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RPM cruising too high

Ron ORon O1984/2010 IM, B.C. Canada
We finally received some nice weather, so I took advantage of it and went for a drive up in the mountains. Some of the drive was on the freeway, where I cruised along at 70 mph. At this speed the tach shows 3800 rpm.
Is this too high? If it is, what is the optimum cruising rpm (if there is one).
My R&P is 4.12, and 4th gear is 0.82
My tires are 185/65-15
Using a rpm/gearing calculator, with my set-up I should be turning somewhere around 3300 rpm, which is more to my liking. I realize that there will be some variances, but 500 rpm seems high to me.
The engine is coming out soon and the tranny will also be taken apart (growling sound when I take me foot off the gas and slow down), so this will be an opportune time to do some gear changes - maybe a switch to a 3.88 R&P?
thanks
Ron

1959 Intermeccanica(Convertible D)

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Ron ORon O1984/2010 IM, B.C. Canada
We finally received some nice weather, so I took advantage of it and went for a drive up in the mountains. Some of the drive was on the freeway, where I cruised along at 70 mph. At this speed the tach shows 3800 rpm.
Is this too high? If it is, what is the optimum cruising rpm (if there is one).
My R&P is 4.12, and 4th gear is 0.82
My tires are 185/65-15
Using a rpm/gearing calculator, with my set-up I should be turning somewhere around 3300 rpm, which is more to my liking. I realize that there will be some variances, but 500 rpm seems high to me.
The engine is coming out soon and the tranny will also be taken apart (growling sound when I take me foot off the gas and slow down), so this will be an opportune time to do some gear changes - maybe a switch to a 3.88 R&P?
thanks
Ron
Ron ORon O1984/2010 IM, B.C. Canada
Thanks for the info, Bob. I'd much rather have your combo, as mine has a large gap between 3rd and 4th. Luckily, it's not too noticeable with my 2265 engine.
Using my trusty rpm/gear calculator, your .08/3.88 combo should rev slightly higher than my .82/4.12.
I used a GPS for my mph. At 70 mph my speedo reads 75.
FM Former Member
Ron, I know I have a 3.44 final, and I am pretty sure the gears are stock swingaxle. No, it isn't noisy. Like Larry said, if it isn't set up right then it will be noisy. I am at 2500 at 55 and about 3000 at 70, like Larry says. I think 3500 is around 80-85, nice speed for interstate driving, right in the torque band.

4th is a little tall sometimes depending on speed, I use 3rd if going 50 or under, or pulling a hill where the speed limit is lower. 55 and up, 4th gear unless I need to spank one of those "ricer" boys!
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