3.661 bore for sleeves/pistons

[xctasy]

Melling 626, 1173, whatever.

3.77375" over bore for 3.701" bore is just fine.


I use Chevy liners CSL331F, with CP brand XR6 turbo pistons. Same 3.632" bore as 3984 cc sohc and dohc Fords from 1993 to date, for 84 thou wall thickness. If you took your 4200 trailblazer out 20 thou, that would be about 74 thou liner thickness, so in our iron blocks, its all good after a 93.75 to 120 thou over bore.

Since the top is locked by a 195 thou ledge in the Chevy liner, I mill it back to 154 thou and use a totally loose 2 thou clearance, so the liners practically rattle.

Ford Corsair rods Rod Length 6.496" Journal Size 1.967, set on a destroked EF crank, 233 cube, 3823 ccs with 3.632 bore and 3.753 stroke

And 109 thou block topper two packed to the block, one Falcon X-flow gasket at 45 thou, another Apco 630 gasket at 45 thou for stock US 250 block deck. Then stock iron non cross flow head on cross flow block.

Kelford supplies the cc 285 style cam.

Everything is locked in, and the US liner engineering is great.

Nothing you are talking about bothers me.

See
viewtopic.php?f=1&t=71038&p=545177#p545177
viewtopic.php?f=1&t=69097&p=547664#p547664


NB// I stack two head gaskets, and apply a steel plate. That's 109 thou or 154 if you add the compressed Falcon X-flow gasket at the base.


The Aussies block plates 500 thou thick in the late 50's when stroking I6 Holdens from 132.5 cubes out to over 180 cubes with custom alloy heads, 36% bigger via a massive 187.5 thou over bore. As long as the ring lands didn't cross the new steel, no problem.

viewtopic.php?t=6557

 

[MustangSix]

Its been a few years but I was able to buy .040" oversize Zero gap second ring sets for the crossflow directly from Total Seal.

BTW, both my 250 crossflow blocks were sleeved. One of them had two sleeves the other just needed one. They had to be sleeved to correct a porosity problem I had when we overbored them. The sleeves were then bored .040" over.

My machinist and I did some benchracing over ten years ago to speculate how big a sleeve we could install. See viewtopic.php?f=5&t=8885

At the time, though, it made no sense. It was going to be very expensive and this was years before Mike developed a head good enough to support a bigger engine. And I had not yet started work on the crossflow hybrid.

 

[xctasy]

I loved that.

See http://www.siamspeed.com/index.php?topic=101880.0

http://www.osgiken.co.jp/topics/rb315kit-top.jpg


The Merv Waggot method of adding a stiff plate and fat liners has been beaten to death in an RB26 block.

Linering is easy, and making it strong is just some flitched plate away.

 

[mike1157]

Well, I stopped by the machine shop on Friday, as they have installed all six sleeves. If I was concerned before, let me tell you, all of that is behind me now. The block looks great, and there was waay more room to install even the thicker .125 wall sleeve w/o detriment.
The pistons are supposed to be done this week, so I'll leave the block w/ the machine shop for the final .020 overbore and finish hone.

I do have one question though, maybe somebody will answer.

Why does the #1 cylinder wear so different from the others? And if it has something to do w/ the water pump, will I be better off redirecting the water between the cylinders, considering I'm using an external electric pump now, instead of the belt driven stocker.?

 

[bubba22349]

Yes your on the right track, it is due to the water pump and coolest water enters there at the front of the block. The front cylinder on inline six runs cooler and the cylinder then wears faster its also the same on most every engine i have torn down including the V6 & V8's blocks too. Thinking about about this problem have wondered about bringing in the cooled water using a manifold to distribute it equally on the whole side of block maybe using the freeze plug openings with the WP feeding the center of the manifold. A side benefit of this is that maybe the engine would also produce a little more power with the temperature of each cyclinder equalized front to back.

 

[170-3tree]

Bubba is right. My 170 had an old-New thermostat in it when I put my aluminium head on. It would stick for a couple extra minutes, I believe then pop right open. Which was fine cruising around until one day it happened and the whole engine froze up. Made it so I couldn't rotate the crank and the cam took some angry hammering to break out. Obviously this is rare, but it's the same principal across the board.

 

[CNC-Dude]

Well bubba, that hypothesis is not exactly true, and may not actually have any truth to it at all, even though it has become the accepted cause of the wear by the "urban legend" inline crowd. In our experiences racing the Chevy 250 and 292's in professional racing, we also found that all the used blocks we came across for cores to make race engines out of had the same front cylinder worn in them as well. Since we did have engineering connections at GM at the time, we discussed this problem with them many times, and there answer was really simple to understand, especially if your a machinist. It also is a problem with many other inline engine regardless of brand, and that is that the front cylinder barrel has to be machined for water pump impeller clearance. This machining only on one side of the casting unevenly releases stresses in the cast iron and causes the front cylinder bore to become out of round and wear unevenly, as well as becoming much thinner than the rest of the cylinder wall. This also makes it more susceptible to the distortions and internal stresses the cylinder endures from the compression and combustion process. Since these casting are not heat treated, this is similar to when you machine one side of a piece of un-heat treated steel flat bar and it curls like a potato chip. Once you do find a block to rebuild, the tens of thousands of heat/cool cycles the block has been subjected to over the years finally has removed all the stresses in the block and it will no longer cause the bore to wear unevenly in the front cylinder and you will not have that problem any longer.

 

[mike1157]

Well, regardless of whether or not it's a lop-sided machining process, or the constant subjection to cooler water, I'm gonna block the front water pump entrance hole anyway ( I hated how the lower hose was crammed between the P/S pump bracket).

I was thinking instead that I build a log "manifold" like Bubba was suggesting for the sole purpose of water distribution, and run it under those accessories, and down the passenger side of the block. Then run 4 1/2-3/4 NPT outlets off of that, and tap them into the block between the cylinders immediately above the freeze plugs. Besides,....what's a few more holes gonna hurt in my already swiss cheesed block gonna hurt?

I've already drilled and tapped 6 1/4 NPT holes in each of the exhaust port cooling jackets in the head. I had a real problem w/ how much water has to be blocked to make the head work. Whether or not any real water now moves around and out through those new holes will have to be better than the steam traps that they once had to be.

 

[bubba22349]

Thanks CNC-Dude for correcting my theory, I was only a mechanic and most of my machine shop experience was back in High school. Yet had observed this extra wear in the front cylinders of many brands and types of engines so would wonder about what was the cause.

 

[CNC-Dude]

Well, there may be exceptions to every rule, but for the "cold water" theory to be plausible, it would have to apply to every and all inlines, whether they have a machined front cylinder barrel or not, and it simply doesn't. There are many different engine brands that offer inline engines that do not have the front of the cylinders machined for impeller clearance and don't exhibit abnormal wear in their front cylinder like those engines that do. One thing I observed is that every engine that has the cylinder barrel clerancing done to them has the front cylinder with excessive wear. The blocks that do not have them machined rarely or never did. Since GM has millions of dollars to research and find out this stuff, and did have an answer for this, I would tend to think they know what they are talking about. When asked if the "cold water" theory could also be an explanation, they said that members of their own engineering team believed that also, but once they began to evaluate and test and research the matter, they soon realized it was not.
Now whether or not this issue should have been corrected by GM and other brands is another matter. Since back in that time, vehicles only had a 36,000 mile warranty and this didn't seem to impact that since many of these engines went 150,000 or more miles without problems related to that, I guess they felt it was acceptable to leave it alone.

 

[motzingg]

^ awesome.

this is such a great forum due to folks like you posting this kinda stuff that just doesn't exist in a book anywhere.

I would be looking for a bore expansion or tapering that lines up with the areas that are machined... i.e. does it hold its shape near the deck where it is reinforced by extra metal, and just bulge out lower down where it has been machined?

Even if it were to be tighter bore clearance due to being colder, you would think that the rings would take up that difference or the piston would scuff if it got small enough, long before the slightly higher spring tension caused appreciable wear. Unless the ring gap crashed, which would show other signs of distress.

 

[bubba22349]

Well, there may be exceptions to every rule, but for the "cold water" theory to be plausible, it would have to apply to every and all inlines, whether they have a machined front cylinder barrel or not, and it simply doesn't. There are many different engine brands that offer inline engines that do not have the front of the cylinders machined for impeller clearance and don't exhibit abnormal wear in their front cylinder like those engines that do. One thing I observed is that every engine that has the cylinder barrel clerancing done to them has the front cylinder with excessive wear. The blocks that do not have them machined rarely or never did. Since GM has millions of dollars to research and find out this stuff, and did have an answer for this, I would tend to think they know what they are talking about. When asked if the "cold water" theory could also be an explanation, they said that members of their own engineering team believed that also, but once they began to evaluate and test and research the matter, they soon realized it was not.
Now whether or not this issue should have been corrected by GM and other brands is another matter. Since back in that time, vehicles only had a 36,000 mile warranty and this didn't seem to impact that since many of these engines went 150,000 or more miles without problems related to that, I guess they felt it was acceptable to leave it alone.

As an experiment I was once thinking of testing the cold water theory by installing temp senders in several different places from front to back of the block. Now days it probably could be done real easy with a budget type IR temp gauge too. I do think as you explained it and its logical that could be the real cause, just like torque plates and bolting on the motor mounts or anything that can distort the block before machining in order to give a truer finished bore.