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Grant Borden, ace.cafe
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November 23, 2014, 04:52:37 AM

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Author Topic: Rebuild: Going Gasketless, Rephasing Cams & AVL Oil Pumps for CI Lung Engine?  (Read 2162 times)

ace.cafe

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #30 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.
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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High On Octane

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #31 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
Scottie J
Denver, CO

1958 Enfield/Indian Trailblazer

ace.cafe

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Re: AVL Timing Cover & Oil Pumps for CI Lung Engine?
« Reply #32 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.
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.

Please visit my new website:
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rep_movsd

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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.


TejK

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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 !

Blltrdr

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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.
2003 Classic 500 5 spd
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TejK

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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.