[engine_work] Xu9j4 Mi-16 Rebuild

[petert 586]

Then you wouldn't need the flex pipe. A better long term solution.

[petert 586]

I've been trying to get my head around why this exhaust works so well and the physics behind it. Is it because the pipes are twice as long, doubling the wavelength and doubling the mass of air that is extracting exhaust/incoming charge from the cylinder?

[kyepan 291]

Thread resurection.

 

So the pug is still going strong, it has however been suffering from an interminable flat spot at low rpm wide throttle openings.

 

Which was temporarily fixed by swapping out the middle box, with another long-life box.

 

 

Within a week... yes a week, the flat spot is back....a year goes by... and it gets fixed again, this time with a different brand of middle box, again it's going like a wet cat out of a bath tub.

 

Other foot notes, I bought a proper four tube carb balancer, and followed the instructions on the GSXR workshop manual for balancing the bodies. It now has no kangerooing either. So it's really rather good at the moment.

 

Sounds great, gets LOADS of looks everywhere, goes like stink.

 

happy pug owner.

 

PS- avoid long life exhausts, their boxes are not high quality.. at all.

[DrSarty 90 1 Cars]

Wow Justin! Epic. Be good to see you again at some point/meet.

 

Did I read you go to Ace Cafe occasionally? I know where it is, although I've never been to a meet there.

[kyepan 291]

On 4/27/2016 at 6:00 AM, petert said:

I've been trying to get my head around why this exhaust works so well and the physics behind it. Is it because the pipes are twice as long, doubling the wavelength and doubling the mass of air that is extracting exhaust/incoming charge from the cylinder?

Just seen that I had not seen this! I don't know, sandy might it was his idea to use it. 

 

Going to do the cam belt, re time the cams, and I think an o ring has gone again. If I had the money is put on a set of jenveys. But it will have to get fixed for now. 

 

Back to flat spot city unfortunately.

[kyepan 291]

A quick update to this. 

 

 

 

The car’s been in hibernation for a year and a half, and looks like a piece of s*it, lots of little bits of surface rust everywhere in the engine bay. Anyway. 

 

As usual It’s developed a flat spot, and also had lost a lot of poke. Filled up with fresh fuel, no better. Drove it back from the MOT, (it passed the emissions with flying colours I might add) @Sandy. 

 

Popped the bonnet and gave the throttle a blip, can immediately hear one of the o rings has gone. Flywheel end number one cylinder. But then I heard a little tap / crack sound after the blips… from the cam belt end… and got very worried. I’ve had a belt go before on my first car, engine off, cover off, sure enough, top run was squidgy, and the long run was LOOSE… pucker my pucker… I hope the belt hasn’t jumped. 

 

I was going to change the belt as it's due on a time basis, but now I’m going to have to do that before anything else. 

 

The extra complexity here is because I’ve swapped to a VTS box, I don’t have the window to stick the timing tab and use the flywheel tooth timing method to find TDC. I’ll have to mark the crank pulley instead. 

 

The belt looked in pretty good condition, so I suspected one of the tensioners has failed, everything on the right hand side of the car looked like it had been in the sea, so It would not surprise me if a tensioner had undone itself. 

 

Managed to persuade Pa to come over and help. 

 

Took all of Saturday to mark up the crank pulley, used the method in my camshaft book, ie, Marked at 0.3mm of piston travel, cranked it through the dwell at TDC and marked it 0.3mm the other side then used some verniers to measure the mid point and mark that too, so that gives you three marks, which as it turned out became quite useful later on. 

 

Then carefully scoring a perpendicular  notch into the front and back edges of the pulley with a needle file, and then scored a line in the block will give you a front and rear gun sight and target to look down when judging if you’re at TDC This should should help improve accuracy. 

 

 

Now I have a confession to make, I always worried that using the tab on the gearbox method was a bit hit and miss, because, how do you know what angle is the correct angle to view from if you only have the tab and the gap in the teeth. There’s no two marks to line up along before looking at the flywheel.  Additionally, where on that gap should you be looking, as its about an inch. 

 

So I was hoping for a more accurate. Evidence seems to suggest, yes marking the pulley is a superior option, despite its smaller size. 

 

 

 

So now the belt is ready to come off, the next conundrum. Locking the cams with verniers, I don’t know why they can’t make  vernier cams with pin holes for the locking pins, so you need a different way of locking it. I chose (incorrectly) to entrust this task to a sealy tool which is like a little figure of H locking armature with pins that fit in between the pulley teeth in four locations. 

 

 

I’ve previously tried every “cam locking tool” in my mates garage, none have the correct spacing, so this seemed like a good alternative.  

 

The tool was a total disaster, doesn’t actually fit in any orientation, and with the engine in the car, renders you totally unable to remove or refit the belt… So plan b. A mad dash to Halfords for a couple of large adjustable and heath f***ing Robinson wins the day with a few mole grips and the flats on the cams. 

 

 

Now this method actually worked really well until half way through the next day, I’ll say more on that later. So with the cams locked up thus, I could have the belt off and tensioners off, replace the water pump,  refit  new belt and tensioners and time. 

 

The belt had a few 3-4mm cracks appearing probably ten in total, the side of the belt was  in fair condition, but nothing majorly wrong, the upper tensioner was perfect, the lower looked like it had been lying in a Rockpool, very rusty, and noisy to rotate, that was the one that was loose. 

 

Chucked the new belt on quite quickly, whilst remembering what I’d forgotten for positioning the tensioners, I always wind on too much front tension. 

 

With the new belt on it immediately became apparent it was much easier to time the engine with the pulley marked, because everything happens at one end of the engine, you can rotate it, look at the DTI, and see the marks with only a little change of position. Also I really felt like I was able to judge TDC repeatably and reliably. 

 

Initially the inlet came up at 3.2mm ATDC rather than the suggested 2.66mm for the Peter T Stage 2.  So it was too far advanced and opening too much, the inlet needed retarding. 

 

The exhaust was low, it was only 0.9mm rather than 1.661mm so the exhaust had closed too much, and was also too far advanced and needed retarding…

 

 

At this point a quick convo with Ant  /. Paul and Tom on WhatsApp came up with the idea of adjusting the front back tension ratio… Now. This would have worked, but it didn’t because… I’d locked the cams in such a way as I could only wind of front tension and wind on rear tension, but the cams needed to rotate a little to take advantage of that movement. I figured this out later on, but needless to say, I only got the values down to 3mm and  up to 1.2mm ish. 

 

Weirdly, the correct lift on both lined up almost exactly where the outer marks are on the pulley. Which was almost exactly a tooth distance. Now, remember the crank turns twice for every turn of the cams, so that is meaningless in terms of distance.

 

At this point I  thought had to move the belt a tooth, so that meant marking the pulley and belt with some white paint, and moving it, a tooth. So it was back to half mast, lock it all up, off with the tensioners, move the belt, back on. Held the bottom of the belt on using the old drive belt. 

 

And hey presto its miles out…. Way too far.  But in doing so I realised I could use the adjustable and heath Robinson contraption to move the pulleys. And therefore put the belt back on in it’s original place and use more tensioner adjustment. 

 

I also -  and this really is becoming a catalogue of errors, mistook which direction I could adjust the verniers, because it had been eons. When I had the belt back and tried to adjust them forwards, they said no thanks. 

 

So back the belt went… to the original position, or so I thought, because I’d only done two marks, I actually went the wrong way as I was under the car when the belt tension came off and it moved. I should have put three marks, one current, one before and one after so when I re tensioned and had a look at the timing. It was EVEN further out… feck… hoping nothing is bent. 

 

At this point I tried to get the belt back in the original position and started running out of travel on the flats with the big fat adjustables, I couldn’t get the cams back. Then they bloody well slipped off and I thought I’d f***ed the lot. 

 

Thankfully nothing seemed to hit (pistons at half mast ) and hopefully valve spring pressure isn’t enough to bend valves… 

 

Belt on in the original position, bearing in mind this is 7pm and I started at 10:30… 

 

Wind the rear tensioner on loads, little bit of front, adjust the verniers (which were sticky as f***, had to give them a good jiggle to get them moving) and bingo, got the timing sorted. Honestly, the hardest bit was making new pins to go in the DTI that were the correct length so I could both read the exhaust lift and get a spanner on the flats on the cam to adjust the timing. Got there in the end though.  

 

 

You’ll be pleased to know, it now goes like a scalded cat… I’d actually say, better than before, a sponk load more savage midrange,  but that’s probably because I spent 13 hours on it in the freezing f***ing cold. 

 

 

Apologies for the slightly choppy nature of this post, just smashed it out in my lunch break. 

 

 

Cheers

J

 

[jackherer 543]

31 minutes ago, kyepan said:

At this point I tried to get the belt back in the original position and started running out of travel on the flats with the big fat adjustables, I couldn’t get the cams back. Then they bloody well slipped off and I thought I’d f***ed the lot. 

 

Thankfully nothing seemed to hit (pistons at half mast ) and hopefully valve spring pressure isn’t enough to bend valves… 

Even when the pistons aren't involved the inlet valves can clash with the exhaust valves, the edge of the valve heads share the same space when open.

 

I'm glad to hear you got away with it

[kyepan 291]

Yes pretty lucky to be fair!

[petert 586]

Well done! Perseverance pays dividends. In regards to flywheel, if you have an 8V timing marker, I can assure you it's more accurate having the larger diameter. A tooth is 6 degrees. Thus if you have the pointer between tooth 12 and 13, the most you can be out is only +/- 0.5 degree.

 

http://www.taylor-eng.com/xu9j4/finding_tdc.html

 

 

[kyepan 291]

5 hours ago, petert said:

Well done! Perseverance pays dividends. In regards to flywheel, if you have an 8V timing marker, I can assure you it's more accurate having the larger diameter. A tooth is 6 degrees. Thus if you have the pointer between tooth 12 and 13, the most you can be out is only +/- 0.5 degree.

 

http://www.taylor-eng.com/xu9j4/finding_tdc.html

 

 

See this is where i may have got confused before. I'm not sure i completely follow from the tooth being 6 deg, and most out you can be is 0.5 as the tooth and notch are about an inch in total, and the notch shown on your link painted white is about a 10mm so are you saying that white painted bit is 1deg? 

 

Cheers

Justin

[petert 586]

From edge of one tooth, to the same point of the next, is 6 degrees. The length of the white section is 3 degrees.

Edited January 25, 2019 by petert

[kyepan 291]

Ah I see, and is tdc the beginning, end or middle of the white bit? That was what I didn't know

 

[kyepan 291]

Holy thread resurection....

 

So the car is out of hybernation, started on the button, drove into london, fan didn't work, managed to escape a major overheat......the list of rectifiable issues is as follows. 

 

Fan fuse blown

Fuel hoses need replacing to e10 proof

Massive oil slick under the car needs investigating

 

And it ran like a bag of spanners..... more on this later. 

 

• After a change of plugs to a 6 heat range and a quick balance of the bodies and it ran better, and made some induction hammer, still not quite right, flat spot, as per usual on WOT at low rpm
• The oil slick i finally figured out was actually my heath-robinson breather/catch tank setup.... which breathed just fine, but didn't catch any oil, which it was venting under the car and was an arse to drain. 

Plan was to:

 

• Clean up the engine bay from the carbon impregnated oil film on everything
• Buy a 100mm L shaped 6mm of ALI to mount to the side of the engine to mount the coil -  because it's cable tied to the strut brace
• Spec and buy a decent breather catch tank setup, fit it. 
• Take out the injectors and send them to be ANSU cleaned because their spray pattern and performance was an unknown, and i wondered if lack of fuel was the issue.
• Change the fuel filter 

 

 

Reality :

 

• Cant undo the hard pipe to filter union, this turned into buying new hard lines and up to fuel filter from STU at baker BM (thanks stu)
• Change the fuel pipe mounting things... again thanks to Stu.
• The lower hard line to filter cause i mashed up the barbed connector getting the pipe off -  again thanks Stu. 
• Some of the under body clips body mounting points were corroded, which needed attention, cleaning up, and paint. 

 

Then onto the breather setup, which is a hand me down pot, with no baffles and nothing, that vents out of a pipe under the car, sub optimal. 

 

Found the Mishimoto breather/ catch tanks with proper baffles, gauze filters and on the top vent filters for £163... found an identical knock off from the same factory for £16.30, and bought two

Found a dual anodised black aluminum fuel pump mount setup, that just happens to hold the catch tanks perfectly, for 16 quid....  a T piece... so i can run them in parallel, thus reducing any restriction on the blow by. 

This has yet to be fitted but you can find all this on ebay from UK sellers and i ordered Sunday, catch tanks arrived today (Tuesday).

They are small, but they have brass taps on the bottom that you can easily drain from.... which makes the whole maintenance thing a lot simpler if i add a couple of clear PVC hoses to drain off the fluid, 

 

Pulling injectors led me to a discovery, number 3 cylinder has always been a PITA to balance on the bodies, and the inboard O-Ring had a big chunk out of it -  think air leak at idle big. So that might fix the issue i always had that that cylinder didn't tally on the bleed screws on the bodies. Thought it was knackered leaky spindles, but, it might be the O ring. It's a bosch so it'll come back with pristine new O rings... lets see. 

 

New hard fuel lines are on, but required dropping the subframe so they could come out over the ARB bushes, my new fave toy -  Milwaukee 600 odd Nm impact driver made everything come apart in about ten mins, where has a decent impact driver been all my life. Going to change the tank to hard line feed and return, also the rail to tank return inboard, as that was chaffed up, more hose inbound. 

 

So lets see if 

 

• a -  the bodies balance up with the new o ring on number 3 cylinder
• b - the injectors fix the flat spot
• c - the new fuse in the fan setup doesn't blow. 
•  

Pug life

 

Cheers

J

 

 

 

 

 

Edited October 26, 2021 by kyepan

[Wallby 39]

Great update and great thread!

 

Just had a quick read through some of the previous pages and can draw some similarities to my own Mi16!

 

I also have the same issue of the breathers and catch can with quite a bit of mayo, so will be interested to see how you get on with the new catch cans, I've had my eye on the same ones ready for a freshen up over the winter.

 

Ready about your cam change also hasn't helped the itch for me to upgrade mine too!

[kyepan 291]

1 hour ago, Wallby said:

Great update and great thread!

 

Just had a quick read through some of the previous pages and can draw some similarities to my own Mi16!

 

I also have the same issue of the breathers and catch can with quite a bit of mayo, so will be interested to see how you get on with the new catch cans, I've had my eye on the same ones ready for a freshen up over the winter.

 

Ready about your cam change also hasn't helped the itch for me to upgrade mine too!

On the cam change, I would stick with the phase 1 cam next time, because i don't have enough compression to really make it work down low or mid range, i think it lost a bit of the mid range savageness which is far more drivable. Perhaps once i iron out the bugs it might return, but i always felt it was faster in real terms with the stage one cam...

 

bear that in mind, with hindsight i should have taken Paul Gardias's  advice (the engineer who did most of the machining on my engine) and decked the block by 0.4mm to zero. I'd love to build another engine to be honest and would go High Comp and moar cam next time!, possibly solid lifters etc. 

 

Thanks for the kind words tho, i'll put some pics up next time.

[kyepan 291]

Quick message for peter t, who's pm box seems full!! this seemed like the sensible place to post.

 

Hope you're well down under, quick question, i'm having a brain fart. 

If i'm using one of your stage one inlets as an exhaust (other than being 180 deg out) should the lift measure the same at TDC as it does when used as an inlet?

Your website specify 1.67mm of lift at TDC when it's used as an inlet, or 0.065" in old money

I've marked the bottom pulley with tdc, but i don't have a degree wheel, so i'll need to time by lift at TDC, I can't really use the lobe center angle value!

 

Long story short, exhaust cam managed to slip to the end of the adjustment on the verniers, so i had virtually no overlap and it only made 160hp on the rollers with new Jenveys... Now sorted back to inlet lift at TDC spec but with these cams it never had the savage midrange punch of a standard exhaust cam and your stage one with woodruff key.. and it always made me question if i actually had the exhaust right. 

 

Appreciate your thoughts when you have a moment. 

Cheers

JB

[petert 586]

Sorry about the inbox. I'll clean it up.

 

Which inlet cam are you using?

 

0.065" equates to a lobe centre line of 109º. That's probably too far retarded. I'd advance it to around 112º, which I'm guessing equates to approx. 0.040" at TDC.

[welshpug 1,657]

I found a degree wheel JPEG via google, printed off and used the timing pin for location, crank pins at mid stroke to 90 degrees from tdc, bit of welding wire under one of the end plate for a pointer.

[kyepan 291]

1 hour ago, petert said:

Sorry about the inbox. I'll clean it up.

 

Which inlet cam are you using?

 

0.065" equates to a lobe centre line of 109º. That's probably too far retarded. I'd advance it to around 112º, which I'm guessing equates to approx. 0.040" at TDC.

all good! so i was doing it wrong, how would I calculate that more accurately? or was your approximate guess a very accurate approximate guess

 

Weshpug, i'd rather avoid the degree wheel... but thank you for the helpful suggestion, really appreciated!

 

Cheers

JB

[wicked 103 3 Cars]

I use the degree wheel to find TDC:

 

 

I measure the piston heigth @ -x degrees before TDC (~8mm below what I think will be TDC), mark the degrees. Proceed over TDC until you find that -8mm again. Mark the degrees again (+x) ; TDC will be halfway; calculate it and mark it on the degree wheel. For the cams I use lift at TDC as well.

 

[kyepan 291]

28 minutes ago, wicked said:

I use the degree wheel to find TDC:

 

 

I measure the piston heigth @ -x degrees before TDC (~8mm below what I think will be TDC), mark the degrees. Proceed over TDC until you find that -8mm again. Mark the degrees again (+x) ; TDC will be halfway; calculate it and mark it on the degree wheel. For the cams I use lift at TDC as well.

 

Yep i got that, marked the pulley a while back using this method, it's the actual degree bit that i'm a bit confused about! I've been timing via tdc for a while. 

Cheers

JB

[petert 586]

The best degree wheel to use is the flywheel and an 8V timing marker:

http://www.taylor-eng.com/xu9j4/finding_tdc.html

 

Yes, 0.040" was an educated guess. Somewhere between 0.040-0.050" will be fine.

[kyepan 291]

Thanks peter! 

 

Timed it up to 1.08mm at TDC 0.0425"

Now sounds really lovely and lumpy at idle, AFR reads very differently too and the character mid range is dramatically different!

Will go off and get it mapped now.

 

As a bit of back story, i've been quietly working away on loads of bits on the car for a few months but not posting up here,

 

• Fitting the new ITBS
• Getting injectors reconditioned
• Modfying injection loom
• Sorting the Oil breathers,
• Fitting a wide band - twice
• Sorting the blowing exhaust
• Build a new fan loom
• Fit new fog lights
• Fix light loom
• Change all fuel hoses from tank through hard pipes to rails. 
• Fit a new immobiliser
• and a massive list of tiny tweaks
• I had a leaky injector on cylinder 3 too (post refurb)

 

Took the car to "track n road"  for mapping and had two issues:

 

1) It was breathing very heavily

2) It made Redic low power (160bhp)

 

 

Steve said  -  exhaust cam is retarded (just by the way it mapped) and that he thinks considering it was overfuelling so much (with hindsight i can explain this) the bores are all glazed up, he said chuck some ajax down it and hand crank to sort that. 

 

 

So off i went home with a not quite right car understandably disappointed and some things to check.

Compression was low 165,165,175, very low on number 4 (120PSI) so is it a valve issue? is it head gasket? are the bores screwed. That said i forgot to do it WOT... 

A spoon of oil down 4 and it came right up beyond the others to what would be considered normal, certainly well in excess of 200psi.

 

I have a borescope camera with 90 deg mirror, so off that went down the bores with the camera, i may try and post some pics, but suffice to say, lt was very very glazed, and you could still see the honing marks on it very clearly, but the glossy sheen was quite distinctive and clear. This was repeated across all cylinders, and i noted that my valve stem oil seals are also leaking on one cylinder.

 

But first, leak down test, so, got myself a leak down test, and unbelievably, it tested fine, no leaks from exhaust or inlet valves, no bubbles, and even with the pressure right up.

 

The plan was two fold, order some oil that is supposed to restart the running in process, snake oil possilby, and consider giving number 4 some colombian re-compression powder (ajax) although i was a bit trepid about that. run the running oil for 250 miles, dump it and change the filter, cross fingers and retest the compression. 

 

I used the 240 miles for a proper spank across to Dorset, A and B  roads most of the way, lots of hills, lots of low to medium rpm with lots of throttle, basically running the engine hard. 

After this it tested

 

1 - 255

2 - 260

3 - 260

4 - 240

At WOT. 

 

The borescope was also quite telling, the honing marks were MUCH less pronounced, it worked, much to the suprise of myself, dad and a few other pug mates who were following the drama.

 

So... that brought me back to cam timing and the posts above. 

Will go back and get the map sorted and HOOOPEFULLY... crack 200bhp. 

 

 

Cheers

JB

Edited August 25, 2022 by kyepan

[petert 586]

Sounds like a good result! Looking forward to hearing of the dyno results.