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Author Topic: Rebuild: Going Gasketless, Rephasing Cams & AVL Oil Pumps for CI Lung Engine?  (Read 2232 times)

TejK

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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.
« Last Edit: November 21, 2013, 04:24:40 PM by TejK »

ace.cafe

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #1 on: October 19, 2013, 03:07:08 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.
« Last Edit: October 19, 2013, 03:11:31 PM by ace.cafe »
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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TejK

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #2 on: October 19, 2013, 03:51:00 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.




ace.cafe

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #3 on: October 19, 2013, 08:26:21 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.
« Last Edit: October 19, 2013, 08:31:33 PM by ace.cafe »
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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TejK

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #4 on: October 20, 2013, 05:13:43 AM »
Thanks Ace  :)!
Appreciate the help. Will keep you updated on how it goes !!
Best,
Tej

TejK

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #5 on: October 20, 2013, 08:29:59 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.

ace.cafe

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #6 on: October 20, 2013, 12:18:34 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.
« Last Edit: October 20, 2013, 12:25:40 PM by ace.cafe »
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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TejK

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #7 on: October 21, 2013, 10:34:23 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

ace.cafe

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #8 on: October 21, 2013, 11:13:45 AM »
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.
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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TejK

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #9 on: October 21, 2013, 04:19:10 PM »
Ok. That's Great !  :)

TejK

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #10 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.

ace.cafe

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #11 on: October 28, 2013, 12:48:00 PM »
That should work.
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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RGT

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #12 on: October 28, 2013, 12:58:03 PM »
Did you lap that entire clearance away? you are a patient man.

Blltrdr

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #13 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
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ace.cafe

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #14 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.
Home of the ACE Fireball 535 Bullet,  Ace GP Hi-Lift Roller Rocker Head . Pistons, cams, etc. Highest performance Bullet engine mods available .  AVL mods. Redditch 700/750 Twin mods. UCE kit soon.

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