Author Topic: Rebuild: Going Gasketless, Rephasing Cams & AVL Oil Pumps for CI Lung Engine?  (Read 11996 times)

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Blltrdr

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Reply #15 on: October 28, 2013, 03:00:48 pm
Well that is good to know Ace. Do you achieve the precise mating of the surfaces using engineers blue on the barrel spigot?
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ace.cafe

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Reply #16 on: October 28, 2013, 03:02:36 pm
Well that is good to know Ace. Do you achieve the precise mating of the surfaces using engineers blue on the barrel spigot?

No, we stopped machining the spigot with a .001" gap at the head gasket surface mating area, and lapped the spigot the rest of the way down with grinding paste, checking frequently until it  just touches down with the paste cleaned off.
« Last Edit: October 28, 2013, 03:05:54 pm by ace.cafe »
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Blltrdr

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Reply #17 on: October 28, 2013, 03:14:40 pm
Ace, what about those that want to do this on the bench without the use of machining equipment. Shouldn't they blue the spigot top surface to make sure the head mates properly? I would suggest taking it to a machine shop but some like to do things themselves.
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ace.cafe

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Reply #18 on: October 28, 2013, 03:42:25 pm
Ace, what about those that want to do this on the bench without the use of machining equipment. Shouldn't they blue the spigot top surface to make sure the head mates properly? I would suggest taking it to a machine shop but some like to do things themselves,
Well,  I would say that the spigot should be lapped down first,  until the head is almost touching the barrel gasket mating surface. Thaen clean off the paste and see how close to touching it is without any paste in there. Then continue to lap the spigot,  cleaning off the paste each time you check it, until it just touches. This way,  it only grinds the spigot down to the right height, and should clean up most/all irregularites in the process.
If the gasket mating surfaces are warped, it will become obvious that the contact is not uniform all around.  Then,  lapping on all surfaces will be needed until it's all in the correct condition/relationship.

The reason I prefer machining the spigot is because the head alloy is softer than the cast iron spigot, and if a lot of lapping is done to grind down a tall spigot,  it might grind too much away from the recess in the head. It is not very thick there near the bottom of the valve seats. I think it's better to machine the spigot down close to the target first,  before starting the process.

When we do this , we machine the gasket mating surfaces with a very light clean up to ensure that all surfaces are square with bore,  and free of imperfections/warps, and then do the spigot work so it all comes out nice.

We have had barrel/head pairs sent to us by exasperated owners who just just could not solve the leaking, and when we did our work the leaks were solved on our first try. Basically,  we have seen it all,  and we just straighten everything out when we do it.

I empathize with the DIY guys, but sometimes there is no substitute for a guy who knows what he is doing, and has a top notch machine shop at his disposal.
« Last Edit: October 28, 2013, 04:18:40 pm by ace.cafe »
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TejK

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Reply #19 on: October 29, 2013, 08:03:28 am
Well,  I would say that the spigot should be lapped down first,  until the head is almost touching the barrel gasket mating surface. Then clean off the paste and see how close to touching it is without any paste in there. Then continue to lap the spigot,  cleaning off the paste each time you check it, until it just touches. This way,  it only grinds the spigot down to the right height, and should clean up most/all irregularities in the process.
If the gasket mating surfaces are warped, it will become obvious that the contact is not uniform all around.  Then,  lapping on all surfaces will be needed until it's all in the correct condition/relationship.

The process as highlighted by Ace is what i followed. I have the crank and the cylinder - head fitted ( dry fit without gaskets) only to check the clearance for the piston & valves with 1 cylinder base gasket.

1. Hand turned the crank and it cleared pretty well with no clashes.

2. Fitted a spark plug to get a vague read on the compression holding with the joint. There is compression which the joint hold (dry) and with only 4 head bolt.

3. Have got the composite head gasket ( copper outers and packing material inside) separated using a blade and each side of the thin copper sheet become a copper gasket with the thickness around 0.01-0.02 mm, which I may use if required.

Have done this for the first time and as Ace correctly points out, may not be as perfect as machined work or like ACE is doing. However, I took the plunge as I guess its worth the effort to have a more reliable CI engine with less chances of blowing valves.

Will update the results once the engined is set and fired.


ERC

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Reply #20 on: October 29, 2013, 02:08:38 pm
Am I missing something here, if you lapped it down to eliminate the head gasket why do you need a composite head gasket in your last message?  The gasket you mention is not a composite one, it's a sandwich one. If you do use a gasket the real composite one would be better.   ERC
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TejK

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Reply #21 on: October 29, 2013, 02:29:51 pm
ERC,
My mistake in referring to the wrong gasket type.You are correct- it's the sandwhich type.

I have gone gasketless at the moment and and the bike is being assembled to be fired tonight.
 
I mention the copper gasket (one peel off from the sandwhich gasket) MAY also fit / maybe used in case it is required as its thickness fall in the range as per the creasy article which is referenced in the earlier posts.

However, that is a secondary option for me in case going gasketless doesn't prove oil proof. If it leaks, i'll have to sand down the gasket mating surface lightly on a flat surface to use the copper option next.

In anycase, will wait till I get the engine running and then evaluate.


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Reply #22 on: October 29, 2013, 03:16:22 pm
I am NOT a fan of composite gaskets.  I always thought they were the way to go until a month ago when my 3 month old composite head gaskets completely blew out.  I'm sticking with solid copper or multi layer gaskets from now on.

Scottie
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TejK

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Reply #23 on: October 31, 2013, 06:30:57 am
Update :

1. Bike has certainly improved on the compression part. Starts really well with a single kick in the morning.
2. Rode it two days at varying speeds and a little bursts of acceleration. No leaks whatsoever and that's put a smile on my face - thanks to all the guidance and patient advise from Ace and hard work for a newbie paid off. Now to drive it for some more time and see the integrity of the joint.
3. Bike has certainly become peppier, initial acceleration is pretty good ( though have been riding slowly and only touched 70 kph once). The bike still has a VM24 carb ( OEM) which is up-jetted and a K&N R1100 filter. It just wants to take off and I am quite surprised at the transformation. The exhaust sounds pretty sweet too.

Interestingly, now my AVL 500 feel like a heavy vibrating tank as compared to the 350CI now !!
4. Best part - No pinging at all !!! And that is what makes me happiest !!

Will ride it for the first 500 Kms and do an oil change, tighten the head bolts, and then put the VM28 on and then play around with the 3-way timing pinion for re-phasing the cams.

Thanks you, Ace for the guidance and advise. Appreciate it and the beer's on me whenever you are in Bangalore !!

Cheers,
Tej


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Reply #24 on: October 31, 2013, 12:08:19 pm
Some serious business Tej!! Great work :D


High On Octane

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Reply #25 on: October 31, 2013, 12:16:01 pm
Awesome!  I know you mentioned tightening the head bolts in 500km, but did you remember to hot torque the head bolts?  I'd like to think that is extra important when not running a head gasket.

Scottie
2001 Harley Davidson Road King


ace.cafe

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Reply #26 on: October 31, 2013, 12:33:01 pm
Glad to hear that things worked out for you.

I might take you up on that beer in Bangalore one day!
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TejK

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Reply #27 on: November 14, 2013, 07:06:31 am
Sorry for the late reply as i was off travelling.

Hi Ace ! Done - Anytime Ace !!

Hi Scottie,
I torqued the bolts cold, then ran the engine for a few kms and re-torqued when warm. I assume hot torquing means with a hot engine/warm. Is that correct?
at 500 kms - I plan an oil change and re-torque again when warm. Is that the right procedure?



High On Octane

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Reply #28 on: November 14, 2013, 12:53:11 pm

Hi Scottie,
I torqued the bolts cold, then ran the engine for a few kms and re-torqued when warm. I assume hot torquing means with a hot engine/warm. Is that correct?


Correct.  Torque the bolts to spec with the engine cold, then bring the engine up to operating temperature and torque a second time.

Scottie
2001 Harley Davidson Road King


Blltrdr

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Reply #29 on: November 14, 2013, 03:47:47 pm
As Ace has stated, the torque spec that he recommends for the head nuts is 20 ft-lb instead of the 24 ft-lb spec the factory recommends. There have been many instances where the stud will distort the threads at the higher value.
2003 Classic 500 5 spd
2009 HD FLHT Police 103 6 spd
1992 Kawasaki ZG 1200 Voyager XII