Gunfreak25

Well I finally pulled the 455 and Th400 out of my truck the other day and I finished tearing the motor completely down a few days ago. Initially I was just going to do a head job but after removing the heads and seeing the cylinder walls for the first time I decided I'd better just do a minor rebuild. Cylinders 3 and 4 are VERY badly pitted. Not the kind you can hone out, but DEEP nasty pitting that is pretty constant throughout the bores. Now, this is going to be a budget rebuild. Very budged oriented, luckily for me this motor does not have to be perfect in any way shape or form since all it's doing is powering a big 13,000 Military 6x6 that has the aerodynamics of a barn and 6.17 gears.

Everything else looks pretty good, but I will be putting in new rod bearings, main bearings, rings, timing set (had factory gear set, floppy as ever!). The "ridges" ontop of the cylinders don't look too bad and the pistons even came out easily enough without needing to ream the ridges down. The pistons measure about 4.125 (plus or minus 2) at the skirt. Can I just get the two pitted cylinders sleeved and bored to match the other cylinder specs? I want to keep my original pistons. I was going to deglaze all the other cylinders by hand. Then will I need standard or .030 oversize rings?

I'd appreciate any feedback. I have done a lot of reading on it all but it can get really confusing. Especially for a guy who's never tore a motor apart before.


BTW, I believe the motor is 1970 to 72 dated. It has GA heads and I am fairly certain it's never been rebuilt before. So it's likely a 72.

ah64pilot

If your pistons measure 4.125" then you can bet it's never been rebuilt. If the pitting you describe is that deep you are more than likely going to have to do a .030" overbore and get new pistons. If you 'sleeve' a cylinder you will bore the whole cylinder big enough to get a new 'sleeve' in place of the old one. To do this would cost almost as much as a .030" overbore and inexpensive cast or hyperutectic pistons. You might as well resign yourself to getting new ones. Also, if you bore it over .030" and use the old pistons you stand a good chance of seizing the engine or gouging a cylinder wall when the 4.125" piston goes cockeyed in the 4.155" cylinder wall. It may not have to be perfect, but there's no use in doing it 'shadetree' and then redoing it when it locks up.

Anyone else have any input? I hope my facts are correct...input welcome.

Gunfreak25

I must not fully understand the whole overbore/sleeving thing. Seems to me like it's simple enough to just bore a cylinder out, install a sleeve and then bore that sleeve to match the rest of the cylinders diameter. Am I missing something? Is 4.125 pretty worn or still servicable? Some blow by is fine with me, like I said. It's not a performance application and does not need to be perfect in any way. Most of you guys here are probably of the drag/strip mindset. Which I can appreciate, but this old girl will never see anything over 3,500 RPM's. It will get me around my small town at speeds of no more than 45 or 50.

New pistons and a complete overbore job on all the cylinders is completely out of the question unfortunately.

Gunfreak25

Well I think I will just pickup a ridge reamer from Autozone to clean the tops of the cylinders up, then run a hone down all the cylinders being as careful as I can. As for the pitting in cylinders 3 and 4, I just assume not worry about them and dump in a can of Engine Restore. I hear the stuff works remarkably well. Like I said, I don't care if the motor has poor compression on a cylinder or two. Just needs to run. If I remember correctly before I tore it apart, the last time I actually had the motor running was for several minutes at idle. It really didn't smoke too bad, and that was with 40 year old valve seals. These are tough old motors and cast iron rings are pretty forgiving, I don't forsee any problems arising from the pitting other than a little oil consumption. I bet that Engine Restore stuff works pretty decently though, takes about 500 miles to start restoring compression from what I have read. Like I said, this is a budget project. Big time. Not everyone has lots of money to spend. Hell, my computer is still running windows 2000 and it was made in 1998. But, it works just fine!

507OLDS

That can of engine Restore is not going to help with a situation like that.Could you possibly locate another 455 block with nicer stndard bore cylinders?Then you could hone that one & reuse your stock pistons. If you bore,sleeve,machine those 2 cylinders,you are spending as much or more than if you just bore all of the cylinders,and purchased new pistons.I would look around for a nice set of used pistons,for the budget.Cast or forged.Finding a nicer block would probably be the cheapest route.

Danny Wiseley

If you can't find another block like Brian suggested, you can bore just the bad cylinders and find some pistons to fit. I've done it, with very good results.
DW

507OLDS

Yes,you "could". When I bought my 72,it had a 67 425 in it,that had been in there for about 3 years before I bought it,and I drove it another 2 years.I pulled it & disassembled it due the the rear main seal blowing out.I decided to take the whole thing apart,and upon doing that,I found that 2 of the pistons were replaced with forged replacements,which had a different weight,but I never would have guessed it.I've seen some other hairy stuff,but nothing I would recommend for the average street car.With you application,you might get away with something like that.I have two +.020 pistons,that are either cast,or hypertectic.I only have two,but if you think they might work,let me know.I'm not sure if you can get rings for only 2 cylinders,and I don't remember if there are any rings on these pistons.I will look.

cutlassefi

All good stuff, but remember when you sleeve it they drive the sleeve in, it's a press fit. Guess what that does to the adjacent bores? Knocks them out of round. And I think you'll find out that the cost of sleeving those two holes is at or more than boring and a new set of cheap pistons. If you do that then you make sure all the bores are in good shape. And for me no amount of additional blow by is acceptable, especially after a rebuild.

Yes you can buy individual sets of rings, they are more money but available.
Fwiw I know someone with the cheaper .030 over Fed Mogul pistons for sale if you're interested.

Jmo.

citcapp

I believe your best bet is to locate a old large body olds from the 70's with a running 455 buy it and junk out the body and install the engine in your truck

ah64pilot

For your budget this seems to be the best route I would imagine. Like I said before, just sleeving two cylinders would be as much or more than buying an oversize set of (cheap) pistons. The machine work to sleeve a cylinder is extensive and not worth it in your case.

I think a good hone and reuse what you've got is a fine idea given that the thing only needs to run for short periods and isn't going to see much RPM. Besides, what's an old Army truck gonna look like if it doesn't smoke a little bit

Either way, good luck with the project. If you have any questions pm me and I'll be glad to help any way I can. I have a fairly hefty amount of knowledge about these BBO engines. I swear I've probably got the Mondello technical manual memorized by now

**To answer your question from earlier**
4.125 is the STOCK 455 bore size. Your pistons measure 4.125 and your ACTUAL block cylinder size is probably something around 4.129 or 4.131 to give you about .004-.005 piston to wall clearance. The fact that you pulled 4.125 pistons out of the engine is a good indicator that it's never been rebuilt, unless of course the guy before you had the same budget and re-ringed the stock pistons lol!

507OLDS

Another question would be: How deep are those pits? Would a +.030" overbore remove them? I had a nice 71 455,that had ONE single pit down in the cylinder.At first we didn't think much of it,and figured we would bore that cylinder first,then determine what the bore size was going to be.We had to go to 4.200" to get it out.It wasn't a big deal because we were ordering custom pistons anyway,and that particular block had some good,thick cylinders,but for someone like you,I hate to see you run into the same issue.

cutlassefi

Thats not necessarily correct, bore size should be 4.125 minus any wear. The clearance is already built into the piston, the piston should actually be around 4.1235 or so.
Measure the bore at the bottom with accurate tools, the most amount of wear will be at the top, then go from there.

greenslade

price to sleeve a cyl is $100 up here.you could bore the 2 cyls .030 over size and get a couple of pistons ,speed pro are about $40 each plus rings.here they charge $35 a hole to bore cyl,fit piston and put rod on piston,so your looking at $100 a hole to install 2 over size pistons.good luck sound like a fun project,how about a picture of truck.is it a single wheel tamden 6 wheel drive with a hydromatic trans,I drove them while in the cdn military,1952-1952 model,go any
where very hard on gas 3mpg with the big inline 6.
ps I had a dodge colt many years ago,smoked like a freight train,I changed the oil add a bottle of restore and no more smoke for about 4 months changed oil again and added restore,smoked worse then ever.

Gunfreak25

Thanks for the replies, all good information as this is all new territory for me. I checked the pitting as best I could and I am fairly certain a .030 or even .020 would get rid of most of it not all of the pitting. At the very least it would make them both seal much nicer than they probably do right now. I never thought about running a couple oversized pistons. I always thought it would "throw things off" but then again I know very little about rebuilding engines. I suppose in my case it would be just fine.

Brian, I may take you up on that offer for the two .020 pistons. I suppose the first order of operation will be calling up NAPA and asking how much they want to do a .020 overbore. Will they handle the rest such as swapping the pistons onto the original rods or can I do that myself?

As for the rest of the cylinders, as I said above I will pickup an Autozone ridge reamer and 3 stone hone and go to work cleaning all the other bores by hand. The ridges are actually very minor and the pistons were easily removed from the bores upon disassembly. After honing all these cylinders will I need standard size rings or can I put .020 rings on standard size pistons? I am guessing not?

Gunfreak25

Greenslade, it is an M211 with the dually tandems and not the more common singles setup like the M135's. It's an old picture but here is the truck when I first received it over 6 months ago.



I know a few other guys who have 502 Chebbys, 455's, 454's and 350's and theirs and most of them with the big blocks are reporting anywhere from 7 to 12MPG. They have 6.17 gears but with 40" tires they are more like 4.50's which helps on gas.

greenslade

http://www.mondellotwister.com/Rebui...irstEngine.pdf
88 coupe posted this link some time ago.joe mondello says if cyl wall clearances are marginal,then you can use over size rings and file fit them.lot of good info in this.

greenslade

Should I attempt to it is in this thread,tried the link didn't work,works here.