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charley norton
05-09-2005, 07:58 AM
Does anyone know what constant rpms is safe for a 289. I have an automatic with 373 gears (I think) and at 65-70 mph, my rpms are over 3000. Seems like a lot for a long trip.

63 R2 Avanti

Mike Van Veghten
05-09-2005, 10:31 AM
How much over.....3000? And how far?
3300/3500 for 165 miles (then the turn around to home, help?
Actually a shot of about 6 or 8 of those miles was nearer 4000 rpm. Minus stop for the potty and breakfast break.

As long as the engine's (drivetrain) in decent shape, shouldn't be a problem.

Sonny
05-09-2005, 11:11 AM
quote:Originally posted by charley norton

Does anyone know what constant rpms is safe for a 289. I have an automatic with 373 gears (I think) and at 65-70 mph, my rpms are over 3000. Seems like a lot for a long trip.

63 R2 Avanti


Charlie, I'd recommend that you look for a rear end with 3.54 gears, max. I have 3.54s in my Lark and I love it. Like I was just telling studeclunker, the 3.73 is fine if you have a 3 speed w/OD, but a tad hard on the engine if you have an automatic. A lower ratio, 3.31 or 3.54, will give you much better fuel mileage, a decent pull on the hills and doesn't work the engine unnecessarily. Red line is about 5200 rpm for your engine, running it at 3200-3500 around town should be fine, long trips is where I think that you'll be at a disadvantage.

While you're running that 3.73, the engine should be able to handle it for some time with no problems, but as it's a mechanical device, common sense tells ya that the more you use it like that, (or put it under heavy stress), the better the chances are that it's gonna wear out/break at shorter intervals. Stude engines are tough, no doubt, but no sense hammering it if you can help it.

Sonny
http://RacingStudebakers.com

charley norton
05-09-2005, 01:40 PM
I kinda figured it wasn't good for it. I wander if gear benders has a setup for the old BorgWarner tranny. By the way Sonny, I richened the mix on my carb and it helped noticeably.

63 R2 Avanti

Roscomacaw
05-09-2005, 02:06 PM
ALOT of Avantis were built with 3.73 axles and NO O/D. The engines can take it in my opinion. Of course - as with ANYTHING - more use means more wear. Common sense would tell you that. Good tune and good oil and you'll go a long way with that engine. Those higher number axles are FUN away from the stoplight - but they aren't much for delivering mileage.:( That's where the flexibility of OVERDRIVE delivers an edge![:0]
I'm with Sonny as far as the 3.54 ratio goes. It's the best stock compromise for performance and economy behind a non-OD tranny;)

Miscreant at large.