I don´t race, but I was wondering anyway...

Do you shift at the same rpm in every gear?

I had a little test last week in the truck at work, and it goes a lot faster if I almost peg the tach in the first gears, and go to a lower shift rpm in the taller gears

Guess big diesel lowend torque has something to do with it, but anyway...

Shift RPM depends mostly on cam, carb, and headwork. Stock motors probably will run faster lowering the shift point in each gear. On juice I have started shifting mine at 6100, both shifts.

_________________
Official Cookie and Mater Tormentor.

Ok, thanks!

Every engine seems to have a different "sweet spot" for shift points, on the current stock 225 1 bbl with a small shot of spray, shifting at 4600 RPMs gets the fastest ET
DD

my motor almost fell flat on its face if i ran it up to 4500, and dam she was screaming at me so i was shifting at about 3800 was pretty good but my motor is bone stock and normally didnt run to well

_________________
Cuda Progress
The dart as it sits now

I shift at 42-4300rpm it just falls flat after that. I'm not sure why though. I have ported the head, headers, 4 barrel, mild cam and electroninc ignition. I thought it would rev harder after all those mods.

_________________

4.125" stroke.

D/W

_________________

If it ain't broke, fix it!

Phil,

I would suspect either cam timing too far retarded (degreed?) or ignition timing too far advanced. With those mods, you ought to at least get 4500-5000 outta it.

My 68 Dart with MP 0.436" cam, bone stock head, and 8:1 comp revs hard to 4600, and will pull OK to 5000. Timing, induction, and exhaust are pretty tuned up.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Wow! is this thread still around

Oh well, keep it going.

Actually, an advanced cam will make your top end go away.......

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

it will pull hard to 4300 and will rev higher but it looses power quickly after 4300 I did wind out first gear to almost 5000 once and it made a REALLY loud pinging sound. It will just stop accelerating in 3rd gear at 4500 rpm(105mph with the 3.23's, 90mph with the 3.91's). I was expecting it to rev higher with the 465 holley over the BBD but no dice.
I really need to get some timing tape and see what my total advance is. my inital is 11* and will still ping occasionally using 93 octane(compression is around 9.8:1).

_________________

...that sounds like a lot of timing for a /6. What's your total mechanical timing? I bet that's your issue.

D/W

EDIT: Duh, I need to learn to read your whole post before I respond! Yeah, get the tape or a dial-back light, OR, just use your tab scale as a guide to mark off 5 deg. increments on your damper. Crude, but it'll give you an idea without any real effort...

_________________

If it ain't broke, fix it!

I shift my race engine at 6200 RPM big cam big valves and injection....I have tried higher RPM but the car does not run any faster.


Dave M

Yep, I bet it's ignition advance. Most early dizzys I've seen would give almost 40 deg total mech with 11 deg initial - WAYYY too much. You want 27-30 deg total mech with that comp and setup. You could pick up as much as a whole second in the 1/4 just by recurving your dist and moving total mech down to about 28 deg. Been there...

Ed, you are completely correct. I misspoke - an advanced cam would limit upper RPM power. My mistake.

Dave, what's up with your bad self! Things are good in NC and I'm looking forward to some road racing in a coupla weeks.

Lou

_________________
Home of Slant6-powered fun machines since 1988

what inital timing are you working with?