Engine smoking badly after rebuild... HELP PLEASE!...

[BliarOut]

Top diagnosis from the pics Puma

[Pumaracing]

camelotr said:

Thanks again. This is a real "Engine academy". I though I know something, but deffiniatly not.

I thinks my engines were done not 100%. I will try to press the machinist do a better work next time. He has the right equipment, and knowledge. I think he was not keen enough on his employee.

The articles are perfect.

Can You advice me more? I think if I would like to come out of this problem, I should at least try to leanr as much as possible.

You're a brave man going back to the same machinist. I hope he does it properly next time. I suggest you examine some of his other blocks before deciding if he actually knows how to do this right.

Yes you can ask more questions. I'll help with whatever I can.

[BliarOut]

Pumaracing said:

camelotr said:

Thanks again. This is a real "Engine academy". I though I know something, but deffiniatly not.

I thinks my engines were done not 100%. I will try to press the machinist do a better work next time. He has the right equipment, and knowledge. I think he was not keen enough on his employee.

The articles are perfect.

Can You advice me more? I think if I would like to come out of this problem, I should at least try to leanr as much as possible.

You're a brave man going back to the same machinist. I hope he does it properly next time. I suggest you examine some of his other blocks before deciding if he actually knows how to do this right.

Yes you can ask more questions. I'll help with whatever I can.

An adage I remember from my apprenticeship, you can cut off but you can't cut back on!

[GavinPearson]

camelotr said:

Thanks again. This is a real "Engine academy". I though I know something, but deffiniatly not.

I thinks my engines were done not 100%. I will try to press the machinist do a better work next time. He has the right equipment, and knowledge. I think he was not keen enough on his employee.

The articles are perfect.

Can You advice me more? I think if I would like to come out of this problem, I should at least try to leanr as much as possible.

I'll give you some advice - drop your machinist.

He may have the best equipment in the world but if he employs people unqualified to use it the results will be abysmal. You have found this out to your cost already.

I would give Pumaracing the work. Actually I will go further - hand him all your parts and have him do the work to machine, clean and build the engines. It will actually be a good value investment bcause the work will be done right.

[camelotr]

That would be the nicest thing. Although as far as I know, Pumaracing wont accept any orders now.

Call me a foul, but I still thrust my machinist. He is an honest and enthusiastic man, soo I give him another chance. Although we will double check everything...

Edited by camelotr on Monday 12th April 07:20

[Pumaracing]

camelotr said:

Call me foul, but I still "thrust" my machinist.

Now you see there's your problem. Never mix business and pleasure

Edited by Pumaracing on Monday 12th April 07:26

[Pumaracing]

Flat6 said:

One point I can confirm - there's definately no pin offset on AE A-series pistons.

I'll defer to anyone who's actually examined one more recently than me because it's 20 years since I built my last A series lump but if so it's certainly most unusual for a cast piston not to have an offset pin. The only engine I definitely recall not having an offset pin was a 1950's Daimler Dart 2.5 V8.

Apart from just getting a vernier out and measuring it an offset pin will also be indicated if there's an arrow on the piston crown showing which way to install it even if the piston crown is symmetrical. The arrow always points towards the front pulley on every engine I've dealt with.

I'd at least hope the Mini Spares Evo pistons have offset pins if Evo is meant to mean Evolution because offset pins increase power output somewhat and reduce piston slap and wear by a considerable amount.

Perhaps the OP can measure both his piston types and confirm the outcome. The offset if present is normally about 1.5mm closer to one piston skirt than the other.

I'm pretty damn sure I have some old A series pistons knocking about still so if I find one I'll check myself.

[camelotr]

I think there were mini pistons with offset pins, but theese "new" items look like symethric. No directon indicator or anything like this.

Donno why. I understand what the offsetting is for. Maybe they do theese pistons to kill a problem source...

[Pumaracing]

GavinPearson said:

I'll give you some advice - drop your machinist.

He may have the best equipment in the world but if he employs people unqualified to use it the results will be abysmal. You have found this out to your cost already.

It reminds me of yet another of my endless store of engineering anecdotes. On this page of my website is a sorry tale about a trainee machinist having a small dilemma with flywheel lightening on the lathe.

http://www.pumaracing.co.uk/FLYWHEEL.htm

Some time later another person of my aquaintance took a very expensive race Pinto cylinder head to the same place for the worn valve guides to be sorted. On the Pinto head the valve guides are just 8mm bores directly into the cast iron of the head with no separate valve guides so to reclaim them you have to drill and ream out the bores, fit iron or bronze valve guides and then recut the seats. The usual size to drill and ream to is 1/2" on the Pinto.

The Pinto head has slightly angled valves. Nothing like as much as most 16v heads or 8v hemi heads but about 7 degrees from the vertical on both inlet and exhaust valves. Young dhead at this engineering emporium slaps the head down on the milling machine, gasket face down, and starts drilling into a guide bore with the mill set vertical. It didn't occur to his tiny brain to check whether the holes he was drilling into were actually also vertical to the machine axis.

Some time later after forcing the drill bit to bend through 7 degrees as it tried to drill a straight line down the guide bores he goes and asks the boss what to do next. All 8 bores were by now oval holes of sufficient ovality to render the head completely scrap.

I think some places, or some people, get things wrong as a matter of course. You can't educate pork as my mate says.

Edited by Pumaracing on Monday 12th April 13:54

[camelotr]

I had a damn good turner a couple of years ago. He was realy good. Not just accurate, nice things he did, but he even had BRAIN to think a bit and try figuring out the best solution. He even managed once to do an SU needle to 0.003mms accuracy...)

After a while things went on wll, bussiness developed, and he employed two coworkers.

And end of the story. The quality droped to the bottom of the sea.

Things done without soul and some insight, are just converting the material to trash.

[camelotr]

Pumaracing said:

camelotr said:

Call me foul, but I still "thrust" my machinist.

Now you see there's your problem. Never mix business and pleasure

Edited by Pumaracing on Monday 12th April 07:26

Well Gentemen... actualy... erm... humho... I wanted to tell You that I trust in him. Nothing age related stuf. You know...

Revenge of grammar.

[Flat6]

Pumaracing said:

Flat6 said:

One point I can confirm - there's definately no pin offset on AE A-series pistons.

I'll defer to anyone who's actually examined one more recently than me because it's 20 years since I built my last

I'm probably closer to most on this subject as I've got the drawings here Although I can't comment on the "evo" piston, I do know that both the large bore Powermax piston (73.5mm) and Minispares "Mega" pistons have central pins too..

[camelotr]

The Evo is the same in dimensions, only the piston cown differs.

[Pumaracing]

Flat6 said:

Pumaracing said:

Flat6 said:

One point I can confirm - there's definately no pin offset on AE A-series pistons.

I'll defer to anyone who's actually examined one more recently than me because it's 20 years since I built my last

I'm probably closer to most on this subject as I've got the drawings here Although I can't comment on the "evo" piston, I do know that both the large bore Powermax piston (73.5mm) and Minispares "Mega" pistons have central pins too..

That's interesting. Basically it means everyone has just slavishly copied the original design even though it's blatantly obvious there's a better way to do things. This is so bloody typical of aftermarket parts. The very first Ford Pinto engines back in the 70s had inlet valve stems with no chrome plating (the exhausts were plated). It's hard to imagine any car company being so bloody cheap as to try and save that last few pence per valve when it's universally known that you can't run unplated stems in cast iron guides - or at least not at high rpm for long. You can just about get away with it in diesels. Ford corrected it once failures started to become apparent. Same with the Crossflow as I recall.

So when TRW added Pinto valves to their catalogue you'll find no chrome plating on the inlets either and when KolbenSchmidt started doing their own valves a few years ago you get exactly the same thing. I unwittingly put sets of KS valves in three Pinto race engines some years ago not realising they were unplated (you can't really tell by eye) and it took just one race to wear 10 thou out of the inlet guides and completely shag the valve stems. Several days in the workshop reaming all the guide bores out, fitting guide inserts, recutting the seats and buying proper valves at his own expense for muggins here. Current spec Ford OE plated valves last forever of course.

Somewhere in each of those companies there'll be some witless little jobsworth who'll say "nah mate, we just copy the original blueprints. More thanmejobsworth to change anyfink."

Maybe that's part of the reason why the A series has always been known for poor cylinder sealing and oil control when a bit of decent piston and ring design could have alleviated it. If people are still churning out A series pistons with no pin offset just because Leyland did so 60 years ago then shame on them.

You also get forged pistons with no pin offset from some of the American "performance" piston companies. I saw a few sets of those slap themselves to death in someone's VW Golf race engine which was eventually cured just by going back to bog standard cast OE pistons on my advice. Even at 100 bhp per litre these gave no problems at all.

Interestingly some of the A series valves in cast iron guides are tuftrided rather than chromed, which also works fine but is an unusual way to do things. Chrome is cheap and doesn't involve heat and distortion in the process. I think they went to chrome with the A+ engine.

[camelotr]

If we succed with the resleeving, I will be left with the other block which has been overbored- thus useless. Atl est with theese pistons. We have here in my country a pretty good piston manufacturer, who is able to do custom pistons at an affordable price.
This gives me an option to have a custon set made for the existing size.
I think it would be good to have some piston pin offset this time. What amount would You advice? Any other modifications that would make any good?

[DaveL485]

Huff said:

+1. Just jumping -in to say - Dave, I really appreciate the detail you post on the what-and-why of careful engine building on PH.

For sure- Probably the most informative poster on PH for us engine geeks

[Flat6]

Pumaracing said:

Basically it means everyone has just slavishly copied the original design

Well not exactly. AE (H&G as was) was the original design, and even as far back as then manufacturers worked very closely with part suppliers in engine development. There's no cost implication in producing a piston with an offset pin so maybe there's a perfectly good reason for this (it's a little before my time so I can't comment ). Of course I'm not saying there haven't been issues over the years due to cost savings on the part of the OEM (your Pinto example being a case in point) or engine design flaws.

A-series doesn't suffer particularly badly from oil control or cylinder sealing issues because of piston design. In many cases it's down to other factors (scuffing from contaminated oil due to the gearbox in sump design on Minis, poor build etc). Advances in ring design have significantly improved both oil control and gas sealing, even on ancient engines such as the A-series (the Mega pistons for example use a more "modern" narrower top ring).

However, in most cases Aftermarket suppliers simply can't afford to offer anything other than the OE design/spec - there's an enormous amount of R&D applied to each new engine development and OE suppliers have a very close partnership with the OEMs. Suppliers fortunate enough to have this relationship can be confident that the performace of their product is as good as OE (the parts of course are one and the same) and in some cases can use their experience with OE application engineers to modify the product slightly for Aftermarket use, if deemed appropriate. Smaller AM companies don't have this resource, and therefore take a very big risk in deviating from the original design, particularly given the increasing expectation of no quibble warranty claims.

Sorry for going a bit off topic there

Thanks for your opinion and advice PumaRacing, you're input on here is much appreciated. It's not often these days that I hear unfiltered opinions

[Pumaracing]

I think the main reason for A series oil control and ring sealing issues is bore rigidity, or the lack thereof. It certainly gets even harder to control as you overbore and lose even more rigidity.

As to offset pins they aren't needed so much if the piston is long in comparison to its diameter, has full skirts, tight bore clearance and operates at low rpm so rock isn't an issue. As you get to shorter and shorter pistons with lower compression height and slipper type skirt designs then rock needs to be controlled much more. That's why those forged VW race pistons with no offset were so bad plus of course they were having to operate at high rpm and being forged ran a lot of bore clearance.

I do recall a test Dave Vizard did many years ago on the Pinto to see what effects the pin offset had. The piston is symmetrical other than that so he tried a back to back dyno test with the pistons in both ways round. I think with the offset the wrong way round it cost 4 or 5 bhp but I couldn't swear to the numbers. I'll ask him if he remembers next time we speak.

However as far as I'm aware there are no downsides to pin offset so it makes sense to have it and every modern engine I've come across does.

[Pumaracing]

camelotr said:

If we succed with the resleeving, I will be left with the other block which has been overbored- thus useless. Atl est with theese pistons. We have here in my country a pretty good piston manufacturer, who is able to do custom pistons at an affordable price.
This gives me an option to have a custon set made for the existing size.
I think it would be good to have some piston pin offset this time. What amount would You advice? Any other modifications that would make any good?

You can still take the second engine to 73.5mm presumably if it's only at 73.0mm now. The Powermax 1380 pistons work fine. I wouldn't go re-inventing the wheel with custom piston manufacturers if I were you. Stick to what's already on the shelf and known to work or you'll end up building in even more problems next time round.

[camelotr]

I do not want to go for 73.5 - if only posible. This is a restored car, and not quite nice to leave its engine without the option of a final rebore. This is the final option.

I have built 3 engines with the pistons of this manufacture without problems. Although 2 were 998 engines and only one 1275. Even this was a stock engine with 63 hps.

This time I wanted to give EVERITHING for my engines, and did not counted the costs, only used the best possible.

The piston maker would use the original pistons for basic design, only add some modifications as I order.

I dont want to reinvent the wheel, just if this would be my next step, why nor get the pistons better with some offset.

How much would it be? 1mm, 1.5mms?