B over bore

[MessingK]

Is there any issue with boring a standard late styled B right to .125 over? .125 and .090 kits cost the same, and .090 over is the minimum that I need to try and correct the wear and pitting in my block. The tractor will mostly be used for general light farm work, not looking to gain huge power for pulling.

 

[Mike M]

Always best to only go as much as needed. This will offer you another bore if needed and also help keep the cylinder walls stiffer. Bore it out and see where it ends up and then order the parts.

 

[jd_adict]

I agree with mike. also keep in mind that the bigger the bore the more compression and it will possibly be harder to start. nothin worse that a rebuilt engine that needs a bigger battery to crank her over.

 

[wilamayb]

I sure agree with the others. Only bore what is necessary. The amount of cylinder volume gain from boring any further over will never be seen or felt in power.

If power is what you are after just use new M&W style pistons. It will wake the old B up a bit. Have the head milled only enough to achieve flatness and have new valves and guides installed along with hardened seats. The B will surprise you with power. It's no trouble to get them a hair over 30 HP on the powershaft with all these parts which is more like 35 on the pulley up from the rated 28. Doesn't seem like much but it's a 25% increase...

 

[thdrduck]

Never heard of boring having an affect on the compression ratio.

 

[wilamayb]

No one here said it did. I said boring increased cylinder volume, not clearance volume. To increase CR you must decrease CV.

 

[gtx1967jewison]

I have a Late B with an over bored power block @ 5.06" & 13:1+ compression, the bone stock 6v starter & an old half-shot car battery whirls it over with Abandon. Faster than it ever did on 6 v with a standard bore.

 

[thdrduck]

Go up one more post. It was stated (not by you) that boring will increase the compression, I just commented that I had not heard of that before.