Now doing a trial belt fit and degreeing cams.
Using the block that I've pulled the pistons and rods out of, gaskets and spacers, 265T belt.........it's near enough a prefect fit.
Because I've lifted both heads by exactly 4 mm, that's 16 mm in total that I've taken out the belt in slackness, it's a much easier and better fit than what I'm running in the car now.

So if the question was.....what's the best way to take the extra slack out of the 265T belt without moving or changing any idlers.That's when used with mivec heads and GTO block.
Then the answer is......4 mm head lift+ 6G74 crank / 6G72 rods.
A bit of a fluke??










I can see I'm going to have a problem when it comes to doing the 3.5/3.8 block because the belt will be too tight...........different mods needed.



I had a bit of a hold up, had to spend $9 on a metre of heatshrink to fix the broken clips.



I'll now have to spend about 20 hours playing with the dial gauge on the cams to get them right.

Been playing around with cam gears.I had to spend $5 on some small nuts and bolts
I've already done the modded but fixed mods about 12 years ago then did it again with the engine that's in the car now.
This time it's modding them to be adjustable, handy for the dyno............so making one set for a normal engine, another set for the mivec.
Lots of mods to do to the mods but it'll work in the end.







Playing with the non mivec first because i've got plenty of spares but only one spare set of mivec gears.This is first up on the engine dyno.No point in making anything look pretty until it runs. If you zoom in you 'll see that the hole is countersunk and more with the grinder so the bolts will go in at an angle and push on either side of the dowel.



In fact it's so simple I don't know why nobody else has done it yet.
All that needs to be done is widen the slot for the dowel, that allows the gear to rotate on the bolt by a number of degrees. Screw adjustment makes it easier, once the centre bolt is torqued up to spec, it's all locked. After adjustments have finished and no more changes to do, it can be made (more) permanent by filling the gaps around the dowel with something like "kneed it" and the adjusting bolts removed.
The "fixed "ones I made previously, I widened the slot with the drill, then built up one side with bronze, filed it back down to be a tight fit with the dowel.


As far as the maths goes for the mivec gears, there's a 13 mm hole in the middle, the dowel is 6 mm, there's 2.5 mm between the edges of the holes.
That means that the dowel is on a 12 mm radius, circumpherence of 75 mm. so 75 mm is 360 cam degrees, 720 crank degrees.1 mm is 4.8 cam deg, 9.6 crank deg. The 6 mm hole has been drilled to 8 mm which gives a max adjustment of 1 mm each way or +/- 9.6 crank deg.
For comparison, the cam gears have 48T, the crank gear is 24T, that's 15 crank deg per tooth or 7.5 cam deg per tooth.
The commonly accepted +1/ -3 (which is wrong anyway) adjustment is actually +2/-6 crank deg. That increases the overlap by 8 deg which moves the power band up in revs.
Someone mentioned Ebay?
http://www.ebay.com/itm/Preset-Cam-Gear ... 1834430817
$200 , then freight, GST....lol.

The label on the box of nuts and bolts...........0.5 mm pitch, so 4 turns from end to end..........perfectly calibrated...........nearly.

Like a lot of my mods, I've been spending more time thinking about it than doing it.

I've got two spare sets of MIVEC gears you can have if you need.

That's handy to know "ravensierra".

It turns out that the factory cam gears are made out of cast iron. I never put a lot of thought into it before but it becomes more obvious when you start grinding them.
The next question should be why?
Cast iron is naturally harder than steel due to the carbon content. That's useful where you want as little wear as possible.
The downside of it is that it's brittle and cracks easily, also it's harder to machine. Cutting a groove with the grinder takes more time. Hard if not impossible to weld but bronze works on it.
Cracks easily......I've broken one already (that's why I'm doing a NA/TT set first)........put too much heat into the middle of it for too long, it made a big bang and broke at 2 spokes and in the rim......never mind, that one had been painted and paint does nothing useful when you're trying to weld of braze something.
The good news is I'm making good progress. I've just refined the method a bit.
What if you make some from scratch out of something that's not cast iron?
What about all the other engines that use cam belts?
Subaru use a very hard brittle plastic for some of them.......when they break they shatter and leave really sharp edges that can slice your hand.
Aluminium?, no, never seen factory ones........only aftermarket.
Why?
It's too soft for long term , high KM usage. The better ones are anodised. That creates a layer of oxide all over the surface, that's a lot harder and wears better.Ideally the cenrte bolt should have a bigger washer to spread the load other wise it might come loose over time.

I went over the maths above for the mivec gears, for the NA/TT gears it's a bit different.

Taking measurements from a 2nd gen rear exhaust gear, it's still a 13mm hole in the middle but the dowel is 4 mm with about 2.5 mm metal between the 2 holes. That puts the dowel centre on a 11 mm radius of cam centre. That's 69 mm to 360 deg, 0.19 mm per cam degree or 1 mm to 5.2 cam deg / 10.4 crank deg.
I've opened up the holes from 4 mm to 8 mm, makes the rest of it easier There's far more adjustment available than will ever be needed at 20.8 crank degrees either way, or 1 and a bit teeth of the belt.

The cirumpherence of the cam gear where the belt runs ......that's 38 cm.....380 mm.
1 mm is 0.94 cam deg.
The max allowable machining of the head / block combination is 0.2 mm.
That will throw out the cam timing by 0.188 cam deg / 0.376 crank deg on the rear bank .
The front bank will be 3 times that at 0.56 cam deg and 1.12 crank deg.

If I need to make a correction of say 0.5 cam degrees, that's one full turn on the screws.

The same numbers apply if you change the thickness of the headgaskets by 0.2 mm.
The factory gaskets are about 1.4 mm.

Anyway I've made a full set of fully adjustable cam gears, not overly happy right now but some sand blasting then epoxy will strengthen everything up.

Preset variable offsets seem better.

Pics is easier.......later on.
Once you work it all out it's really easy, like everything is???

I got a bit held up on the bored and stroked projects, got held up playing with modified cam gears. That part has been put off to one side temporarily so I can have another tidy up.







This is just the N/A 3 litre, got to finish wiring it up, make a control panel, mount the various bits out of the way somewhere.


Was looking at a toy train, the ones which take kids for rides around the park, had one in the WS. Kubota 3 cyl diesel, drives an alternator, electric motors to drive the axles........proper control panel. Looking at that makes things a bit easier.

The wiring loom is on but there's some spare plugs, Also after looking at the ECU pinout, there's wires from ECU to alternator as well as AC. That should be one plug that goes into the body loom. There's power feeds from the key and battery. There's other wires for instruments and lights too......so there's quite a lot to sort out.
Got a small computer table with wheels....battery for the starter motor, will need to make the alternator work to keep the volts up. There's no diagnostic socket so will need one.....hook it up with MMCD. The MFI relay It's a spare but don't know what from,(google says 1994+) , it's got the wrong no of pins to plug in. The plug in the loom has 9 wires in a 10 way connector, the relay (E8T08472) is an 8 way connector.


Once that's going and I've got some data, I can swap over to the 3.5 (3.35).I haven't done anything to the cam gears on that yet but I've dummy assembled a spare Pajero 74 block with spacer plates, N/A heads and 265T belt to check fitment and required mods.
The cam gears, I need to sand blast them, that means fixing the blasting cabinet first. The gears get very tight on the cams after heating with the oxy acetylene....got to lever them off again.



The eccentric pulley is backed right off, I'll mod the idler on the right, easiest way is with a spare eccentric one, let out a bit of slack so I can take it up in the right place.
With the above setup I can use the 91 mm crank , bore it to maybe 95. could get 3.9. It's got a modded GTO 2nd gen TT sump on it, I 've already sorted the brackets, just minor extra mods for the spacer plates.


The 3.35 is now on the floor where I can get to it a bit easier.

72/74 stroker on the floor with dial gauge checking cams



Measurements taken, calculations made.
More pics of timing marks.







As you can see with the crank at TDC, the rear bank is too far advanced, the front bank is even more advanced but there's a bit of slack in the middle of the belt because the pin hasn't been pulled on the tensioner.

Calculations say about 3.5 deg on the rear bank and about 6.5 deg on the front bank. That's "crank degrees". Not to be confused with "cam degrees" which is how aftermarket adjustable cam gears are marked.


Rather than messing with cam gears which is very time consuming, there's an easier way.



Well that was easy?
A second hand part from a 4G63, modified of course.


The last pic doesn't look right due to the camera angle but it's spot on.


In the meantime the courier has just dropped off another set of RB conrods....that'll get me going on a 3rd one.
The 2nd one being the stroked '74, that's making slow progress, just having to do some mods to a machine to narrow the rods by about 1mm as I refuse to pay someone else to do it for me.

The belt is on, the tensioner is roughly in the correct position, I've also offset the idler (bolted into the "wrong" hole) but haven't tried to time it up yet. That's with a spare pajero block spacer plates, extra gaskets and N/A heads. There's no pistons in the block here.







Got to mod the mods for the alternator bracket and for the PS bracket due to the spacer plates.
The idler sits too far out and need to do some grinding under it so I can space it back in, to the correct amount.

Reading on another forum, someone was thinking about using these to make a 3.8 into a 4.0

https://www.summitracing.com/int/parts/ ... /overview/


Sounds like a good plan.
With a 6G75 block and a crank stroked out to 95 mm, Nissan rods, if it works , it'll make 4212cc?
IF.
Those pistons use a press fit pin rather than fully floating (74 and 75 pistons are fully floating, 72 are press fit) so that makes it a bit more tricky.


Can probably get a set of those through STA parts?


In the meantime I'm still thinking on the easiest / cheapest way to make the small end of the rods a bit bigger, it's a 21mm pin and needs to go to 22mm, fully floating. It's got bronze bushings 21mm ID, 24mm OD so just boring or honing or both should work.



edit, got it sorted.
Made a tool out of a spare 22 mm gudgeon pin, cut the right hand end down to 21 mm on the crank grinder (as a guide), cut the middle down to 21.75 mm, put some slots it it so that it cuts, did the cutting in the lathe, tidied up with sandpaper wrapped around a pin. They don't fit yet, will finish off on the "rod hone".
The big ends are finished (narrowed to the correct width), I've got a second set half done.
Narrowed using the crank grinder.....someone told me it wouldn't work, but you get that?



making the small ends of the rod bigger.


End result.


Total cost of modifying them........nothing.

Next chapter..........How big in the bore can we go?

Need to measure it. That's a bit tricky. The easiest place to get to is the front of the block with the waterpump removed. Head removed too.

It's easy enough to measure the distance of the front of the no 1 bore inside to the front face of the block. The front face is like a fixed mark due to the oil pump etc.It's also easy enough to get a measurement from the front face, through the water jacket to the bore outside.
I've gone through some blocks and got some measurements.
6G72 (30M)..................................Bore 91.1 mm.......... 17.25 mm, 12.5 mm = 4.75 mm wall.
6G72 TT 4 bolt...(overbored)...........Bore 91.6.................17 mm, 12.5 mm = 4.5 mm wall
6G74 Pajero GDI and Non GDI 3.5.....Bore 93 mm........... 16.25 mm, 11.5 mm = 4.75 mm wall.
6G75 (380)....................................Bore 95 mm.............15.25 mm, 9.5 mm = 5.75 mm wall

edit, I've moved a 74 block so I can get to it a bit easier, remeasured yet again. That's at the water pump outlet, no 1 cylinder but taking measurements there doesn't mean it's the same on every cylinder all the way round.

I was reading on another place yesterday that some N/A 6G75s get taken out to 97 mm.

Unsure of the max that people have taken 6G74 blocks out to.


So what's general consensus?

Here.
http://www.3si.org/forum/f42/big-bore-e ... 72-200505/

http://www.aussiemagna.com/forums/showt ... hp?t=70634

Reading the Aussie magna posts.........it's the "other" 6G74 block they use, mine is dummy assembled, looks like I'll need to measure it.
None of those wall measurements agree with mine either.
How did THEY do it?


Now that I've got the 74 block to an easier place, I've also just finished narrowing a second set of rods, I've dummy assembled the crank, 2 rods and 2 pistons. Just to see how it looks. Using 74 SOHC pistons, 22 mm pin hole, with 21 mm pin in the rod, so there's a bit of slop, also used standard size bearings, so slop there too.
Here is no 1 cyl at BDC, the counterweights just clip the piston skirt / pin boss. I was expecting that anyway and will need to trim it a bit.


At TDC, the piston sticks out the top my about 1mm. I can either fit a thicker gasket, trim the piston top, or both?


So that there, as it is....3.7 litres. With all the pistons in of course.
I can't get any better , more accurate measurements until I've finished the pin ends of the rods and got the correct bearings in place.
There's zero block clearancing to do.

I've stripped down the 6G75 block, taken out the crank.
Put it up on a table with some spare engine mounts. They won't fit of course so I'm just going to look at it for a few months until they DO.
The Pajero mounts won't fit either so just as hard to make that block RWD.
The block is out of a 380, I think the mounts were originally on the gearbox?

I've taken a pair of 30M heads off a 30M block, so now got 2 sets of 30M heads ready for me to rebuild.
I've got a 30M block, crank, pistons /rods there so thinking about putting that together then onto TM as a reconditioned shortblock. No heads

The "boy" has got his new workshop up and running, got the machines in there...........the hot wash, safety clean, crank grinder, boring bar, vertical power hone, surface grinder, linisher, rod hone, lathe... that's still at home but going there soon.

https://www.facebook.com/search/1734544 ... rface=tyah

He just got a 2 post hoist fitted on Monday.


I think the next step will be to take a spare 6G74 block over there and bore it to 95 mm so the 6G75 pistons will fit. They're already out of the block.

So a different "boy" to the Custom Works boy?

Only got one "boy"......no he walked out of there...long story.
That's what happens to most partnerships, the woman too.

So anyway, he's started all over again from nothing except for the same machines which the family paid for.

Good call to get out early, workshop partnerships always seem to turn to custard eventually.

Another long overdue update, not much progress really.
I've got 4 engines dummy assembled. I've done pretty much all this for a total budget of zero so far.
I'll need to spend some money soon in order to make some progress, that's for balancing and nitriding 2 cranks, then bearings and rings and maybe a couple of timing belts.
The 1st pic, that's just a standard but rebuilt 3.0 N/A DOHC. I pulled out the injectors for flow testing so that put me on a different track for a while.Well worth doing though.
This is the one which will eventually get wired up and connected to fuel and cooling etc.and be a start for an engine dyno.



The next pic, That's the dummied up stroker 4 bolt mivec 72 block with a stock crank for now and no internals. Got a pair of big Rajays hanging off it to rice it up a bit.




The 3rd pic, that's a 74 pajero block, 3N (N/A) heads, got the head and intake spacers on, standard crank for now but it'll get the 91 mm crank in it.It's got my TD04 15G turbos on, it'll be made as a drop in for a GTO to look factory like, it's got a 4 bolt GTO sump on the bottom. Ignore the intake manifold, it's off a 3.8, that'll go on something else.
I might drop this into my red GTO,? Someone else might want it?





The 4th pic, that's a 6G74 mivec, I'm just cobbling it together for RWD fitment to something else.
The hold up at the moment is the cooling system because my TIG welder has run out of gas.
The coolant pipes at the top don't fit due to the extra height of the heads. That's using a mixture of SOHC and DOHC pajero parts.




In the meantime, to help with the finances and the learning curve, I landed myself a new job (thanks trademe)
With this crowd here.

https://www.youtube.com/watch?v=vfCSGdmBJHI&t=1s

They've had their own engine dyno for over 30 years, it's based in Gracefield and an offshoot of the old DSIR,  The dyno is getting upgraded to handle the torque of a 13 litre  diesel, it's all going to be brand new and made in NZ.

did you mention GTOs in your CV? 

Scruffy wrote:

did you mention GTOs in your CV? 

No, not once.
I just referred him to my youtube channel........then an hour later the phone rang.
You're just the sort of person we're looking for.
When can you start?

Hah that's awesome.

I've dug this out after sitting for too long.




I must have put it off to one side when I ran out of welding gas.


There's still several parts which don't quite fit right and need more modifying.
Pretty much every part here has already been modified in someway.
The cylinder block is a 6G74 from a Pajero.
The block was cut into to make the engine mounts fit.
Still to fit oil squirters to it too.




The sump is from a 4 bolt 6G72 and modded to fit the block, still some small welds to do..
I've spaced up the heads by a few (3 or 4) mm to allow the stroker crank, rods and pistons to fit, this has required more mods to the various brackets.





The water crossover , above the bellhousing, that was already modded (lengthened) but had to further slot the holes to fit.
The lower intake manifold, that's from a SOHC Diamante 6G74, modified.  I've made intake spacers for between the head and lower intake manifold.They took quite a bit of making, I got the first set a bit wrong, that's those on top of the engine. the holes for the intake ports are angled.I'm now happy with them.

There's no pistons or conrods in the block yet, this is just an outside trial fit to find all the bolts etc, then I'll build a proper shortblock and swap the outside parts over.
The exhaust pipe still won't quite fit yet, the alternator bracket isn't finished, nor the turbo brackets although the turbos are mounted,  my old 15Gs.
Once it's together , it should be an almost drop in fit to a normal GTO.
Spot the horrible ricer aluminium Y pipe.








The idler on the right, had to lower it to slacken the belt, had to cut the bottom out of the lower plastic cover to clear. That can get fixed at some later stage.
Also got to take care of the gaps to the plastic cambelt covers. Maybe 3D printing some new redesigned ones would be an option?
The heads are 2nd gen GTO N/A. There's no lash adjusters or rocker arms fitted yet either.
The cams still need timing properly too.


I've also got hold of a flashable ECU from a Galant VR4 to help it out as well as getting close to a pair of GT35 truck turbos.


Roll on summer.

A bit of an update.

I've paused on these for a while and now got back into it.

The 1st 2 photos show the modded 6G74 crank in a 6G75 block with 6G75 pistons giving a stroke of 91 mm and a bore of 95  mm for 3.9 litres (.3870.669 cc)
Using the modified Nissan rods the pistons at TDC are just about 1 mm short of the deck. There's no clearancing needs doing down below.
The 6G75 block was just for trial fitting while the spare 6G74 block is bored from 93 mm to 95 mm....which is now done.
The walls will be a bit thin, so I'll half fill the block with block filler. The crank still isn't balanced nor nitrided.
It's just dummy assembled with old, stock sized bearings.
The next job with the 6G74 block is to fit oil squirters to it which is quite easy really?
Its actually the same part no as for the 4G63 late models as well as the 6A13TT.




The last photo shows my 4 bolt 6G72 block with Pauter rods, JE pistons, destroked 6G74 crank to give a bore of 91.6 mm and stroke of 84 mm to give about 3.35 litres (3321.7555 cc).....same capacity as everyone else's 3.5 strokers. Again the crank still isn't balanced or nitrided yet. I had to do yet more clearencing of the no 1 counterweight due to the Pauter rods being 0.008 inch shorter than stock rods. The rings are in, It goes around, there's no contact, it just needs torquing up.



At the same time I've made a bit of progress on restoring this too.

It's only 2WD but OK for most.
The other half of it will make an engine dyno though.

https://www.youtube.com/watch?v=6w5hYTMOh_E

The 6G72 shortblock is now torqued up, sump, oil pump, rear seal glued on. The shortblock is ready to run but the top end isn't.
I've reused the mivec head gaskets, 3 mm spacers (all glued down) then fitted used composite TT gaskets (the last dummy up used cometic gaskets instead) and spare heads, just to get the spacing right, time the cams, check alignment marks etc, with old belt. Adjustable idler on right (ex 4G63) to get the timing correct for the rear head, front head seems OK. Dial gauge/ degree wheel coming up next.I've got to degree the cams properly and then mod the cam gears to suit.
From memory a mivec gasket is aout 0.4 mm, the TT is 1.4 mm so that gives the head a 4.8 mm lift.Being stroked by 8 mm means the piston top will be 4 mm higher out of the block........so going from that, I've cut down the piston tops but haven't recut the valve recess  in the pistons, but the maths says I've now got an extra 0.8 mm piston to valve clearance. So far so good.

I was thinking of doing a similar thing with the adjustable idler.  So the Subaru one has the lip on it to keep the belt in place?  How well do you reckon it will stand up to the tension?  I guess once it's in the right spot you could loctite the sh** out of it.

I've been meaning to ask, is there any way to tell which camshaft is which on the Mivec heads?  I've had everything chucked into boxes when I moved overseas so it's all mixed up now.

I've just been doing a bit of editing.
It was actually off a 4G63. Yes it's got a lip on the front edge, it's a sleeve pressed on over the top , otherwise the same part as the 6G72 eccentric idler.
I'm not sure of the hardness of the idler but was thinking of getting it adjusted right then drilling and doweling.
Otherwise get a grade 10 bolt and torque it up tight.

The cams?........from the position of the dowel to the front lobes.

I'll get another pic.

Degree wheel and dial gauge


I even made a solid tensioner to keep the belt tighter during degreeing. Otherwise you get erratic readings.
That's the only thing they're good for.

As measured, the front and rear banks are pretty much the same as each other for timing events but both a bit "out" from where they should be with respect to the crank. Need about a 10 crank degree advance.

This is very interesting. 
What is the purpose of the 3mm spacers under the heads?
Could the same effect be achieved by lowering the pistons 3mm?
Are you going to slacken the extra tensioner to get the advance needed or are you going to use adjustable cam gears?

It's because it's a (close to) zero dollar build.
Yes, I could shorten the pistons or rods but that would require special parts which cost special money.This is with all "off the shelf parts" if you count Pauter rods or forged pistons as stock........stockish dimensions.
It keeps the CR down, takes up the excess slack in the belt etc.

Adjustable cam gears aren't available for these heads / cams so it's a case of modifying the stock ones if I can't get the required adjustment from the 2 eccentric gears.
Again though, aftermarket cam gears are low quality and overly expensive. The normal aftermarket adjustable  6G72 cam gears could be modified to work but then again, what's the point when I can modify the factory parts and it's better, easier and cheaper.

Decompression plates are nothing new, they don't get promoted because there's no money in it for anyone.
They've been tried and proven over many years.


Just to sidetrack a bit thanks to google
http://www.theminiforum.co.uk/forums/to ... on-plates/

So some big diesels come out of the factory with them?

Another link.
http://www.ferriday.co.uk/decompression-plates/
The reason they're not popular (as a guess)........is because kids tend to follow what goes on in Murica and they're into V8 engines.
V engines make things a bit more complicated with the intake manifold sealing in the V and requiring an intake spacer too. 
In line engines like BMWs are easy.

Right, well, that degreeing was quite easy.........spent about a whole 3 days on it. Measured opening and closing points on all 4 cams, cylinders 1 and 4. at 0.1 mm lift, at 0.2 mm lift. at 0.3 mm lift and finally at 0.5 mm lift.Different numbers come out every time of course.........so when you ask someone else........did the numbers come out the same every time etc.........when they answer YES.........start pissing yourself laughing.
As it is with no adjustment the no 1 intake is about 104 deg centreline, the no 1 ex cam is about 106 deg, the no 4 ex cam is about 107 and the no 4 intake is 104 so that's a bit of a fluke..........intakes the same and exhaust near enough.

But what are they supposed to be?
That's easy...it's on the mivec forum.
The stock numbers are there.
Intakes about 110 and exhausts about 108.

But that can't be right either?
The relationship between int and ex on each bank if fixed.If one gets bigger, the other should get smaller? ...maybe?
Measured with the belt tension held by the auto tensioner, not with solid tensioner to keep everything tight.
So I'll just leave them alone and get on with building some heads.I'll just worry about it later on.?


OK so what's everyone else's centrelines?....no. no idea at all.

BTW I've been doing lots of reading as always..........there's a few things going on in USA..........the strokers all seem to be blowing up ????????

lol.
Something to do with oil starvation to the bearings?



I made a comment years and years ago that the mains in the billet cranks aren't crossed drilled.
Stock mains are.
I upset a lot of people at the time.
That's all I need to say.


OK time to build some heads......next year.

But I might make a start on a 95 mm crank?
You'd want one that's cross drilled in the mains?