Folks,

I am really glad I found this forum and the interest in the 400. When I built my 400 about 8 years ago, I could find very few sources of information on this old motor. At that time I could not find any pistons other than the standard deep dish for a CR of 8:1.

I was somewhat disappointed in the results of my build and it was because, I think, of the lack of compression ratio. I used an RV Cam, Edelbrock, 600 Holley, adjustable rocker arms, dual exhaust with manifolds and I pocket ported the 2V heads.

I was convinced that the Aussie heads would be the easiest way to correct all this, by just getting a set, porting them, doing the valves and bolting them on. Now that I have found some experience on this forum with the detonation problems of that setup, I think the piston route is the way to go.

My truck is a 4X4, so I can get the pan off easily without raising or pulling the engine. I have never been a fan of changing pistons unless it was overhaul time and the block was bored to fit the pistons. In this case, however, I think I am going to get a set of the Badger pistons in the same o/s as my engine and just check clearance. If they are a little loose, so be it. If they are tight, I will hone to fit.

I have a two post lift and all the facilities for such work so the only worry I have is the piston fit.

Your thoughts?

Have a great day,
Doc

 

What timing chain are you using? If it stock it has a 4 degree retard in it, that will make it somewhat disppointing. If it is stock change it to a good true double roller chain. You will fell the change.

 

I don't think you can get the pistons out the bottom. Also using lots of initial timing may help.

 

I can't remember exactly what timing set I used, but it was an expensive tru roller type with three keyways and I set it straight up. I also degreed the cam as I always do when building an engine.

Don't get me wrong, this engine is not a slug. It pulls this 5,000 behemoth at a pretty respectable pace. I've towed about 8,000 pounds of cattle with it and it doesn't do bad, but I know that if the CR were up it would be more snappy.

Thanks,
Doc

 

I've been building and rebuilding engines since I was 13 years old. I'm now 55 and an ASE Master. I am quite aware that the pistons won't come out the bottom. But the pan has to come off in order to unbolt the rod caps so that they will come out the top.

I have optimized the ignition timing and carburetion. As I said, the engine is no slug, but I know the difference that a decent CR will make.

My main question involved looking for experience in doing such a shadetree piston change. Except for emergency single cylinder repair, I have never changed pistons without boring the cylinders to fit the pistons. Changing all eight pistons in a block that was not bored to fit the piston set is my concern.

Has anyone ever used this approach?

Thanks,
Doc

Have a great day,
Doc

 

How many miles on the engine? Since you have built so many engines do you expect to have a ridge at the top of the cylinder based on the mileage, will you be able to get the old pistons out? Not to mention getting the new ones back in.

Since you have to tear apart the majority of the motor to get to the pistons I would just pull the motor out and make life easy on yourself.

I have only built a couple of motors but I was under the impression that it was important to have the cylinder properly prepared for new rings for best performance and longevity.

good luck,

Bruce Hawkins

 

The engine has probably less than 20,000 well cared for miles. I expect not to find a ridge. If there were a ridge, I have a ridge reamer. In the days of in frame overhauls it was quite common to simply ream the ridge out of the way and pull out the pistons. Putting them back in is no problem even if there is a ridge in place. The worst part of a ridge is not the fact that they must be reamed, but that it may indicate excessive cylinder wear.

I guess the younger crowd here is not very familiar with the in frame overhauls that used to take place on a regular basis. In the case of a frame that allows easy oil pan removal it is much easier and quicker to simply pull the heads and pan while the engine is in place, push out the pistons and then put everything together, provided that no machine work on the block is necessary which would require its removal.

In those days, in frame overhauls of straight sixes usually involved about 8 hours work. This included R&R of head, pistons, cleaning piston grooves, putting on new rings and rod bearings and then putting everything back together. If the time included doing the valve job on the head it was a little longer, but the head would typically go to the machine shop for the valve work.

For a V8 it would often be 10 to 12 hours work, sometimes 16. In the sixties, most cars began being made such that it was more difficult to get off the oil pan, then in the seventies it became more common for it to be impossible to pull the oil pan without removing the engine. Luckily the engine and lubricants were getting better and engines were beginning to last longer so the inframe overhaul became less common. On todays cars it is virtually non existent.

Cylinder preparation as you call it is easily accomplished with the block in place. It involves nothing more than cylinder wall deglazing with a hone. Actually it has been proven that with cast iron rings there is no need for breaking the glaze in order to get proper ring seating. This is against conventional wisdom, but was proven by Ryder labs about 25 or 30 years ago to be fact.

Again, my question is for anyone who may have replaced pistons without boring to fit. Has anyone ever done this with any success? I have never replaced a set of pistons without the machinist having one of the pistons in hand and bored the block to fit them.

Have a great day,
Doc

 

I have done it in dirt track cars, I usaly put new rings in and mains and incerts. I run one like that for two years, one first, alot of 2,3,4,5 places.

 

Thanks for the reply f100.

Have a great day,
Doc

 

I think the oddest thing I ever saw was taking the heads off a 292 to grind the valves and it had 1 and only 1 .040 piston in the # 8 hole. Everything else was standard. Having done single repacements as well as complete overhauls, Here's my two cents worth on your project. When I was Boring and Honing blocks and using Badger Pistons in the late 1980's I always had to carefuly check the box for size. Typical box of Badgers would almost always have 1 big piston and 1 small one. ( TRW's were even worse) Say the box size would be 4.0283 ( for a .030 over), The big one might measure 4.0285 and the small one might be 4.0280. That was a half thou difference in the box. Since any detroit stack of tolerence was .001 we never worried about it, but one would simply assign the two pistons to say holes #8 & #4, hone for proper clearance, and the assembler would put it together that way. Maybe we were being picky about our work as the piston to wall clearance was usually 1 1/2 to 2 thou and we would have been in spec anyway. Incidently Metalevy pistons from Brazil were always perfect and you couldn't find .0001 difference in any ten boxes of them.
After saying all that, a couple of months ago I bought a box of .030 over Badger flatops for my own 400. Giving in to old habit I checked the box and was pleasantly surprised to find the piston finish vastly improved over the older ones and though there is a size difference in the box it is only about a 2 to 3 tenth spread. They have been bought out and I must say that new managment must be good for them.
I would certainly give it a shot, sounds like you know what your doing. I wouldn't just ball hone it though. Maybe a light touch with the 400 stones ( or more if you need to size it some) and follow with the ball hone to crosshatch. I'd leave the ridge reamer in the tool box too, 20,000 miles of ridge will probably disapear under the pressure hone.
Go for it

Well thats my 2 cents , maybe what it's worth

Ken

 

Ken,

Thanks a bunch. That is the kind of experience I'm looking for. Yes, if I have to hone, I would not use a ball hone. I consider that only as a tool for glaze breaking.

Have a great day,
Doc

 

I have done piston replacements in the past, usually because of a problem with one or more pistons. When replacing pistons you should hone the cylinder to reduce the ridge and to prepare the cylinder wall for seating the new rings. A cross-hatch pattern is recommended. This will work fine with a low mileage motor.

 

Talking about braking in rings, has any one started their motor and ran it with no water for a short time to help seat the rings? What did you put on your rings when installing them? I was told and have used 2 stroke oil, seems to do ok.

 

If there is a ridge on the cylinder it could break or chip the new top ring at tdc, the old ring is worn to the ridge & when you put in a new piston & rings in it may hit the ridge especially a different style of piston & mfgr.
Those old spring loaded hones are junk. They only follow the bore, they can't straighten a out of round or tapered bore. If you just want to break the glaze I would use a ball hone.
As far as clearance goes, no one here has a crystal ball. Get a good bore gage & mic. Always mic the piston where the mfgr says, not at the bottom of the skirt. A cast piston will be around .002. I'd guess that around .006 of clearance you might start to hear some piston knock.

 

The bores are in good shape with little mileage and lots of oil changes. There has not been enough usage to cause taper, out of round, ridge or anything.

If I have to add a touch of clearance I will use a hand hone. Yes, it will follow the bore, but we're not talking about a worn out cylinder here.

I have mics, snap gauges and lots of experience using them. I'm not worried about being able to make some minor clearance adjustments if necessary.

Thanks for the comments,
Doc