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Running in BMC A series


estate_

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Had a 1300 do this exact thing after a rebuild.

Used a set of Hepolite pistons and used a single piece oil ring. Big mistake.

Most aftermarket pistons only have small oil return slots / holes where the oil control ring goes.

The solution was to fit a 3 piece oil control ring and inlarge the return holes.

Was also using double valve springs without seals, smoked on startup and when getting back on the throtle after slowing down. This is normal.

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Didn't take photos before cleaning up so shall have to run it again and get photos, main concern is down the bores appears to be wet with oil as do the plugs, and the pistons are pretty black after such a short period, I've got a photo of the plugs:

 

 

http://iforce.co.nz/I/5rhwlb5y.0u5.jpg

 

 

Interesting re: the 1300, again I am not sure of what pistons/rings are in it currently. The following are photos from when I had the sump off of both the bottom of the pistons and the bores

 

 

http://iforce.co.nz/i/zqwnkceh.qwa.jpg

http://iforce.co.nz/I/42gkoagk.nfq.jpg

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  • 2 weeks later...

Updating this:

 

-Gave it some decent days of solid cane, to no success, still smoking and burning oil something chronic

 

-Pulled head off, pistons out, it looks as if someone had once honed it nicely, then for whatever reason gone and wrecked it with emery giving it some pretty horrid marks in a near horizontal direction, so it was left with a very inconsistant patchy surface with deep scours then glossy patches, it wouldn't have run properly in a million years like this. It's almost as if it had been nicely honed, sat around, forgot about, then the bores rusted a bit and one day he went shit I'd better throw that engine together and flick it off, giving it a sand to get rid of the rust. I can only spectulate hah. The pistons are(well were) brand new, so he seems to have put so much work in, then rushed the last bit to sell it or something.

 

-I have now honed the bores and they are now measuring almost perfectly 66.07mm with a nice cross hatch. The pistons are a 5 ring piston, non OE but not sure what manufacturer etc, however they are on stock conrods. They are marked +1.5mm 060, and comparing my bore size with factory this is something like 3mm over a stock 948 bore, however the 998 shows a 64.58mm bore, with 64.58 + 1.5mm equating to exactly what my bores are it seems he has bored it out to suit 998cc 60 thou over pistons. Have ordered a set of rings so hopefully they will fit. Again the bores are very very good, not tapered, out of round or anything, so he has definitely bored them recently so who knows why he skimped on honing properly.  

 

-Another thing I've found while I had it apart is that the cam followers are a bit funny, these engines have a basic bucket type cam follower, and the oil returns from the head down the pushrod hole area lubricating the cam lobes etc from the looks of it. On this rebuilt engine there are no holes in the cam followers, so the oil seems to pool in the followers and the surrounding area until it is high enough to flow down the slot between the followers. However this can't be getting much oil to the cam lobes as the drain point is between them, and leaves oil sitting right beside the tappet door vent pipe, which has been spitting out heaps of oil.

 

-The old engines cam followers have holes in them so it drains through, lubricates the cam lobes, and doesn't pool beside the breather tube. So i'll put those in it. Just seems odd hah. I won't worry too much about it, just put the cam followers with the holes in them in the new engine unless you lot can think of anything I can't

 

 

 

Anyway, bit of a wall of text, so have just put the main points in bold, but the summary of it all is that it should be all sorted and under way, thanks to all of you for your insight and suggestions. Hopefully will get my hands on the parts I need early this next week and be putting it back together very soon.

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gap those rings in the bores they are going into for maximum sealing abilities. Solid lifters were used in some models (forget which), I've always preferred the drilled type for reasons you mention. Check valve guides also.

As frosty said, some pistons aren't up to much, I have drilled bigger oil control ring drain holes into replacement pistons to cure smoking.

Some A series bits I've come across new have been intended for industrial motors, post up pics of the pistons if you can.

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I wouldn't change the cam followers unless they have been refaced. If they have been broken in to a different cam in a different block you may have lifter rotation and wear issues.

I think the non holed ones are more a competition item as they can break where the drilling is. Remember the cam also gets a good splash from the crank flinging oil around (hence 2000+ rpm cam break in).

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That oil is far too thin, running in or not.

Drain it and fill with Penrite 20w60 asap- compatible specification to the original 30w

 

That Penrite 20-60 was what I ended up running after the running in oil in an attempt to help the issue, will be the oil I end up running I would imagine. I have actually got a different oil on its way for run in as not keen on the 15-40 again - this stuff which is a genuine SAE30 and non friction modified so should be good for the initial few km to bed in?

 

gap those rings in the bores they are going into for maximum sealing abilities. Solid lifters were used in some models (forget which), I've always preferred the drilled type for reasons you mention. Check valve guides also.

As frosty said, some pistons aren't up to much, I have drilled bigger oil control ring drain holes into replacement pistons to cure smoking.

Some A series bits I've come across new have been intended for industrial motors, post up pics of the pistons if you can.

Will gap them for each bore when I get ahold of the rings, haven't got too much info on the rings yet, meant to be ACL brand and he wasn't able to tell me much more so no idea what oil control ring setup is on it, will check if they will suit when they arrive in store. Bit tricky being stuck with him running 60 thou pistons, limits my options for getting rings. I'll grab a photo of the pistons now in regards to the oil slots. 

 

Will pull the head down tomorrow to see how the valve guides feel etc, and see what is going on with seals or o-rings or anything. 

 

 

I wouldn't change the cam followers unless they have been refaced. If they have been broken in to a different cam in a different block you may have lifter rotation and wear issues.

I think the non holed ones are more a competition item as they can break where the drilling is. Remember the cam also gets a good splash from the crank flinging oil around (hence 2000+ rpm cam break in).

 

The ones with holes haven't been refaced, some of them do show marking/indents where the cam was running and they haven't been rotating much, others are fine. Might come out with an oil stone and some persistance? The nice thing is the followers can be removed without too much drama should I change my mind on what ones to run later. 

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The ones with holes haven't been refaced, some of them do show marking/indents where the cam was running and they haven't been rotating much, others are fine. Might come out with an oil stone and some persistance? The nice thing is the followers can be removed without too much drama should I change my mind on what ones to run later.

They are ground with a radius. Get em refaced if you want to run them.

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Hmm perhaps they were meant to have a radius but both these sets seem flat, I'd better look into that.

 

On another note I'm thinking I may still get a little stuck with rings. Went into partmaster yesterday to sort out rings, he's found a listing for .060 rings for a 998 which he said he would sort out on Monday and couldn't get any additional info on, however doing a bit of looking into it now I think they might be no good, as the listed ring set from ACL is "PS1145-060" which is showing as 12 compression rings and 4 oil rings. So that doesn't cover the two oil rings per piston, and presumably means that it is a one piece oil ring too. Bugger.

 

I'll send an inquiry to FES/Johnson rings and see what they can do. Where did you guys end up sorting your 3 piece oil control rings, any ideas?

 

Something like this maybe 

http://www.minimania.com/part/RA17927-60/Piston-Ring-Set-060-998--1100-5-Ring-Piston

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Ah yup okay, straight edge and light shows a slight curve in the old engines set, the ones with holes, most of them are fine and slight radius however a few have wear marks of where the cam has begun to dig in. The ones in the new engine however definitely are flat and look like they've been refaced recently, but flat. Might be worth getting the worn ones with holes refaced in that case.

 

Not much showing up for strong bros, some sites saying they have gone under, other listing addresses in Sunnybrae and Diana drive in Wairau area. 

 

EDIT: Yup seems they are on Diana drive, just missed them today so will try again tomorrow, certainly looks like the place to go

Edited by estate_
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