427Hotrod

Well....finally made it to the track last Sunday with the Vette. Didn't quite pull off my 8 sec timeslip...but made a lot of headway.

I knew clutch management was going to be the biggest bogey to get my arms around. When N/A I used 7.5 turns of adjustment on the McLeod Soft Lock and a good bit of centrifugal weights. That worked perfectly. Now with boost...I figure at launch I'm down some power with 2.5 points less compression and 20* less cam. BUT...I also know about a millisecond after launch there's a lot of boost coming on with those relatively small turbos.

I decided to take a stab at it and dialed in an additional 1.5 turns of static pressure. That makes 1420#'s total which is quite a bit.

The first two passes were a 9.74@139 mph and a 9.68@135 mph. What was really weird is on the first pass the 1/8th mile MPH was only 112.59 and on the next pass it jumped to 120.97. Well that sucks...it could do 113 mph before the turbos!! Obviously there's some weird stuff going on.

So I decided to look around under the valve covers to see if I could notice any seriously missing parts contributing to no power. Ran the valves...nothing wrong there. Plugs looked OK. My laptop computer wasn't acting right on data logs so didn't have anything there to look at.

Next pass ran a 9.67@140.72 mph. 1/8th mile was back down to 113 MPH. Jeez.

At this point I resigned myself to dropping the lower part of scattershield and dialing in some more clutch pressure. Seemed to be a lot of revving going on but not much pulling. The funny part is the car drives NICE when the clutch is slipping! I put 2.5 more turns on it and headed back to the line.

This time it ran a 9.80 with a LOT of wheel spin and leaving black tracks all the way to the 1000' mark. Was a lot slippier ride...but the MPH came up to 147.73 with 118.53 at the 1/8th mile. 60' was only a 1.67 vs previous 1.40's.

Since it felt better overall I decided to "hot lap" it and pulled right back to the line. I dropped launch RPM down and short shifted it at around 5500 just to see what would happen. It didn't like that stuff at all. I guess she's used to my normal style of driving and rebelled a little. Only ran a 10.40@134.58.

So I let it cool for a little bit and checked the air pressure in the slicks and pulled back around again. This time I launched at around 4000 RPM (trying to find a happy medium) and drove my normal style. Seemed to work better and it ran a 9.27@153.35!! Now we're getting somewhere!!

I was only able to get in one more shot before the day ended....this one was a 9.30@151.70. 1/8th mile MPH was in the 122-123 MPH range on these last passes.

So...overall it was a good day. The rods are still in it. I pounded on it and no oil leaks or drama. I've got a ballpark on clutch setting...which will always be a little weird given the weight of this thing at the line (3980 LBS) with me and 3/4 tank of fuel and the oddball combination of 3.07 rear gears and a stick trans. I was able to bug our buddy Doug Flynn for some help getting my data logging going (he was out Moto-X riding but answered my call- THANKS DOUG!!) so I'll need to dig through all those runs and see if I can see where the intermittent issue is. Fuel? Boost? I didn't have boost cranked up...so there's a lot more in it. This was mainly about getting it down the track at all. The MPH is showing I'm in the game considering weight and the tune. Even ran it through mufflers all day!

I dropped it off at my rollbar guy's shop on Monday morning so he can modify things to make the hardtop fit and add the 'chute mount as I prepare to see if I can get it over 200 MPH at the TX Mile later this month. Then I'll go back to the track and earn that 8 sec timeslip!!

But it sure was a heck of a lot of fun banging gears in this dude!!


JIM

BLUE1972

looks good

v2racing

Sounds like you had a good time and are getting a handle on it. Turbos can be a trick to launch with a stick and foot clutch. Can't spin them up against the converter like an auto with a transbrake.

chevymans 77

Looks like fun

That thing is crazy fast for a street car, can't wait to see the 8 sec pass.

get someone to film it so we can all see it

Neal

Wee

Looks like you are having a ball with it....That's what it's all about. I never really knew there was that much to drag racing...Thanks for the insite.

Brian

ajrothm

Bad *** Jim! I was watching the live stream from work, hoping to see you make a pass and I never did. A friend of mine told me it went 153 so I knew you were going in the right direction.

That has to be one of the trickiest setups to dial in for sure. No doubt it will take many passes to get it all lined out.

I figure 1000 rwhp at 4000lbs will go 157-158 or so with the stick on a clean pass....If not 160.

I can't wait to see how you do at the mile. 200 or bust!

427Hotrod

Thanks Allen......I have no doubt there's a lot more in it.....but it was fun to get a few runs under my belt and at least know I'm going the right direction.

JIM

Solid LT1

Single disc clutch? I see a multi disc in your future if what you have is a single....nice job Jim!

427Hotrod

Yep...it's a single disc. Probably need a dual to allow some surface area but still allow some controlled slippage.

Found a few more pics....

JIM

Big Block Dave

Stick car getting' down!

Luce

Yes sir. With more than 200 HP, there is a lot of fineness in drag racing. More with a stick, then even more with turbos. To the 2nd power with both. The first half of the race is modulating your power so you don't turn the rubber in your tires into lubricant.

I've never had my Cobra on a drag strip, but I know from street driving it's hard to quickly get off the line without boiling tires and/or losing control. You can't open it up all the way until 3rd.

The thought all you have to do is mash the right pedal and keep it straight is not at all true... unless maybe you're driving a prius.

Good job Jim.

Jebbysan

Always like reading your posts......you are a very knowledgable and down to earth dude.......

Tell us about your rearend setup....pics?

Jebby

427Hotrod

It's a Dana 60 made out of a NOS Hemi housing. The Hemi ones had a pinion snubber mount that is perfect for fabricating a front mount bracket. Non Hemi ones (like a truck) didn't have that provision. This housing was in a box marked 1971 and never had axle tubes pressed into it.

It uses a special posi unit that was provided to factory racers back then. Apparently since axle science wasn't that great yet..some of them liked running a posi instead of a spool in case one broke you didn't go into a wall. The biggest difference was the spider gear treatment and the cross-shaft was bigger. It was also in a box dated 1971.

Since the highest gears for a Dana 60 are 3.54..and I couldn't find an O/D trans to handle the power at the time...a set of 3.07 gears for a Dana 61 were modified to fit so I could go highway cruising. Took some machining of the gears and the carrier. There are aluminum bearing retainers to hold inner axle stubs in place. Had to weld/drill/tap a couple of bungs to housing to attach them. Attached to the axles are Spicer truck U-joint flanges with u-bolts retainers.

There's a 3/4" aluminum plate attached where rear cover would go with countersunk Allen bolts. Then a stock type (Muskegon heavy duty) cover attaches to it. The strut rods attach to that plate in the correct spot to keep camber change where I want it (nil).

The half shafts are 3.5"x .134" wall tubing with 1480 series U-joints. The outer stubs are from Tom's.

The rear spring is a 5 leaf Daytona with an added main leaf. Rear shocks are QA-1 adjustables. The trailing arms are stock. The strut rods are by Vette Brakes with heim joints.... custom made but awful close to what a C-4 would use.

Everything bolts to stock mounts. I made a front bracket and then I took the "sombrero" crossmember and sectioned the center and moved it back 3/4" to account for the adapter plate on housing. I also added a small "wing" to it while I was at it so I could drop 4 bolts through the welded in crossmember behind the differential and use it as a limiter. I figure the differential is trying to climb on a launch..so I could use the rear crossmember to do something other than just sit there.

I lost all the internal pics in a computer crash years ago..but here's one of it while in place. It looks like Vette stuff..just bigger! I haven't touched it since installing it about 13 years or so ago. If it blew up tomorrow I couldn't complain!

The top two pics are of a similar one we found out a Super Stocker and had Mike Dyer (Traccdog) restore years ago. It came out of a race car and had 4.88's and a spool...so it's similar but different. But you can get an idea of how it compares to regular Vette stuff. That thing used an incredibly heavy steel welded together rear cover and spring mount. But it worked too!

JIM

v2racing

Nice work! I like it and would love to have a setup like yours. I prefer the Dana 60 to the Ford 9". Very strong and uses less power to turn than the 9".

I'm hoping my super 10 will hang in there if I ever get the car together again. Body shop has had it for 3 years.

69ttop502

My gosh that thing is huge!

427Hotrod

LOL.....yep. Let's see...there's a Vette with an 8.2" ring gear....a Mopar with an 8.750" ring gear....a 12 bolt with an 8.875" ring gear, a 9" inch with 9.00" ring gear....and a Dana 60 with 9.750" ring gear.

It's a heavy combination back there for sure....but as I mentioned I haven't touched it since installing it (other than the front mount on the frame died. The poly bushing I used wore through the mount and looked like someone had used a hole punch). Interestingly I never felt any vibration or anything out of the ordinary since that little "wing" I added kept everything in place even though I was pulling wheelies and running 140+ MPH the weekend before I noticed it! Built a stouter frame mount and it's been fine.

JIM

427Hotrod

Body shop jail!

I think mine will stay like it is with the home garage paint that was on it when I got 20 years ago. Not a show car but has held up well considering what I do to the poor thing!

JIM

cv67

Love the way your car looks!
not many guys banging gears running those times everyone goes to auto bonus points for you

tpi421vette is knocking on the 8 sec door still using a stock 6 spd.
Just plain cool, cant even imagine what a car that powerful feels like

427Hotrod

Thanks. It would be a whole lot easier running an auto.....but I like having fun. I'm not trying to build the fastest thing out there....I want to have fun with it and banging gears is a heck of a lot of fun!

If I was trying to set records or doing serious racing it would be whole different setup or likely a whole different car. I didn't plan on going this fast originally...it was just a nice little convertible to ride around in. But you know how things morph into bigger things!

Good part is it's still a nice little convertible to ride around in and I can drive it anywhere without drama.

JIM

Jebbysan

Nice work back there......good old meat and potatoes thinking......go big and forget it.

Jebby