farmall Posted June 22, 2015 Share Posted June 22, 2015 Hey guys, I recently put a 4 speed in my 72 monte with 350 and 2.73 gears in 12 bolt. I really like everything about it except for taking off in first gear. On level ground, the engine lugs a little bit. When taking off on an incline, you really have to slip the clutch. I plan on driving this car wherever I want, including hours of continuous running on interstate. I am wondering what a comfortable RPM range is for that type of driving. I know that a 4.11 or so would be very fun but I am more interested in a having a good driver. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Leghome Posted June 22, 2015 Share Posted June 22, 2015 We have 3:73's in our 72 and seems to do rather well on mileage most of the time. Once n a while I get heavy footed though Quote Link to comment Share on other sites More sharing options...
farmall Posted June 22, 2015 Author Share Posted June 22, 2015 Is that with an overdrive transmission? Do you feel comfortable with hours of driving at 65 MPH with that combo? Do you know how many RPMS you are turning? Quote Link to comment Share on other sites More sharing options...
ripleydale Posted June 22, 2015 Share Posted June 22, 2015 I think the 3.73 might be a little steep if you're highway/freeway driving. I have 3.42's in my car with a 5 speed. My transmission has a 3.37 first gear so even with the 3.42 rear I have to come out of it pretty quick. You might not have as much launch with a Muncie or whatever else you might have in there. I remember putting a 4 speed in an old Monte I had with 2.73's. I loved it on the highway when you could punch down into 3rd and just blast by everybody. But you're right, there was a lot of clutch slipping for a smooth takeaway. Quote Link to comment Share on other sites More sharing options...
Vaughn Posted June 22, 2015 Share Posted June 22, 2015 I'm running the factory 3:31 gear set with a M20 and 402 Motor. Works very well on the highway up to 70mph, after that, I get the typical big block drone. Quote Link to comment Share on other sites More sharing options...
monte70car Posted June 22, 2015 Share Posted June 22, 2015 Keith I have a set of 3.08 gears in my garage, I can throw them in the truck for Carlisle. Quote Link to comment Share on other sites More sharing options...
MCfan Posted June 22, 2015 Share Posted June 22, 2015 It depends on how you intend to drive your Monte, but you don't need to go higher (numerically) than a 3.31 to get an acceptable launch with an M20 and a 402. And, with a 28" tall tire (i.e. 275/60-15) you will only be taching 2800 at 70 mph in 4th gear. You can obviously get a quicker low end if that is what you want, but you will pay for it on the top end. Your choice ... Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted June 22, 2015 Share Posted June 22, 2015 I had 3.31 gears in my old 12 bolt, It pulled around 3200 RPM at 75mph with 245/60/r15 tires. This was not a 4 speed though, it was a TH350 automatic. Quote Link to comment Share on other sites More sharing options...
Leghome Posted June 23, 2015 Share Posted June 23, 2015 The 350 ran 2600 RPM today coming to PA at 69 MPH Quote Link to comment Share on other sites More sharing options...
farmall Posted June 23, 2015 Author Share Posted June 23, 2015 Did it feel comfortable Larry? Were you concerned that it was too high for a long run? I'm used to my diesel truck which runs about 2000 at 65. Im just not familiar with what is too much for my 350. I wouldn't thing 2600 would be too high. Quote Link to comment Share on other sites More sharing options...
LS5 Posted June 23, 2015 Share Posted June 23, 2015 I am running the exact same as Vaughns.......... 331's in the 12 bolt with my 402 and M20 4speed. Up to 70 miles an hour and she drones looking for another gear. but 70 for me and she cruises just right. Darren. Quote Link to comment Share on other sites More sharing options...
Leghome Posted June 23, 2015 Share Posted June 23, 2015 I was comfortable with it but after a while even with all of the sound deadening I installed this past winter the drone did get annpying Quote Link to comment Share on other sites More sharing options...
John S Posted June 23, 2015 Share Posted June 23, 2015 I have 3.31 with M 20 and 350. My tach must be off because I run according to the tach, 3100 at 65 MPH with 235 70 15 tires. The posts I have read with same rear end run lower RPM. Could tach be off? I was going to hook up temporary tach to double check. But does 3100 at 65 with 3.31 sound right? Anyway I like the 3.31's. John S Quote Link to comment Share on other sites More sharing options...
monte70car Posted June 23, 2015 Share Posted June 23, 2015 The RPM's being different then other could be the tire size. I turn 1950RPM's with m 700r4 trans and 2.73 gears on a 26" tall tire. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted June 23, 2015 Share Posted June 23, 2015 my tach is off too John at 70 mph you should be turning 2780 rpm's at 65 mph you should be 2580 rpm's play with this John http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php Quote Link to comment Share on other sites More sharing options...
bigscaht Posted June 23, 2015 Share Posted June 23, 2015 3:42 would be cool also......wish i had a fourth gear Quote Link to comment Share on other sites More sharing options...
John S Posted June 24, 2015 Share Posted June 24, 2015 Thanks Sam I thought something wasn't right with 27.95 in diameter tires. I think I have a 71 tach in the car the redline is 5000 I thought on a 70 350/300 redline was 5500. Am I right on this? John S Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted June 24, 2015 Share Posted June 24, 2015 that doesn't matter I've seen both tachs in small blocks and big blocks Quote Link to comment Share on other sites More sharing options...
VETTEWITHLEGS Posted July 14, 2015 Share Posted July 14, 2015 Just my .02 cents, my old '69 vette,(I know, it's not a monte!) had a M22, then a M20, 3.23 rear, 396 BBC. 0-70 MPH and never got over 1,500 rpm. would burnout in 1st and 2nd, bark in 3rd, and do 140mph (a little faster RPM) just before 4th gear shift point. Rear gear is the key, IMHO. You should have plenty of torque with a rear gear 3.23 or taller. I got 15mpg on her hwy and 12 around town. tires were G 70s or 60s, 15". Quote Link to comment Share on other sites More sharing options...
farmall Posted August 1, 2015 Author Share Posted August 1, 2015 I just got my car back after having the 3.08 installed. Seems pretty good. I only drove it a mile home so didn't get to evaluate it much. Looks like a good excuse for a drive tomorrow. Quote Link to comment Share on other sites More sharing options...
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