[RicksGTO]

you should be able to get it into the 9.25 to 1 range fairly easily with flat top pistons, zero decking and milling the heads about .030 -.040. I am working on my '72 455HO motor and when I measured the heads (which appear untouched), they actually measured closer to 106-108cc's so with a little milling they will be in the 100cc range.

[Lloyd-TX]

Originally Posted by 68bird400HO

Judge273,

Curious as to the specs on your motor. I will be building mine soon and am debating about keeping it within PS guidelines or going for a little more. I am guessing that Dan used a cam close to the 068. Does the cam used actually have the same low lift of the 068 (0.407) or is it an aftermarket grind (2801)? What about the compression ratio. In the SD vs HO article I thought he mentioned he got the HOs CR to 9.4:1. How did he get that with the 111cc chambers of the 197s? Using the online calculators, it seems the best I can get to is about 8.8 (flat tops, zero deck, slight milling) without milling a bunch off of the heads or going to a domed piston.

Mike and Dan can certainly answer better than I, but briefley Dan does.

Blueprint the engine to NHRA stock specs, per PSD rules. Overbore to maximum allowable, custom pistons to increase CR, custom ground camshaft to decrease the LSA and increase the lift. Good stock-angle valve job. Spot-on mchining, assembly and tuning techniques.

http://www.geocities.com/psmcdr/rules.html

[Judge273]

Pat,

I am still learning. Your best bet is to talk to Dan or Mark on the spec's, and for any advice as well. I know Dan starts with the heads to determine how much work was done if any to them beforehand. This will determine the compression ratio target, and in the case of mine was 9.5:1 which is close to max. He did use a modified cam very close to the 068 specs, and custom pistons to increase comp as I remember within P/S rules.

He also does a desktop dyno build and then trys to beat it. He gave me a lot of options to choose from. All I know is his HO cars, and Mark's TA prove the results at the track, and they look great doing it.

Chris and I recently saw Mark's 70 RA IV TA, and it was stunning!

[gloryrestoparts]

Originally Posted by Judge273

Chris and I recently saw Mark's 70 RA IV TA, and it was stunning!

thats an understatement. I thought I was going to see it at Stanton, but plans changed. If I had known, I wish I had taken some pics of it when I saw it at Dan's

[Mark Weymouth]

We built the HO and SD on my side of town for the article, Dan and I live 120 miles apart, so they tend to be his side or myside builds. The RA III/IV and 350 HO comparo's we each took care of one motor apiece. When we lost the cam lobe in my HO Scott Tieman had my car as he usually races it. Dan then did it on his side of town. We will be doing an article in Pontiac Enthusiast on the updated build when I get off my butt and write it.

To answer the compression ration issue. On '71 motors you can take your heads from the factory stated 111cc's down to 98cc's. You can use a .000 deck in combination with 3.1cc pistons. A gasket thickness of .030 which we find to not produce enough squish. When all is said and done if you ran a +.070 bore w/a legal +.0015 off set grind on the crank you get just shy of 10:1. It is 9.9+ actually.

The cam is the one I developed with endless hours of dyno time and input from Dan along the way. It has evovled with each build and dyno session. It is now very well refined. We have refined it not just in HO's but in RA III's and HO 400's. It is now in it's fifth generation.

We follow all the rules very religously. The .050 duration is 212/225 just like the factory 068. It has the near the maximum allowable lift of .424 on each side with 1.5 rockers. Pontiac factory tolerance allowed +/- .011 on lift. If you take the intended lift of .413 that Pontiac spec'd that is how the NHRA rules hit .424. It is also the tolerances that Pontiac turned in to the AMA in '71.

This cam has taken us from a Melling 068 dyno run on the first HO of 370 hp to our now 403 hp level. Along with other changes mind you. The cam can account for 15+ of that change. It really is a just a well blueprinted version of the original. Like all the PS motor build ups it is careful attention to the detials that pays off.

RA III's have shown even better progress. We took the melling base line 068 also at 370 hp for a RA III. The 1st gen cam used in my brothers '69 T/A made 387 hp. The third gen version had a '67 HO 400 making 412 hp and now the latest gen has similarly built RA III's capable of making 420+!

For RA IV's we have found the factory cam to be simply amazing. We have tried many different brands and options but the Melling replacement isalmostperfect.

To date we have only given cams to customers who are having Dan or I do the motors as we really are not in the cam business nor want to be. For internal tracking of which generation we are at we now call it our JW Racing 068M cam.

I also developed correct valve relief cc'd pistons for this application and those are the pistons that are used in all the HO's discussed in these postings that Dan or I have done.

I would recommend Dan to anyone. He is limited as I am to how many of these we can do (hence why Dan handles some of my personal motors). He is extremely careful and particular about his motor builds. I simply can not express enough how good he is.

I hope this is helping everyone because I am becoming very self concious with all this talk about ME ME ME. I just feel it is in the best interest of all us die hard Pontiac guys to have our cars out there making the most possible and putting it to all those brand X cars

Mark

[Lloyd-TX]

Mark, I can't begin to express how much I (and I'm certain all of us here) appreciate your input.

For obvious reasons, I'm certain that many aspects of your (and Dan's) Pontiac PSD engine program cannot and SHOULD NOT be revealed nor sold. The camshaft is a perfect example. One cannot begin to put a price on the years of experimentation and experience you both have put into this deal.

One question does come to mind that should be of great interest in this thread - what brand of hydraulic lifters are you and Dan speccing for your builds?
I have an NOS set of 5232675 RA IV lifters squirelled away for my build if Dan thinks they would be a good choice.

As I stated in an earlier post, once I get back on my feet financially (divorce, etc.), I will be sending my '72 HO engine to Dan for him to build.

Once again - thanks!

[Mark Weymouth]

Lloyd I will answer the lifter issue if you let Dan and I dyno the '72 HO when the time comes.

We use Crane lifters exclusively now. We have made changes on the dyno with several of the big brands and smaller a like. Cranes make the most power and hold the rev's well beyond anyone elses. One major brand even gave me a free set to test and promised 20 hp over the Cranes. This was right before they would be available to the public. All they asked was for a copy of the dyno session. I gave them the copy of the session and the lifters back. I am sure they were surprised they were down 17 hp and about 600 rpm to the Crane lifters.

The Judge ran into lifter/rpm issues and that is when the test sessions started to inclued lifter testing.

The T/A's RA IV was being turned to 6800 on the dyno on the Cranes to see where the harmonics would change. They did not and I was getting a bit stressed about how high my numbers matching motor was going. Most of the session was done with a top rpm of 6400. In the past the other major brand of lifters were a mess by 6000 rpm and they were the vaunted anti-pump up variety.

Mark

[Lloyd-TX]

Mark - not only will I allow you and Dan to dyno my engine, I insist upon it, LOL!

Interesting about the Crane lifters, and thanks for that information.

Have either yourself or Dan ever dynoed the RAIV lifters?

[68bird400HO]

Mark,

Thanks for the additional information on the engine building and testing you and Dan have performed. Your posts are always interesting to read regardless of whether it pertains to the 455HO or not.

[RicksGTO]

very interesting, to see the numbers you are getting out of finely tuned stock built motors is amazing!....420hp from a RAIII with any close version of the 068 cam is just incredible! Makes me wonder why I am using anything but the 068 for my current engine!

[Larry Navarro]

dammit!.....this has me thinking about sending my SD motor to you guys!!! I always thought about doing PSD with the '73 but with the knowledge of "J.W.", it may just be the ticket to kickin' brand-X butt!!

[Mark Weymouth]

I believe Dan's first test long ago was with the factory RA IV lifters. It was a stock rebuild and it made 390 hp. This is how I recall it but we are talking about ten years ago.

Personally I have had cars with them and they do not hold the rpm and do nose over more quickly than the Cranes. Now with that said we are talking about rpms that your HO I hope will never see. If it does it likely meant something went very wrong.

Larry I have been itching to get at another SD. My brother has one I have been nagging him over. I am certian we have some wiggle room for improvement over the 395 hp we got out of Paul's. Those SD's with their bigger duration cams sure do rev. Unfortunately the lack of compression and said cam hurts the torque production compared to a HO.

You guys have me so rev'd up and it is snowing around here and salt has been laid already. My season is over and I now am dying to going run something.

Mark

[threefidee]

The first pic is of a guy from the Army trying to open Mark's hood and steal his lifter and cam secrets

12.60's anyone ???

[OVERULD]

That is an absolutely gorgeous car. I like the true duals - I bet it sounds awesome! I bet he goes over speed bumps very carefully (if at all) - oh that's right - they don't have speed bumps on the 1/4 mile track do they.

[Mark Weymouth]

That was the first day we had it out at the track. We tested both the SD and HO that day.

The true duals are gone. We have a PYPES cross over muffler on the car now. The exhaust change gained nothing but lost nothing also.

Mark

[Mark Weymouth]

While looking at the pix Jody posted you can see Paul's SD in the back ground. It no longer runs those tires but rather it has bias ply's on her now.

The Vette is an LS6 '71 with 13K miles and all original including 100% original paint. On that day getting her going with 100% factory parts, not even jetting changes, it went 13.1's @ 107 w/3.36 gears.

We have since set the original motor aside, put 4.11's in it and a new exhaust. It now turns 12.0's @ 116 with 1.77 short times. We have a bit more sorting but it is close to done. That is my brothers main PS car.

You guys need to join us we have a lot of fun.

Mark

[2manyT/A'S]

Originally Posted by Mark Weymouth

That was the first day we had it out at the track. We tested both the SD and HO that day.

The true duals are gone. We have a PYPES cross over muffler on the car now. The exhaust change gained nothing but lost nothing also.

Mark

I'll BET you gained some ground clearance & if you ever drive it on the street,that's almost as IMPORTANT as 10th's (you SHOULD get over the speed bumps way faster NOW)

NICE CAR!!!!

[Judge273]

Mark,

Tell Dan to put those AMC's on hold and get the GT-37 back in the shop for the Sept race. We're burning daylight! I want to line up with him in that Javelin!

[Mark Weymouth]

Your not going to want to hear this as I just hung up with him and we are dynoing a SC/Rambler motor I just finished up next Thursday.

But yesterday was a roller stroker 461 with mellow street hydro roller and roller rockers. It only has 9.4:1 compression and some mildly cleaned up '71 #96 heads. It made 417 hp and 512 tq on pump gas.

Headers added about 10 and 10 to the power.

The GT37 is a must do as you I am sure already know my attitude about your car.

Mark

[threefidee]

Lloyd, be careful if you let them both dyno your motor. Here is a pic of Dan and Mark (hiding) dynoing my 350 HO motor. One bank of the motor was pulling much stronger than the other