What Shift Rpm

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DART340

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Right now I shift at 6000, do you guys feels this is about right or? My combo is 408 magnum motor, scat forged crank, forged h-beam rods, forged 9 to 1 pistons, 501/513 288/292 roller cam, edelbrock magnum heads, m1 single plane w/750 quick fuel, paxton supercharger w/ 16lbs boost, turbo action 727 w manual valve body and 3400 stall, 391 gears and 315/60/15 m/t drag radials all in a 72 swinger
 
Im far from a pro in this area so I'm interested in seeing what replies you get.

To my untrained eyes I see odd things in the combo. The intake is made for higher RPM, those tires are very tall and the RPM range 3400-6000 very narrow.

My guess is the cam spec says 6000 or a bit more.... I don't know.



Obviously a lot of money is into the build... Have you had the car on a Dyno?
 
Is that cam hydraulic or solid, my guess is it's hydraulic based on those specs. Are the heads ported? You got flow numbers? You need a bigger cam and carb, 950 or so and that engine will probably like 7500 or so. You need to experiment and see what it likes best, then gear it to go through the traps at the best shift RPM.

You also didn't say what the car weighs or what it runs. How tall are those tires?
 
The first time the car was together everything was the same except factory magnum heads, 12lbs boost and 275/60/15 mt drag radials. My wheel spin was terrible. 2.0 60 ft 11.46 time 122 mph. So I am gonna try larger tires with the same 3.91. No dyno on the new setup but with the 12 lbs and stock heads it made right at 670 hp
 
Your traction issues are probably more than tires... I pull better 60' times on my E70-14s. Sounds like you need to get your suspension set up.


Guitar Jones... "How tall are those tires?"

A 315-60-15 is getting close to 30" tall.
 
I am running 3" inset 3200 lb superstock springs, coilovers, subframe connectors, cage and 90/10 upfront with /6 torsion bars, pinion snubber
 
I believe the suspension was working fairly well but tire limited. It builds large amounts of torque right off idle. I can dig up my old dyno pulls but it was something like 590 ftlbs. This was at 12lbs now it will be 16bs
 
You failed to answer whether that cam is a hydraulic or solid and are you running aftermarket rocker arms and dual valve springs. What we're getting at is whether you're going to be "valve float" prone or not.

Terry
 
Your traction problems are bigger than worrying about what RPM to shift at.

Why would you have coilovers and super stock springs?
 
Sorry I logged off last night. Its a hydraulic cam, crane roller rockers and the edelbrock springs that came with the heads
 
Okay. I did this with my SRT-4. Run that car at your local dyno tune shop, get a print out of max RPM n Torque. At its peak in power or inbetween power and torque is where you want to be slapping in gear or shifted shifted. I just love teating and tuning. That worked for me guys... my SRT-4 was no Dart, Barracuda or Duster but it was dialed in. No longer have it. Tuned it at this guy Jay's shop called N2MB in South Plainfield, NJ but heard he move to Florida. Good luck.
 
I'd take her to at least 6500. With those hydraulic lifters she may get into valve float as they pump up so be careful. Pay close attention tho to how the engine feels and whether she starts to nose over, it'll be like she's kind of running out of steam. With the adjustable Cranes why not go with solid rollers and add 1000 RPM.

Terry
 
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