Hello, fellow /6 racers. I've been running a '70 Duster occasionally for several years now. It is "street/strip", 225 bored .060", stock bottom end/oiling system (Moroso adjustable sprg., 65 PSI), Comp cams 264 deg./.440" lift, if I remember correctly, fully ported/polished/blueprinted taper plug head, stock dia. (backcut) valves, 9.14:1 compression, stock Chrysler Elec Ign (orange box, light adv. springs), Accel S/S coil, Clifford Research full length headers, Offy 4V intake, modified/tweaked Carter 400cfm carb, 4294S, stock Carter fuel pump/lines, Nippon-Denso starter/alternator/A/C compressor (yep, got air conditioning!), dual snorkel functional "ram induction", flex fan, mildly tweaked stock 904 trans, 2.74:1 first gear planetaries, 3.23 open gear 7.25" rear-end.

Best time to date is 15.70@90mph on 22" drag tires/open headers (although the open headers seem to make little difference). This seems to be about the limit for this combination. Also, the car always seems a little "flat" off the line, doesn't stumble or anything, just seems a little dissapointingly sluggish, then it picks up and shoots off like a rocket at about 100 feet out, perhaps. It honestly feels like a turbo is spooling up or something. 60' times seem to consistently hover around 2.42 sec. Tire spin on the racing tires is not a factor, not even with an open differential. I started out with the stock converter, then I installed a TCI "breakaway" 10.75", "2600-2800rpm" unit which actually stalls behind the /6 at between 2100-2200rpm, if memory serves correctly (no tach in car). I now wish I had chosen a little bit more "aggressive" converter.

My questions are, for anyone who would like to share their opinion, what converter would work best with this combo? What type of converters do some of you with similarly built cars run? Also, I have been considering for a while now adding a small shot of nitrous to pick things up on the top end. The bottom of the motor is basically stock, as stated, cast pistons and I built things a little on the loose side to get a few extra horses. I'm thinking a "top shot" right through the carb for simplicity, plus I have no room for a nitrous plate. Will I end up scattering the motor, or can I safely add a very small shot without inviting major disaster?

Thanks,
"DW"

P. S. - Are there any planned /6 events or get-togethers going on in GA the rest of 2003? I usually run the car at Silver Dollar raceway and occasionally at Atlanta Dragway. I saw a /6 contingent once at Atlanta, but I wasn't running that day.

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If it ain't broke, fix it!

Dennis ther is a Mopar weekend at Paradise Drag Strip in Calhoun Ga. the last weekend in Sept with a Slant Six shootout points race try to come up its about 60 miles north of Alanta at exit 317 on I-75. Charlie Schmit has had some god luck on a basic stock 170 moter with nitrios might give him an email or ask for him on this site he browes often. Thanks Possum Parker







its in there Bagel

I'd get something in there that will stall at at least 3000. That is some BIG MPH for a 15:70 car. A good converter and some 3.91 gears and that thing should run high 14's easy.

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Official Cookie and Mater Tormentor.

I'm with Dennis here. Get a 2800+ RPM converter - 9.5 or 10" at largest. A good 10" will stall to 3000 and almost drive like a stocker until you get into it. Midwest converters or Continental Converters make good units. Any stall speed rated for a V8 will give you much less on a Slant (typically 25-35%), as you found out.

Make sure to get the alloy pump drive hub too - the plain steel ones will crack/break even on a medium-built Slant.

Welcome to the site!

Lou Madsen

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Home of Slant6-powered fun machines since 1988

2.4 60 ft time is kinda slow, there must be something besides the 3.23 gear and tight converter that is holding this combo back. May-be the distributor is "over advancing" with that one light spring.

The good news, the soft start helps keep the 7 1/4 alive!
You get the car to leave hard and the times will drop like a rock. (and the rear may scatter the spider gears )
DD

I think I kept the factory light spring, removed the heavy one and replaced it with a super-light Mr. Gasket one. I have wondered if my curve is where I need it to be. I guess it's just trial and error since I don't have a distributor machine. What do you think, maybe try two factory light springs and take out the super-light one? One thing, under no-load, off idle like coasting along at a low rpm, the engine seemes to break up and mis-fire a little. I wonder if that should be telling me something. I have just assumed the carb is a little lean under high vac/no load.

"DW"

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If it ain't broke, fix it!

I'd try a looser converter and more gear, either a 3.55 or 3.91. I'd think if you start searching while the 7 1/4 is healthy, you could find an 8 1/4 rearend for the car. It would probably last forever unless you put a transbrake on the car.

I have done lot's of distributor curves over the years and having a staged spring system helped "street / strip" cars a lot.
Let's talk through a distributor advance set-up, assume the initial timing is set at 10 degrees BTDC (advance)
In general, you want one real light spring, (primary spring) set so it returns the weights back to zero at your idle speed. (a solid return in the slots, no flutter or bounce at idle) If done right, the mechanical advance will start-in right off idle. Let the light spring do all the work for about 15 degrees of advance, that will come-on fast depending on how light this spring is. You should see 25 degrees of advance pulled-in by 2000-2200 RPMs. (initial + mechanical)

Now set-up a second spring to kick-in and slow down the advance for the next 5-7 degrees. This is done by having a long loop on one end of the spring, this second spring does no work until the second spring bottoms-out in it's loop. I like to have the second spring pretty stiff so I can use this spring to limit (set) the total advance at the "shift point" RPM. Said another way, don't let the weights hit the ends of the weight slots fast and hard, have a stiff enough second spring to slow the advance to near nothing in the 30 -34 degree total advance area. If the springs are so light where the weights fly-out to the ends of the slots to stop, the weights bounce off the ends of the slots and cause timing flutter & high RPM mis-fire, that may be what your current set-up is doing.

All this is pretty much what is already built into factory distributors, yes, those factory engineers spent weeks, even months of time with engines on dynos working-out the advance curves. A performance SL^ running higher compression and good fuel can usually take faster advance then the factory came-up with. (Lighter springs) I can usually look through a few factory distributors, find the one with a big loop / stiff second spring, swap-in a lighter primary spring, set the tensions so these "hit" at the right moments and thats it, done.

Truth is, that for a drag car or other high RPM Slant, it helps top-end HP if you can pull some total out of the curve near redline. A spring driven distributor will not do that and a few other nice things for us, that is why todays engines have a computer adjusting the timing, many times per second.
DD
http://www.dutra.org/doug/draft-webpage ... ibutor.htm

Wow, and I always TOSS the big, thick spring!

OK, it's settled, next test and tune I'm taking a spare distributor and a bunch of different springs and swapping them around. If my times pick up, I have you to thank... Much easier than swapping converters, too (but that's the next big job).

Thanks,
"DW"

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If it ain't broke, fix it!

By the way, V8440, I'm staying with the 7.25, at least untill I start having problems. I'm definitely staying with the 3.23 in either case. Car started out as a 2.76, and believe it or not, even though I'm wringing the $#*+ out of it from time to time, it is still a fairly regularly driven street car with air conditioning that sees interstate use. The super-short tires I run at the track help out a lot, they get the revs up actually a little better than a 3.55 would on "normal" height tires, anyway, if I remember the math I did on it.

Problem with the 8.25 is the big bolt pattern, I have some custom 14X7" small BC ralley wheels that I run on the rear AND I like the light weight of the teensy 7.25 I'm sure something will give eventually, I'll probably end up putting in a heavy/overkill 8.75", but that'll probably help plant the tires if they ever get to where they want to spin...........

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If it ain't broke, fix it!