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I have torn down a B18. The pistons measure pretty consistent 0.006-.0078" piston to wall clearance at the skirt. The green book says to re-bore at 0.010". By that measure, i would just re-ring and hone.
The bores are very consistent 3.34765-3.3470, (it was bored to 0.030" over by a previous owner. So new 30 over pistons would likely still show around 0.005" clearance which is higher than green book "new" specs of 0.0016" max.
Any experience out there that is relevant is much appreciated. I'd like to avoid new pistons if possible.
dean
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What brand of piston is it? An aftermarket piston might possibly be 85mm.
How wide are the rings? 2mm & 5/64" are awefully close too.
What is the side clearence of the top ring? The top ring groove is where the piston wears out. Have a VERY CLOSE LOOK for or at the step on the top side of the top ring groove. 0.005" ring groove clearence is the maximum for a quicky re-ring job.
.005" side clearence on a Mahle will be a little noisy, but depending how you drive, could go for a long time.
Also, in a cheap rebuild, you should be fine reusing the bearings, the rear main is the only bearing I have seen wear beyond limits due to dickheads who like to ride the clutch, etc.
If the cam has 8 good lumps, reuse that too!
The 2nd ever B18 I rebuilt cost me just $20 bucks for a box of Sealed Power plain top rings and about $2 dollars for a set of generic grade 8 nuts for the rods(THESE ONLY GO ONE WAY, Gr8 markings outwards)
NEVER USE CHROME TOP RINGS. If you ever get NOS Mahle Pistons, toss the rings & by some moly top rings instead. Don't use Hastings rings of the 're ring' type either, they have excessive pressure against the bore.
I like to add an O-Ring to back up the Square O-Rings on the oil pump pipe too & the oil pump, if OK, could use a new standard pressure spring.
I also use 'wick in' type Loctite after torque the rod bolts, new oil pump bolts gr8 or Allen head with medium or 'wick in' type Loctite, new Gr8 bolts with high tensile flat washers for the cam lock plate, no stupid fold tab thing, just more Loctite. Use high tensile washers for the head bolts too and always use greenbook spec oil on the threads and flat sides of Main bolts, Rod Bolts, Head Bolts and the cam nut, else the torque value is useless.
I have more tips if anyone wants them.
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Good stuff. thanks
I dont know brand of piston. I googled markings and nothing came up. They are marked as 030 so i assume they are 30 thou over std.
The ring side clearances with the new rings all measured between 1.5 and 2 thou. The new rings are cast iron. I am a little worried about the ring gap; around 022-028. They are +030 rings but the bore being about 003-004 over that has opened the ring gap. I went ahead at this point and used them.
The cam is relatively new as i replaced the cam and lifters a couple years ago.
Good thought on the o rings. i will look into that.
I decided to replace all the bearings with aluminum. The copper was starting to show on a couple of the crank bearings.
I used new bolt locks on the cam shaft plate. Also checked that i have about 3 thou difference between the ring and the camshaft plate.
I have assembled everything except the lifters, pushrods, and rockers. It takes about 15 ft-lbs to get the thing turning and around 5-10 ft-lbs to keep it moving. Considering that i liberally used assembly grease, i figure this seems acceptable. If anyone has other advice, happy to get it.
thanks for the feedback
dean
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If it's together, then chuck it in.
If the lifters are put on the same lobes they came from, then that's no problem.
Get her going & IF you used plain or moly rings, drive it with a fair amount of full throttle in bursts from 2500 to 4000 rpm, drop the oil & filter after 150 to 200 miles, let her cool, then run through the tappets. Add new oil & filter & it's run in. Drive normally.
Oil: Make sure it has enough ZDDP for the cam.
Filter: I use 1 pint filters from other manfacturers. For breaking in I like to use genuine Nissan or Toyota oil filters, afterwards, the typical Ford filters of decent quality.
What cam & springs do you have?
What do you want from this engine?
Do you have something in mind for a future engine?
Next time it's apart, toss the B18 rods & upgrade to the early B20 rod, which is a direct swap, but are beefed up around the rod bolt area.
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Thanks. Yes it is back together. Waiting for some ZDDP in the mail. I put a new cam in a few years ago but forgot which one it was. Springs are standard B18...New when head was rebuilt last year. Just want it to run well. Not planning to race or anything. Just reliable and smooth running.
dean
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If you don't what cam is in it, how do you what to set the tappets to?
With stock springs, the only cam to use is the K cam with low compression or K inlet - A3 Cosworth exhaust lobe (or similar) with high compression. There is no point to the old A, B, C or D cams. The K will beat the ancient A,B & C cams in every way, the D only beats the K above 5500 in an 1800cc (and flogs the stock valve train)
I harp on about using the K with stock springs because the marginally better D is too harsh on valve seats, if you have any kind of port work done on the head, the most important part of the port job is the valve seats. The D cam will flog the seats if you rev much past 5000rpm & risk dropping a valve. Once the valve seat needs a regrind, then you are forced to go to a bigger valve, which is not always a good thing. The K was developed in 1973ish for the 1974 K-Jet cars. The D was developed for the B18B Amazon Rally Pack WITH dual springs. Isky's duals have the same pressure as the stock single springs BUT the singles flail about and flog the valve train in 5500rpm zone. The stock spring goes to 8000rpm on the D, but do damage.
ROCKER ARMS: When you tighten down the four bolts, make sure the worn area in the foot aligns with where they were running on valve stems. Replace the nuts with some generic Gr8's + use slightly longer rocker shaft post bolts, Gr8 Hex or Allen heads & some HT washers.
Check your lobe lift, that will give you a decent clue to what cam you have, then you know what the tappets clearence to use.
Valve cover screws: Panel beat this area flat, then use a washer to spread the load better.
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Hi,
I did some research on Grant and they are of course still in business as the OP is buying some from his parts house.
I never heard of them either!
I made a post To place questions about the condition of the cylinder bores of which brought up the question of rings to run in those slightly oversized bores. I was concerned that the rings and oil film support the pistons.
Ring tension is important, of course, but its the type of material and thoughtfulness of design that gets more of my consideration.
His response was that .... he left it up to his parts man.
In his case he is not going to have the material to get normal tension to hold the rings against a cross hatch pattern.
To help wear in his rings to seating status he might want to consider not using a chrome alloy.
There are coated piston rings they are made to scuff in differently.
I don’t claim a great knowledge in that area.
Like him I leave it up to the ring manufacturers.
The link below and others are correct is stressing the use of ring expanders on the upper compression rings and which side goes up!
https://www.youtube.com/user/HastingsPistonRings
Like a Volvo you got to let it Roll.
You may want to get a tall mug of drinking fluid if you go out TOO far on the YouTube!
There is somewhat of an education out there ... if you can wait OR wade through some long winded presentations.
Mostly its those that read or fake what they don’t know that bothers me! (:)
https://www.waynet.org/waynet/spotlight/2003/030521-perfectcircle.htm
When I was growing up “Perfect Circle” had training films in our vocational machine shop classes.
They are now out of business and Dana now owns their brand name! It’s popularity now, is unknown to me?
Hastings is another piston ring company, along with Cooper Tires. When I taught Machine Shop for about three years I used video to make my students realize the processes and their economic impacts of mass production.
https://www.youtube.com/user/HastingsPistonRings
Like a Volvo you got to let it Roll a Ways to learn about the details of good stuff or whatever is lame!
The truth be told I haven’t ever purchased any of these products but it has affected my thinking about them over the years with other products. I appreciate training materials!
So consequently, I might be prejudiced towards some brands, but I have learned better to use loyalties in decisions all the time!
In the machining world “perfect” doesn’t exist as It comes down to how close you want to look!
Phil
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Hi,
When I grew up, in the machining world of the sixties, I heard of this process being done in the automotive sector. I have never seen it done, so, the link quickly explains my thinking for you.
https://www.youtube.com/watch?v=4uzZYPIGbZE
I have done this process to some valve guides of my 1974 360 CID Ford Engine at 19,000 miles.
The pickup had just left it’s warranty at 12,000 miles despite numerous other warranty filings on engine performance. This was the early years of smog controls! Mechanics just waved their hands in the air!
I was shocked when I got a letter stating Ford would recognized the issue. This was about two years after.
They would only warrant the parts though and not any labor cost.
I did both of the heads rework because the heads were not torqued down properly from the factory. The subsequent coolant loss steam cleaned the valves and one cylinder piston and it clacked as it aged more.
They would only warrant the parts though and not labor.
I still have the truck and I managed carefully to get 180,000 on it before it threw a timing chain.
I have kept it because my wife put the down payment on it and she won’t let me sell it.
I parked it 15 years ago on jack stands! I hate it!
Consequently, I have not owned another Ford product!
Volvos have convinced me that I could have done so much better in 1978 with my GT!
Anyway, the procedure might give you back an engine with less piston slap.
Your lucky in that it’s a low compression engine and that in itself can make it a viable option.
The trick is finding the person with the skills or that machinery.
You are looking at hand fitting them to each cylinder anyway!
That’s what the factory did, really well, as we know!
The cylinders you are measuring cannot be honed round.
It’s a process for final sizing and for the crosshatch finish to help seat the piston rings.
Boring them is the only process to make them round.
I’m sure they will show them being slightly oval with that many miles on the block.
I hope you are using a “dial bore gauge” instrument to check the full length of those cylinders in both directions.
Read up and pick your final outcome wisely!
Phil
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Thanks for your reply. Yes I am using a bore gauge which has 0.0005 resolution. I dont see any ovality in the cylinders. At least within the guage accuracy. I've decided to accept the approx 0.007 clearance and just hone and re-ring.
dean
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Hi,
Round huh?
That’s interesting that you don’t have some bore wear in an oval fashion since the bore is .007 over the piston diameter. That’s quite a bit.
Have you heard this engine run before the tear down?
If so, was there piston slap noise when warming up? Did it clack or did you find rod bearings wiped?
The excessive clearance got there somehow? What’s is the estimated mileage on this engine or rebuild before?
If it’s so round, maybe it was over bored and the crosshatch hone was done too lightly and the engines rings didn’t wear-in properly, since you said it was using oil?
Of course, this back ups that engine was done before, in the same way that you are proposing?
Man makes history, since he the only one that records it, so repeating it, is back on us!
Machineman
If the original and properly fitted pistons are here, Was there a ridge at the top on the cylinder showing up? I’m curious!
There should be a step up top where the rings don’t run in the bore.
With .0035 per side wear should have removed all of the original crosshatch pattern. How was that? What type or grade of rings are you considering for that scuff in period?
The Swedish know their metals and Swiss are proud with their precision work in their days of laborious craftsman. Just something to think about or not?
When you say you are going to hone and re-ring, you are going to need a crosshatch pattern or at least break the other glaze! That shouldn’t take much honing, but remember, you don’t have a whole lot more material to work with.
I suggest that because it’s so round and not tapered top to bottom!
You had better use a “flex hone brush” to acquire that. It has balls of abrasive on wires.
BRM invented these during my working days and these guys know finish honing!
If the pistons are round, knurling can a raise pad area up and help hold oil in the area to add support to the piston skirts. This area at the bottom of the piston is its bearing support for the upper rod end.
Between this area on the piston wall and riding on the rings it keeps things aligned in their holes.
Story ...
Back in my “really” young days it was a joke to say, “Oh-oh! He’s wound that engine up until you can hear the pistons switching holes.” Rev limiters were the ignition points bouncing! Nah! Kidding!
The engine would actually pop and miss fire around the dirt track!
At first, when I heard that statement I tried to imagine that happening?
I eventually figure out these “grownups” were getting my goat!
It’s called “ Valve Floating or unburned fuel out jumping out those straight up pipes!
Anyway good luck and I sure hope this rework, works out for you!
(:-)
Phil
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The rings i ordered are from VP Auto and i think they are made by grant.
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posted by
someone claiming to be C1800
on
Wed Dec 23 22:16 CST 2020 [ RELATED]
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“ The rings i ordered are from VP Auto and i think they are made by grant.”
Steering wheels? R maybe I mused something...
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Grant made piston rings, I don't think they are in bus. anymore. They didn't have a good reputation.
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Do a compression test when it starts to smoke. Make sure you crankcase venting is clear.
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Make sure to us a ridge reamer to remove the notch created. Then use a ball finishing hone. If you fail to remove the cylinder wear ridge at the top of the cylinder wall, the new rings could hit and crack.
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The cylinders were very glazed. no evidence of cross hatching. Very little if any ridge at the top. nothing i can catch a fingernail on except on one cylinder and its really minor. I did use a flex hone to restore the cross hatch and yes machine man, i believe you are correct....it was burning oil because the rings never wore in properly ...there was no noise indicating piston slap. There is minor scoring on the piston skirts. I would go ahead and bore out further and upsize the pistons but to be honest, i dont expect to be putting that many miles on this thing. i just want it to run ok and not make a blue cloud on acceleration. And it seems like the few engine shops left here in the Austin area are either busy or dont want to mess around with a 50+ year old four banger.
dean
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If you are having a re hone and new rings, they will need to run in. BUT, they don't want to be babied as that will likely just glaze the bores again. Make the rings work with a fair amount of good acceleration in the gears. Don't take the revs too high. Change oil after about 250 miles. At least at 500.
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Another major source of the blue smoke is the Intake Valve stem seals and worn valve guides. Look at you cylinder head and see if you have any valve stem seals. Piston down stoke doesn't just pull a vacuum on the intake manifold. Do you have smoke on each start-up?
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The head was just reworked at a reputable machine shop with new valves, guides, springs, seats, and seals. It doesnt really smoke on startup....only after running a little while.
dean
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