Cam install/Spring height/Rocker dilemma

[Tony D]

Braap beat me to it, if #1 is at TDC, you have your choice with that dial vernier caliper to do a BDC check on any of the other two, and then with simple division, knowing the crank radial/vertical movement is only going to be another 60 degrees to BDC (or from BDC) you can figure out the sweep -vs- vertical travel in the remaining stroke and figure it in additon to the present location of the piston to determine total stroke.

 

Or did I explain that in too addled of a way. I kow what I'm meaning to say, but probably not conveying it that well...

[Babalouie]

Braap beat me to it, if #1 is at TDC, you have your choice with that dial vernier caliper to do a BDC check on any of the other two, and then with simple division, knowing the crank radial/vertical movement is only going to be another 60 degrees to BDC (or from BDC) you can figure out the sweep -vs- vertical travel in the remaining stroke and figure it in additon to the present location of the piston to determine total stroke.

 

Or did I explain that in too addled of a way. I kow what I'm meaning to say, but probably not conveying it that well...

 

Ok, here goes....with #1 at confirmed TDC, #2~5 are sunk approx 2/3's down the bores, with a deck to piston measurement of 65mm.

 

A friend of mine who is a lot better at trigonometry worked it out at 85.5mm stroke...I think what's basically happening is that the rod angle is probably screwing us up.

 

This is the closest pic I got of the exhaust ports (I've already boxed the head for shipping so I can't take any more pics today), they seem pretty rectangular rather than hexagonal:

[BRAAP]

Braap beat me to it, if #1 is at TDC, you have your choice with that dial vernier caliper to do a BDC check on any of the other two, and then with simple division, knowing the crank radial/vertical movement is only going to be another 60 degrees to BDC (or from BDC) you can figure out the sweep -vs- vertical travel in the remaining stroke and figure it in additon to the present location of the piston to determine total stroke.

 

Or did I explain that in too addled of a way. I kow what I'm meaning to say, but probably not conveying it that well...

 

I may be wrong here, haven't ran the math, but doesn't rod length also come into play? In my other crankshaft project studies learning about the 2nd order harmonics and rod to stroke ratios, etc, as I understand it, different rod lengths will have the pistons at different points in the bore for a given crankshaft rotation due to rod angularity. Rod lengths will alter the rod angularity throughout the stroke, therefore the position of the piston in the bore. This is most notable closer to TDC and BDC. Longer rods tend allow the piston to dwell at TDC longer over a given degree of crank rotation vs shorter rods.

 

If this is correct, knowing the rod length is critical.

 

Other options are just pull the pan and check for a V-07 crank, or pull the front cover for access to the chain tensioner and just rotate the crank till another piston hits BDC, measure the stroke. Or cut a cylinder head down so that you can utilize a cam tower or 2 with a scrap cam to hold the cam gear and chain so you can rotate till a visible piston reaches BDC. I have such a beast myself. A small section of N-47 head, cut off in between the intake and exhaust valve of the #1 cylinder, the front cam tower, and the cam cut off flush to the tower. Works great for having access to all the pistons, (half of #1 cylinder is exposed) while rotating the crank with the front cover/chain in place. Also works for transporting short blocks with the timing chain set, (That is what it was originally used for).

[Daeron]

Wait a second... it seems that its almost DEFINITELY a stroker at this point and we are trying to figure out how MUCH of a stroker (LD crank or LD crank turned for even MORE than 3.1)

 

 

So why not just get one piston at BDC and measure from the crown of the piston (whatever plane on the piston is even with the deck at TDC) to the top of the firing deck????

 

If deck clearance is perfectly flush, then the stroke is the distance from the top of the cylinder wall down to the crown of the piston at BDC, right???

[BRAAP]

Wait a second...

 

So why not just get one piston at BDC and measure from the crown of the piston (whatever plane on the piston is even with the deck at TDC) to the top of the firing deck????

 

If deck clearance is perfectly flush, then the stroke is the distance from the top of the cylinder wall down to the crown of the piston at BDC, right???

 

 

You are exactly right, though the problem "is" getting the pistons "to" BDC!

Head is removed, timing chain tensioner tool in place!... Not really a good idea to just rotate the crank at this point...

[Daeron]

You are exactly right, though the problem "is" getting the pistons "to" BDC!

Head is removed, timing chain tensioner tool in place!... Not really a good idea to just rotate the crank at this point...

 

Well, I caught that part, but is it SO impossible to maintain the timing chain where its at while rotating the crank through 30 degrees? You caught me, I haven't had my head off yet, OR dickered with a timing chain. My 4 1/2 years of DDing never included timing chain work, or even a valve adjustment (though I have gotten THAT one out of the way since then.)

[TimZ]

Well, I caught that part, but is it SO impossible to maintain the timing chain where its at while rotating the crank through 30 degrees? You caught me, I haven't had my head off yet, OR dickered with a timing chain. My 4 1/2 years of DDing never included timing chain work, or even a valve adjustment (though I have gotten THAT one out of the way since then.)

 

As I recall, he already had the radiator pulled - hence my suggestion to just give up on keeping the chain blocked, since it's not that much more work just just pull the front cover and stop worrying about the chain. He's going to be waiting around for a while on the head work anyway...

[2eighTZ4me]

Well, I caught that part, but is it SO impossible to maintain the timing chain where its at while rotating the crank through 30 degrees?

 

Absolutely it is. If you've never done one - the chain chock basically locks the motor down by wedging the chain against the tensioner and the guide on both sides into a V pattern. The bottom end is "locked" into position by the chock. If you so much as move the motor a couple degrees, the chock will get shot out of the V as quick as you can say oh sh..!! and, unless you have the handy dandy tool (spare head) that Paul has, you'll never keep enough tension on it with your bare hands to keep the tensioner from ejecting.

 

I'm with TimZ - you've gotta wait anyways on the headwork. I'd offer up a timing cover gasket pair, but shipping to Au. would probably negate the free nature of the gaskets. You could possibly get by with some RTV on the old gasket if you didn't tear it up upon timing cover removal. Then - once in there, you can check the tensioner and guide for wear as well.

 

Just make SURE that when going back together with the chain, that your bottom end is at TDC, and you follow the FSM guide of 42 teeth on the chain from the mark on the crank gear to the 1 o'clock mark on the cam timing gear. I use a dab of yellow paint to mark the 2 link marks. My guess is the shiny links on the chain have probably been covered with oil sludge by now.

 

That is indeed an interesting head. It is not a P90 for sure. Exhaust ports aren't hexagonal at all. It looks to be an N42 or some (JDM?) derivative thereof.

[Tony D]

Rod length will come into it, but look at the calculations with the three commonly available rods used, and you will see the differences in the strok derived.

 

Some calculations will not come to a 'standard' crank trhow, and can be discarded.

 

One should be very close to either the L28 or LD28 stroke.

 

They are different enough in stroke that the different rod length would throw the calculations far enough off to make the results discardable easily enough.

 

As you can see he came up with an 85.5 stroke.

 

Hmmmmmm, what crank does that sound like? L28 or LD28? Factor in L24 Rod Length, L28 Rod Length, and it should become obvious (as close as you can get without a physical measurement) and be pretty certian what is in there.

[Babalouie]

Well I figure it's a good idea to bite the bullet and remove the timing cover, drop the sump, etc. It'll allow me to rotate the crank, and so all sorts of good things like verify the stroke, re-confirm true TDC etc. And having a peek at the interior of the crankcase to see what crank and rods is in there would be cool too.

 

But as Paul said, I got the chain wedged, so turning the crank at this stage is out of the question. For me, and the limitations of the tools I have at hand, the biggie is taking off the crank pulley.

 

I'm thinking...remove the chain wedge, let the tensioner pop, then do the trick of locking the gearbox in 5th and undoing the crank bolt that way. Given that the engine was quite freshly assembled, it's possibly not going to be seized on that tight. If that don't work, then I'll try removing the starter and wedging the ring gear with a really big screwdriver.

 

I'm not that keen on trying the method of using a long breaker bar against the chassis rail and then bumping the starter, since I'm worried about the chain getting sucked down into the timing cover and getting wrecked.

[Xnke]

To my inexpert eyes, that cylinder head looks like an N33. Large intake, small exhaust, although both of those valve sizes are non-standard, I think. Aren't N47 valves 35mm and 44mm?

 

Anyway, the N33 has the large intake, and small exhaust, wheras the late E88 has the large exhaust and small intake. The N33 has the N42 /middle E88 style chamber as well, and could easily have been welded to close it up like a P90.

 

Of course, there are mystical P50 and P81 cylinder heads reportedly out there as well...I have never seen or heard of one outside of the Ozdat engine calculator. The N33 I have seen, though. Supposedly, the P81 has round exhaust ports.

 

Also, remember the Kameari 85mm billet crank...still available at over 3KUSD...

[Daeron]

I am going to ask something, a detail I am not 100% clear on....

 

Were all cylinder heads originally the same height, from firing deck to valve cover mating surface?

 

I'm not even close to sure on how to verify this guess, but after poring over the photos I am going to revise my guess to say EXTREMELY shaved N42 (or variant, see BRAAP's comment about the vertical casting marks on the sides of the head below) with UNSHAVEN valves.

 

 

 

This head was discussed in the L6 Head ID thread, and braap had this to say on it then:

I’m not real familiar with L-series cylinder heads for other markets/countries other than domestic USA market. Though I am pretty certain that this head is NOT a domestic USA head AND it has been modified.

 

1) Injector slots and injector manifold mounting holes along with carb mounting holes indicates post 1975 production.

 

2) The EFI Intake mounting holes “appear” to be 8 x 1.25mm, (Same as the carb and exhaust mounting holes), instead of the typical USDM 10 x 1.25mm, though the pictures could be deceiving and those holes could be the 10 x 1.1.25mm holes. (See picture below showing the mounting hole size difference on an US market N-42 head.)

 

3) In looking at the manifold face, note the 2 bolt hoes above the #6 exhaust port?…. NOT on any USDM L-6 cylinder heads.

 

4) Note the vertical casting lines above and between the ports in the unmachined portions of the head near the valve cover...

 

5) The measurement of the intake port opening means absolutely nothing in identifying that head as it had been “port matched” (opening of the port had been enlarged by hand), evidenced by sanding wrap marks left in the port entrance and the injector slots indicate most of the material removed in the intake port was removed from the roof of the port.

 

6) The casting number had been removed. The picture is difficult to tell but it looks like a sanding wrap finish.

 

7) Pics of the combustion chamber and clear well lit pics of the area surrounding the intake valve guide boss would help greatly in identifying this head, so long as the intake port work did not consist of altering the guide boss.

 

 

I looked through the Head thread for some time. I was looking for what looked, to ME, to be the most distinct feature on that combustion chamber; namely, the "heart shape" described by the second quench pad on the spark plug side of the cylinder!

It took me forever because I was focusing more on closed chamber head designs, but then I saw that the N42 heads had that sort of indentation for the valves... I don't know, maybe I am seeing things. I keep going back and forth between photographs of cylinder heads in all sorts of positions, with all sorts of lighting, at all sorts of angles, in all states of carbonation.

 

It seems to me that the key features in IDing it are this second quench pad (because the area around and between the valve seats looks like untouched factory to me) the flashing marks, the 8 mm bolt holes for the manifold, and lookitthat!! Those two extra holes above #6 exhaust port! Aren't those right about in the right place for the coolant modification??

 

One thing I was totally unable to do with the available photographs was compare the oil and coolant passages in the head to the various other designs. It seems to me that that comparison would give us a baseline for what kind of block it may have come with, and based upon that the other questions can be deduced.

 

One final datum to be extracted about your mystery head lies in the intake port, and I must confess a lack of intimate familiarity with the different designs. However, this picture:

is a little bit TOO close to the port; if the camera were slightly further back it would give us a bit more perspective by which to make the comparison to these:

"worked" P90 ports, by BRAAP, this is the pinks head

 

Virgin E31 intake port courtesy of Noddle, Tasmanian IIRC so this is a pacific market E31 for the record

 

 

P90 courtesy of JimZ. Port work has been done but IIRC not a great deal, mostly just around the guide boss and port matching; the CCs on this head looked untouched. I know the entire port has obviously been hit with a grinder, but my memory is telling me that he had done a minimal amount of change other than what was needed to blend the port match and the valve guide work.

 

E88 port courtesy of Locodrftr, uncertain what work has been done but I think nothing. (Note flashing at 3 and 9 o'clock)

 

 

 

This head needs to get the combustion chambers included in the Head ID thread. (and I STILL haven't gotten around to attempting to condense and organize the data there.. soon!)

[Babalouie]

Here's the good word from the cylinder head guy:

 

Rocker problem solvered.

The head has had some higher installed height retainers & taller springs fitted - probably to allow extra room to avoid coil bind with the big cam.

The taller retainers need extra thick lash caps so the rockers clear them - so the base circle of the cam has to be reduced.

Fix is easy, a set of stock retainers & a new set of stock height crow valve springs will fix.

The valves are stock length.

I grabbed a stock retainer from upstairs & dummied it up with stock lash caps - heaps of rocker adjustment, nice wipe patter on the lobe = all good, easy fix.

Porting looks good, real good. The only thing I'm gonna critisize is the surface finish on the intakes - it's been polished, no good, needs to be roughed up a bit.

Also the exhaust short turns are a little sharp where they meet the bottom cut of the seat - nothing 1/2 hr with a die grinder won't fix.

The porting has broken through to water on one of the intakes & has been welded up a little roughly - I just need to smooth it over a bit & pressure test to make sure all is good.

I'll CC it later today - once Babs works out the stroke, deck height, crown volume etc we can work out compression & go from there.

It'll be a good motor once sorted if the head indicates how good the bottom end is.

[Daeron]

Awesome, did this engine builder have any guesses as to which casting it is?

[2eighTZ4me]

Rocker problem solvered.

The head has had some higher installed height retainers & taller springs fitted - probably to allow extra room to avoid coil bind with the big cam.

The taller retainers need extra thick lash caps so the rockers clear them - so the base circle of the cam has to be reduced.

Fix is easy, a set of stock retainers & a new set of stock height crow valve springs will fix.

The valves are stock length.

 

THANK YOU!!! Wasn't that what I was trying to tell you guys all along???!! Maybe I didn't do it in the clearest of fashion - but that was EXACTLY what I experienced with my head and the different retainers/springs. I even had it documented in another post.

 

THANK YOU - I've been cleared.

[Babalouie]

THANK YOU!!! Wasn't that what I was trying to tell you guys all along???!! Maybe I didn't do it in the clearest of fashion - but that was EXACTLY what I experienced with my head and the different retainers/springs. I even had it documented in another post.

 

THANK YOU - I've been cleared.

Yes in fact you have been officially vindicated

[Tony D]

It made sense to me when you said it, but after John said move on...I figured it was implied tobe clear to all...

 

LOL

[Babalouie]

Latest update from the head specialist:

 

Chambers are 32.5cc - erk!

 

I'm guestimating about 5cc in those valve reliefs in the pistons & assuming zero deck height.

 

If it's stock stroke it'll have comp around the 11.8:1 mark.

If it's a 3.1 stroker with 83mm stroke then comp will be about 12.4:1

 

Too high, way too high.

It needs to come down to 11:1 to be ok on pump 98.

 

Can you get E85 locally? - that may be an easy(ish) solution.

 

Failing that we gotta find another 4cc of unswept volume for stock stroke, 6.5cc for a stroker.

 

That's assuming the valve reilefs are around 5cc.

 

Doable in the head for stock stroke by sinking the ex valves .020" (the intakes are already pretty low - don't want to sink them further) & taking a little metal out of the chambers by hand, which I want to do anyway as the valves are a bit shrouded at low lift as they are now.

 

If it's a stroker it may be pushing it a bit to find the extra volume in the head.

 

I guess from here the only way to know which way to proceed is to find out the exact stroke, deck height & valve relief volume.

 

The other issue I though of was head gasket - gonna have to be a custom jobbie to suit the bigger bore, but I can organise that without too many probs.

 

Oh, & the mystery deepens:

 

This is not an L28 head.

 

It does not have nissan cast into the side of it, nor any other usual identifying marks.

 

Dunno WTF it is.

 

It's had 3mm, .120" milled off of it to get the 32.5cc chambers - which is a lot, but not too much for a datto (I had .180" off my L20b's head & it was fine).

 

 

Actually, looking at it again, I think I may struggle to find much more than 2-3cc in the chambers.

 

It may be a case of machining a dish into the pistons or running on E85

 

A 60mm wide by 1mm deep dish would get 2.8cc, combined with unshrouding the valves & sinking the exhaust seats that should be enough.

If not a 1.5mm deep dish would be ok - the crowns will be thick enough to take that & it'd give 4.2cc.

 

Actually, if you take the existing valve reliefs into account a 1mm dish will probably only get 2.5cc & 1.5mm 3.9cc

 

 

So...it looks like the head was milled quite a lot for that lovely 100RON fuel that they got in Japan.

 

Plan A at the moment is for him to open up the head chamber volume as much as possible, then when I pull the block, he'll hel me do some sums to see what sort of dish we need to machine into the pistons to drop the CR.

 

BTW, "E85" is this ethanol- based fuel that we have in Australia, AFAIK it's got an octane of approx 100RON or better, but it's only available in a small handful of gas stations (and nowhere near where I live).

[2eighTZ4me]

Running E85 requires a complete overhaul of the fuel system. It eats rubber, and isn't very fond of aluminum either.

 

Reference this thread for a more detailed explanation.

 

http://forums.hybridz.org/showthread.php?p=964008#post964008

 

I would think just by going with a 2mm head gasket, you could save yourself a bit of money in machine shop costs. The gasket is pricey, but would probably negate your cost from the machinist, or at least be fairly close. Then it's bolt on and go. I'm not good at the math, and haven't studied cylinder volumes in detail, but a stock HG compressed is supposed to be 1.2mm, that would give you .8mm additional unswept volume across a 90mm bore. What does that equate to? They also make a 3mm head gasket (believe it's a Kameari part) - so there are options other than carving up your head. Sinking the valves just doesn't sound like a great option to me. But hey - I'm not a machinist!

 

Keep us posted.

[Babalouie]

I think a 2mm gasket buys you an extra 5cc or something. That would probably be the ticket, but this particular engine builder says no to thicker gaskets on n/a engines.

 

His theory is that a thicker gasket reduces the squish areas of the combustion chamber a lot, and hence you get less mixing and hence lean spots which cause detonation. No probs on a turbo engine where the mixing is naturally better tho.

 

Well...let's see how we go, it seems as if we might have no probs at all if my engine is a plain ol' 3.0L rather than a 3.1L stroker.