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186 Engine Rebuild

Started by _duggan208_ , Feb 18 2015 12:34 AM

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#1 _duggan208_

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Posted 18 February 2015 - 12:34 AM

Hi all, I've had to pull my donk out, so I thought I would make up a members project on my 186 red. Its only done about 500 miles but suffering from very low oil pressure, leaking rear main, a previously badly resleaved harmonic balancer and a few other problems. On inspection my bearings were ripped to shreds, as I expected, plenty of scuffing and deep scores likely due to extreme fuel dillution from an extremely over rich mixture and low oil pressure. The crank snout is a fr0cking mess, the balancer has been slipping around and almost ripped the key out out the keyway. I'm looking at another blue crank tomorrow. The pushrods scrape on the head. The HQ race pistons have scuff marks on the skirts, so I'll get the block honed again. The hone marks don't look quite right (wrong angle) don't know how I missed that when I put the engine together. Fortunatly the block looks to be in good shape. My super light flywheel was tight and showed no signs of coming off. My clutch has dug a trench in the bell housing so some more clearence grinding. So I'm going change a few things, fiddle around and try some new ideas. I trust that i'll get some different opinions on issues for me to chew over. I'll start with the crank and gradually work my way through, however, being a mature aged student its gonna take some serious time to achieve. my goal is just over 300 RWHP, NA, street car and pump fuel.

regards

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#2 RIM-010

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Posted 18 February 2015 - 10:01 AM

300rwhp out of a streetable NA 186? I'm very very intrigued...

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#3 yel327

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Posted 18 February 2015 - 12:03 PM

Does it use a 202 crank?

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#4 _duggan208_

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Posted 18 February 2015 - 09:01 PM

Yes it was a 202 blue crank, today I picked up a black 202 crank. I'm going to shape the leading edge of the counterweights into a tear drop design. I'm not sure if the trailing edge will have any effect, let along the leading edge. May as well take a bit of weight off the counterweights because of the lighter piston and pin combo. Grind off all the stress risers as well. There will be no knife edging and won't be cross drilling the mains this time.

I only need to find another 50 odd HP to reach my goal. The last time on the dyno the tech would only rev to 5 grand due to very low oil pressure but it still made 250 rwhp. The cam which I'll use again will make power up to 7000. The cam and the down drafted ports at 5 grand are only just starting to work, so I'm confident for the 300.

Regards

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#5 Ice

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Posted 18 February 2015 - 09:28 PM

Yes it was a 202 blue crank, today I picked up a black 202 crank. I'm going to shape the leading edge of the counterweights into a tear drop design. I'm not sure if the trailing edge will have any effect, let along the leading edge. May as well take a bit of weight off the counterweights because of the lighter piston and pin combo. Grind off all the stress risers as well. There will be no knife edging and won't be cross drilling the mains this time.
I only need to find another 50 odd HP to reach my goal. The last time on the dyno the tech would only rev to 5 grand due to very low oil pressure but it still made 250 rwhp. The cam which I'll use again will make power up to 7000. The cam and the down drafted ports at 5 grand are only just starting to work, so I'm confident for the 300.
Regards

Wow 250 rwhp nice little combo by the sounds of things

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#6 Steve TPF

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Posted 18 February 2015 - 09:35 PM

Awesome pics! I love how you built a bike around the 202! Just be careful that rocker cover breather doesn't hit you in the nuts.

Not sure how you're gearing it to the rear wheel though. Does the flywheel press against the rim to make the wheel spin?

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#7 _stroker 208_

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Posted 19 February 2015 - 07:46 PM

Hey can I ask what engine number prefix is your 186?

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#8 _duggan208_

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Posted 19 February 2015 - 10:12 PM

186 P 54692, i've no idea what they mean, I'm sure someone will tell me.

Regards

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#9 _duggan208_

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Posted 19 February 2015 - 10:16 PM

Bugger me, the holden 6 isn't all that long, I've even got a spare RD frame, never get it regoed, bloody be nice and dangerous to ride, Oh I've also got a spare 161 lying around, don't need a gear box.

Regards

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#10 _duggan208_

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Posted 28 February 2015 - 10:58 PM

I've got my dirty rusty black motor crank, bloody hell its heavy, needs a diet especially a rotating mass diet. I've looked into gun drilling but I can't see how you could get a drill bit any where near the crank throughs. Need to see if anyone up here (sunshine Coast) can pendulum cut the inside of the counterweights. Going to look into ball milling and will grind the leading edges of the counterweights into a bull nose and deburr all the stress risers off. I've been having a close look at Scat cranks, taking note of how they reduce rotating mass. I've also noticed extra weight on the 1 and 6 crank throughs, I might take some of this off to match the other crank throughs. I noticed that the Scat crank throughs are all similar shape and weight. Has any one fiddeled around with shaping, reducing rotating mass out of these bloody heavy cranks?

Regards

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#11 N/A-PWR

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Posted 01 March 2015 - 12:17 AM

Talk to STRAIGHTLINEMICK

He machines these cranks to a knife edge Jon.

Has any one fiddeled around with shaping, reducing rotating mass out of these bloody heavy cranks?

Regards

another

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#12 _oldjohnno_

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Posted 01 March 2015 - 07:20 AM

Daves right, buy one of Micks cranks. Or alternatively, just use the black crank as is. The weight isn't really a problem, and you can easily make them worse if you don't know what you're doing. I'm betting on 330hp.

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#13 _Bomber Watson_

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Posted 01 March 2015 - 08:43 AM

I've got my dirty rusty black motor crank, bloody hell its heavy, needs a diet especially a rotating mass diet. I've looked into gun drilling but I can't see how you could get a drill bit any where near the crank throughs. Need to see if anyone up here (sunshine Coast) can pendulum cut the inside of the counterweights. Going to look into ball milling and will grind the leading edges of the counterweights into a bull nose and deburr all the stress risers off. I've been having a close look at Scat cranks, taking note of how they reduce rotating mass. I've also noticed extra weight on the 1 and 6 crank throughs, I might take some of this off to match the other crank throughs. I noticed that the Scat crank throughs are all similar shape and weight. Has any one fiddeled around with shaping, reducing rotating mass out of these bloody heavy cranks?
Regards

If you look a bit closer you will see the crank throws for 2-5 are offset to the throws by a few degrees.

Tmk this is why 1 and 6 are bigger.

Cheers.

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#14 S pack

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Posted 01 March 2015 - 10:53 AM

Daves right, buy one of Micks cranks. Or alternatively, just use the black crank as is. The weight isn't really a problem, and you can easily make them worse if you don't know what you're doing. I'm betting on 330hp.

When I had the blue crank installed in my red 202 I talked to the engine builder about lightening the crank. His reply was for a streeter it's best to leave the crank as is esp as I am using a lightened flywheel. I got the impression ones money was better spent improving other aspects of the engine.

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#15 _oldjohnno_

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Posted 01 March 2015 - 11:28 AM

Exactly, you're not gonna lose any races over a couple of kg crank weight.

The factory engineers aren't dumb, and there's a reason for the odd counterweight configuration. Sometimes the end weights are overbalanced to manage snout and tail wobble, sometimes it's just a way to achieve good balance while keeping the overall weight down. I wouldn't mess with it, but if you just can't help yourself get one from someone with a proven record.

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#16 N/A-PWR

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Posted 01 March 2015 - 12:48 PM

Has this Black crank been modified?

http://holdenpaedia....rpc.preview.jpg

Just getting to know the Little 6 family better.

Just wondered if the knife edge done.

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#17 _Bomber Watson_

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Posted 01 March 2015 - 12:55 PM

Yeah thats been hacked and slashed.

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#18 _Agent 34_

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Posted 01 March 2015 - 06:35 PM

Another good read is "are harmonics killing my engine". This talks about knife edge cranks and the affect on the Holden six .

I'm also starting some planning for the new engine . I have had some detailed discussions with another race who swears by just using a red crank . Now I know that this may cause discussions of the wobbly nature, but it's worth thinking about when discussing taking weight off a blue black crank. The last couple of guys that I speak to at the track r running s full weight crank OR a steel crank

Obviously I have not spoke to everyone ,

Do you have any pictures of the bearings that you pulled uut.

Disclaimer - I'm no expert on this matter

g

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#19 _duggan208_

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Posted 02 March 2015 - 01:24 AM

The old bearings will be around, I'll put up pics. I've never been convinced with knife edging due to the balancing issue. The counterweights are there for a good reason, i've always thought that knife edging takes too much weight off the outer edge of the counterweight and lessens the centrifical effects as the rpms rise. I'm thinking that as the big end go's around BDC the weight of the counterweight helps put the piston down the bore and offset the force on the block. IF I take weight off I feel that the big end crank throughs may be the best place to concentrate on. The crank will loose some fat when the mains are ground down to the 186 block. I think i'll leave that odd weight alone on 1 and 6. If I muck around with it I probadly won't go over board with it. Also my flywheel is very light, looking to add some extra weight to it, I do love the way it revs. I appreiciate all the advise there's alot to learn and put into practice.

regards

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#20 S pack

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Posted 02 March 2015 - 11:55 AM

I suspect if you were to lighten the crank counterweights then you would also be best looking at lighter connecting rods and pistons to match.

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#21 _duggan208_

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Posted 03 March 2015 - 12:00 AM

Yes I have HQ race pistons, all weigh the same, thinner moly rings and thinner pins probadly not much lighter than stock but I spose it all adds up. I would love to afford some serious rods but the good old starfires (a bit heavy) seem to be up to the job so far. polished beams, shot peined and balanced. I might stay away from taking weight off the counterweights and look at the big ends. I've been looking closely at high end cranks, they avoid lightening the counterweights and get stuck into the big ends, extra grinding, ball milling and gun drilling etc. But, might be better off saving my money and investing in a rattler balancer. i'll do some home work before I act.

Regards

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#22 N/A-PWR

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Posted 03 March 2015 - 12:10 AM

Good Information Jon thank's,

I do know standard big-end bearings can take a hiding for a while,

( unless oiling is the issue )

But it would be nice to know what the best big-end bearings there are out there to use, without alteration.

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#23 _Agent 34_

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Posted 04 March 2015 - 05:19 AM

Jon,

I've done a bit of homework in this rod area over the last few months. I spoke to a bloke in our club and also discussed many options with him

the . straitline mick option - he says ( the racer) has the best combo has access to rods, mick can supply the rods and pistons ( the rod is longer than normal ) ( and it runs an altera Nissan) piston - you need to off grind the crank - mick does the whole lot. not group nc compliant. good pistons with coated skirts and rods are good - can use full or knife edge weights on crank.

I'm now chasing a honda rod and piston combo and am waiting on the part no for theses - these are group nc compliant ( havent done too much on this yet) but by all accounts there as good as the above.

Pretty sure that both these run the smaller journal size as honda uses a smaller big end.

you will have to check with ,mick on a piston, rod and ring set but was pretty sure it was around the 1.2 mark

the honda set up is a bit less

the nissan set up by all accounts is the one i would go with if the engine did not have to go into a race car which I'm going to log book. After again talking to the crank grinder at length discussions were had about this set up and the grinding offset of journal ( off and smaller ) he was adamant that strength was not the issue with the diameter reduction BUT that it is the shoulder on the journal which destroyed the bearings and caused issues. So what i gathered was that getting this right was imperative to the operation of the crank and bearing combo.

micks combo - good rods - good pistons - teflon coated skirts- floating pin -- Crank mods - grind and offset. Total planning - deck height - comp - over bore size.

This may be too much for where you are currently with the build but thought i would mention it as mick's name was covered in an earlier and you also talked about the rods.

The racer who uses this combo is an aircraft engineer and have taken these to work and crack tested and also done other test on the rods and they have come up a treat.

hope this helps in someway

G