Piston Rings Don't fit? 1980 Ford 302

[Russell]

Working on my Dad's 1980 F150 302 4x4. It had low oil pressure and the ring gear was so warn the starter would not engage any more. I would rather pull the motor than the trans and it about time for a quicky rebuild. We just wanted to replace the rings, bearings, oil pump and timing chain.

The first set of rings they sent the wrong box. They sent 30 over rings well their was no gap after a bunch of filing we figure it out. The next day we got the "right" rings 4.000 STD Sealed Power E251X. There was about an 1/16" gap. Put one of the old rings in it had about an .028 gap I think the upper end of the spec was .020 gap. Far as I know this engine has never been apart.

Anyone ever had this problem? Susgestion? Don't want to overbore.

[BBR]

Get some std bore file fit rings maybe?

[Russell]

Get some std bore file fit rings maybe?

who makes them? who sells them?

[Beagle]

source from a local engine rebuilder is what I do. Hastings has a dealer list, if you are low bucking it. IM me your zip code, there should be something close by.

Did you say 1/16, like .0625? Time to get a bore gauge and find out for sure what you have!! Even a snap gauge and 20.00 6" caliper from HF will get you close.

A .028 top ring gap on a 4.00x bore is probably okay. If you were gonna hit it with Nitrous, I'd say give it that much anyway. It's just saying your bore is probably tapered and worn at the top. You will get different measurements probably if you push them further down the bore.

The first ring package probably has a -030 on the part number, I'm not sure what the story is on the second set - does it look like somebody filed them already? That's crazy!

[Russell]

Yes over .060 the two biggest fingers combined on the feeler gage did not fill up the gap.

This motor will never see N20 its a farm truck I bet it never goes over 4k rpms If the ring were removed with care I would put them back in but they are no longer useable.

I have 6" caliper but not in the same city as the motor. I know I should buy a micrometer and bore gague just don't want to spend the money.

I am sure there is some taper their is a small ridge but I don't see .030 to .040 worth.

The rings did not look filed, we had 3 sets of rings -30 and two sets of STD rings.

PM sent

[Beagle]

take a look at this drawing, it's a great explanation of how a little growth in bore makes for a great big difference in ring gap:

http://www.hastingsmfg.com/ServiceTips/ring_gaps.htm

[milner351]

That's a great drawing.

[Russell]

That is a great drawing, but the gap on the old ring was .028 inches. the new ring was .060+ so the gap on the new ring was more than twice the size of the old one, do ring grow over time? Either the ring is small or the hole is big. It was "running" before.

[anotheridiot]

If you dont have a caliper with you, can you tell us the gap between the piston and the cylinder wall with a feeler gauge? Maybe that would help diagnose the problem. Were car and truck blocks the same bore on that engine? I am really a chevy man, but know there might have been some changes to bore and stroke between a car and truck motor, just cant find any info on that, all I see is the bores were all 4.00 inches.

[Orange65]

File fit standard bores or get a third set to see if they have the same problem at the "correct" set you have. I also think I would try another name brand. .062" is way too much gap.

[Beagle]

I get what you're saying, huge difference. Without measurements everywhere, I can't really say a lot more than beats the hell out of me, I've had to file standard top rings in a standard bore with 100k on it... that is a mess! Where were the gaps taken at? Same depth? I'm guessing you squared them up with a piston... same location down the bore? I need to go out in the garage and check some junk anyway, but the stuff I stuck back together moons ago was .018 top with it down just below where the top ring "tops out" in the bore and I wanted just a bit more.

No faster than I move, I can probably send you a ring from a set I have here if you want to check it. How big of a hurry are you in? With the drawing I could understand a .06x top gap if you were worn .012 , that's .006 per side, not a lot. You can feel it on the ridge... I have zero idea where a .028 turned into a .06x plus on a replacement set, though. That sounds screwy... push them down to the bottom of the bore and check them again?

[Russell]

Dad was checking the gap about an inch into the hole. I can see the gap being big b/c of the taper but it should be big on the old ring also. I ordered a standard set of hastings rings this will be set #4 if they don't work, which I will not be holding my breath. Its going to $$ to find the problem and $$ to fix. I might look for another motor or short block.

[OldMachinist]

Before you get carried away, do as beagle suggested. Put your .028 ring in cylinder 3 1/2 inches down from deck and push it to that point with a piston without rings installed so it will be square. I have seen blocks with a seemingly small ridge barely clean at .030. If you can feel wear it really needs bored.

[Scott Liggett]

I did the rering and new bearing rebuild on my 454. Worked out great. I just dingle ball honed the cylinders, polished the crank, and had the rods/pistons resized and cleaned. Threw it all back together. Got it all from my machinist cheaper than anywhere else.

[Caveman Tony]

Mis-labeled box of rings?

Crazier things have happened.

If properly boxed/labeled, then there is some serious wacky bore taper goin on, and def needs a proper measure to know EXACTLY what yer dealin' with.

Borrow a bore gauge somewhere?