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Old 03-21-2012, 09:30 PM
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Concerned about rearend ratio

Ok I thought I had it all figured out...350 eng..700r4--3.42 rearend. NOW the neighbor sold me a virgin 67 327 block for 50 dollars. Bam game changer. Now im putting the 327 in my 55 pickup.Reason... everyone has a 350 but since this is going to be a daily drive is the 3.42 rear to high for the 327. I know the 350 had more torque and would probably been the better choice but I wanted something different. Im running 15/235/75 tires. I guess there 28.5 inches. And what stall do I run. I could go with taller tire if need be. The 327 and the 700r4 cant be changed now.Money spent already So what do you all think. This is a total buildup so im taking pictures to post.Figured Id want until im further allow to post them. Its pretty torn apart right now. Oh ya carb...qjet..agian catching crap

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Old 03-22-2012, 12:33 AM
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Here's 3 rpm examples with the numbers you gave.... 1. 3:42 @ 70 mph with a 28.5" tire = 1975 rpm, 2. 3:73 @ 70 mph = 2154 rpm, 3. 4:11 @ 70 mph = 2374 rpm. So you see even a 4:11 rear will still be very highway friendly with a 327 and around town with the 3:06 first gear it will have ample acceleration.

The stall you choose depends on the cam but for a 327 daily driver I would try to keep it under 220 deg. Again that's up to you, how you want it to sound and just what kind of street manners you want. The bigger the cam the more stall you will need. A properly built Q-jet will work fine for your application.........good luck
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Old 03-22-2012, 12:41 PM
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Thanks for the reply..The reason for concern is due to my lack of knowledge on automatics.Question...If you use a 2000 rpm stall and a 700r4 has a .70 overdrive, then if your rpm is only 1975 at 70 mph, Does that mean you will never get into overdrive or get lockup. what is the relationship with the stall convertor and overdrive. I know stupid question. Right now the truck has 3.08 rearend and i figured that is way to high, I would have way to high of speed before overdrive kicks in. Is that right.
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Old 03-23-2012, 01:30 PM
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I still have 3.08s in my truck with a 350 and a 700r4 with ah 2400 stall converter and with the converter not locked up(just because still havent put a lockup kit in it yet ) it cruises at around 2k in O.D. and it goes pretty decent.with urs being a daily driverand gas prices soaring i wouldnt go any lower than 3.42s, i have a 3.73 rearend iv been puttin off installing just for that reason but will be puttin it in anyway with the tall gears it drops off as soon as it hits 2nd.also 327s still have decent tq there not just for rev power they putem in late 60s impalas with tall gears&powerslides! An still went decent .and btw dont b ashamed of running a Qjet i love Qjets i run 1 on a 350hp 350 now and always have on allmost my chevys ive had ,mpg&power when u need it cant beat em...
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Old 03-23-2012, 06:38 PM
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Well I went to the machinist today to insp my block after cleanup and noticed something that i should have caught earlier.Bad coreshift. So the 327 is out im not sinking money on it. Back to 350 block with 4 bolt mains. Everything else will stay the same. But Halftonhotrod what kind of mileage did you get with your 3.08 rearend. I might go with that since your 700r4 had no problem with it.
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Old 03-23-2012, 09:04 PM
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Msgt....you have to watch your engine combo if you're going to run a 3:08 or so with an OD trans. You don't want to lug your engine waaaay down in the hopes of getting better gas mileage. A 350 or any engine for that matter with performance upgrades will want to cruise in it's "sweet spot" which should be around 2200-2500 rpm, again depending on the upgrades.

When you run to low (numerically) of a rear end it will lug the engine and actually cause it to use more gas. To each his own but I would be very careful in choosing the ratio, ask your machinist what he would use in regards to your final combination. Show him the examples I gave you in my earlier thread. ....by the way, what branch are you an E-8 in? Viet Nam vet here, just wondering.
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Old 03-24-2012, 12:48 AM
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That was one area I was worried about was the lugging. The ratio of 3.08 rear would give me a approx. 1795 rpm at 70. With your input I think I will change to a 3.73 rear. I was debating that anyway , you confirmed it. I would like a 3.42 rear but I cant find one up here.I have found a couple of 3.73. And I was in the Marines, I retired in 98 with 22. Miss the troops..Damn good people. what branch did you belong to 327nut?
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