Engine condition

[vping]

I've got to be honest, before yesterday other than assisting friends in high school. I have never taken apart or rebuilt an engine. I've got to say it was really cool to dismantle this and I got to use my new engine stand and do it with my son to boot who really does not dig cars yet. My question is this. How does this look inside? The engine freely turned and to me does not look that bad inside. As I was snapping some pics I thought it would a neat thing to have start threads and document each of these processes and have the pros of the forum help out the novices. Could be a cool learning experience and confidence booster for some. Any way here are pics of the crank and the pistons. Other than being dirty how do they look? The bearing are still nice & thick and everything looked well lubed.

 

[DrEntropy]

Looks decidedly like it was time for a rebuild by the condition of that piston.

Have the crank polished and take the mic's to it. What size are the main/rod bearings now? You may luck out and not need to cut the crank. Pistons, welllll... Clean 'em up with some "Easy Off" oven cleaner and thoroughly check 'em. Check bore with regard to scores and "lip". Also have a good look (measurments) at the 3 cam bearings.

 

[vping]

Is the wrist pin held in with a lot of force or will Or just press out.
Another question I have:
Does the difference between a 3 main & 5 main pertain to the "main" caps that hold the crank in? This photo being of a 5 main.
I'm going to take the crank out after I make a tool to remove the end bearings. Looks like they are held in there fairly tightly.

 

[Baz]

Vince, I'm about a month behind you, please keep the pics / progress / knowledge coming.
I am one of the 'novices' you refer to! /bcforum/images/%%GRAEMLIN_URL%%/hammer.gif

 

[DrEntropy]

Pins in an 18GB are pressed in. I've a crude method for removing: A block of 4"x4" cut 2" deep with a radius the same as the piston diameter and a hole drilled thru the center point larger than the pin and drift it out with either a brass drift or a deep socket a bit smaller than the pin diameter.

5 mains means five main bearings to hold the crank: A web between each rod journal. The three main engines had a center web and one each end.

For the mains caps I have a tool fabricated much like the one illustrated in the Bentley manual. They're a tight fit, BTW.

 

[vping]

I have a small arbor press that will come in handy for the pins. The tool I was thinking of making was an inverted "U" that would span the main cap. I would have a hole drilled in the now top of the "U" and would thread a bolt into the main cap as I tighten it, it should pull the cap right out. Getting the correct length is key but I can calculate this.

BTW this is not my engine from the '67. It is a spare I have which I am using as a learning tool.

How can I tell the year of the block or the head for that matter.

 

[DrEntropy]

Look for the little "clock" in the casting. Right side, low on the block directly below the oil filter location.

 

[vping]

This is all I can find.

 

[DrEntropy]

That's an 18V engine! Not a '67 MGB for sure. Later, not sure of the year. Basically the same, but subtle changes to smog certify them. Lower comp, head castings, etc.

Tony oughta know.

 

[AweMan]

There are a number of things that need to be checked thouroughly
the crank shaft journal sizes, the crankshaft main bearing journal sizes to ensure that they are within specified tolerances.
Note If the crank isnt scored or out of round and only worn 1 or 2 thousandths you can purchase bearings to remedy this problem {1 or 2 thousandths thicker}.
next you need to check the cylinder taper if the cylinders are tapered in excess of the tolerances then a rebore is required. {IF you need to rebore, new pistons will be required.} So cleaning up the old ones might be fruitless until you know if you can reuse them.
Overhauling an engine and NOT replacing the cam bearings is FOOLISH.
When I rebuild an engine, after dissassembly I take the whole mess {block, head, Pistons w/rods and crankshaft} to the machine shop I frequently use and they tell me what needs to be done to what component. Then I go from there. Normaly I use them to do whatever machine work that needs to be done. They also magnaflux the block and head to check for any cracks and tank boil the block and head squeeky clean.
Once they finish thier part I am ready for re assembly and dont have to wonder if I missed something critical. As far as wrist pins go if they need attention the machine shop does the work on them also.
Yea some of this work I could do myself and save $ or two but I.M.H.O. its NOT worth it in the end.
Just my thoughts
Kerry

 

[DrEntropy]

If cam bearings mic out to be in tolerance with regard to cam journals there's little reason to change 'em. I've been FOOLISH for years... BTW: If it were a client's engine and not mine, it would get new cam bearings. I'm not THAT foolish.

The condition of the bores will dictate whether or not it'll take rebore (and to what extent) to make them straight. New pistons will be required if the bores are oval or deeply scored.

Of course tanking ('boiling') the block means replacing cam bearings, freeze plugs, etc.

I'd rather do my own teardown/inspection/measuring. That way I ~know~ what I have rather than taking someone else's word for it. I've seen many an engine trashed for lack of info on the idiosyncratic needs of each by machine shops.

Just recently we're likely seeing such with a BCF member's Triumph engine.

 

[AweMan]

The machine shop I use is owned and operated by a personal friend I went through highschool with. He also builds and races Alcohol engines.
He through out the years has done machine work for me on many projects and never steered me wrong.
However, that isnt saying ALL machine shops do the same caliber work he does.
It is always a good idea to get as many recomendation as you can, as to whom to have do ANY machine work you might require.
Bieng a NOVICE and trying to build an engine I would deffinately get someone to at least watch over my shoulder while determining measurments and what is worn and whats not.
Kerry

 

[drooartz]

Kerry -- does your mechanic handle small bore motors? I'm starting to look for some recommendations for someone local to work on my 1275 project.

 

[Bugeye58]

Vince, according to my charts, that's a 1972, non-overdrive engine. 8.75:1 CR. I pretty much echo the other opinions. Measure, measure, and measure again.
I'd be careful using "Easy Off" on the pistons, as that stuff can violently attack aluminum. Before I tried that, I'd measure the bores, measure the pistons, and figure out if there was even a chance of reassembling them again. If you are going to have to bore the thing, the pistons won't fit, so why waste time cleaning them up?
I'd also say that a new oil pump is called for, as it is on any rebuild.
Keep us posted.
Jeff

 

[Bugeye58]

Kerry -- does your mechanic handle small bore motors? I'm starting to look for some recommendations for someone local to work on my 1275 project.

Drew, in LBC circles, 1275's are considered "Big Bore". /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
Jeff

 

[drooartz]

Jeff, I have this vision of taking the 1275 down to a shop and having the mechanic ask me what brand lawnmower it goes to. /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

 

[Bugeye58]

Drew, I have a very good machinist buddy who asks me basically the same question every time I walk in the door. He generally builds stuff for either Sprint Cars, or high dollar boats. I usually just flip him off, and go use his stuff to do my work!
Well, one day his 16 HP Kohler engine for the garden tractor happened to be sitting on the bench when I came in with a 948 block and crank. I taught small engine repair for a few years at a local community-ed program, and offered to fix it for him, free, as I was used to such tiny engines.
It felt good to have the upper hand for a change!
His wife still laughs about that!!
Jeff

 

[70herald]

While you are taking things apart, make sure you mark location and direction for the main bearing caps, connecting rods, etc.
These parts (caps) are machined in location and MUST be put back in the same location! The big end bearing caps are probably marked for their location and direction they face.
I would be hesitant to reuse the pistons. The ring landings do wear. Then the rings start to flex If the pistons really are in good shape, and you decide to reuse them, you will need special rings which are cut slightly differently so that they won't hit the ridge which wears into the cylinder bore.

Either way, you need a machine shop which you will trust to measure everything.
There are a few tools which you need to put it back together properly. Most important is a torque wrench. If you don't have one yet now is the time to get one. I would recommend the cheap "pointer type" they are less expensive, and less likely to be damaged or knocked out of calibration than the "click" type.
When you put everything together double check everything.

 

[vping]

I kept everything but the piston in order. I know where each main goes and I have each cap with each piston but don't remember which piston went to which cylinder. Was most Likely going to part this engine out anyway, Sell everything off of it. I've no need for it and have a few more engines to toy with.

 

[Baz]

Errr Vince, see my 'pulling the motor' thread in MG, you may have a buyer.....