[techedge]

I have an H20A (SV620 V6 2.0L) engine I changed the timing chains on but now find (thankfully before I re-installed the motor) that a lot of the noise was probably from the big-ends! So to cut a long stroy short, I need some advice on big-end shell thickness, and undersized bearings.

Platigauge tells me I have over 0.25mm clearance (limit specified in SV620 S/M is 0.09mm! - I only had blue Plastigauge). S/M further specifies (page 6A2-72) that 0.25mm OVERSIZE shells have a thickness of 1.610mm+/-0.005 - here's the question:

Does this mean the NORMAL shell thickness is 1.610 - 0.125 = 1.485 (or is it 1.610 - 0.250 = 1.36) [ie. the OVERSIZE is specified as a DIAMETER but the bearing shell thickness is a RADIUS-thickness (and there are two on a diameter)]?

I'm measuring* my very badly chewed about bearing shells to be 1.465 to 1.475, so I assume they have lost some material (it ended up as grey sludge in the sump) from the normal 1.485 +/- 0.005 ...

OK, now I'm wondering if somehow my engine was previously rebuilt with a ground crank but assembled with normal big-end shells rather than oversize shells - this could explain the large clearance, but would anyone be stupid enough to do this?

*I measure with a micrometer (not calipers) and place a 5mm drill bit between the concave side of the shell and one face of the micrometer - I calculate the shell thickness as difference by subtracting the drill bit diameter.

[fordem]

The norm is to measure the diameter of the crank journal - doing it that way would answer your question on whether the crank has previously been ground, and also let you know, if it needs to be ground and undersized bearings used.

[royce]

If they are anything like G16's they will have letters? stamped on the sump mounting face telling you what the original sizes were

[techedge]

Now there's daylight I got a better measure of the situation. Here are some figures from my micrometer on the crankshaft itself (I limited measurements to just one crank becasue they are all just as loose as each other - all in mm - resolution of micrometer measurements is .005) - Crank Pin measurement (#4 piston):

A - 49.865 (in the direction of piston travel)
B - 49.895 (lateral, least wear direction)

Right off we have .03 out-of-round which is three times the limit (see SV620 Service Manual page 6A2-72). The nominal crank pin measure is 49.991 and my worst (A) measurement gives me a clearance difference of 49.991-49.865= 0.126 compared to the standard-shell wear limit of 0.08 so it's nearly 60% more than the wear limit!

So, (after doing the sums) replacing the bearing shells with standard shells will not solve my rattle (quite apart from the out-of-round being way over limit. Only realistic solution (should I keep this engine) is to get the cranshaft reground, and then no point doing that unless I get oversize pistons/rings and have it rebored too! It sounds like it's going to cost me more than its worth!

Anyone have any suggestions?

[droverdave]

techedge wrote:

It sounds like it's going to cost me more than its worth!

unfortuanetly thats often the case when repairing engines, you can either spend the cash and know its 100% or take the gamble and get another engine. For instance i just spent $475 getting a G13a head machined flat and valve grinded (incl gasket kit). whole G13as' seem to go for $100....

Id have a chat to a machinist to get an idea on what costs you are up for for crank grind, bearings, pison and rings. I dare say it will be over the $1200 mark to get it back together, thats with you doing assembly work at home:S

[atari4x4]

personally i'd smash in a low kay H25a or H27a & call it good, add on all the consumables & gaskets etc on top of the machining i reckon it would be up there with the cost a replacement motor.

[Ace]

Instead of the drill bit you can buy reasonably cheap a ball end that slides over the end of your micrometer to measure curved thicknesses like this. You just wind it until closed, write down the thickness and subtract from your measurement. Just an idea

[techedge]

droverdave wrote:

... you can either spend the cash and know its 100% ...

More faith than I have Drover Dave!

I've been down the road of trusting a machinist to do a good job at the right price once too many times (well, more than once to be honest! it started in the 1970s when I had a Hillman Imp - this was when alloy motors and overhead cams were a novelty...).

I'll say no more other than that I only trust my own work now - I'd rather spend the money on tools for the next job than trusting someone else to do most jobs properly. So, knowing when to fold is an acquired skill IMHO!

Peter.

[techedge]

atari4x4 wrote:

personally i'd smash in a low kay H25a or H27a & call it good....

Yeah, agreed on a low-K solution, but donno if more CCs is the way to go. Probably impossible to find a low-K H20A too!

If anyone has a spare good H20A bottom-end, then I'd be happy to mate it with my top-end!

Peter.

[atari4x4]

there is no substitute for cubic capacity... i'll be going down this path, rather than trying to freshen up the H20a in my wagon.

personally you can't beat a factory built & sealed motor.

[Ace]

How about " I'd rather spend the money on tools for the next job than" giving tools my hard earned money. Don't get me wrong I am not saying engine builders are muppets nor that they take your money but.. If you can assemble at hm and "if" your accept you may do it again in your lifetime, also that you may fk it up once or twice . Tools are mans best friend, at least mine don't act up like the dog...

[techedge]

atari4x4 wrote:

there is no substitute for cubic capacity... You don't need a tractor to pull a hoe!

So that's a bit like saying there's no subsitute for big tits - and if I don't like big tits then I have a problem. Well, maybe that's stretching the analogy, but it's been a while since I've felt the need to impress someone else through my vehicle's capacity (speed, shine, etc...). I like your tractor comment better!

The point is that there are very few 4x4 situations where power is going to do something that skill and gearing can't do - I do my 4x4ing for myself (usually to get somewhere where I can hike or cycle), not to impress anyone else. Anyway, this is getting a bit off-topic!

What's an H25A worth? Anyone have one for sale?

[want33s]

techedge wrote:

The point is that there are very few 4x4 situations where power is going to do something that skill and gearing can't do - I do my 4x4ing for myself (usually to get somewhere where I can hike or cycle), not to impress anyone else. Anyway, this is getting a bit off-topic!

Extra cubic inches does increase horsepower all things being equal but what I believe Atari had in mind was that extra cubes also means lots of EXTRA TORQUE.
Torque is what a 4WD really needs for crawling or towing or just turning big tyres.

[atari4x4]

want33s wrote:

techedge wrote:

The point is that there are very few 4x4 situations where power is going to do something that skill and gearing can't do - I do my 4x4ing for myself (usually to get somewhere where I can hike or cycle), not to impress anyone else. Anyway, this is getting a bit off-topic!

Extra cubic inches does increase horsepower all things being equal but what I believe Atari had in mind was that extra cubes also means lots of EXTRA TORQUE.
Torque is what a 4WD really needs for crawling or towing or just turning big tyres.

yes that is what i'm getting at & they're about 2k for a H25a, but it's best you ring around for a quote.



what's with all the coloured type? it's fucking annoying as shit.

Quote:

FYI only Royce uses Red when he's threatening to pull the plug

[techedge]

So, been wondering about this, I think I should get an idea of how much it would cost me to just do the crankshaft (I take in just the shaft)...

Can anyone recommend a machine shop? Anyone had an H20A crank reground and have a rough price? Anyone have just an H20A crank that's still servicable? What about a complete H20A that's otherwise not going anwhere but would have a good crank (I'd buy the whole motor).

[atari4x4]

bigrig91 had a h20a that he pulled out & replaced for a h25a, shoot him a pm he might still have it, pretty sure it needed a freshen up