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Cyl Head shaved to Min thickness, How many degrees to adj? 

 

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 Post subject: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Sun Jul 17, 2011 6:24 pm 
Oompa Loompa
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As the topic says, I have the head shaved down to min thickness and the timing is out really badly.
The mechanic assures me he timed the cam in correctly as I supplied a vernier cam gear to do so.
It runs really badly and just sounds like its pinging off it's nut.
I got it home and checked for myself and it's been advanced as far as the gear will allow.
Doesn't seem right to me.
Has anyone had experience fitting a head shaved to min. thickness with V/gear.
How far did you need to adjust the gear?
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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Sun Jul 17, 2011 7:55 pm 
Getting Side Ways
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if its pinging have you tryed playing with the base timing?

 

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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Sun Jul 17, 2011 7:57 pm 
Getting Side Ways
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You are confusing cam timing and ignition timing.
I have seen completely stock engines needing the cam adjusted 3 marks on the rollmaster gears to get correct cam timing.

Add in a shaved head, stretch in the chain and you could very well need what you've got.

If it pinging badly, it's will be the extra compression. Choices are, use 98 octane feul or retard the igntion timing or both

 

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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Wed Jul 27, 2011 1:01 am 
Stock as a Rock
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My head has minimum thickness with a stock cam gear, Wade 1636 cam, stock ecu and has no problems after 10,000ks. Considering I did it myself and am a complete novice I could never understand how people have this sort of trouble with shaved heads.
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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Wed Jul 27, 2011 11:24 am 
Getting Side Ways
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slammeb wrote:
My head has minimum thickness with a stock cam gear, Wade 1636 cam, stock ecu and has no problems after 10,000ks. Considering I did it myself and am a complete novice I could never understand how people have this sort of trouble with shaved heads.



sometimes things do just go wrong, even a mechanic can do something perfect 99 times but on the 100th look out all hell breaks loose.

 

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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Wed Jul 27, 2011 1:22 pm 
Getting Side Ways
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slammeb wrote:
My head has minimum thickness with a stock cam gear, Wade 1636 cam, stock ecu and has no problems after 10,000ks. Considering I did it myself and am a complete novice I could never understand how people have this sort of trouble with shaved heads.



It's because you are a complete novice that you can't understand it.

Basicly what you've done is suck it and see, which that time worked out ok.
If the cam timing in your engine was checked you will find it is out along way and correcting it would improve performance.

Due to the incorrect cam timing you may have lowered the combustion pressures enough to prevent detonation that may have been induced by the increased compression.

Fixing your cam timing may bring about detonation. It's the domino effect.

 

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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Wed Jul 27, 2011 5:44 pm 
Getting Side Ways
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I agree that the adjustment being maxed out one way doesn't seem right - if i was doing it - and keep in mind I have set up my own cam with dial indicator etc. several times - if it went all the way to the end like that I'd jump the chain a tooth and start again...

I never have had that happen tho - from std mark I've always had ample adjustment range.

 

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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Wed Jul 27, 2011 9:33 pm 
Oompa Loompa
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I thought much the same about jumping to the next tooth and winding it back again.
Trouble is I'm limited to time, tools and experience enough to do it myself confidently.
Turns out the head was 2mm under stock thickness @ 104mm from deck to gasket. I was told it had only had 30 thou taken off.
Mechanic was nice enough to tell me after he fitted it and wanted payment. Top bloke. Basically he has done a botch job and palmed it off. After taking it elsewhere I'm told it has bottom end issues. Highly likely the valve gear crashed before timing in the cam.
I'm now up for a full motor exchange after paying for all the work done already.
You thought Harleys sounded like a bucket of bolts, should hear my Falcon!
Need a low km block asap. Preferably AU with sump mod to fit E-series chassis. I've got another head ready to service and fit.
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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Wed Jul 27, 2011 10:14 pm 
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fitz wrote:
I thought much the same about jumping to the next tooth and winding it back again.
Trouble is I'm limited to time, tools and experience enough to do it myself confidently.
Turns out the head was 2mm under stock thickness @ 104mm from deck to gasket. I was told it had only had 30 thou taken off.
Mechanic was nice enough to tell me after he fitted it and wanted payment. Top bloke. Basically he has done a botch job and palmed it off. After taking it elsewhere I'm told it has bottom end issues. Highly likely the valve gear crashed before timing in the cam.
I'm now up for a full motor exchange after paying for all the work done already.
You thought Harleys sounded like a bucket of bolts, should hear my Falcon!
Need a low km block asap. Preferably AU with sump mod to fit E-series chassis. I've got another head ready to service and fit.



If there is anything wrong with the bottom end it was pre-existing, they just wear out over night.
Pistons are strong, IF the valves made contact you'd have valve issues not bottom end issues.

In your first post you said shaved to min thickness, Now you're saying you were told only 30thou???

If the cam is timed correctly, going a tooth and retiming it won't change anything, All it will do is "look" different on the gear. I suggest you actually check the cam timing before jumping to any conclusions.

 

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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Wed Jul 27, 2011 11:22 pm 
Oompa Loompa
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Tickford 6

Head was bought, being told 30 thou taken off. I thought it was that much in total. I stuffed up cause I didn't measure for myself. 30thou had been taken off in the last service. Lesson learnt.

Mechanic fitted head. Told me its 2mm thinner than previous head after realising there's a proplem.
I measure old head to cast markers on end of block, measuring 104mm, then started this thread thinking it was shaved to min. thickness.

There have been no assumptions here other than what I thought was minimum.
I'm going by what I'm told by qualified mechanics and some simple observations on my behalf.

It idles and starts okay but rattles bad and won't make power over 40km/h.

Now I'm faced with deciding on chasing the problem pouring more time and money into it with no guarantee of a good result. Or starting fresh with a new motor and exhausting what little funds I have l left after spending alot already.

Thanks for you input guys. Lets call it a wrap on this thread.
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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Thu Jul 28, 2011 10:04 am 
Getting Side Ways
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I wasn't suggesting the OP jump a tooth.

My point was that THE MECHANIC should have done so to indeed change the look of it - as in no longer have the adjustment slots maxed to achieve correct timing - presuming he WAS setting it to be correct - which is looking unlikely.

Actually checking the timing is of course the right thing to do - I'm inclined to think that's not right at all. As a quick, down and dirty initial check tho, I'd have been willing to move the adjustment slots back toward centre just to see if there was any obvious improvement or otherwise.

 

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 Post subject: Re: Cyl Head shaved to Min thickness, How many degrees to adj?
Posted: Thu Jul 28, 2011 10:43 am 
Getting Side Ways
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So basicly there was a whole bunch of mis information on every ones part. Lesson learned, life goes one.

I don't see the point in scrapping an engine just because you don't know whats wrong with it.
Call some of the reputatble performance work shops in you town and ask if they can check the cam timing for you.

 

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