2001 Pure Stock Drags
 

So, anyone else headed to Michigan this year? Pete & JJ are making the trip down from Canada, and I'm supposed to certify Wednesday, but what about everyone else? Marlin: is Neil gonna be there this year?

[Edited by Chevy454 (09-10-2001 at 07:42 AM).]

Re: 2001 Pure Stock Drags
 

Rob;
I don't think Neal is going to the event this year. The 'certified' class is hard for some people to fit into their schedule.
M

Re: 2001 Pure Stock Drags
 

I knew Neil wasn't signed up to certify, but thought he might have been planning on attending the regular activities. I also understand the scheduling problems with the certified stock tech...but, it's all for a good cause https://www.yenko.net/ubb/smilies/images/icons/wink.gif.

Re: 2001 Pure Stock Drags
 

What......Neil's not coming this year!!! Not even for the regular event????? Guess I'll have to down size my beer order! https://www.yenko.net/ubb/smilies/images/icons/laugh.gif https://www.yenko.net/ubb/smilies/images/icons/wink.gif See you Thursday Rob. With this certification thing, it's gonna be interesting!!!
Peter

Re: 2001 Pure Stock Drags
 

Well, I should likely wait for Rob to announce it but he's still on the road for another 9 hours. Rob had to race "the Stude" for the best two out of three. What a coincidence! It took three, but he got the job done. Car ran a couple of 13.0's. So close to the 12.99 he could taste it.He worked hard for it as he had a lot of problems, but never gave up. Passed his certification with flying colours. Congrats Rob, enjoyed spending the week-end with ya!
There was about 120 cars and he was in the top 16 fastest. Only 6 certified! 3 were DQ'd for not passing tech as they refused to be P&G'd. Dan and Bob put on a first rate show!
Oh ya...almost forgot... #1 qualifier was a Supercar! ;)
Peter

[Edited by COPO PETE (09-15-2001 at 08:38 PM).]

Re: 2001 Pure Stock Drags
 

Pete
Was Randy Miller there?
And if so what did he bring.

Re: 2001 Pure Stock Drags
 

Pete:

No problem with posting the info! Drive was no big deal...only 790 miles from MMM to the house! Pulled in the drive way about 3am (I think?!) this morning...only took about 13 hours coming home (I must have hit all of the lights just right https://www.yenko.net/ubb/smilies/images/icons/wink.gif).

Like Pete said, it took 3 tries, but I FINALLY got the best of the Stude. I had him on the first run, but was in a coma on the line, and gave up .3+ off of the line. But, I sqeaked out the next 2, and the rest is history. Oddly enough, that is THE CAR that I was wanting to get paired up with! I knew we would be close, and I think Bob/Dan probably made it happen.

I had to settle for 13.0s@106, as I could never get the 108 back on the big end, but I noticed Gateway has a test-n-tune Wednesday night...may sneak up there and see what happens. BUT, I gotten swap in some new rocker studs before I do ANYTHING!

And for you guys that don't know, or haven't heard, Pete yanked his iron engine in favor of an aluminum peice! With just 2 weeks of time on the engine, Pete was in the 12.30s, and that thing has 11s (in PURE STOCK TRIM) written ALL OVER IT! Just a matter of time!

Thanks again, Pete, to you guys (JJ, Tim, Gary(?)) for letting this musclecar crazed redneck hang out with you well mannered Canadian Gents https://www.yenko.net/ubb/smilies/images/icons/wink.gif!

[Edited by Chevy454 (09-16-2001 at 08:32 AM).]

Re: 2001 Pure Stock Drags
 

Rob, glad to hear you made it home safe and sound! Hope any and all influences you may have picked up from us " Well Mannered Canadian Gents" will fade away shortly.
Randy Miller did not make an appearance this year.
Peter

Re: 2001 Pure Stock Drags
 

Anymore more details about the event? What was the quickest car?

Re: 2001 Pure Stock Drags
 

No Ron, I had the white COPO car there. I just slipped a ZL-1 in for the race 2 weeks ago. I need more seat time, but managed a best of 12.34 @ 113 mph. Passed certification with flying colours as Rob did. My F70-14's arn't too excited about the switch! After tech was done and 3 cars weeded out for refuseing to p&g (were running about 119 mph) that left me #1 qualifier and 6 Pak Bob #2. In the end, I got caught up on my sleep at the light the first round, and then had premature excelleration the second round, but was still happy with #1 qualifier. https://www.yenko.net/ubb/smilies/images/icons/laugh.gif
Peter

Re: 2001 Pure Stock Drags
 

Pete does that mean you have 4 Copo cars as I have seen the yellow Chevelle , Orange Camaro and the Smallblock Nova and a white Camaro also that is running 12.30,s!! Thats awesome and really tuff on us Mopar guys but what a great collection!! Ron

Re: 2001 Pure Stock Drags
 

COPO PETE was that a real (old) ZL-1 you are running or will they let you run one of the NEW ZL-1s

Re: 2001 Pure Stock Drags
 

Sounds like everyone had a good time! Pete I take it you had the orange Camaro there and ran 12.30,s! Man thats hauling! And everyone is talking about the Studes but I see Rob took em out! Glad to see my Canadian friends had a good time and a safe trip! Ron

Re: 2001 Pure Stock Drags
 

Part #'s on the block do not matter, as long as the cubic inch is correct. The block I was using is the new GM block. What a work of art! The heads were a virgin set dated November 68 as was the intake, being untouched GM.
Peter

[Edited by COPO PETE (09-17-2001 at 05:26 AM).]

Re: 2001 Pure Stock Drags
 

Who/what came out on top? Was it a Buick?

Mike

Re: 2001 Pure Stock Drags
 

Just a quick note from one of the Studebaker fans. If Ted had to lose a shoot-out in his Studebaker, he could not have chosen a better car or a kinder group to lose to.
I wish I'd have been there, but from all I've heard, it's been a friendly competition with our the Studebakers gang, and I applaud you guys for that. On behalf of the Studebaker guys, we'll be back.

Re: 2001 Pure Stock Drags
 

<BLOCKQUOTE><font size="1" face="">quote:</font><HR>Who/what came out on top? Was it a Buick?<HR></BLOCKQUOTE> https://www.yenko.net/ubb/smilies/ima...ns/shocked.gif

No, it wasn't a Buick. The quickest qualifier was our very own "CopoPete", in his '69 COPO Camaro w/ZL-1 engine. I think his qualifying time was a 12.34, BUT he participated in the "Certified Stock" tear down, as did Bob Karakashian, the #2 qualifier in his '69.5 SuperBee w/440 6-pack. It's pretty cool that the top 2 qualifiers were "certified". Pete's engine only came in at 10.8:1 compression, and has a TON of room to improve...truly a package capable of 11 second ETs in Pure Stock trim. he's only had it going 2 weeks, so when he gets it dialed in, LOOK OUT!

Avanti:

Nice to see you stop by! I've gotta say, that the rivalry that has develop between our car and the Studes has been a lot of fun. The Stude people I met this past weekend were all VERY friendly, and showed great sportsmanship. In the back of my mind, I was hoping to get paired up with the PBW (that's "Plain Brown Wrapper" in Stude-talk), and that is how it worked out...also, from what I heard after the race, the crowd enjoyed the rivalry as well. Hope to see you guys next year!

Re: 2001 Pure Stock Drags
 

A Win for the Home Team!
Way to go Chevrolet guys.
For Manners and for Speed. https://www.yenko.net/ubb/smilies/burnout.gif

Re: 2001 Pure Stock Drags
 

Great job guys. I hope to see a report on the race in one the magazines or web sites. I wonder if they would allow a ZL1 motor to race a 69 Corvette body? Only two ZL1 Corvettes were produced so it wasn't allowed by NHRA in stock classes. Would that matter for the Pure Stock drags? A 1969 Corvette may be a little bit quicker and faster since it can use a wider tire then the Camaro (F70x15 Vs E70), has better front to rear weight balance, less restrictive exhaust system, and a little better aerodynamics. I was thinking about this because I saw a 1969 Corvette for sale with no engine or trans. Was an original 427 390hp car and even has an L88 hood on it. Would make a nice ZL1 Corvette clone. I better stop thinking about it.

Re: 2001 Pure Stock Drags
 

Joe:

A ZL-1 Corvette is definitely legal, as it was factory produced. You aren't the only one thinking about that combo...

Re: 2001 Pure Stock Drags
 

Pete

How much HP and Torque did your ZL-1 put out? Great job at putting the Bowtie's on top.

Jim Lerum

Re: 2001 Pure Stock Drags
 

Jim:

You are right on about the size of the ports, and the fact that the manifolds kill them! When I participated in the "Certified Stock" tear down this past week, I was the only Chevy car there on Wednesday, and I heard several people comment on how Chevrolet had "other intentions" when designing their hi-po BBC heads/ports. There was a 440-6, a 455 Stage 1, and Hemi also certifying that day, and they all commented on the seriousness (sp?) of the Chevy heads straight from the factory. BUT, the great equalizer is the crummy exhaust manifolds. That is one area the Hemi cars are definitely ahead of the game.

Re: 2001 Pure Stock Drags
 

I also think that the more compression that is run, the better the big ports function with the stock GM L-72, L-78, LS-6 cam. I think Pete's L-72 motor is a good example of why more compression is required. The lifters needed more lash to shorten the duration of the cam to fit the compression. I figure that the right dynamic compression should be 11.8 to 1. When you think of it, Pete's motor was running a lift of .480's after the lash was set to get the proper dynamic compression. Their are some good book out there that explain this very well. Pete I'm not picking on you as you have some great really quick rides, it's just that everyone is probably familiar with the really good article on your COPO dyno L-72 in MCR. Look forward to the ZL-1 dyno session. Which soon to be published issue will it be in?

Jim Lerum LS-6

PS: The 291 cast heads have 327cc ports which also hurt the low end port velocity for building torque. This right where we need to operate with the manifolds.

Re: 2001 Pure Stock Drags
 

Jim:

Tell me more about lash vs. duration vs. compression, etc. This could be very useful...

Re: 2001 Pure Stock Drags
 

Jim, The car was weighed just before we pulled the motor and right after to get a accurate comparison, same fuel,etc etc. It weighed about 200 lbs to the ounce less. I run UAP NAPA 50/50 gas shocks on all four corners, as were not allowed to run race shocks. Valve lash for the street so far is .035 on both intake and exhaust. I shift at 7000 every gear and it goes through the end at 7200. Second gear is really loose! But a fun ride! https://www.yenko.net/ubb/smilies/images/icons/laugh.gif
Peter

Re: 2001 Pure Stock Drags
 

Jim, I understand what your saying and I agree 100% and it all goes against everything I've done. These GM cams are rediculous and silly. Without giving it that much valve lash I pretty much had no brakes. It could'nt produce enough vaccuum to operate them. Also from going from .024 to .035 I picked up 30 lbs of cranking pressure. Bottom line was I could'nt launch the car with no brakes. Et and mph were not effected at all with the change.
Peter

Re: 2001 Pure Stock Drags
 

Really neat Peter. Thanks for the info on the shocks. Again I look forward to the article on the motor. Did Tom Shaw come to do the article on the dynoed motor?

Jim

Re: 2001 Pure Stock Drags
 

465 hp threw the stock exhaust manifolds! Sorry the rest of the facts will be coming out shortly in MCR. They followed along for the day at the dyno. The real story is when we put the headers on!
https://www.yenko.net/ubb/smilies/images/icons/laugh.gif
Peter

Re: 2001 Pure Stock Drags
 

Cool Pete, glad to see that the magazine has come back once again for some Chevy power dyno sessons. It will hopefully reillistrate that the exhaust manifolds on the big blocks are really restrictive because of where the power is made. It's not the average big block that other manufactures designed with low RPM torque in mind. The intake port design says it all, RRRRRRR PPPPPPP MMMMMM's. How much weight did the car drop when the ZL-1 was installed? What type of shocks do you use?

Re: 2001 Pure Stock Drags
 

Peter:

I would think that you would beable to use as much of the exhust duration and lift as you wanted. If you can't it's because the exhaust maniflolds are allowing too much reversion. Use a balance pipe just on the other side of your torque converter housing. You can get them from Jeg's for $35.00 US. The car will run considerable better 2500rpm and up.

Jim

Re: 2001 Pure Stock Drags
 

Their you go guys, that tells you what .011 difference in valve lash will do to a really strong motor. I didn't think it would of increased the cranking pressure that much but it had to help the torque curve a bunch on the bottom end.

My hats off to you Pete for your fine tuning skills. How many inches of vacumm did the motor make at normal lash and your revised lash?

Jim

Re: 2001 Pure Stock Drags
 

Now we are talking! Ok, Jim, so what is the "optimum" compression ratio for the standard L-71/L-72/L-78/LS-6 cam (.520/.520)?

Now, I understand why Pete did what he did with his ZL-1: he needed the lash for the brakes and to make up for the ZL-1's natural lack of a bottom end, both due to the big cam. BUT, I noticed in his L-72 dyno test that he ran a lot of lash as well, not as much as the ZL-1, but still well off of the factory's 24/28 mark.

Pete: did you get the email with the muffler/crossover tests?

Re: 2001 Pure Stock Drags
 

Pete, did you have to run the 780 vac sec as your ZL-1 carb? I'm sure it was tough getting the secondaries to open properly. If I remember right, the lowest spring tension is a 6.5" of vacuum. I would assume that when you saw 2" of vacuum you said oh sh!t.

Jim

Re: 2001 Pure Stock Drags
 

You need to give me some time on finding measurements for the cam as I can't find any information on when the valve actually closes. I have a cam that I'll take over to a buddies cam doctor(measures lobes and gives read outs)and see what it comes up with. If anyone out there has the measurement for an LS-6/L-72/L-78 cam put it on the site. It can not be a measurement at .020 or .050 as these don't qualify. It must be lift off the base circle.

Jim

[Edited by JLerum (09-21-2001 at 03:40 PM).]

Re: 2001 Pure Stock Drags
 

<BLOCKQUOTE><font size="1" face="">quote:</font><HR>I would assume that when you saw 2" of vacuum you said oh sh!t.<HR></BLOCKQUOTE>

That would probably be MY reaction! Oh, and I am looking for the cam specs...

Re: 2001 Pure Stock Drags
 

I don't know what Pete is running but the ZL1 engine is a lot different then a L72.
The ZL1 engine was a L88 with an aluminum block. I have seen different spec sheets on them but according to one spec sheet It used a 850 Holley Double pumper, 12.1 compression, open divider intake manifold, a bigger cam, a transistor ignition system, and some other differences vs the L72.

Re: 2001 Pure Stock Drags
 

There are some subtle differences between the ZL-1 and the L-88, but I can't remember off hand which carb Pete was running...I think it was the 850, but I wouldn't swear to it.

Re: 2001 Pure Stock Drags
 

Jim. ! 2 inches of vaccum at 1000rpm. With the inreased lash the motor went to 5 inches. It was interesting to note that we had the motor idling at 1000 rpm., increased the lash to .035 and with no other change the motor idled at 1700 rpm. It was nuts. Originally we thought we had a vaccuum leak and ran around the intake with a torch. No increase in rpm. Then we stuck the torch down the carb....no increase in rpm. Man that had us confused. We then stuck the torch tip in the pcv hose, and it picked up about 400 rpm.
Thanks for the tip, I am as we speak looking into a crossover pipe!
Peter

Re: 2001 Pure Stock Drags
 

Duration is the time that a valve opens to the time that a valve closes. On a cam card you get duration on the intake and the exhaust valve. These measurements are usually at certain standard lift values so that you can compare cams. The most important thing to know is when the intake valve closes (use a degree wheel) as this determines how much air/fuel mixture is caught in the cylinder. The later the valve closes the more static compression you need to help the dynamic compression of the motor. The term dynamic compression is the functional compression an engine understands when it is in motion (running). Because of the intake valve closing point being so important, you must build a motor so that the intake valve closes just right for the compression.

In the case of running in a class like Pure Stock Muscle Car Drags it is a little different. When running the (stock) cam you must pay attention to your compression. Design the motor so its compression ratio fits the cam by decking the block, ccing the combustion chambers, and or selecting head gasket thickness. The stock cam is defined by the rules so you must make the compression fit the cam. Do not think that more compression is always better because you can have too much compression for a cam. A good example would be the Buick Stage 1. The PSMDR allows you to blue print the motor to NHRA specs. The specs submitted to AMA would allow this motor to push almost 13.0 to 1 compression. The stock cam valve duration would keep you from using all this compression advantage and would be less than competitive.

To fine tuning a solid lifter cam motor you can change the intake valve closure 2 ways. The first would be on how you degree the cam during setup with the timing chain (advanced or retarded). This is the most effective way to move intake valve closure. When the cam is advanced the intake valve is closed sooner, increasing cylinder pressure effecting low-end torque. Retarded the cam closes the intake valve later and helps top end horsepower. Again this is because better high RPM cylinder filling.

The second would be adjusting lash. (IÃm finally answering your question) The looser the lash the more slack the camshaft lobe must take up before opening the valve. The lifter will have traveled farther up the lobe delaying the valve opening and closing the valve sooner on the back side of the camshaft lobe. In effect you have removed some duration. The other unfortunate result is you have lost lift. Extra slack in the valve train keeps the lobe from displacing its full lift to the valve. This is bad because we know that BB Chevys love lift.

If you are really able to sit on a dyno for an extra day, a lash loop should be tried. Isolate the intake valves and increase/decrease their lash in .004 increments to see how the engine responds. Then try the same thing with the exhaust. This will tell you how well youÃve chosen your compression or camshaft.

If you are running a rapid lift solid lifter camshaft you must be careful how you adjust your lash. Most of these rapid lift cams run .012 to .014 lash(very tight). You can not allow much more lash than the manufacturer has on the cam spec card. If you do the valve train will accelerate so fast that you will get broken valve train parts. Surprisingly you can run considerably less lash. Hope this is informative and gives some insight.



Jim Lerum




[Edited by JLerum (09-24-2001 at 07:11 AM).]

[Edited by JLerum (09-24-2001 at 07:12 AM).]

Re: 2001 Pure Stock Drags
 

I don't think this will help you any more, but for those curious, here is the CAM CARD for the L-71/L-72/L-78/LS-6 . Also, here is a CAM CHART with some more info on this cam.

[Edited by Chevy454 (09-24-2001 at 08:56 AM).]