Ford 950 Overbore kit

[740]

Looking for an opinion from some Ford experts.
Just purchased a 1955 Ford 950 that appears it had new sleeves and pistons installed, in my opinion less than 200 hours ago. There is no wear in the cyls. what so ever. Oil pressure was 70 to 80 psi. Compression 130 psi before I tore it down, on all cyls. The reason I pulled the motor is because the rear main and front crankshaft seal leaks like a sieve. On the dyno, it has 48 HP. I was thinking of installing the overbore kit to gain a few more HP before I knew what the condition was. My question is how much will I gain from 3.90 to 4.00 bore. Since my sleeves and pistons are like new, it doesn't make much sense to replace them. How many .001 can we plain off the head safely to gain a few moer HP? I want to use this tractor for pulling. I welcome your advice.

 

[souNdguy]

why not stick a 192 in there.

other options are heads with smaller combustion chambers for more comp ratio.

70-80 oil psi? wow.. over 55 once warmed, and 60 cold would make me wonder....

hopefully Dean will post. he's had some conversations about lp machines and parts for higher comp ratios..

soundguy

 

[740]

A 192 would be great but they are about as easy to find as hen's teeth.

 

[Matt L]

I milled .080 off my 134 head. Then ported it and did a 3 angle valve job. It really woke it up.

I still only had 110psi on the best cylinder. My engine is pretty wore out tho.

 

[PitCrew]

I think the 172 gas head is about 80ccs, I don"t have my notes handy. I had mine milled to 64cc. I have mine overbored to 4.160, same as a .030 over 192. On a 4" 172, with a 64cc head, the stock .062 head gasket, and assuming the piston is .025 below the deck. you should have close to 9.92 compression. Is this a dedicated puller?

 

[740]

Dedicated puller, I guess so. Pulling since 1998 with a 740 Ford, with a 172 engine installed and a Sherman over and under. Developes 52 HP. This tractor has over 400 wins and 60% are first place.

Reason for building another Ford, our club began cement pulling about 4 years ago along with the transfer sled and dead weight pulling. We run 13.6 x 38 on dirt and 23.1 x 26 on cement.

I am tired of switching tires. That is why I am building another Ford. I will be 73 in 1 1/2 months so it is time to stop switching tires. The 172 in my 740 developes 52 HP. It has a 134 head installed and the overbore kit installed. I would like to get equal HP out of the 950 with the 3.90 kit since it appears to be like new. I would like to take .200 off the 172 head but don't know if I will have problems holding the head gasket.

What do you think? I have been advised that I could use studs rather than the head bolts and torque the nuts on the studs to 90 ft. pounds. What do you think about this?

 

[PitCrew]

My compression is 11.5 to ! I think we took .120 off the head, and installed bigger valve. Didn't much porting but alot of bowl work.

4.130 bore, stock stroke, a bullet cam, real close to 70 HP. I used the bolts, and ended up blowing the head gasket between 2 and 3. I changed out to 7/16 (early motor) arp studs from a SBC set. Really doesn't help to over torque, I think mine are at 70 lbs, same as head studs in a SBC. Heat cycle it, and re torque, no problems yet.