i'm thinking about building a "budget" v8 stroker motor based on the 400 "cleveland" motor. it turns out that if you offset-grind (stroke) the 400 crank, the connecting rod journals end up about the size of the 240 & 300 I6 - and the lengths of those also happen to be right for what i have in mind...

my question is, what kind of rpm can these rods handle? i've read some of the "max rpm" messages here, and it sounds like the rpm of these motors is limited by the amount of airflow you can get through the intake, rather than by the strength of the bottom end, right? has anyone here built a 240 or 300 I6 that could rev to 6000 or 7000 rpm? if so, is connecting rod strength an issue at these levels?

thanks

 

does anybody know if the 240 rods have the oil-squirter hump on the big end, and if so, are they on ALL years of 240 & 300 rods, or just on some years?

 

The limiting factor on a Cleveland style engine isn't the rods, it's the oiling system. For a stock system, I'd call about 5000/5500 rpm about max. For high rpm operation you have to bush the lifters on one side to boost the quantity of oil to the bottom end and that makes it a solid lifter only proposition. They do make restrictors that screw into the oil hole above the mains that restrict oil to the cam bearings and to the right side lifter galley. The feed to the right side lifter galley is the main problem because it robs oil from the rear main and subsequently #8 rod to feed the right side lifters.:-X23

 

[updated:LAST EDITED ON 29-Jan-02 AT 09:40 PM (EST)]A stock 240 or 300 rods will handle 6000 rpms with just some ARP rod bolts. If you want it to handle 7000 rpms you will need to have the full treatment ( ARP rod bolts, polishing, shot peening, etc. ).

As far as the oil squirter holes the 65-67 240 rods did not have them. The 68-74 240 rods do have them.

If you need some 240 rods I have 6 68 240 rods I'm selling for $50.00. If your interested email me at
Fordman75@webtv.net

Ted