My 'New' engine.

Technical MGB discussion
Ian Fozzard
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Re: My 'New' engine.

Post by Ian Fozzard » Wed Jul 22, 2020 10:10 pm

Graham,
I think your "+90" questions have been discussed and answered above,

Ian F
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Simon G.
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Re: My 'New' engine.

Post by Simon G. » Thu Jul 23, 2020 3:06 pm

The first thing you want to be checking for is scoring on the crank and cam journals - 'cos if you've got any it'll need remedial treatment, regardless of what any measurements are.
(As long as the journals are well within tolerance fine scoring can be polished out - a job you can do yourself with care and some good measuring instruments - for which I recommend a visit to a certain online auction site where you can pick up good used kit at pretty good prices.)
The cam follower wear could have several causes - old followers, wrong oil, incorrectly treated/finished components. I've seen cases where the followers look like that but the cam is still good, but also where the cam has suffered as much as the followers.
Hopefully the oil filter will have done its duty and taken out all the damaging stuff before it's got to the bearings, however the oil pump is 'upstream' of the filter so it might be lunched.
(Speaking from recent experience of destroying a very carefully and very expensively rebuild motorcycle engine in 900 careful miles - for which all inquests, including oil analysis, has failed to come up with a definitive cause).

SG

(Post held in 'moderation' for quite a while - is that normal around here??!)
Last edited by Simon G. on Thu Jul 23, 2020 10:13 pm, edited 1 time in total.

Hazza1190
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Re: My 'New' engine.

Post by Hazza1190 » Thu Jul 23, 2020 3:25 pm

Cheers guys, some more updates if anyone's interested!

The camshaft itself looks okay. I cant see any wear on the lobes which is good. I will, however, measure it on a dial gauge when I can to make sure there's no wear. The camshaft has 'K6715' or 'KG715' written on the front. It also has 08087 on the front. I cant find any notes on this. Do you think its a kent 715 (just going off of the 715 on the front) :?:

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The cam bearings themselves are pretty screwed so they'll need replacing so will send them to the shop o get that done.

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There's also some wear from the cam chain on the cover. Is this unusual?

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Cheers!
Harry.

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Peter Cresswell
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Re: My 'New' engine.

Post by Peter Cresswell » Thu Jul 23, 2020 4:13 pm

Hi Harry
You seem to be getting on with things!
I reckon that is a Kent cam, but ring them to check (01303 248666) the markings. It is quite a good cam particularly when used with a weber carb which you have. According to Peter Burgess in his book, it can give high 90 bhp at the wheels which is more than the standard engine at the flywheel! It is the Kent equivalent of the Piper 285 I am running. I don't know what the '08087' means but Kent do some profiles onto standard cams so it might be a 'reprofiled' cam. Ask Kent about this number as well.
Your cam followers need replacing and are not expensive, but buy them from one of the reputable parts suppliers. They are under a lot of strain so the better the quality the longer they last. If you have any doubt about the quality the buy them from Kent. I used Mini Cooper S Iskenderian followers which fit and have a slight bigger diameter surface (to help spread the load a little) as the chamfer at the sides is smaller, but they were fiddly to get the rocker angles right as they are drilled deeper than the MGB ones.
The cam bearings - the front one at least, looks very worn and has started to pick up - that's the 'tearing' pattern across the surface. They need line boring once fitted, so it is an engineering shop job. Get them to fit them them before they clean the block to get all the swarf out from fitting them.
The cam chain has a tensioner which looks as if it might not be working correctly so check it to see. The chain shouldn't hit the inside of the cam cover, and would make a lot of noise by doing so.
I have been reading back through your thread, and in your first post you gave the capacity as 1860cc. This size is obtained using +060 pistons - It is actually 1868cc if you do the sums. Incidentally if they are 0.90, they would be almost an Inch bigger diameter and you wouldn't have any cylinder walls left to see the cross hatching! Even 0.60 is more than 1/2 inch bigger diameter so that isn't possible. I'm sure you will find they are +060 thou.
No doubt you will have more questions as the work progresses, so keep the post coming!!
Pete
Pete
1969 MGB Roadster
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Plus 32 other cars since 1965

Hazza1190
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Re: My 'New' engine.

Post by Hazza1190 » Thu Jul 23, 2020 5:00 pm

Hi Peter,

Thank you. :) It all makes sense now regarding the cam, i cant believe i didn't notice it before! Its not 'K6715' or 'KG715', its KC715. K C for Kent Cams! :lol: Atleast i know now, and i have just read that in peter Burgess' book so im happy with that. The lady on the phone guessed that the '08087' was just a casting/identification number. Just got to hope that its not worn on the offending cam followers.
I have read the stories of the cheap followers so will definitely go with the best ones i can afford! So maybe i'll go for the Kent ones.
Yeah like you say the cam bearings knackered, ill be sending it off to the machine shop to get done properly. Again, i'll look for the best ones i can find.

The cam chain was a bit of an odd one. The tensioner was working but was pretty worn. However, the opposite side of the chain (other side to the tensioner) did seem oddly slack so im thinking that was the cause. I'll use a new chain obviously. The one on the car was a 'Rolon' chain and tensioner.

Yeah the +90 is puzzling. Im almost certain all of the pistons are written as 0.90, all have a destictive '.' between the 0 and 9, which is very odd. Is it possible that it has liners fitted? I'll have a good look this evening when i take apart the big end.

Cheers,
Harry.

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Peter Cresswell
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Re: My 'New' engine.

Post by Peter Cresswell » Thu Jul 23, 2020 5:42 pm

Hi Harry
The only way to be sure about the bore size is to measure it. The standard bore is 3.16inches, so with a +090thou oversize it would be 3.25inches and with +060thou oversize it would be 3.22inches.
Measure to be sure!
Cheers
Pete
Pete
1969 MGB Roadster
2011 MG 6 TSE Magnette
2007 Mercedes SLK
Plus 32 other cars since 1965

Hazza1190
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Re: My 'New' engine.

Post by Hazza1190 » Mon Jul 27, 2020 6:41 pm

So, the bottom end is now dismantled and lets just say that I think I have found where all of the metal has come from...
See the picture below, it is the bearings from journal 2. It seems very odd how its worn/filled up the holes like that, its almost as if the bearing shell didn't fit into the cap correctly (it sit on the crank just fine, but seemed very loose in the cap/block). Pic 1 is cap side, and pic 2 is block side.

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2.
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All (piston and caps) bearings are +40 over. Most the journals unfortunately seem to have sustained some wear/damage and therefore require another regrind. I have a standard size crank from my 1973 engine that has never been worked on. Is it worth getting that one done to +10/+20 or is it better to keep the original and go to +60? If I do change the crank is there any issue in using i may face, using the 'new' engines conrods for example?

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Cheers,
Harry.

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Peter Cresswell
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Re: My 'New' engine.

Post by Peter Cresswell » Mon Jul 27, 2020 9:01 pm

Hi Harry,
Sorry to hear your continuing bad new!
The bearing look to be very worn - more 100,000 hard miles than 500! As you say, this is very likely to be the source of the swarf you have found in the engine, along with some wear from the cam bearings and cam followers.
From your comments on the pictures, it sounds like you have a problem with the con rods. The bearings should be a tight fit to both halves of the conrod big end - in fact I think they should 'spring into the rod and big end cap. They should not be able to move at all, so something is very wrong there.
Since you have another engine, you could consider using the best parts from this 'old' engine and the 'new' one. If the crank in the 'old' engine has not been reground yet then that is a better bet than the 'new' one going to 60 thou undersize. I would also use the rods from from that engine as well. take a look at the pistons from both engines and decide which are the best and it may be better to have the 'old' engine block bored to suit the best set. Then fit new rings. Having the rotating parts balanced can make a huge difference to how an MGB feels, so that is very worthwhile considering.
Once you have fully striped down both engines and have all the parts for comparison you can make a judgement as to which parts from which engines as best to use going forward.
Have you gone back to the seller to complain? There is a good chance he might not have known the true condition of the engine, but it is likely that it showed low oil pressure, especially when hot. I think the price should reflect the fact that basically you have an MGB engine suitable for reconditioning plus a number of rather nice parts. An standard MGB engine for reconditioning is worth about £100 (you would get around £50 if you weighed it in at a scrap yard!). On top of that the Weber Carb + Alloy Manifold would cost around £700 new, the sump £320 new, Timing gear (£120 new), spacer set £20, tubular 3 branch manifold £250 etc. I would expect to buy/sell second hand parts for about 50% of the new price, so you can see that you can easily put a value against what you have, and if you paid more, try asking for a refund for the excess. Back up your claim with pictures such as these here as evidence it was in poor condition as bought.
Hopefully there will be some good news in there somewhere!!!
Pete
Pete
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2011 MG 6 TSE Magnette
2007 Mercedes SLK
Plus 32 other cars since 1965

Hazza1190
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Re: My 'New' engine.

Post by Hazza1190 » Mon Jul 27, 2020 10:36 pm

Hi Peter,

Yes they are well and truly screwed! My original engine which had at least 125k miles (could have been 235 but unlikely) weren't even as bad as that!

Sorry i may not have described it correctly. It was only 1 bearing that was loose, all the others were very tight. The loose one is the excessively worn one that I pictured in 1 and 2. It was from the main bearing 2 on the crankshaft and was slightly loose. This may be down to the wear, a good idea (which i'll try tomorrow) will be to put the better bearing from 4 in and see if its also loose. It was not a conrod bearing.

I think i'll use the crank from the original engine as its unmolested so makes sense. I could also use the block from the original car if needs be, would be nice to keep the engine number i suppose! The pistons in the new engine seem brand new, still very shiny below the rings. I still need to measure them to find out the .90 dilemma!!

I haven't complained, i have shown him all the pictures in the hope that he'd offer some money back out of kindness as he may have noticed that me being young i have to save between each of my investments into the car. He has 2 v8's..! It was truly only used for 500 miles by that owner, then 8-10,000 by previous owner (but didnt have much history as it was through a dealer). So it was my risk that i unfortunately hasn't payed off as well as id hoped. Oh welll.

Considering all the parts that you say, I haven't lost out too badly to be honest.

Cheers,
Harry.

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