[engine_work] Autocross Mi16

[zeolite 0]

Still haven'tgot a new cambelt but I thought I would use an old one to time up the engine.

 

[zeolite 0]

Thanks for the move Ahl.

 

A wee reminder of what it was like before

 

Note the crap start (no comp engine) and hear the beastie howl when banging off the rev limiter. 130db at last measure

Should have 50bhp more this year

Edited April 5, 2007 by zeolite

[zeolite 0]

Engine now back in. Just have the plethora of hoses to connect up.

 

[welshpug 1,657]

a right hooker with the servo on the left? whysat then?

[Miles 331 1 Cars]

Silly point but I hope you put the head gasket on the right way

[B1ack_Mi16 67]

At least the oil-returns seemed quite a bit strangled in that picture of the gasket, didn't line up too well with the block at all.

[petert 586]

Since you've been liners about, it would have been wise to check the protrusion. There's no margin for error when using copper gaskets. I also hope you skimmed the head.

[zeolite 0]

What are you doing to my head guys! Why didn't you post this when the engine was still on the stand?

 

Anyway protrusion was checked and was good although I didn't skim the head as I felt it was good enough.

 

As for the gasket, i thougt it only went on the one way over the dowels. Is it right or not?

[petert 586]

Is it right or not?

Not the way it is in the picture. Sorry, but I only just found this thread today. I don't normally look in this section. Also, did you use any copper sealant? Such as "VHT Hi Temp Copper Gasket Cement"? Loctite also make a product but I can't recall the name. Less important than the protrusion however.

[zeolite 0]

Thing is, I cant remember if I changed it after the pic because it does look wrong. Looks like I have to take the head off again to check.

 

I didn't use any sealant. I wasn't aware that it was necessary

[B1ack_Mi16 67]

Can't you just see at which end of the block/head the part of the gasket that protudes sit?

[zeolite 0]

Well the tab protrusion bit is in the wrong place according to another built up engine I have lying about so the head will have to come off again. C'est la vie.

[Miles 331 1 Cars]

I must admit I don;t look in here that often either, At least it was spotted before you fitted back in the car

[PumaRacing 2]

Since you've been liners about, it would have been wise to check the protrusion. There's no margin for error when using copper gaskets. I also hope you skimmed the head.

 

I have to say I don't really see how solid copper gaskets work at all on protruding liner engines. Even the OE gaskets have a built in silicone ring round the block flange to seal the oil and water channels properly in case the fire ring doesn't compress enough over the liner protrusion. I have a concern that with a solid gasket what actually happens is the head must bend somewhat and that can't be good.

 

I think if compression ratio or squish is an issue then the way to do it is machine the block and liners until the desired figures are achieved with a normal gasket. Lots of work of course but better than water pissing out of every orifice because the gasket isn't sealing the outside of the block. At the very least I'd be using a good bead of silicon on the block flange with a copper gasket and then just keeping fingers crossed. Actually I wouldn't be using a copper gasket at all if my neck was on the line for the engine build. I'm not saying that people haven't done it and found it works but for how long and it seems very wrong from an engineering POV. OE gaskets are pretty cleverly designed bits of kit and having the right amount of crush in the right places takes some doing.

 

I have fewer objections to copper gaskets on a cast iron block when all it's doing is sealing two flat surfaces but even then I'd always use a normal type out of preference and machine things as necessary to set squish and CR.

 

In a previous thread I calculated what happens at temperature as the block expands more than the liner and the protrusion reduces and then increases again as the engine cools down. The gasket needs some flexibility to cope with this and the last thing a solid gasket has is any of that. I think I'll keep a watching brief on the engines that have solid gaskets fitted and see what happens in the longer term before finalising my own views on things.

[PumaRacing 2]

My tools had arrived namely, piston ring pliers and honing tool so it was time to get on with it.

 

First job was to hone out the liners.

 

What I think you might not realise is just how much you're crushing that liner holding it in a vice to hone it. By the time you've gripped it hard enough to stop it moving you've squashed it 5 thou across that axis. You'll just about get away with it because you're using a sprung loaded brake cylinder type hone and not a professional Delapena type which hones to a fixed and truly circular size with a micrometer feed. Try that with one of those and it'll lock up solid against the small axis or hone it out to an oval shape.

 

Holding liners properly means making up a jig which clamps them from the top and bottom as they're held in the engine. It's a major PITA as it means a new jig for every type of liner. I spent a day making my 205 one from a scrap block and head on the milling machine and even then it's not quite ideal.

 

Using your type of equipment it's probably better to get a spare pair of hands to just hold the liner on a bench for you while you hone. At least it'll then have a decent chance of staying circular while you hone it.

[PumaRacing 2]

Silly point but I hope you put the head gasket on the right way

 

In the pic it's on the wrong way round. It needs rotating 180 degrees. I hope it didn't stay like that.

[zeolite 0]

Firstly the HG was on the wrong way so thanks for spotting that chaps and I am officially a numpty! Would you believe that I am trusted with nuclear sources? It is a pity you didn't spot it before the engine was fitted as it is a total bastard with the cant on the engine and the lack of space between the chassis and pulleys. I am grateful nevertheless.

 

As regards the honing; the liner was actually just sitting in the vice with practically no grip. The man doing the honing is a time served toolmaker and a proper engineer (otherwise known as Dad!) unlike myself. we were aware of the distortion issue.

 

As for the copper gasket I will go and find some copper gasket sealant as Petert recommended.

[crf450 0 1 Cars]

What I think you might not realise is just how much you're crushing that liner holding it in a vice to hone it. By the time you've gripped it hard enough to stop it moving you've squashed it 5 thou across that axis. You'll just about get away with it because you're using a sprung loaded brake cylinder type hone and not a professional Delapena type which hones to a fixed and truly circular size with a micrometer feed. Try that with one of those and it'll lock up solid against the small axis or hone it out to an oval shape.

 

Holding liners properly means making up a jig which clamps them from the top and bottom as they're held in the engine. It's a major PITA as it means a new jig for every type of liner. I spent a day making my 205 one from a scrap block and head on the milling machine and even then it's not quite ideal.

 

Using your type of equipment it's probably better to get a spare pair of hands to just hold the liner on a bench for you while you hone. At least it'll then have a decent chance of staying circular while you hone it.

 

Dave you've changed, I was looking through this thread and scrolled down to this picture of someone holding a liner in a vice which looks like it should be in a forge without so much as a set of soft jaws and I was excited at the prospect of reading how you chastised them for what to anyone that has a basic engineering understanding looks unbelievably bodgetastic, but instead you gave a really informative polite reply. I'm sure a few months ago all you'd have thought these sorts of actions would have warranted was a flaming with double portions of sarcasm, I must say I preferred the old Dave .

[petert 586]

I have to say I don't really see how solid copper gaskets work at all on protruding liner engines.

 

They actually work better on wet liner engines than they do on flat blocks that haven't been o-ringed. They're supplied in a full annealled condition (extremely ductile). When torqued down, the liner bites into the soft copper. The bore decreases in diameter. Naturally you have to allow for this. Having an 83mm bore with an 83mm gasket is a no-no. I wouldn't use a copper gasket on a cast iron block that hasn't been o-ringed.

 

Everything needs to be squeaky clean, flat, square and parallel. It's a true mechanical seal. Nothing new about it.

 

One particular race engine that I built over three years ago is still running fine. Three years is the maximum life however due to their obvious long term corrosion issues. Strip it, anneal it, then put it back together.

 

Decking liners is just one method and one which I prefer for DFW engines. I take 1.3mm off those decks. How many people can hold a liner square while they deck it? More chance of getting a leak from a leaning tower of pizza!

Edited April 26, 2007 by petert

[petert 586]

These lads look like they might know how to hone a liner!

 

http://www.perfectbore.com/

[Ahl 4]

Dave, I formally invite you to come up to my place and hold onto my liners while I hone them!

[Col 0]

dave bolton

[zeolite 0]

Gosh is it nearly a year since I posted last.

Updates coming soon.

[zeolite 0]

Ha updates!

 

The MI is in a garage in Scotland and I am working in Singapore after 5 1/2 years in the USA.

 

Life happens and plans go West.