Rebuilding Motor for 67 Mustang - Piston Question

[z3r0c00l]

I'm rebuilding the motor in my 67 Mustang. I believe it's a 302 from 1978.

The Block Casting is: D8VE 6015 A3A Z

I measured the piston diameter which shows as 4.020

I was debating ordering new pistons and am wondering if I should go for +030 or just clean up the cylinders a bit and install new rings. I suspect new rings will do the trick but one of the pistons did drop when I moved it our of the cylinder. It did not hit the ground but did fall and got hung up on the chassis somewhere. A very small nick in the top outer edge is noticeable. Funny, I learned to cover the cylinder holes for the rest with tape ever so lightly to hold the piston from dropping. Worked out well for the rest.

I have not measured the bore yet. The tool I have will likely only get the top of the cylinder. The cylinders are glazed a bit but I suspect they will clean up nice with just a bit of honing. I have a set of mild stones I can use.

The stamping on the top of the piston shows X1 and then what looks like an etched drawing of the relief with 27 at the top and 607 at the bottom.

The reason for all this: Lots of smoke was puffing out of the exhaust. I'm fairly sure I had an oil problem where it was leaking past the valve seals but I figured since I was replacing those I may as well clean up the entire engine.

For now I want to just clean it up and get it running well again. I suspect I'll want to find a period correct 289 if possible. I bought this car about 6 months ago from someone who also did not know the origin of the motor.

Thoughts,


Patrick

 

[rbohm]

two questions;

1: what is the piston to wall clearance? if it is with in reason you can just put rings in assuming the bore is also not out of round too far.

2: is there a ridge at the top of the cylinders? if so is it noticable? if you can catch your finger nail on the ridge, assuming there is one, then you probably should bore to the next oversize, in this case .030 if the bores only need cleaning up.

 

[z3r0c00l]

The cylinders all seem to average around 4.049 across and 4.0.59 top to bottom

No ridge at the top of the cylinders.

Seems like a lot of clearance.

 

[D.Hearne]

Well this isn't related to your question, but you do have a winner there in the block. It's basically a mex block with the smaller std main caps. Sumbitch weighs in at 136 pounds. Thicker all over. Should be able to bore it to .060 if need be. If you do buy new pistons, watch the pin heights, they range from 1.585 to around 1.620. The taller the better to acheive a zero deck clearance and higher compression. It's funny though you found that engine in a 67 Stang, I had one exactly like it a few years back. Same block, same .020 overbore.

 

[z3r0c00l]

Yeah. I was actually a bit disappointed when I researched the block but as you say I may be able to bore it a bit more if needed.

I figure I'll rebuild for now and build up a 289 while I drive the Mustang.

I suspect I'll just do a re-ring for now and see how that holds up.

It was blowing so much smoke I was wondering if someone was going to report me.

I also saw that the valve seals were all cracked and had sediment from the seals in the heads. Almost all seals were toast and so I need to work on the heads as well.

I should go in and get the block and the heads machined but as I say I'm really wanting to spend my time on a 289 build from the same period and so I'm going to see if I can just clean it up and squeeze a year out of the motor.

p

 

[D.Hearne]

I ended up giving mine to a freind who's into dirt track racing. He was impressed at the construction of the D8VE block. He'd never seen one. I had already found the weight info in Ford's 5.0 book, but he gave the block a going over and he said it's thicker everywhere over all but the Mex blocks.