I have been putting off doing some minor engine work (having far too much fun driving it), but the time has come.
I removed the head today and found quite a bit of carbon - easily cleaned off.
Bores all measured between 3.781 and 3.782 (side to side and front to back) with no measurable taper, no scoring and no ridge. Got lucky there.
Problem is I would like to install aluminum pistons while its down but if I go with +.030 pistons that would leave me with only about .001 clearance and I know that won't work!
So am I missing something here, or is there no way to install the aluminum pistons without engine removal and boring?
Thanks
schuh
To get an accurate piston clearance, you must place the new piston in the bore and measure with a long feeler gauge. You will need several different sizes,(.001,.002,.003,.004,.005 etc.
Insert the piston in bore, upside down along with a feeler gauge. If the gauge can be pulled out freely you have more clearance than that size gauge. Measure opposite the piston pin.
if you're desperate, it can be bored in the car, but I don't recommend it. I believe either Victor Page's book or the Ford Service Manual show this being done.
When I put aluminum pistons in my 25 block, each bore was a different size. I allowed the machine shop to start at 10 over, and incrementally they came clean at 30 over
.030 over pistons are made for .030 over bore size. You're OK. In fact your better than OK since you'll be close to .005" clearance which is good for aluminum pistons.
Richard
I guess thats what i don't understand.
What would be the actual measurement on a .030 oversize aluminum piston?
I think from your comment it would be something like 3.776" ?
Thanks everyone for the comments!
schuh
Bud, Richard is correct that , the clearance is generally built into the piston. A .030 piston would be 3.777 approx, give or take .001.
You will also take a little out when you hone the cylinders to break the glaze.
Bud, you won't have a ring ridge as the top ring comes to the top of the block, you will most likely find a taper wear down farther in the block. KB