This getting old!! But I'm working on it!!!

Took the Vette up to Bowling Green Ky to attend a Vette play week. We had track rented and I was all set to nail that 9 sec pass finally!

I had it in *race mode*. That means headers open, new 10x28 slicks, carb spacer on. Otherwise.....it's all the same as normal street driving.

FYI- it's a pump gas 540, G-force 5 speed, 3.07 gears, 3650 lbs race weight, IRS suspension.

Big storm front blew through Wed night...looked like it might be cancelled..woke up to rain! Then we went out to track anyway and entered the sauna as it quit raining.

I don't have a weather station...but the numbers I got from some guys that did showed 78% Humidity, avg of 29.62 Baro (low of 29.42!) and temps in the 91-94* range all afternoon. Yeeeeeech!!! That's as bad as TX!!!

I was also looking forward to finally getting to play with the new Mcleod Soft Lok clutch. It worked perfectly...but I need to do some more tuning. Good news is it took my crazy out of control wheelie flying launches down to nice smooth manageable and dead straight even on some pretty high rpm launches. Bad part is I need to add more static to it. Turns out my car weight, TQ curve and gearing is going to have to have more to keep from excessively slipping clutch during launch. I initially used some settings that other folks suggested..and they were a great starting point. But my combo is a little odd. I didn't make any changes to setting of clutch because I didn't want to change too much at one time. I was also trying new stiff sidewall slicks and they were working great too.

First run was a 10.15@137.8. But 60's were only 1.62...about .2 off it's best of 1.41. I made several more passes all between 10.15-10.22 with similar 60's. MPH stayed right at 137.6-137.8.

I tried a low rpm launch once and it slipped clutch badly and slowed to a 10.32.

Then tried a 5000 rpm launch and it actually took it well....but it still needed some more clutch pressure..I was getting some slip on the shifts. Still no faster.

Then we decided to try and *HP* our way into the 9's. We had brought my buddy's new AED 1150 Dominator to test against my old homebuilt 1050 Dominator. We had already tested it on his 632 against my carb a few months ago and it had beat mine by almost 40HP even though A/F and BSFC were very similar. They were both tuned perfect...we just verified that a 632 needs a LOT more air than a 1050 can provide!

Carb felt great...responsive etc.....but still ran a 10.22@ 137.2! I LOST Mph with it! This is the second time I've tried a bigger carb on my 540 and both times I've slowed and made less power even after going through jetting etc. I'm sure I could have spent some time with it tuning it some more, but it wasn't going to get much better..it was very close as it was.

I then put my carb back on...went out and ran best MPH of the day...a 138.2 as the weather got a little better at end of the day. ET still right around 10.20 it seems.

Good thing is I was able to borrow a High $$ carb to test with and verify that I don't need to spend money there! My motor just doesn't need it.

Anyway, it was a heck of a fun day anyway. I got to make a bunch of runs, they were all actually pretty consistent for a street stick car and nothing broke! All the rods are still inside! I'm very happy with the old 540..it just keeps delivering!

The new clutch IS helping a lot. The best this car has EVER run has been a 10.04@141.26 in MUCH better weather conditions. I was down .2 in 60's in terrible weather and still ran within .011 of it's best ever run. A few weeks ago I got in one run with a 10.10 with the same rotten 60's.

I don't think I'm going to touch anything on it except to add some static and maybe a little centrifugal for the clutch. This will bring the 60's back in line. Even on the 5000 rpm launch I was barely getting a 1/2 turn of the tire....so I need to hit them harder with more clutch and walk that fine line between clutch slip and dead hook and violence. Keeping the rpm up after the launch is really helping the recovery after the launch and allowing it to make up a good bit of the time lost on the 60's.

I'll just keep it ready to go at anytime and keep my eye on the weather channel!!

There's GOT to be a 9 sec pass in this sucker somewhere!



JIM

You sound like me last year trying to get in the 10's, all you need is to get one of those 1.4x 60ft times and you're there, sometimes its hard for it all to come together at the same time. :D

In air like that, you did good.
I wonder what your car would do with some of the radial Hoosier...Daddys?
I've heard they are good for a solid tenth.....on cars that like them.
Ron

I would definately add MORE static and forget any centrifugal. I would imagine there are very few people who run these race bred setups in cars that weight 3500 lbs with a 3.07 gear. Regardless of the gear reduction the 5 speed offers. I know you like to cruise but your going to have to sacrifice a little of that gear...............I would say at least a 3.42. It will be interesting to see what happens to the MPH if you do. If and when you put more gear in the car , then you can play with shock tuning and chassis control to maximize everything ...............I'm sure your already aware of these things.

I would definately add MORE static and forget any centrifugal. I would imagine there are very few people who run these race bred setups in cars that weight 3500 lbs with a 3.07 gear. Regardless of the gear reduction the 5 speed offers. I know you like to cruise but your going to have to sacrifice a little of that gear...............I would say at least a 3.42. It will be interesting to see what happens to the MPH if you do. If and when you put more gear in the car , then you can play with shock tuning and chassis control to maximize everything ...............I'm sure your already aware of these things. Jim has a oddball DANA housing built by Strange and there is much modification that was required to fit it to the Vette. Changing gears is fairly difficult as the 3.07 gears had to be machined on the back side to even fit in the case. Going from 10.0s to 9.90s is a barrier that is kind of hard to get over. We tried to get there for over a year before we got the right weather and everything fell into place. The day it happened my son ran two 10.00s and then the 9.98 in 180 ft. air and then got beat by a mildly modified Hyabusa motorcycle. The 540 avenged the loss to the motorcycle and he never picked on us again. You might even consider boring your 540" out to 555" which is good for a little extra. Reher-Morrison has new modifications for the Dart 355 CNC heads which they say picked up a hundred horsepower. Their new 565" motor with these heads made 1020 H.P. but had 13-1 compression, not exactly streetable.

Hi Jim, I looked up the city of Bowling Green and on my map it shows the town to have an altitude of 496', (national weather service shows 544'). Given this information i think someone gave you some bad weather information. A barometric reading of 29.4-29.6 for this altitude would equate to more like an absolute reading of 28.9 or there abouts. We were at Mo-Kan Dragway for the last two days and John's Kestral 4000 was giving readings of 29.8 while my Performaire showed 28.89 and the other variables were 89 degrees, 48.6 humidity, and a density altitude of around 3900'. The weekend befiore at Tulsa the air was over 4100' D.A. with 94* Temps and 50% humidity. Calibrating his station back to zero gave identical readings of 28.88 so your air was probably much worse than you thought. The local weather service gives "corrected altitude" readings which show much better barometer readings than you actually have. Here at Tulsa the weather at the airport generally shows mid 29 baro. readings while my weather station shows mid 28s, Absolute D.A., in early summer conditions. It's been mid summer for a couple of months now with daytime temps in the low nineties, and only one cool spell. I think that global warming is centered right over my house.

Jim - If your "10.0" brake ever breaks, we've got one you can borrow!!

Regarding the clutch... as Joe noted, don't worry about the centrifugal, just keep adding static until you find the sweet spot. Then up the launch rpm a little and start over.

Regarding the carb... our carb guy tells me that the 1150 dominators are much more suited for mountain motors. Based on the minimal shift recovery needed with a 5-speed and our high rpm power band, he recommended a stretched out 1050 or (preferably) a 1250 for our new 381 sbc. Point being... if you are going to test against another dominator, use a 1250... not an 1150.

Dang Jim, I was hoping you would do it at the vette get together and smoke Oliver in the process.

Regarding the carb... our carb guy tells me that the 1150 dominators are much more suited for mountain motors. Based on the minimal shift recovery needed with a 5-speed and our high rpm power band, he recommended a stretched out 1050 or (preferably) a 1250 for our new 381 sbc. Point being... if you are going to test against another dominator, use a 1250... not an 1150.

If I could only sell Bill Burke on this :sad:

They let you run that fast with an IRS (even an aftermarket heavy duty one)? Don't get discouraged you need to play with things. Your MPH should get you into the 9s if you can get everything else working right.

They let you run that fast with an IRS (even an aftermarket heavy duty one)? Don't get discouraged you need to play with things. Your MPH should get you into the 9s if you can get everything else working right. Mike, This was a very popular setup in the early seventies and Jim's has a lot of heavy parts, 1480 "U" joints and oversized half shafts. This DANA won't be the first thing to break if something goes south in the driveline. I think the slipper clutch will keep everything from breaking but in all likelyhood the tires will just spin before anything breaks. I have a friend whose DANA 60 never saw any maintenance for 15 years of solid drag racing and nothing ever broke till he changed gears. The pinion nut came loose, backed off and chewed up a set of gears.

Jim
which cam is in it now?
the roller or flat tapet?

Thanks guys.....

Harold...now that I'm thinking about the info....it does appear to be worse. I got a note from another guy saying the humidity was in the low 90's most of the day at the track and the BEST it ever got to was that 78% number. Your info on baro reading really screws it up. I hadn't looked that far.

Raf- I had the same old roller in it. 266/272 @.050 93 octane.

Mike-There's lots of fast IRS cars running around. The Pump Gas Drags has had several of them, and I know of quite a few low 9 and high 8 sec ones. Mine is a weird setup....but so far it's working well.

John- Yeah I was hoping too...but Oliver was no where close!! He was in low 11's.

Ron- I was going to try the MT drag radials, but decided to get the MT Stiff sidewall slicks instead. They definitely act a lot different. Pictures show they are nowhere near as flattened on the launch...but of course the clutch wasn't hitting them as hard either.

Joe- I have 9 grams of static on it and it was shifting well and holding at high rpm fine....but I definitely need more static. Once I do that I may be able to pull some centrifugal out of it....I'm deep in the learning curve on this dude. For sure I have a tough situation for it, but I know of another Vette with 3.08's and a G-force running low 9's@147. But he does have a few advantages.....mainly about 550 lbs less weight, steeper trans gearing, 8600 rpm shift points and a good bit less TQ at lower speeds. But I'll get there!

Roger- Thanks---your help has got me this far!! I'll probably be picking your brain soon! The first time I tried a bigger carb, it was literally a beautiful Dominator off a very well known Pro Stock racer's car. He converted it to single four use for some friends and they let me dyno with it. It was likely in the 1400 cfm range! Anyway, under 5000 rpm it was pretty soggy even on the dyno, but at 5000 that baby clicked on and it looked like you took the A/F ratios and BFSC and hit the *repeat* button all the way to 7500 rpm! It was incredible,,,but it only added 6 HP. Until I change something, it doesn't look like it wants much more carb. I figured an 1150 would be an improvement....but it just didn't do it. But we do have a custom built 1250 coming for another 598" project and I'll test it too to see how it does.

Sure made me feel good that my homebuilt old style streetified Dominator is still able to hold it's own though!

Just to give you an idea of weather conditions/performance. Some friends from Canada were down with their 434" 23* nitroused Vette. The weekend before they ran some 9.0's@154. They were really hoping to hit an 8.99. The best they could tune to was a 9.44@ 150. On motor they were in the 10.70's!! Usually good for 10.20's. Another buddy was in Bowling Green the weekend before with a nitroused Vette and ran it at the same time all the Buick Turbo guys were playing. He was down to 11.30's@116-117 vs 10.70's@123-124 the weekend before. A bunch of the new Z06 505 HP Vette's were running. All the magazines are quoting 124-127 mph trap speeds, the best I saw was some 12.40's@115-116 even on some slightly tweeked ones. Another modified one of a buddy that recently put 535 RWHP down after cam and some mods was hoping to hit 130mph trap speeds. Best he got was 123.

It was an UGLY day to be racing!!


JIM

Weather changes really make or break a day at the track. Some less experienced racers think that there is something going wrong with their motors when they encounter a bad weather day. Warren Johnson said the air was so thin at Denver one year that "the birds were walking". It had a Density Altitude reading of about 10,000 feet. The cars really slow down in that kind of air.

Harold....How did you know who's "trick" Dominator I tested on the dyno?


JIM

Jim, if you want to try a different dominator you're welcome to try my Braswell. It's based on a 1050. The venturi's are 1.78" with 2.07" throttle bores. Total airflow probably isn't much different than your 1050, but I'd bet throttle response and shift recovery are better and would et better. Just let me know and I'll meet you at the track.

Thanks John....that would be fun. I know there should be better out there. We toured the Holley factory again while we were in Bowling Green. Had a great time!!

I gotta figure out when to go to track...except around home that 'ole roll bar issue is going to crop up again!

JIM

Thanks John....that would be fun. I know there should be better out there. We toured the Holley factory again while we were in Bowling Green. Had a great time!!

I gotta figure out when to go to track...except around home that 'ole roll bar issue is going to crop up again!

JIM Don't the safety nazis just ruin all the fun, all the time? I'm thinking of buying and riding a motorscooter just to show my displeasure about their mandatory seat belt law. Obviously from the amount of tickets they are writing there are lots of other people who don't like being told they have to Buckle up either. I now just buckle up when i see one of "them" and unbuckle after they pass. There were two people killed here the other day and one was belted in, while two others in the car were critically injured when it was hit by a train. How does anyone with eyes and ears not see or hear a train coming. At two o'clock one morning i counted one blow his whistle 56 times going thru four crossings in our small town.

My question about the IRS was pertaining to the rules. NHRA pretty much banned them in the 80s because of safety problems when a half shaft breaks.

You know, I need to research a little, but I've never been questioned on it.

From my understanding the issue was that the halfshaft acts as the upper link of the suspension and if it breaks the trailing arm can flop around some. The *fix* that NHRA accepted was to have some sort of aux. link to hold in case something happened. Tom's Differentials came up with a horizontal link that fit loosely to a bracket on diff mount. It did nothing for traction, but it met the safety rules. As far as I know that's the big issue. They may want halfshaft loops too...not sure.

Mine was designed with extra upper links to be used...I just need to get some made and get them on there.

JIM