially 10" wide Goodyears with 4.56s,a friend had them on his 69 F RAIV. Then I bought 9x 30 Goodyears. Went 12 teens. Car had stk Pontiac parts. Cam was stk lift.Needed to be debugged. Then tried 4.10s. Broke rear then got busy and car sat for yrs. Initially NHRA had the SD in G/SA. Made for lots of crying from competitors.

[ponyakr]

"...I will dig through my old HO newsletters and gather info on any class cars they featured..."

That's great ! Please do post it here. May have the answers to some questions I've had.

I got those for a few years. Don't know why, but it seems that the only ones I have left are the extras I ordered of the Aug '75 issue that featured the '68 E/SA Bird my girlfriend drove.

But I do remember that several Stock & SS cars were either featured or at least mentioned, in most every issue.

[ponyakr]

"...Initially NHRA had the SD in G/SA..."

Are you absolutely sure of this ?

The reason I ask is because the later pics of the H&M SD455 T/A show it running E/SA.

AND, John Clegg's '73 SD455 Formy ran D/S, @ Indy '73.

So, are you saying that for the 1st few months of '73, an SD455 T/A would have run G/SA ?

That's moving up 2 whole classes, in just a few months, of the same season. NHRA don't usually make changes that big, that quick.

So, does that mean that maybe they used the factory NET rating of 290hp, at the beginning of the season, then gave it an NHRA hp "factor" rating before Indy of '73 ?

Very interested in knowing the exact time line of any & all hp rating changes that year, for the SD455.

[Stan Weiss]

You can get the Nov 1977 news letter from the Mission Garage Web Site

http:missiongarage.com/photogalleries/high_output_news77/the-high-output-nov-1977.pdf

Stan

[sdbob]

The 74 SD of Fred Davisson ran at Pomona in G/SA. Lost to Beneseks(spl) Buick.Not sure of shipping weight of 74. I was at Fred's house when/after he got his. I ckd my local NHRA track ,in spring of 74 in their book yes it was G/SA,for a 74 TA. I checked the tracks G/SA record in 74. My new SD nothing touched went 14.18-20 with lots of wheel spin.The record was slower than that I remember!

[Stan Weiss]

Originally Posted by Paul Ceasrine

Egbert,

For 1972 NHRA Stock Class, it was for 1963 and newer cars.

1962 and later cars were 'out'. 'It was a '10-Year Rule'.

At the 1972 NHRA Winternationals @ Pomona, California only
22 Cars entered the field of '32 Classes'.

Nearly everyone was out of California or the Northwest Division.

The 'dominant' cars were the 1972 Buick GS 455/270 HP 'Stage 1' which was re-factored to '315 HP' and classed in;
'C/SA' = {11.00 to 11.99 Wt/Hp}.

There were 'no' Stock Eliminator Championships at the 1972
* Gatornationals
* Springnationals
* Summernationals
* Grandnationals.

Because of extremely low 'Street Stock' participation.

Looks like NHRA did not have it together for the Winter Nationals. And HP came quickly thereafter.

Stan

[ponyakr]

In '73, the weight break for the Stock G classes was 11.00 to 11.49 lbs/hp.

According the the current info on the Class Racer Info site, the NHRA listed weight for a '73 SD455 T/A is 3633lbs.

So, ya'll can break out your calculator & figure out the NHRA hp factor range that would be required for a '73 SD455 T/A to run in G/SA, during the '73 season.

D = 9.50-9.99

John Clegg's SD455 Formy definitely ran D/S @ Indy that year.

E = 10.00-10.49

F = 10.50-10.99

G = 11.00-11.49

I'm guessing that NHRA increased the hp factor before Indy. But, I have no proof of that.

Here's a "copy & paste" from the Class Racer Info site.

"...Herlsow & Merlock from Scotch Plains, New Jersey

1973 Pontiac Firebrd Trans Am SD-455 {455/310 HP} re-factored to 345 HP.

1975 = E/SA..."

Don't know WHEN it went to 345hp. Maybe not until the '75 season ?

Don't know how low it started, nor when, nor how many times it changed between the initial factor & the 345hp factor.