Farm Equipment - AC rat rod

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AC rat rod

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=155205
Printed Date: 20 Aug 2025 at 8:48pm
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Topic: AC rat rod

Posted By: d17brown
Subject: AC rat rod
Date Posted: 31 Oct 2018 at 9:00pm

considering a rat rod project with a 301 diesel turbo engine. Any idea what tranny might bolt up or be a good candidate for rpm and gear ratio?

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phil

Replies:

Posted By: PaulB
Date Posted: 01 Nov 2018 at 6:57am

Ratios will all depend on what size tires you plan on using. Here’s a bit to go on. I had a 69 Astro with a 2100RPM 238 and a RT910 with a 4.10 rear using 10.00X20 tires. It would do about 65 flat out. Then I got a 79 model with a 1900 RPM Formula 290 mated to a RT9509. That would top out a little faster. Now my 93 pickup with the Cummins and manual w/overdrive as ordered from the factory with a 4.10 and 233/85/R16 would go abot 85 with the motor turning about 2500RPM. You need to decide more of what you are planning on ending up with and do the math.

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If it was fun to pull in LOW gear, I could have a John Deere.
Real pullers don't have speed limits.
If you can't make it GO... make it SHINY