[Jack Ferris]

Good reading all the way around. I have ridden in all these cars, but I was only 6-7 at the time. My father used to drive them every day as company cars when he worked for Pontiac. I do recall in past conversations how customers complained about the RAIV and drive ability. Especially the automatic cars. Let's face it, they were not targeted at ma and pa to take on a Sunday drive. Neither were the LS6 Chevelle's and the hemi Cuda's. But many ended up doing just that. I would agree the mild mannered HO cars likely did run better and surely were more user friendly.

[Formulajones]

Originally Posted by 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,

Speaking in terms of drag racing since that's what these cars were intended for, the 68 ram air II's are the best total package out of all the pontiacs out there.

67-68 birds are the lightest of the bunch so that's a huge advantage. Again look no further than the pure stock drags and you'll see a handfull of 68 round port birds running. Jim Mino was the first to bring this to light in the 80's when he was cleaning house at the muscle car drags against all comers. When Pure Stock was born a short time later these little birds quickly became the car to beat. It's HP to weight ratio is very good.

They are consistently the quickest pontiacs at the Pure Stock drags hands down and easily run with any of the big dogs that have a 50+ cubic inch advantage.

[Formulajones]

Most any real gear head or old timer like myself compares a cars performance on the dragstrip, the oldest measuring stick. Lets face it, that's what started this whole muscle car craze.

When you guys start talking about all around street cars and driveability that really changes the ball game, especially when there are no rules and guys are sticking any camshaft or cylinder head on a car, stroking, etc....the whole mess becomes impossible to compare, we aren't talking about "stock" packages anymore. You can throw money and parts at any car and make it perform exactly how you want. There are no rules on the street.

When thinking in that sense, of course any car can be made to be a pleasure to drive. Anything with an 068 cam is going to be very docile and easy to drive back and forth to the grocery store or take a vacation with the family. The HO cars were a great example of that yet still had respectable performance thanks to cubic inches. They are a pretty nice overall package for a street car.

[PureSD]

My recently purchased '71 Formula 455HO M22 will be delivered to me in just a few days. I'm excited to compare against my SD but will have to wait till spring time. The SD is a TH400 so it will be a different experience and feel. I'm extremely excited about the '71 455HO especially after reading 70RAIII's post.
The '71455HO was rated at 335hp and the '72 455HO at 300hp. What was the difference between the two? Just Pollution adds?

[Formulajones]

Are these cars stock for comparisons sake?

Driveability is going to be nearly identical between the HO and SD, those cars are a toss up.

Again, look at the pure stock drags, there are a couple of very good running SD's and HO's currently running,,,both examples run nearly identical times and there are more than 1 of each to compare. I believe they have all dipped into the high 12's at about 110 mph now.

Very respectable running cars that are restricted to their stock camshaft, with the only major change being a 1.5 allowable bump in compression over "advertised", which these engines desperately needed. Even with that bump it can still be a pump gas car because you only wind up at about 9.9 - 10:1 final. With that being the only major change from OEM I'd say they run pretty damn good.

[necdb3]

71 and 72 HO's are near identical. The only difference was in how the horsepower and torque were rated. Gross (71) and net (72). No pollution controls on either except TCS.

[transam1972]

perhaps someone knows the important differences between the years...aren't the heads slightly different?....I believe 71 has a 800cfm carb. and 72 is 750cfm...any slight intake changes?....seems to me 71 had extra black hose plumbing...I do not know what that is,just emissions?

[1971WARBIRD]

Originally Posted by transam1972

perhaps someone knows the important differences between the years...aren't the heads slightly different?....I believe 71 has a 800cfm carb. and 72 is 750cfm...any slight intake changes?....seems to me 71 had extra black hose plumbing...I do not know what that is,just emissions?

there were a few changes, but more technecal then i am good at.
the 71 head has a better high lift flow potenial because of some small changes in the port shape. i have had it explained to me, just can't explain it myself.
1972 had a small change to the intake floor that has been documented to decrease flow slightly, all FACTORY over the counter replacements have this change if produced after 1971, no matter what part number.

[starlightblack]

http://www.mecum.com/auctions/lot_de...gn=FL0114-F232

[bird72]

71 intake has better flow I believe. 72 heads have funny port notch cut outs. I can attest RAIV cams work very well in a 455, but harder cold starts, lumpy idle charecteristics, and as said with auto, shift kit and higher stall converter. I think a built HO or SD trumps a 400CI usually, but stock I would bet on RAIV with both in tune. How car is set up is big as power curves, RPM ranges, gear ratio, tranny are the deal breakers. As great as HO and SD's are, both are handicapped by less than ideal factory cams in relationship to the rest of the engine potential.

[Jack Peters]

'71 had a net of 310 vs 300 in '72.
Used to run against a '72 TA with the T-37. I would line up with my front wheel at his back and would pull him in 1st and 2nd gear where my back was at his front. His 3.42's vs my 3.55's. He was probably heavier. He was running F60x15's and I was running G60X15's. We probably did that 15-20 times with different drivers. Both 4 speeds.

We couldn't go any further as there were buildings at the end of that. We were on a private ramp at an airport so it was a bit limited as to what we could do.

[1971WARBIRD]

another thing to think about, do you want any add ons?
with the 455's you could get A/C where you couldn't with the RA IV.
in 1970 they did a track test bettween a RA III 4speed stripped GTO and loaded RA 455 auto GTO. they were so happy at the end to say the RA III out ran 455, then they got into details;400 stripped, 4 speed, 3.90 gears-455 loaded as i remember about 300 or more pounds heavier, auto, 3.31 gears. the 400 did out run it a couple times, but the 455 won several as the 4speed had to leave the line perfectly to hook up, the 455, just put it in gear and drive away. when it did out run it, it was only by a few tenths, and as i remember, each hundred pounds is a tenth?????

having said all this, i would love either, and either is a great car with most things depending on tune and driver that day.

['ol Pinion head]

There were slight differences in the 197's & 7F6's, the most obvious being the relocation of a water sending unit hole in side of the '72 head & the revised heat crossover passage. Chambers are the same, valves are the same, slightly more restrictive exhaust port on the '72 model 7F6's. Not all 7F6's had the notches in the intake side divider.

The 71 HO carbs were flowed at 832 cfm by a carb builder/racer in Alabama about 20 years ago. The '72 HO carbs were all 750 cfm. the difference didn't seem to mean much performance wise, as most have reworked both carbs for optimum performance with their combinations. For an engine combination that in bone stock condition was over by 5200 rpm , the larger cfm '71 HO carb reasoning has always bewildered me. Back to 750 cfm for '72 had to do somehow with emissions. In a race built RAIV, can see the need for larger carb...higher rpm range & higher volumetric efficiency will create a need for a bigger carb.

[Brad Pringle]

I can tell you from driving both SD and HO car they are very driver friendly cars. I have never been in a RA4 but since I own a 67 400 firebird and grand prix convertible that I cant buy gas for it sits most of the time. They are fun to drive but can pull into gas station and buy gas. From the fun and driveablity standpoint HO /SD are the way to go. If anyone wants to take me for a ride in their ram air IV I am up for it. thanks

[Jack Peters]

Oh, yeah, I forgot to make sure you all know, mine had the 066 not the 068 cam from the factory. A mistake. Still got it.

['ol Pinion head]

Originally Posted by 1971WARBIRD

another thing to think about, do you want any add ons?
with the 455's you could get A/C where you couldn't with the RA IV.
in 1970 they did a track test bettween a RA III 4speed stripped GTO and loaded RA 455 auto GTO. they were so happy at the end to say the RA III out ran 455, then they got into details;400 stripped, 4 speed, 3.90 gears-455 loaded as i remember about 300 or more pounds heavier, auto, 3.31 gears. the 400 did out run it a couple times, but the 455 won several as the 4speed had to leave the line perfectly to hook up, the 455, just put it in gear and drive away. when it did out run it, it was only by a few tenths, and as i remember, each hundred pounds is a tenth?????

having said all this, i would love either, and either is a great car with most things depending on tune and driver that day.

Whole heartedly agree with your last paragraph Warbird! STAY SAFE & GOD bless you!!!
Interesting you mentioned the '70 performance Pontiac A-bodys. I've read only one period roadtest of a '70 455 4 speed GTO, & the 1/4 times were in the 14.5-14.4 range with 3.55 gearing. John Sawruk noted in print the quickest '70 Performance model Pontiac that Pontiac Engineering tested as new was a silver 2 door post T-37 (or Tempest) with a WT 400 & a 4 speed. Several hundred lbs lighter & had the A-bodys freer flowing dual exhaust. Am sure that is disconcerting to several '70 RAIV owners, but so be it. we can all agree a lot of hp/torque was bottled up in the stock exhaust system. Unlike others am not leaping forward to Pure Stock competition..apples & oranges!

In '71 the 233 series A-bodys were also Pontiac's quickest. Torque being applied in a lightweight A-body chassis again ruled. No magazine roadtests on the 455 HO equipped 233's, but original owners heading to the track shortly after they took delivery gave bone stock times in the 14.1-13.7 1/4 mile range. In speaking to the original owner of the Engr Coupe, Mike recalled a 14.01 @ 99. That's in most likely the heaviest T-37 HO post car built. Assembled with 3.31 posi & a M22 & heavy factory A/C, P/S, AM-FM stereo, & heavy 14x7 honeycombs, all added over 175 lbs, def not a lightweight. Jack Peters has noted similar original times on his original '71 T-37 Post, & has noted his engine was misbuilt with the smaller "P" cam! definitely leaving a few 10th's on the table. My HO GT-37 was built less than a week before Jack's & with P/S being the only power robbing option ran a best of a 13.62 on original G70x14's through the exhaust in summer of '71. No sea level track, no headers, no convertor swap, no lower gears & cam swap, all that came later.

Back to '71 HO F-body's... have ran across several stripper manual strg '71 HO Formula's that were ordered with M22's for NHRA & AHRA drag racing. Def the best F-body platform to go quick in '71. None of these so ordered '71 HO Formulas were ordered with pwr disc brakes, P/S, or RA aircleaners, the RA aircleaners were heavy & owners figured that in. Instead, two of the such HO Formulas I've ran across ran just a deep drop 14" aircleaner base snugged down with carb return springs to the intake, this allowed smooth airflow into the Q-jet at the strip.

Pure SD's recent stripper M22 HO Formula is a rare discovery with its original drive train. Know I stirred up the previous owner with my comments last summer about the "dealer added" P/S, but he was clueless to the application. . Needless to say the previous owner before him adding P/S & a Formula wheel & keeping the car on the street factored a lot in it having its born with numbers match M22 HO Formula today. Congrats PureSD on bringing it east.

[2manyT/A'S]

We also need to remember that the 70-73 Trans ams were a "road race" chassis/body with a "drag race" drivetrain.... that 160 speedo was fairly optimistic with 3:42 or 3:73 gears in the back...

Those cars just begged for a 5 speed (with appropriate rear gears) right from the get go...

[70RAlll]

Originally Posted by 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.

Yes I left the 72 HO out because , and a big disclosure here:

I am only quoting what I have heard from others, I have zero experience with the 72 HO engine. I know there is a large ,well....quite adept at starting threads, contingent of 72 Firebird owners on this board. I have no malicious intent leaving the 72's out, just stated my opinion/experience with these cars..

But have heard the 72 round port heads didn't flow as well as the RAIVs' 614's or HOs'197's did and that 72 was really the beginning of the smog/pollution restriction era on 2nd gens Firebirds.Didn't 72's have a EGR valve or something similar??If I am wrong, then I am wrong. Don't claim to know much about 72's past what they look like, so don't slam me for not knowing.. SD has to be included in round port comparisons due to the wonderful over engineering Pontiac performed as their last gasp of muscular car/performance air. If you really look at it, 71 was the last year for just a standard engine,no pollution controls etc, and Pontiac finally got it dead on with the massive torque from the 455...And if my original post didn't infer..then here is my opinion...I think 71 was Pontiacs hi water mark with Trans Am performance,styling and just simple affordable American muscle.. and would say this even if I did not own one. Personally would take a perfect 71 HO over a RAIV or SD for a fun driver.

[70RAlll]

Oh. and good thread to who started this. When I read the first post I just knew we would all end up arguing over this.. Quite good information here.. Been a while since I've seen so many different contributors to a thread ,all with valid, fact based information.. good thread..

[70RAlll]

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??,

CompCams has a roller cam ,something like 226/230, which is a step above the stock 68 cam that runs quite well in a 455. The roller cam is a drop in component but you will have to buy their roller lifters.Advantages are quicker ramps on opening and closing and seems to run better., I ,for one, have no problems massaging the internals with upgraded technology like roller cams.. If your engine is stock, this alone will help tremendously. you will have to tune the carb to any cam change, and personally if mine with the engine apart at the very least I would install new rings on the pistons just to "seal" it up real good.. would even check and see how much additional compression you could get from shaving the heads. been years since I built one of these and lost the memory of the math on this.. sure others here can chime in with the right answers..