Unofficial Royal Enfield Community Forum

Royal Enfield Motorcycles => Bullet Iron Barrel => Topic started by: TejK on October 19, 2013, 09:27:15 am

Title: Rebuild: Going Gasketless, Rephasing Cams & AVL Oil Pumps for CI Lung Engine?
Post by: TejK on October 19, 2013, 09:27:15 am
Hi All,
I am planning to upgrade my 350cc CI bullet with a Compression piston which I got from Hitchcocks. Before I get the the work done on the engine, I was considering if it was possible to attach/fit the AVL 350cc timing cover with the oil pumps to the standard CI engine. Or if those oil pumps can be fitted into the CI timing cover?

1. In essence I am hoping to have a better oiled engine and maybe more oil will carry off the extra heat with this mod ( if possible). It would be great if someone can advise if this is workable or if there is an alternate way to improve the oil flow.

2. Will adding a small oil cooler help in this mod?

I understand that it maybe too much extra work for just adding a high comp pistom, however, I ride the bike on a regular basis through south India and the temps can can be quite high and i don't want to have a seized piston with the extra heat.  :-\

Kindly advise. Any suggestions will be appreciated.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe on October 19, 2013, 04:07:08 pm
It's a big job, and not worth the effort. It's been done many times, with the common comments being "I wouldn't do it again".The AVL pumps are not positive displacement pumps,  so they allow drain back from the return lines which is a partial contributor to wet sumping issues in the AVL. They do pump more oil, but they over oil the head, so you must have valve stem seals fitted, which many iron barrel engines do not have as standard equipment. Otherwise,  you will get oil down the valve guides which can cause higher oil consumption and even cause detonation when it gets into the combustion chamber.  It's not hard to fit seals, but they are a must with that much oil in the head. Also, the floating bush OEM big-end bearing may build too much pressure with that much more oil feed, causing stress to the pump drive spindle when the oil is cold, possibly stripping teeth off. The AVL pumps were made to feed a roller bearing big-end, which needs more flow and doesn't hold pressure. I recommend hi-flow positive displacement pump replacements for the stock iron barrel pumps when changing to an Alpha roller bearing big-end.

The oil isn't responsible for much cooling in this engine. It is mostly air cooled, and the oil doesn't do much of the cooling. Your best course for cooling improvement is to fit an alloy barrel with that new piston. And hone a correct piston-to-wall clearance for that forged piston, so it won't seize. The amount of clearance depends on the type of piston.

And last, but not least, do not push the working compression too high for the intended fuel. Unless you intend to use the Indian 97 octane fuel, you will need to keep the working compression under about 135 psi on a cold cranking compession test.

These recommendations come from a lot of hard won experience. Failure to observe these guides will yield costly problems.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: TejK on October 19, 2013, 04:51:00 pm
Thanks Ace !!
Like they say " Experience is Knowledge 8)". Helps to know the pitfalls from those who have tried the mods.

Guess its too much of an effort with hardly any gains. I am planning to keep the floating bush on the bike for the build.  Will add better oil pumps on the bike . Planning to go with the same barrel at the moment as an alloy barrel is not an option - need the bike back and running within the next week :-[.

I am going to lap the head & cylinder surface spigot joint for better over all heat sharing between the head and the barrel.



Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe on October 19, 2013, 09:26:21 pm
With the floating bush in the big end, the std oil pumps will be okay. If you fit the hi capacity pumps, be especially careful to allow the oil to heat up sufficiently before giving it hard throttle.  A decent warm-up time can go a long way toward saving your pump drive spindle and worm nut.

If you lap the head to go gasketless, it helps eliminate oil leaks if you smear a little blue Hylomar around the pushrod tunnels when you assemble.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: TejK on October 20, 2013, 06:13:43 am
Thanks Ace  :)!
Appreciate the help. Will keep you updated on how it goes !!
Best,
Tej
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: TejK on October 20, 2013, 09:29:59 am
Additionally, it would be great if you could help me with the rephasing of the cams. I have the 3-way timing pinion also ordered for this.

However, while reading some older posts on the iron engine, it read that the old Redditch Model 350 had the inlet cam advanced by a tooth as compared to the current Indian made CI bullets.

With the increase in the compression, will a re-phase help ? And can I do the 1 tooth adv/retard on the engine with the compression increase?

Would appreciate any info or any pointer to do the re-phase ( older posts, however, I could not find any on searching for a 350cc).

Its really great of you to advise and help a relative newbie on engine mods.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe on October 20, 2013, 01:18:34 pm
The cams are the same on the 350 and 500. The Redditch did not have 1-tooth advance on the inlet, but it had somewhat retarded inlet and advanced exhaust compared to the modern India-made cams.

To re-phase, you actually should use a degree wheel and dial-indicator to check the actual valve timing because these cams vary quite a bit in production.  However,  moving them in a retarded direction is the "safe" direction in terms of concern about valve/piston clash, so if you want to just go ahead and do it,  then it's basically safe to do. If you don't know what the actual valve timing is, then you will probably have to take the barrel off more than once to adjust the gasket thickness under the barrel to adjust your working compression. But that's pretty easy to to.

To do it,  you just bring the engine to TDC on the compression stroke so that the dots on the cams are aligned next to each other in the normal installed position. Then you just pull ONLY the inlet cam out on the spindle until it is disengaged from the gears, rotate the inlet cam counterclockwise one tooth(which retards it), and put it back into engagement with the other gears WITHOUT MOVING ANY OF THE OTHER GEARS OR THE OTHER CAM AT ALL IN ANY WAY.
This retards the inlet cam timing by 18 degrees. It also lowers your working compression considerably, which helps you to achieve a good working compression figure without needing to put a big stack of spacers/gaskets under the barrel when you install a high compression piston.
The result of this mod is a higher revving capability, without any loss to the lower rpm torque as long as you get the working compression uo over 130 psi but below 150 psi(depending on your fuel octane).

If you find that the compression results are a bit low psi, and you don't need such high revving, you can use the 3-way timing pinion in the advanced keyway to advance both cams by 4.5 degrees, and then you don't have to pull the barrel and the compression will come up a little from the cam advance.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: TejK on October 21, 2013, 11:34:23 am
Wow, that's a pretty good explanation - and very helpful.
Thanks for taking out the time and answering my newbie queries so patiently. Appreciate it. Would it be alright if I PM you in case i run into any unforseen issues with the re-build. Am aiming to have zippy 350 with decent revving capacity
Thanks.
Tej
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe on October 21, 2013, 12:13:45 pm
You can just post your questions here.  That way everyone can learn. And there are other members here besides me who are able to answer some of these questions, who might want to participate.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: TejK on October 21, 2013, 05:19:10 pm
Ok. That's Great !  :)
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: TejK on October 28, 2013, 12:26:30 pm
UPDATE Friends:

1. Engine dismantled and the cranks balanced, new floating bush, better quality bearings
2. Re-bored cylinder to specified clearance as per Hitchcock's instructions
3. Head Cylinder spigot and gasket ares lapped to mating finish ( took over three days of beers, music and lapping and lapping and lapping)
4. Mild cleaning of the inlet an exhaust ports with a flap wheel, removed some steps on the small side radius
5. New valve guides and valves

will be assembling the engine in a day of tow. Posting the pictures of the various steps for reference.

To Moderator :Is it possible to change the topic to one reflecting a rebuild & lapping to help others who are searching for similar threads.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe on October 28, 2013, 12:48:00 pm
That should work.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: RGT on October 28, 2013, 12:58:03 pm
Did you lap that entire clearance away? you are a patient man.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: Blltrdr on October 28, 2013, 02:19:56 pm
I'm not sure this is correct. I think there should be some clearance figured in for torquing the head down. These pages have been posted before. http://www.royal-enfield.net/articles/creasey_article_4_p2.pdf
http://www.royal-enfield.net/articles/creasey_article_4_p1.pdf
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe on October 28, 2013, 02:44:05 pm
I think Creasy says this because he wants to be sure that the top of the spigot is fully seated. In reality, we have done this gasket elimination with no .001" gap there, and it works fine, and still even needs a very light smear of RTV or Hylomar there around the pushrod tunnels to be sure of a good oil seal.
I think as long as the spigot goes all the way home, it's fine.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: Blltrdr 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?
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe 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.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: Blltrdr 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.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe 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.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: TejK 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.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ERC 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
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: TejK 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.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: High On Octane 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
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: TejK 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
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: AVL Power! on October 31, 2013, 12:08:19 pm
Some serious business Tej!! Great work :D
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: High On Octane 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
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe 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!
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: TejK 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?

Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: High On Octane 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
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: Blltrdr 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.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe on November 14, 2013, 03:58:27 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.

Correct.
I don't even attempt to get them up to 24. The most I use is 20. They don't need even 20. Trying to put any muscle into torquing these things is a recipe for pulled threads.
I also see no need for any super studs either, because the studs will pull right out of the alloy engine case long before the studs suffer any problems.
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: High On Octane on November 17, 2013, 02:30:15 pm
Ace - If the threads going into the engine are prone to pulling out, couldn't this problem be alleviated by inserting steel helicoils in the engine case?  Or would this make room for more problems?

Scottie
Title: Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
Post by: ace.cafe on November 17, 2013, 05:08:02 pm
Ace - If the threads going into the engine are prone to pulling out, couldn't this problem be alleviated by inserting steel helicoils in the engine case?  Or would this make room for more problems?

Scottie
It can sometimes help, if the alloy temper is good enough to hold them.
Often times, when you put helicoils in, then it just pulls the helicoils out of the aluminum case around them.

The best thing to do is down-rate the torque values, because not much torque is needed.
The most common cause of destruction of these threaded holes is trying to solve oil leaks by over-torquing the head nuts. With a "spigot" style head system, adding torque to try to seal the oil will never seal the oil, but it will pull the head studs right out of the engine. or warp the head, or both.
Title: Re: Rebuild: Going Gasketless, Rephasing Cams & AVL Oil Pumps for CI Lung Engine?
Post by: rep_movsd on November 26, 2013, 09:14:01 pm
Speaking of which...
A routine retorquing job to 18 lb-ft turned into a barrel overhaul as it tore one of the crankcase stud threads completely. The complete thread came out like a spring on the stud.

I had to drill into the crankcase about 1 inch deeper than normal and tap it, to install a longer stud with loctite red thread sealer. The crank case seems to have enough material in there.
I'm going to keep that stud at 15 lb-ft.

Title: Re: Rebuild: Going Gasketless, Rephasing Cams & AVL Oil Pumps for CI Lung Engine?
Post by: TejK on December 03, 2013, 08:15:04 am
UPDATE:

1. The bike has about 500 kms on it now and has been totally oil tight !!
2. The rings seem to be seating on the barrel and the compression ( gauging from the kick effort) seems to be increasing.
3. The VM28 has been added to the bike and the jetting needs to be sorted out now.

4. The best part - The de-compressor delete ( never used it anyway) !! And the spark plug from the AVL engine ( long reach) was put in its place. Added an extra ignition coil ( series)  and tested both the plugs for spark - and they both give a strong spark at each plug!

Now I have a lovely zippy Cast Iron Twin sparky (maybe more pollution friendly also now) .

For the sake of experimenting, I did no modifications to the head, spark plug( long reach) etc as discussed in another post and it fired right up with no compression losses.  8)

Interestingly staring the bike with only one plug connected and then connecting the second plug results in the engine rpms rising by a couple hundred. I am guessing the additional plug is probably improving the combustion efficiency  :P

Now to ride it like it is and evaluate if this additional plug and play will hold out.
Cheers !
Title: Re: Rebuild: Going Gasketless, Rephasing Cams & AVL Oil Pumps for CI Lung Engine?
Post by: Blltrdr on December 03, 2013, 04:07:12 pm
When you converted to twin plug did you block the exhaust passage for the decomp? My machinist plugged mine in the process of doing the rest of the head work.
Title: Re: Rebuild: Going Gasketless, Rephasing Cams & AVL Oil Pumps for CI Lung Engine?
Post by: TejK on December 04, 2013, 06:26:10 am
Blltrdr,

No I did not do any mods to the head.

As the plug block the hole, I don't think any gases can leak out of the combustion chamber. And on the exhaust valve side, due to the inherent high speed of the exhaust charge there should be no flow into the dump hole for the decomp.

Is there a requirement to block this ?? Suggestions will be welcome.