[Steve C.]

With our magic wands just port (or buy) the cylinder-head of your choice so that it has enough airflow capable of supporting the rest of the combination and be adequate for the rpm you run in your combination, in all liklyhood more potential flow will not help performance. And for the few that want to run truck motor combinations that wheeeeez out at lower rpm's the small ports work out fine but for the many that want and expect performance at a higher rpm your going to have to step up the airflow.

[Larry Navarro]

That's not necessarly true Steve. We've seen those truck motors "wheeeez out" at lower RPM and overtake those higher RPM combinations, but that's another discussion in itself.

[Steve C.]

Larry, re-read what I said. Nothing false in my statemen that I know of.

And of coarse some lower rpm combinations can have the potential to out run some combinations that makes peak power at a higher rpm. It happens all the time.... as well as the opposite. Some like and use the lower rpm truck motor approach, sometimes just because its so often regurgitated at them, but many others like and enjoy a more spirted approach to speed. What ever personaly turns you on.

[Motor Daddy]

Plus the simple fact that when I want to pass someone, I DOWN SHIFT! Imagine that, increasing the RPM and gear to go faster. What a concept!

[gjn]

Originally Posted by Skip Fix

"As far as expensive, it's really not. His combo has been tuned through the years by trial and error" Yes very well tuned down to every detail, and awesome car in every aspect down to the paint and interior. The goal was to go fast with as many factory parts as possible in a low rpm "street" range and it does specatcularly.

I'll disagree on the expensive part-look at the total cost and TIME in swapping all the parts on a car or massaging them. Just paying yourself for the time much less the many parts, gaskets for making swaps is expensive. Track entry fees for test and tunes. I think at one time I heard there were well over 2500 passes on the car. Figure $20 a time entry at the track plus gas getting there. Yes the intake,heads may initially be cheaper but just add up freshening with good internal parts(valves,springs,guides), porting, etc, etc.

".

Steve, this combo is well documented. That takes all the guess work out of the combo if you were to copy it. I agree with your assessment of his overall expense; however, it would be relatively inexpensive for someone to copy his combo in comparison to building a high RPM motor.

[Steve C.]

gin- In the context here, in your opinion at what point is a combination "high" rpm ?

I believe Skip's easy to duplicate, and done at moderate cost, hyd flat tappet combination made its peak power at around 5700 rpm (or so).

( side note- "cost" factors should be eliminated from the conversation! )

[gjn]

Steve,

My experience is only with Pontiac low RPM motors. Prior to my cam change, I shifted at 5,200 rpms (now it looks to be 5,400). To be honest, I was looking to buy a 67 Nova SS or a 68 Firbird 10 years ago when I purchased the Firebird which I just happen to find first. I had no idea of the difference in between Chevy and Pontiac at the time. My initial rebuild of the 400 had to be one of the worst mismatched combos ever. I had 8 to 1 comp with a cam that required 9.5 to 1, stock converter, and 3.08s. It had so little torque, I could barely turn the radials over with out major power breaking. My cranking compression was 135 PSI. Fortunately, I was able to rebuild the motor in 2004. I had at that time found the Street Performance Pontiac site and modeled my motor after several of the featured cars. I didn't like the idea of Rhodes lifters (for what ever reason) and really wanted a 3.25 gear so I could cruise at 3k rpm at 70 mph with a 26" tire. By then, I had read/researched for hundreds of hours and figured out that the entire combination matching was the key to success. I ordered a stroker kit from Butler, had them port the #16 heads to flow 250 cfm at .5 and had them help select the cam (XE 274). I was able to get that combo down to 12.36 @ 111 with a 650 dp and 2.4k stall shifting at 5,200 RPMs over the course of a year (my first pass was 13.8 @ 101). I went to a continental converter 10" 3.2k stall and a ProSystems 800 CFM carb and ran a best 12.002 @ 112 the next year. For various reasons, I rebuilt the motor and decked the block and changed to a customer grind cam by Straightline Performance 236/250 .510/.510 112. Last weekend, I went out and ran a best 11.935 @ 113.33 on my second full pass with this combination. The only other change was the ET drag radials form ET streets. Right now my biggest issues are hooking and small tube headers 1 5/8" with a 2 1/2" exhaust with an h-pipe. I am going to unhook the exhaust at the collectors this weekend to see how much it is costing me.

I love the Pontiac engine/head design of high velocity ports/torque monster motors and am so thankful I found the Firebird before I found a 67 Nova. I run a low RPM 5,400 motor with a highway gear 3.25 that enables me to cruise at 70 mph at a comfortable 3k rpms, with a hydralic cam that is reliable and cheap, on pump gas, in a car that could be a daily driver (if I needed it to be) that runs 11.90's. I don't have to run a drag gear to get this kind of performance or wind the motor up to 7k rpms. Once I sort out the traction issues and can afford to pop for exhaust, I think I will be in the 11.70 range. A chevy guy came up to me after 11.935 my run and asked what gear I had, I told him it had a 3.25 in it and he just shook his head in disbelief and started laughing. They always say, man what would it run if it had a real gear in it?

Could I have run 11.90's with with the Nova. Most definitely; but, it would have been a screaming 406 with a lot more gear/cam or a big block with bigger ports that would require more cam and gear. It definitely would have been less drivable on the street. I have yet to see a Chevy that is set up as mild as mine or some of the noteworthy street strip guys that post here at KCIR. I am not saying they don't exist, I just haven't seen them.

For street strip it doesn't get any better than a Pontiac tractor motors in my opinion.

What do I consider high RPMs, north of 6,000....but you have to consider the source. I am not an all out racer.

[Larry Navarro]

I may be in the market for a set of K-heads just for weight savings. I want to run the '79 on a new road course that opened up down here and I think the weight savings and smaller ports would contribute to overall acceleration, braking and handling.

[slowbird]

You low RPM guys with your 455 dont know what you are missing. Buzzing a 400 to 6500rpm is so much more fun. I did the low RPM thing it just did have the thrill that the 400 does.

[uneasyrider]

What it really comes down to is physics and not debate. Flow rate (Q) is velocity (V) times the area (A) plus friction factors but Q=VA will work just fine for this discussion. The fact of the matter is there is a reason that they put dual runner intakes on engines and it isn't because they look good at least as far as the factory is concerned. If they could get the job done as well with a cheaper to manufacture single runner intake they would. Here's a neat little site I found that talks about some of this stuff:

http://www.eng.fsu.edu/~shih/eml4421/students'%20web%20pages/manifold%20tuning/intake.htm

There is a balance in a conventional intake manifold and carb set-up between the turbulance needed to keep good fuel delivery and the boundary layer formation. You get the walls of the runner too smooth and the fuel condenses on the wall, too rough or too small and the losses become too high to get the flow rate needed too large and the velocity is to low to properly suspend the fuel and fill the cylinder. Thus the multirunner intakes on a direct port injection system. No fuel delivery issues to deal with in the runners, the best of both worlds in velocity over the rpm range.

Great book to pick up used on Amazon or one of those: Cams, Valves and Exhaust Systems - Peterson 1968

[Skip Fix]

I don't remember any Pontiac motors actually being in trucks,maybe a wagon ambulance, now my 409s that I raced(so I'm probably the only one who raced a true truck motor) were Larry! And they shifted at 6000 before they "wheezed out"!!

All I'm saying is Jim's combination to run as fast as it does is like Cliff said, you don't just drop a motor in and go fast it takes alot of time to get just right, and that takes time and dollars. You aren't going to buy swap meet cast iron intake, 6X heads,Qjet and put then on a 455 shortblock with the same Wolverine cam drop it in any Pontiac and run 11s!! It takes a well put together short block, perfectly ported heads and intake. Many runs jetting and timing tests for that combination. Jim has shown us it can be done with as many factory parts as possible, so an example for those who want to do that to tyr and equal.

Larry that 10.99 is with the STREET pump gas motor with parts ANYONE can duplicate,no more expensive than Jim's motor, it has only 6 passes to get in the 10s,it's goal was 11.50s! New goal a street pump gas motor! "Race" motor is going in another chassis, so same 4 motors, more cars and even an extra motor for that 65 GTO once it ever gets done! What's that bigger motor you have run on pump gas? Different motors and chassis parts for different goals-one previous motor was built to autocross in a specific class, the next motor (400) was built to race a specific NMCA class and held a class record -so the different motors were all built with different goals. The 400 with a factory intake, Q jet and mufflers ran 12 teens @ 111mph @ 3850lbs with much less CI. And how many combinations has the 79 had? Factory motor,455 HO, now a 470 with small chamber heads? And ALL my cars still less $$ than that SD car of yours

GJN- I still disagree that "anyone" can copy Jim's combination cheaply and run as fast as he has. Even Cliff said it takes time to tune them, you don't just drop a big motor in and go fast. If you have seen the progression of Jim's wagon from the 12s to the 11's as he meticulously tweaked EVERY detail you would see few others will take the time to do that. Jim also has the same "expensive" bottom end that "high rpm" Pontiac motors use, 6.8 rods stroker crank.

I have seen way too many "copies" using a cast iron intake, ported D ports, Wolverine cam run in the 13s because they did not. How many folks running Q jets have epoxy smoothed the entry? How many run an insulated cowl intake with no air cleaner? How many have done time trails with multiple cam intake centerlines to find the best? I'll bet less fingers than on one hand.

The other big variable is Jim's chassis, yes it is 4000lbs+ but it has almost a 50-50 weight distribution allowing it to hook and use more low end torque than most other A body chassis and especially a leaf spring car can because of the weight in the rear. So he can use the very bottom end range.

Yes copying Jim's combination closely is a great blueprint with solid basis using good parts picked together,but the fine details are where most others deviate and get left behind his car at the track.

Tom I will still disagree that strictly port size HAS to skew the rpm range higher. Our own Pontiac 455 HOs had bigger ports than D ports and worked in the same rpm range, why if size HAS to skew rpm range did they not go much higher? They are 180cc+ from the factory engineers for a street motor! Someone please explain that one to me, since I'm not getting the concept. Larry did your smaller HO motor have less streetablity than your larger D port motor now?
As those references you mentioned "If you have a motor with small ports that flow enough air" - that is the whole key, needed airflow can trump velocity as Cliff's motor showed going faster in the same rpm range with larger KRE heads. If larger means higher rpm range that didn't happen.Most ported D ports that flow what Jim's do ARE larger 180cc ports too. There are also too many dyno results posted here with KRE heads and even E heads that have power peaks on 455s at 5700, hardly above the 5500 D ports. Many head design experts believe too much velocity is bad.

Recently Chevy article showing three different heads with the SAME port size on the same motor(no changes besides head even chamber size was constant) showed the same variations in rpm power range as we use proving the big heads make higher rpm needed. So if it is just port size affecting rpm range how can the SAME sized heads by the same manufacturer have different rpm ranges? Other factors such as quality of flow is why, and the higher peak rpm head that was designed with wet flow technology also had the most AVERAGE torque, so it IS a better street motor even with the higher rpm peaks.All less than 6000 rpm with a 215cc head on a 383.


I do agree you can go too big on heads(as well as headers)as the Ford Boss and Cleveland motors did and the BBC rectangle ports did for their initial sized motors, once you start stroking like we have in our Pontiacs 460+ motors(or the Fords and BBC have) the needed quality air flow needs a larger port at still less than a "race" 6000 rpm.

[Steve C.]

Here is an interesting post taken from the street section...

"car has a XE274H now pulls good through 5500 but the car does not seem to be running as it should, judging from the cars that I have raced the car should run about 13.5-13.8 and I expected this combo to put me well into the 12's."
Here is his combo....
462ci
71 "YC" block Scat rods trw/forged pistons "N" crank
Edelbrock 87cc heads
Harland sharp 1.5's
850dp jetted 79/86 on a performer rpm

Where is he making peak power with his 230 degree cam ? About 5000 rpm or so.

I have a friend here in town that used a hyd flat tappet cam with 236 degrees duration in his .030-over 400 with a 4.250 crank. The heads were unported Edelbrock 87cc castings with a cleanup only and a good valve job.
He used a Performer RPM intake with a Holley 750 carb and 1-7/8" headers.
On the dyno this combination made its peak power at 5200/5300 rpm.
Still not a lot of rpm's.... dispite the "way too big" 215 cc intake runner volume

( Of interest, he slapped the motor into a Trans Am with gutted interior and no hood for weight savings. It had the origional factory installed torque converter, TH400 trans and 3.08 gears. The car ran 12.36, letting the transmission shift itself and on borrowed Nitto drag radials. And it was a dream on the street with PLEANTY of low rpm torque )

[Steve C.]

An important note about the amount of testing Jim has made over the years with his wagon. It's not that he "HAD TO" make all those passes to "get it right" or dialed in, he did so because it was his hobby and enjoys it so much. It is a passion with him. And just as important I also believe he did all the hundreds of various tests just to "prove" his and others theories were correct. He and I are friends and we have discussed this so I believe I can make this statement.


Related....
I suggest that if you took all the people that have duplicated Jim's or Cliff's proven 5000 rpm combination exactly as they have done with little or no devation and who have sussessfully run mid 11's with it at a similar race weight you could probably count them on ONE hand !

[Motor Daddy]

Steve C. Take my car for example. 3860 lb 79 Firebird, 400 + .060", cast pistons, stock crank and rods, 62 heads ported to 239 CFM, 9.33:1 compression, Crower 60310 cam, Torker II, Holley 750, 3.42 gear, 1 5/8" headers, 2 1/2" mufflers and tailpipes (quiet), Stock suspension, plain Jane street tires, pulls 12" vacuum at 900 RPM idle, gets over 14 MPG hammering on it, and cruises at 2250 RPM at 75 MPH:

[email protected] spinning to almost the 1/8th mile mark

This was a one time run on STREET TIRES, never track tuned, or any changes made.

No replacement for cubes? bwahahahahahahahaha

[Steve C.]

Larry, save your money on the K-heads. Since I'm changing to the new 505 combo and the 462 will be sitting idle.... why not borrow some round port headers and lets slap my old motor in your car for interest Now with the small, and tame, 248 solid roller installed it wheezes out at a comfortable 5600 or so rpm and will run a 3750 lb race weight to a easy 11.50 or lower ET. And with a whimpy 9.7 compression it will run on crap gas.

[gjn]

Originally Posted by Skip Fix

GJN- I still disagree that "anyone" can copy Jim's combination cheaply and run as fast as he has. Even Cliff said it takes time to tune them, you don't just drop a big motor in and go fast. If you have seen the progression of Jim's wagon from the 12s to the 11's as he meticulously tweaked EVERY detail you would see few others will take the time to do that. Jim also has the same "expensive" bottom end that "high rpm" Pontiac motors use, 6.8 rods stroker crank.

Steve, I never said cheaply. Inexpensive, yes. What does a 455 block and rotating assembly go for these days? $500 to $800? 6X heads ported to flow 250 cfm by Butler/Kaufman? $1,400. Everything else would be the same regardles of what you are building. Remember, he was in the 11's with his 455 before the "eath mover" motor. I agree it's all in the details and I am surpised that so many people try to re-invent the wheel and build their own combo. I fall into that category (I wanted to keep the original block and chose to stroke the 400). If I knew what I know now, I would have copied David Kawallek's motor to the T. Everything was listed on Boyles site and an e-mail to David would have anwered the last few quetions. I would have know all the parts, where the cam was dial in, spacer under carb, jetting, timing, headers, converter, exhaust, necessary head flow, gear, tires, etc, etc. The motor would have been on par out of the box; but, getting it to the ground would have been another story at the track in a my first gen. Luckily, I met David at the track and he helped me tune the combo at an excelerated rate due to his test and tuning of his 81 TA. That is why, I was able to tune it from a 13.6 @ 101 to a 12.36 @ 111 with only a carb (750 vacuum secondary to a 650 DP) and tire change in 9 months.

I would suggest to someone wanting to build a street strip Pointiac to copy a known combo to the T (every aspect). Why go through the expense of switching parts and trying to build your own combo? Unless this is what you enjoy and you have the ca$h to do it. Where I have spent most of my money is trying different parts and different parts and different parts, etc. If I would have followed Jim or Dave's car to a T, I would have saved several thousand dollars over the last 6 years.

[Skip Fix]

Copying a known motor as I said before is a good starting point.

I don't think to many folks are running in the 11s with a $500-800 short block, at least not for too long Yes I know guys that have run 10s with cast rods too. But to dependably run them at that level for long better rods and good machine work are what Jim and Cliff have had done.

The only difference in expense would be $1400 250 cfm Butler D ports vs $1800 out of the box KRE or E heads flowing 260-280cfm +/- additional porting in the combinations you are describing. Cliff has documented what they did on his car. Intake cast iron-porting time or an RPM, many folks even Jim have had an RPM on at various times.

There are many of us whose detailed combinations are listed here. My old 400 is on Bill Boyles site also, good for 12 teens.

My current "expensive" combination I have described many times and has only one "special" part that was only worth 5hp. 2 bolt YH 455 block and crank, $400 SCAT rods, 0.030 Ross pistons- like most folks using. UD flat tappet hydraulic similar to one Jim's brother Floyd used,only has a 112 LS, installed 107 IC. Plain hydraulic lifters. Mainly 1.65 HS rockers-just like Jim. No line boring,no 4 bolt caps just decked and a torque plate hone.

Now the "exotic" pieces-extra valve springs from an another motor, bare E heads that were KRE CNC ported, KRE supplied stainless 2.11/1.66 valves-same price as the ones for D ports. Used Torker II bought here on PY-cheaper than a new RPM, out of the box Holley 850 DP bought here on PY, jetted one step leaner-cheaper than a Cliff modified Q jet(which I do have one also). An HEI distributor with a total of 38 degrees advance.

The only out of the ordinary piece is 1.8 Crower rockers on the intakes only in place of the HS 1.65s.That was the extra 5hp.

I recently picked up some coated round port headers here on PY that were similar cost to buying D ports and having them coated so don't say alot more expensive headers.

So there you go, other than a little more cost in heads no more expensive to reproduce.

David is a nice guy, met him at a Dallas event years ago and even had a time trial against him

[60man]

Originally Posted by slowbird

You low RPM guys with your 455 dont know what you are missing. Buzzing a 400 to 6500rpm is so much more fun. I did the low RPM thing it just did have the thrill that the 400 does.

Done both....
First 464 was shifted at 5,600 (truck motor)
Present 462 is shifted at 6,400(or so)
My 505 will be shifted at about 7,200-7,400..
So much for 4.10 gears I guess..

It all depends on what ya want and rotating assembly can take....
and of course the old wallet..

[gjn]

Originally Posted by Skip Fix

Copying a known motor as I said before is a good starting point.

I don't think to many folks are running in the 11s with a $500-800 short block, at least not for too long Yes I know guys that have run 10s with cast rods too. But to dependably run them at that level for long better rods and good machine work are what Jim and Cliff have had done.

Skip,

Didn't mean to imply you could run a short block, I meant obtain one for $500 to $800 and then spend the $700 to $1k on machine work. I would opt for aftermarket rods and pistons too for insurance(but, you don't have to). My point is if you copy a known performer that meets your performance quest, you can save a hell of a lot of cash. That is what helps make it inexpensive. If I had copied Dave's motor, and copied a 1st gen Fbody that suspension that proved it could hook. I probably could have had enough cash left over to have a very nice paint job. I went through 4 carbs, 3 converters, two exhaust systems, 2 ring and pinion changes, 2 sets of shocks on the front and 3 on the rear, 3 manifolds, 2 radiators, etc, etc, etc because I didn't how to accomplish the performance levels I wanted.

[Larry Navarro]

Two guys that haven't posted much lately are Dave Sober and Mike Cooke.
These guys can throw "swap meet" parts together and with some tuning, run damn fast in the 11.20 range.
Both use home ported D-port heads with cfm figures in the 260-270cfm range, cams in 240-250 duration range, street dominator/torker2 intakes and Holley carbs. Both of the cars weigh in the neighborhood of 3700lbs.
There's alot of vehicles that have problems accomplishing this performance, even with "new tech" parts.
Where's Floyd Hand? I think his LeMans runs mid 11's with "bargain" parts too.