Got my gears changed from the 2.73's to 3.90's. Got to the track to try them out and didn't expect what I ran. Someone please shed some light on this for me.
Previous best: w/ 2.73's Shifting at 6k
60'- 1.786
330'-5.193
1/8- 7.965
mph- 90.52

new best with 3.90's shifting at 5700
60' - 1.74
330'- 5.065
1/8 - 7.84
mph - 89.83

first run shifting at 6k
1.74
5.08
7.86
90mph
1000' 10.27
93.54 I think that was off because my other 10.28 1000' run was at 101.39mph but I was shifting at 6500 and the short end didn't do well shifting there.
Car hooked good with no spinning stalled about 2k with these gears. I was sure expecting something different. Also when I got the chance to run a 1000' foot twice, I was taching 6k 30' before the markers.
26/8.5/14 MT Drag slicks
388 (stroked), H-beam 6"rods, srp9.7cr, afr195, 282s cam, airgap, full roller rockers, 750 speed demon.
Please let me know what I can do to improve times.

Thanks,
Shane

How is your timing set up? ie: initial, total advance, and all in by what rpm...

Rod

I'd say jetting and timing is in order. With your low compression and aluminum heads you might be able to get away with as much as 40 degrees timing.

What carb you running? How is it jetted?

timing is 16,35 in at 2800rpm
750 speed demon, 76,83 plugs read good
I agree that timing and jetting could gain me some time, but I ran a 7.96 with the exact same setup before with 2.73 gears. Everybody preaches gears, I just spent $400 gaining a tenth, I could have bought NOS for that price and gained alot more than a tenth. (venting a little) I'm just curious if the gain i got is tipical, and if it is why is everybody putting up with 3k at 60mph for so little a gain.

Shane

<BLOCKQUOTE>quote:</font><HR>Originally posted by sweems:
... Also when I got the chance to run a 1000' foot twice, I was taching 6k 30' before the markers.
26/8.5/14 MT Drag slicks
388 (stroked), H-beam 6"rods, srp9.7cr, afr195, 282s cam, airgap, full roller rockers, 750 speed demon.
Please let me know what I can do to improve times.

Thanks,
Shane

<HR></BLOCKQUOTE>

There are a couple of things that don't add up to me. With 3.90 gears, 10% comverter slip and 26" tires, you should be running about 110 mph @ 6000 rpm, yet you say your tach was at 6000 before the strip clocked you at 101.

From a previous post:

Got my car out today and ran it on a marked off 1000' on the street (really a 1000'). I didn't have any kind of time referance but it hit the shift light at 6k at the line in 3rd. I thought I had 2.73's but after running it today they have to be 3.08's. Because with my tire size (245/60/14) I would be doing 115mph w/ the 2.73 but 100mph with 3.08's.

Did you have 3.08’s or 2.73’s in your car? Did you count the teeth when you changed the gears?

When you ran the car before, did you finish the 1/8 in second gear close to 6000 rpm? Now you are midway through third at 4900 rpm or so. Changing shift points can make a big difference in your times, and if you make the same mistake twice in the 1/8, it makes even more difference.

There are a lot of factors that affect your e.t., such as weather, wind, staging depth, lane choice, traction, shift points, etc. If you use a 1.56 multiplier for the 1/8 e.t.’s, you went from a 12.42 in the 1/4 to a 12.23, a gain of about 2 tenths. A good converter would get you a couple more.

Calgary Drag Racing has an excellent article on analyzing time slips:
http://www.calgarydragracing.ab.ca/ Just click on Tech Tips

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1967 Nova coupe daily driver
406, 10:1, 224° cam, Q-jet, 700R4, 3465# w/driver
11.75 @ 117 thru the mufflers
18 mpg on the road

[This message has been edited by onovakind67 (edited 10-06-2002).]

First off with 2.73 gears those times are outstanding. Especially the 60' times - I really don't know how you pulled that off with only 2.73 gears and a 2000 stall.

After the switch you are running about a 12.2 1/4 mile ET at about 110 if I had to guess. A little more converter (like 3000) would really help those 60' times - if you can switch converters you could improve your 60' times to 1.6's IMO with some sticky tires. Remember a 1/10th reduction in 60' time usually means 2/10ths reduction in 1/4 mile ET.

I think with some more carb, valve lash, and ignition curve tuning you could pick up a couple more mph. Also, with some more suspension tuning your 60' could drop another full 1/10th.

With the 282s cam I wouldn't worry about going past 6000 R's if I were you through the traps, but I got my fastest ET's shifting at 6000 - 6200 RPM. I had my combo well past 6000 on the chassis dyno and even though the engine was running lean power didn't start to fall off until over 6500.

So I think you should be able to get your combo into the high 11's pretty consistently with some minor tuning and suspension tweeks.

I wouldn't put too much trust in those 1000' passes on the street, its really hard to know for sure unless you are on the track with a real timer and certified distances.

ono..., when I posted the time on a street 1000' I was running a 4 speed. I am now running a th350. With the mph calculator I figgured the 115 because it was 2.73's printed on the side of the ring gear, I just didn't think there was any way it would run that fast in a 1000', had to be marked off wrong (couldn't imagine that with a bunch of teens marking it). The 1/8th I ran before , a 7.96 in I was running through the traps at 4500 in 2nd.
eric68, the stall with the 2.73's would flash at 2700, I have some traction bars that will be here tommorow (CCE) even though it doesn't have a traction problem with the current setup.
I guess my biggest conplant is, it ran very good with 2.73's, and I could have took the 400 dollars and bought a bigger stall and traction bars, done some more tuning and improved my times without gears, and had a more street friendly gear. This also goes for a word of causion to those that think gears are going to make a big differance. Maybe if it wasn't a stroker and had so much down low it might have made a bigger diff. Is it possible that the clutches in the tranny are slipping a little causing more of a % for the rpm's.
Shane

see if you could barrow a 27 or 28" tire&lt;slicks?&gt; that would help out your RPM problem, but may hurt your 60'... but also you could launch at a higher rpm?

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My '68 Camaro (http://hometown.aol.com/Dougs68Camaro/index.html)
Doug G.
68 Camaro
406 ci.
13.5@102 W/ 2.73POSI.

...This also goes for a word of causion to those that think gears are going to make a big differance...

The same holds true for a lot of 'performance' parts, the legend and lore are often greater than the reality of the situation.

I would expect that with a 42% increase in leverage on your chassis you would see some traction problems. I think your 60's should drop at least a tenth with the new gears.
I have a similar situation with my 60' times, they really haven't improved much since the start, high 1.6's, but my e.t.'s have gone from 12.60's to 11.75 with other changes. Traction problems can be hard to analyze. What chassis changes have you made, like frame connectors, roll bar, etc?

Living with 3.90 gears on the street makes you appreciate the wonderfulness of overdrive trannys. If I have my 4.10's in rhe car, with overdrive it's like a 2.87 rear, and I have lockup to boot. When I put the 3.25's in, 2000 rpm is over 65 mph.



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1967 Nova coupe daily driver
406, 10:1, 224° cam, Q-jet, 700R4, 3465# w/driver
11.75 @ 117 thru the mufflers
18 mpg on the road

onovakind67,
I haven't made any changes to the chassis yet. I have some CCE traction bars that are going to be in today. I am going to put those on and see if it changes anythting. There not the slide a link there just the ss slapper bars. I do have to admit that with no more I have done to the car it runs good, I would just like to see a 7.6* 1/8th time.

Shane

You know, it is funny but I like my 3.31's, so I like my engines to really grunt, except for my junk 301 and old full house 409!!

If you build enough midrange grunt into your engine, it will amaze you how mild gears will run!! And you can still have halfway decent gas mileage, tooo...

Take a look at the old big barge, 383 and 440 street MOPAR's with their torqueflites and 3.23's and you will see what I mean... And the great big 455, Deuce and a Quarter Buicks fit in here too.. pdq678