[Formulajones]

I agree with Ferris.

I'd definately want some converter behind it if you run an auto.

[Jack Ferris]

Originally Posted by Formulajones

That's what is sweet about the pure stock drags, the rules apply accross the board so any gain or advantage you find in the rules is the same for the next guy.

Help me out understanding the rules in "Pure Stock". As far as the engine goes I get that. What about the rest of the car? What about the high dollar automatic transmissions that NHRA Stock and Super Stock use? or the high dollar slider clutches? Are they allowed in pure stock? What about gear ratios in the diff? These cars are purpose built for the class right? Along with suspension mods, weight relocation and whatever makes these cars about as far from "stock' as one could get. So, is this class basically based on a factory engine, but any other chassis/drivetrain mod is allowed?Im not trying to be a wise guy. Just want to know more about the class.

[Formulabruce]

Originally Posted by Formulajones

I wouldn't say the HO is more refined, it's just a victim of strict emissions and lower octane unleaded fuel that was making the scene at the time.

The heads and intake were the major pieces from ram air IV development that were carried over to the 455 with minor changes (to keep the description brief). If the engine would have had the camshaft and compression ratio to go with it you would have had a very potent package. As is, it's still a nice performing engine that will run on the cat pee gas we have nowadays. So under those circumstances, in some peoples eyes it does make it appear to be a more attractive package.

Basically a 1970 455 HO ( GT platform only) 10 :1 CR

[Formulabruce]

Originally Posted by Jack Ferris

Help me out understanding the rules in "Pure Stock". As far as the engine goes I get that. What about the rest of the car? What about the high dollar automatic transmissions that NHRA Stock and Super Stock use? or the high dollar slider clutches? Are they allowed in pure stock? What about gear ratios in the diff? These cars are purpose built for the class right? Along with suspension mods, weight relocation and whatever makes these cars about as far from "stock' as one could get. So, is this class basically based on a factory engine, but any other chassis/drivetrain mod is allowed?Im not trying to be a wise guy. Just want to know more about the class.

Great post, you are 100% correct. Even "factory" engines are not so factory.
"supposed to be stock suspension..."
I watched a stock 71 Cuda AAR with disc brakes , get brakes gone, all impact bars, GONE, and lots of lightening, when done, you couldnt tell... same treatment went into a "ZL-1" Camaro
So its back to "stock appearing" in my book
Also a Trans Am was never meant to drag race....makes me sick seeing them on the drag strip, and looks dumb too

[2manyT/A'S]

Originally Posted by transam1972

my engine is 100% stock...I hope to never have it rebuilt or modified...however, can a RAIV cam go in a H.O.?..what happens?..obviously I am sure there are other things to fine tune...interesting idea to upgrade a H.O. to RAIV standards,if only this was 1972...time span and gas what it is doesn't make it feasible I suppose...I am on the lookout on this forum for modified H.O.s...any ones thoughts on limited mods to the TH400?...such as a shift kit?, does it need it?...I wouldn't(I don't think?!)but a nice looking Dual Gate would be cool!...I have never been able to enjoy my H.O.perhaps 500 miles in my life??,

I run a 744 grind in one of my 71's....that one is in between the 068 & 041 and works real well ...IMHO......car is stock,stick,tuned with a Flowmaster exhaust...

I believe Pontiac HAD a high compression round port 455 in the master plan for 1971,but the EPA put a stop to that.

[Formulajones]

Originally Posted by Jack Ferris

Help me out understanding the rules in "Pure Stock". As far as the engine goes I get that. What about the rest of the car? What about the high dollar automatic transmissions that NHRA Stock and Super Stock use? or the high dollar slider clutches? Are they allowed in pure stock? What about gear ratios in the diff? These cars are purpose built for the class right? Along with suspension mods, weight relocation and whatever makes these cars about as far from "stock' as one could get. So, is this class basically based on a factory engine, but any other chassis/drivetrain mod is allowed?Im not trying to be a wise guy. Just want to know more about the class.

Originally Posted by Formulabruce

Great post, you are 100% correct. Even "factory" engines are not so factory.
"supposed to be stock suspension..."
I watched a stock 71 Cuda AAR with disc brakes , get brakes gone, all impact bars, GONE, and lots of lightening, when done, you couldnt tell... same treatment went into a "ZL-1" Camaro
So its back to "stock appearing" in my book
Also a Trans Am was never meant to drag race....makes me sick seeing them on the drag strip, and looks dumb too

The rules haven't changed since I've done it. We are talking pure stock here....

As far as the engines go,,,they are as stock as one could expect after 50 years. The rules allow 1 mojor change and that's compression ratio. That's for obvious reasons. After 40-50 years of use these engines have been rebuilt 2 and sometimes 3 times or more. They need bored, decked, milled, etc... All of which will increase the compression ratio, you just can't help that. So the rules implement a .070 overbore maximum and a 1.5 compression bump over the "advertised" compression. Since rules dictate all casting numbers must match the HP and model claimed, you can't use aftermarket blocks.
Heads are as cast, no port work allowed of "ANY" kind, same goes for intake and exhaust manifolds. All have to be factory correct for the HP and model claimed. They aren't worried about date codes.
Carb is also the same way, and chokes must be present and functional. Cam and valvetrain also have to be stock per HP and model claimed. They only allow 130 lbs. seat pressure on the springs which is stockish, this keeps people from spinning these engines higher than a stock engine would normally go and making more power.

So for all intensive purposes these engines are as stock as one can be, and believe me this stuff is checked, they will perform complete tear downs for certification, they check bores and strokes, camshafts etc.. to make sure everything is on the up and up for your model and HP claimed..So everyone is on an even playing field.

As far as suspensions, no trick springs or fancy shocks allowed, sway bars must be attached and functional. No traction bars allowed etc....
A couple things they will allow are "no hop" bars on coil spring cars, and they allow clamping the leaf springs on a leaf spring car,,,,,that's it.
Now you can tweak things like pinion angle. Another trick that I employed was to shim the front sway bar frame bushings so they didn't "crush" the bar. This allows the front end to move more freely. Most guys now just hone out the bushings so there is no "crush". Technically legal because the bar is still hooked up and functional. Some will go as far as to employ a similar tactic to the control arm bushings.
Another simple trick I did on the front suspension (and it's not really a trick) is that I ran, and still run, oil filled shocks on front because they move more freely than a gas filled shock. These simple mods are all in an attempt to hook those little bias ply tires.
These simple and basic tricks got me 1.8 60 foot times on stock rubber. Others have gone even quicker nowadays.
There are no trick transmissions allowed, no lightweight parts allowed in the engine or transmission. They do allow rearend gear changes of your choice since most cars came optional with just about anything anyway.
No fuel system upgrades of any kind, it must all be stock.

As far as lightening goes, it's not allowed at all in pure stock. One of the reasons why people will choose an advantageous platform for racing this class to begin with. You may see things like heater and radio delete, just like cars were back in the day, but you won't see door bars cut or lightweight suspension pieces. Low option, small package cars that are already lightweight are the best ones to start with.

Formulabruce seeing brakes gone (or more likely lightweight brake package), door bars gone, was most likely a F.A.S.T. series car. Completely different. They appear stock and parked right next to a pure stock class racer you wouldn't be able to tell them apart, but the rules are different in F.A.S.T.
Engine rules just as above but they allow stroker cranks (has to be stock block though) They allow all the porting you want, but again has to be stock cast parts. They also lighten as much as they want, making most pieces and brackets out of aluminum (once painted you can't tell) and swiss cheesing anything out of sight. Radios and gauges may appear intact and functional but on the back side all guts are removed, it's out of sight.
Overall the F.A.S.T. cars must appear as the day they rolled off the assembly line, but anything out of sight is fair game. There are literally dozens of tricks in the F.A.S.T. class that would take a book to list here, but I've typed enough.

[Jack Ferris]

This answers my questions. But, how do the rule makers police the trick transmissions? Im assuming winner gets the routine teardown on the motor? But do they do the trans as well? Do they get technical like NHRA does by measuring port volumes ect? Do they allow protest and all that if somebody feels another racer is "cheating"?

[Formulajones]

Originally Posted by Jack Ferris

This answers my questions. But, how do the rule makers police the trick transmissions? Im assuming winner gets the routine teardown on the motor? But do they do the trans as well? Do they get technical like NHRA does by measuring port volumes ect? Do they allow protest and all that if somebody feels another racer is "cheating"?

Yes to all those, but the winner doesn't necessarily get a "routine" tear down afterwards. There were some protests that went on and tear downs were a result. I don't know if the protesting still goes on but I would say it probably does. If you suspect someone of cheating tear downs can be done. If they find anything out of the rules you are disqualified until it is corrected. Yes they get technical just like the NHRA and they employ the tricks used to measure bore, stroke, compresson etc...

You can even volunteer your car before hand and have all this done before a race, which then your car becomes certified.

There are a handfull of very quick pure stockers that have exploited what was already an advantageous package.
A couple of L88 Corvettes which are an excellent package for many reasons and I believe they still reign top. The 68 ram air II Firebirds are very quick, great engine, well designed exhaust manifolds and lightweight car, good package and probably the best there is as far as pontiacs go in the pure stock class. There are also a few pure stock Hemis and 6 pack cars that are very tough.

[Jack Ferris]

So you can only race a car that the factory installed the engine in yes? So a Yenko Camaro with a 427 for example would not work because it was a dealer installed motor. Is that correct?

[Formulajones]

Originally Posted by Jack Ferris

So you can only race a car that the factory installed the engine in yes? So a Yenko Camaro with a 427 for example would not work because it was a dealer installed motor. Is that correct?

Yenko's and COPO's are allowed to participate, even the COPO ZL1 versions are allowed because they all started life as production order cars from the central office, the only difference with the Yenko is that Don spruced it up with a decal package. But they were all available and sold to the general public and came with a warranty.

The only cars that aren't invited are the cars built specifically for racing that generally didn't come with any type of warranty, cars like the Hemi Darts, Swiss Cheese Pontiacs, any of the lightweight cars like the early Dodges and 409/427 Impala's. Simply because these were cars not available to the general public, you had to be an established racer at that time to get your hands on one. So they aren't really mass produced production cars, so to speak.

I think the rules specify any V8 rear wheel drive car with dual exhaust up through 1974 or there abouts, that came with a 4 barrel carb, is generally accepted as a performance oriented car and can compete.
That includes any car that you want to build as a clone, it doesn't have to be a real car, however the clone built must represent the HP and model claimed to be right down to the correct casting numbers, trans, rear, etc...
There are quite a few real cars that compete, I'd say probably 70% of what you see if I had to guess. There are clones mixed in, and most of those you'll see in the F.A.S.T. class.

[4birds]

In stock GM form, as if you just drove a 70 RAIV T/A off the dealers lot and pulled up next to a 71/72 455HO T/A that just left the dealer also, I think the RAIV would win a 1/4 mile street race by just 1 or 2 car lengths. It would be a close race. I have driven both cars in close to stock form. 2 different animals. They both have their advantages and disadvantages. I have also driven a 455HO T/A with stock 70 RAIV 614 castings and Crane blueprint RAIV cam. Now that was Fun! It would have kicked both cars asses. (It didn't take long before it blew the head gasket from the high compression) Like Jack said, there are soooo many variables. 2 absolutely IDENTICAL cars will run different quarter mile times. Just my opinion from real world past experiences.....

[transam1972]

since the RA IV and H.O. were the last true incarnations of the Pontiac block,how do they compare to previous versions?...in other words what are the best of the best Pontiac motors?...if only it could have evolved from the H.O. and the SD ....I can only imagine a version of those engines in all of the 1979 Trans Ams

[PureSD]

Originally Posted by transam1972

since the RA IV and H.O. were the last true incarnations of the Pontiac block,how do they compare to previous versions?...in other words what are the best of the best Pontiac motors?...if only it could have evolved from the H.O. and the SD ....I can only imagine a version of those engines in all of the 1979 Trans Ams

I'm sure will start a huge debate, but this is what's great about this site....healthy informative debates that is. My vote is the SD455. When considering all its unique aspects, reliability, performance on today's gas, and the capabilities of serious racing provisions(dry sump), it's the winner in my book!

[1971WARBIRD]

Originally Posted by transam1972

I am on the lookout on this forum for modified H.O.s...any ones thoughts on limited mods to the TH400?...such as a shift kit?, does it need it?...I wouldn't(I don't think?!)but a nice looking Dual Gate would be cool!...I have never been able to enjoy my H.O.perhaps 500 miles in my life??,

a good shift kit works nice. a friend of mine builds his own for us, but Trans Go are good kits.

you do realize you have a slap shifter in your TA if it is still stock. pull back into low, push up and to the right you have 2nd gear, let it center it's self, push up and to the left and you have drive. you would not believe how many guys I have met over the years that didn't know they had a ratchet shifter in their car.

when I built my first 71 HO, I did: +.030 TRW pistons, new valves, Hooker headers(back then couldn't find good manifolds), and a crane blazer cam, 218-230 duration, .450-.465 lift on a 114 centerline. this was just a little bigger than the factory 068 cam approx. 215-225/.410-.410. 3.31 posi, 4 speed, LR60x15 radial TA's, it was a fun ride.

[transam1972]

I would like to think are a few #1 Pontiac motors, and I may be wrong...what of the 1968 Ram Air II?...or perhaps it is because it was the first round port?...I would think RA IV is up there,

[70RAlll]

I would say the 71 HO was a better running motor, as delivered from a dealership, than the RAIV. 71 HO was the fastest running engine between 71-74 series of Firebirds 455 ci engines-including the SD's(sorry SD guys). The RAIV's cam was too much for a 400 ci engine. when tuned correctly it can run well, but it was a service nightmare back in the day(from what I have heard)- had difficulty with idling/running rich therefore. All of us who have/or have had Pontiac 400 ci engines must admit they are sort of a disappointment. They just do not have the torque numbers that the 455's do. And the IV had less low end torque that a regular 400, it's power was in the upper RPM's, but as we all know street racing red light to red light (which is a beauty of Pontiac engines) was all in low end torque.. The 71 HO was the best of the 2nd gen 455's, even better than the SD in my opinion. The HO did not have the mystique of the Super Duty, but it was the best of its breed of engines. The last Pontiac engine that was pretty much bare engine without any pollution controls/restrictions. Yes the SD had great internals, but the HO's were sufficient. The 71 HO's engine originally came with Pontiacs 068 camshaft. The RAIV's 400ci engine cam was a bit much for the car, but as a rule.. moving up 10-20% in ci's allows moving up a step or two in camshaft. The HO will benefit and run well with a RAIV's camshaft or similar( a couple steps above the 068 which was used in the RAlll's(400 ci engines) as well as the stock HO).

If I were building a new 455 HO, I would use a roller valve train ,including a roller camshaft, would not mess with porting the heads, just gasket match and clean up any burrs, run as much compression as available(9.75-10.00) considering current gasoline. And for straight-line racing/red light to red light driving, the TH400 cannot be beat with a Muncie. Personally I prefer the Muncie, but an automatic is idiot(me) proof and always allows for lower et's.
This RAIV vs the 1971 HO engine rivalry has been going on for years. Even knew and saw a survivor RAIV where the original owner was embarrassed his car only had a 400 under the hood after the 1971 engines were released. He put 455 callouts on the scoop and rattle can painted the engine 71 HO color to hide the fact he only had a 400 ci engine. Truth be told, as delivered the RAIV was not the best running engine. With custom tweeking, could run ok, but the 71 HO was a fine engine as delivered and if anything was a bit under cammed. I have often suspected lowering the compression(which is commonly accepted as Pontiacs concession for the EPA) was not the only concession GM gave the EPA, but the cam choice were in fact what Pontiac did to appease the Fed's. The HO engine could have easily been delivered quite street able with a RAIV or similar camshaft. As someone has already stated, no substitute for cubic inches , and the '71 455 HO was the least messed with per pollution/gas buring regulations of the 71-74 455's.

So long answer to your question, in my opinion the '71 HO is the best running and easiest to improve upon without drastically changing( up compression and up cam) of these two engines . The RAIV is hindered by being a 400 ci based block. The HO is too similar to the RAIV(intake design,head design etc) which makes me thing Pontiacs engineers understood better than I do that the larger ci's was the answer for their performance round port program. Yes the RAIV has the mystique for their low production numbers, but short of 5000+ RPM racing, the IV was not as streetable as the HO-not by a long shot..

disclaimer
this is just one guys opinion, I do not portent to be the tree of knowledge when it comes to Pontiacs, so I could be wrong. This is just y opinion. Oh, and I have no malicious intentions here and apologize if my post offends any members of this board- that is not my intention.

[transam1972]

well said 70RAIII,...that was not the answer I expected....since I own a 72 455 H.O. I have gained new respect for it....I do not think there will be a debate here

[roundportponchos]

I have a 71, luckily it was orig down to starter. Had nos RAIV cam, lifters, valves put in,, It's a runner,, unfort now in resto prison, awaiting it's pardon from it's 8 yr long sentence..

Originally Posted by transam1972

my engine is 100% stock...I hope to never have it rebuilt or modified...however, can a RAIV cam go in a H.O.?..what happens?..obviously I am sure there are other things to fine tune...interesting idea to upgrade a H.O. to RAIV standards,if only this was 1972...time span and gas what it is doesn't make it feasible I suppose...I am on the lookout on this forum for modified H.O.s...any ones thoughts on limited mods to the TH400?...such as a shift kit?, does it need it?...I wouldn't(I don't think?!)but a nice looking Dual Gate would be cool!...I have never been able to enjoy my H.O.perhaps 500 miles in my life??,

[Judge273]

Notice RAIII never mentioned the 72 455ho in that analysis. If I read it correctly and have to agree torque is fun in a car when it's all about driving.

[roundportponchos]

sorry to hear about your friend, wow 60, not very old. I'm only 15 yrs younger, makes you realize, life is short..

Originally Posted by rexs73gto

I'm not trying to highjack this site but please go to the post Loss of a friend & read them if you are a friend or know Bruce Zalai, he was a big SD fan & owner who we lost on wed. He had just turned 60 on dec. 2nd. Thank You for reading & rest in peace good friend.