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Old 09-06-2006, 08:31 PM
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need help deciding on using 700R or turbo 350

I have a 38 Chev slowly going together, 350 sbc 8.5/1 compression, 204/214 cam, Edelbrock manifold, Holley 600 and 10 bolt GM rear end with a posi 2:73 gear.Chassis is done and I'm putting in mounts.Everyone says use the turbo 350,but I want to use a stage 1 700R4.My problem is I do not know if the dif gear ratio is too high to use a 700R.Will I be doing 90 at idle speed?Can I pull a gear that tall?.The 700 should get off the line easier tho. Which trany???
Thanks Cisco.

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Old 09-06-2006, 09:38 PM
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I would probably go with a 700 in this case, although you would be cruising pretty good with those rear gears and OD...
As mild as your motor is, if you properly setup the lockup converter, it will be fine in OD, even at very low rpms, say 1600-1800.
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Old 09-06-2006, 09:53 PM
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need help deciding on using 700R or turbo 350

Any ideas on rpms at 60 mph with a 28 to 29'' tall tire with a 700R and a 2:73 axle? And yes I want mpg out of this car, wanna drive it and it's all rural or highway here. thanks Cisco
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Old 09-06-2006, 10:42 PM
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Looks like about 1400 rpm at 60 mph. 1600 at 70 mph.
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Old 09-06-2006, 11:27 PM
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need help deciding on using 700R or turbo 350

crap, can I cruise that low without jerking the U joints out? Guess I'll have an excuse to drive 80. ;O) Cisco
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Old 09-06-2006, 11:30 PM
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need help deciding on using 700R or turbo 350

how did you figure out the rpm? Cisco
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Old 09-06-2006, 11:41 PM
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Quote:
Originally Posted by TheCiscoKid
crap, can I cruise that low without jerking the U joints out? Guess I'll have an excuse to drive 80. ;O) Cisco
AS mild as your combo will be, it will cruise fine at 1600 rpm, however you will want the converter to unlock under any load conditions, this will raise rpm by about 300-400 rpms usually and that will put you where it needs to be at light load.
You will want to use a vacuum switch for this.
I would use a 4th gear lockup with a vacuum switch, see how that works and them possible a speed sensitive setup added in like B&M's lockup kit.

I used a 350 Chevy in a 72 Camaro with a 6 speed for a couple of weeks, it would run along OK at 1600 rpm with a cam very similar to yours.
You will also want a very good low speed carb or EFI. A Quadrajet would work well.

I figured RPM using a calculator I have on an auto program I use.
You can find calculators online to do this, some are downloadable, others you use online. You could make a spreadsheet to calculate it for you.

Tire size, rear ratio, trans drive ratio, mph, and engine rpm.
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Old 09-06-2006, 11:54 PM
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need help deciding on using 700R or turbo 350

Thanks for your time Jake !! Is a Holley 4160 speed sensitive? Cisco
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