I have the motor out of my truck, and the original plan was to put a LTD 302 in it, but I decided to take the heads off and look at the bores before I started pulling the motor on the LTD.

The motor had low compression, and would leak oil out of the airbox after about 20 miles of driving(ick I know) so I figured I had a broken ring(s) or a hole in a piston, well everything in the rotating assembly is fine! I did measure the cyl. bores, and they are all at about 4.004, which according to the service manual is the high limit of the tolerance.

The choice I have to make is weather to still pull the 302 out of the LTD, and "hope" it all bolts toghether, or re-ring this one.

If I re-ring this one, the plan is to hone each cyl bore 5 strokes, buy the speed pro 4.005 moly ring kit( 5 thousands over rings) and cleavite77 .001 undersize rod bearings.

None of my bores measure egg shaped, and I did not hear any piston slap when the motor was running and cannot see any scuff on the piston skirts.

Does this seem like an ok route to go? As long as this motor makes it 50k i would be extreamly pleased. Any feedback good or bad would be appricated.

thanks

 

i think thats a good plan , dont forget your freeze plugs , cam bearings and such while out make sure you get the right cam back in this truck too

 

TTT

To The Top (built in filter makes you type 10 letters)

 

I would have or check the crank journals before buying any bearings. It may need to be turned down for a good clearance fit. Remember your oil pressure depends on the clearance of the rod and main bearings. The more the clearance the less pressure you will have and that's what makes the life of the engine.

 

Use regular iron rings. Moly rings want a perfect bore to seat.

 

Thx for the great tips Dstrick32 and Bdox!

 

ok, I am a part time metalurgist so to speak, so I was laying in bed last night thinking about why Moly rings would want a perfect seat.

Molybendium or Moly for short is a alloying agent placed into gray or ductile Iron to harden and improve wear charateristics. Moly melts about 500 degrees F lower than Iron, and forms a semi-solid crytaline spyrical structure.

Now when moly forms the above mentioned structure in a microscoptic state, it actually lubricates the cyl bores (minor) and AND repairs damage to the cyl walls and the rings! This is the major advantage of moly, not the increased tensile strengths and yeild improvement.

In a semi solid crystaline spyrical structure, (tiny invisble round *****) the moly actually finds all the small valleys and craters in the rings and cylinders and will infact weld "up" these tiny valleys and craters, giving you greater wear characteristics compaired to regular gray or ductile iron. This is where Molybendium shines!**see side note at bottom of page.

But becuase of the increased tensile strength, If your cyl. bores are oblong or eggshaped, moly rings will be less likely to conform to the out of round shape. so if you use a telescoping gauge on your bores at several differrent heights and degrees, and find yourself within .002-.003 inches at the top and botttom of the bores at several different intersections. moly rings are still the best solution. If your bores are out of round more than .003 inches, i think anyone would suggest that you go to the next size over pistons.

So Bdox, you are saying that Moly rings want a .0001-.001 tolerance to seat properly? I could actually believe this, if I had some hard evidence, but currently and finding it a bit to tight in my opinion. Can your please provide me with some personal experiences, or the specific article you read?

Thanks in advance,

**Moly in grease is also a great help. unfortunately I cant remember if it needed to be a .03% or .3% addition to be a substantial benefit.

 

The reason I suggested regular iron rings is that they do wear, and will conform to an irregular cylinder bore. Moly rings, because of their lubricity, take forever to seat in anything less than a (near) perfect bore. I was going with your description of the engine and honing technique. If you read the manufacturers' instructions for moly rings, they require a very fine finish also. Moly rings, if they begin life in a perfect bore with the correct finish will outlast regular iron by a wide margin. But in this case, my concern is that they would never seat properly so you would likely have oil consumption and that the compression would be somewhat compromised.

I am NOT a metalurgist. I WAS and engine builder/mechanic/tech/fabricator. So this is the voice of my experience. I have rebuilt hundreds of engines and in the course of doing so, on a number of occasions I had to re-do someone else's rebuild. In cases where oil consumption was the problem due to rings, it was almost always moly rings that had failed to seat properly. (Some rings not properly installed too.) These were motors that had not been rebored or had a coarse finish applied to fresh bores. (And at 62, I am old enough to have seen how my work held up in the long term.)

The 'filling quality' of the moly you describe works, but only on miniscule imperfections. It's not enough to compensate for an 60 grit stone or a measurable out-of-round condition. In a complete rebuild I would always suggest moly rings.

 

Thank you Bdox for the great insight. I will go with regular rings. I truelly appriciate your input.

 

I would also suggest boring the thing anyway. If you are 0.004" over std, that is already too far. I build engines for a living as well. To me, there are two choices, do it right, or do it again. You will not be happy with std pistons in a 0.005" over block... and that is if you use a bottle brush hone instead of a 3 stone one. Add in some nice hard new rings, and you can kiss that baby goodbye. I know the initial cost is considerably higher, but look at it this way as well, 302 engines(in my experience) seem to have a habit of forming tiny cracks at the corners of the piston skirts. Wait until one of those lets go.

 

Ok now that my re-ring idea is looking a bit shaky, Lets change the question.

It is a 1992 F-150. I have a 1991 Crown Victoria with a 302 in it. It was my Fiance's Grandmas car, and the tranny had the TV cable come off the TB taking out D and OD, it has 100k on it, used no Oil, and was allways grandma's car, no one else ever drove it.(tranny just went this fall)

This engine "should" bolt up. The cam and timing chain are the same, i will change the oil pan, oil pump, oil pump pick up tube, intake, injectors, fuel rail, flywheel, headers, and accesories.

If the KS hole is not present on the transplanted engine, I will drill and tap it.

The only problem I have heard of is that the 302 in the mustangs had a tendancy to spin the pilot bearing, so Ford made a rev change for the mustang.

This rev change was to cut a key way into the crank to help. if the LTD has a mustang motor in it, would this "keyway" not allow me to install it in a STD transmission truck? This is the only problem I have heard of.

Again any help is greatly appreciated.

 

New motor or re-ring???

New motor! Why waste time on re-ringing??

 

To make a $400.00 dollar truck run for another 50k. I drive a Camaro in the summer. I should get 3+ winters out of this truck for a total investment of under $1200.00

 

If all this is correct, it implies a .002" ridge which is easily honed out. If the .004" is allowable per the factory manual, it's usable. That's why they write the specs.

I don't see any reason why this engine shouldn't be re-ringed and put back into normal use. That is assuming that all parts are checked and found to be within tolerances.

However, don't forget to address the issue of valve guide wear while you've got it apart.