Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
Hi Jamie
You have a degree plate at the other end of the engine, albeit uncalibrated. All is on the basis of a standard or simply ground camshaft.
By taking points further down the cam flank the effect of wear on the nose is avoided. Ideally should drive camshaft in the normal direction but backlash with gears seldom significant.
Many claim after market gears often different. What differences have been experienced? For Seven driving as intended does a slight advance assist?
Joined: Jan 2019 Posts: 1,481 Threads: 17
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Location: Bala North Wales
Car type: 1933 RP Standard Saloon
There is always room on the forum for technical stuff. Even if some of the information is not directly relevant to all of us, it makes for interesting reading, and you never know! (See Howard's post above.) Knowledge is never wasted.
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Fingers crossed, but I think that I have sorted this now. I need to do it again more carefully tomorrow to make certain.
Regards,
Jamie.
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Location: N W Kent
Excellent news, once you get into the groove it doesn't take too long to dial in a cam. Not quite so straightforward for you as a "first timer" -pun intended- when there were no timing marks to give you a clue as to where to start.
Joined: Aug 2017 Posts: 312 Threads: 9
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Location: TINOPAI NZ
HI STUART,
Your reply to the Question with a step by step guide and photos was great,
this is the type of response that enables members to understand why and how things a done and gives them the confidence to try and get it right
Some times on this Forum answers are only opinions (which every one is allowed )
but for people who do not have a back ground in Engineering can be confusing
When working on small HP engines especially, getting the small Detail right is very important.
So just take your time no need to Rush.
Colin
NZ
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26-05-2021, 01:50 PM
(This post was last modified: 26-05-2021, 02:06 PM by Jamie.)
A quick lunchtime update. As far as I can measure at the moment, I can either get the inlet valve on piston 1 to open at about 5 degrees before top dead centre or about 10 degrees after TDC. I assume a slight advance is preferable if this is how the pattern part has been made?
Regards,
Jamie
Joined: Aug 2017 Posts: 741 Threads: 8
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Location: N W Kent
Hi Jamie,
What are the ATDC maximum lift figures in these two cases? the reason people don't usually time camshafts off opening and closing figures is that the maximum opening figure is easier to get accurate/consistent results from.
Running the cam advanced will lose top end power without picking up anything you'd notice @ low RPM. Running the cam slightly retarded -not as much as 10 degrees, gives good top end power, but the low down power loss is likely to be noticeable in a heavier car. As the old engine builder saying goes, 'with cam timing as with a pub, late closing is always better than early opening'
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26-05-2021, 03:08 PM
(This post was last modified: 26-05-2021, 05:50 PM by Jamie.)
Hello, Stuart.
I have now measured the angle for maximum lift on inlet valve 1. My degree wheel is quite small with tiny markings, making it difficult to be precise. However, as best as I can judge the valve is open fully at 108 degrees. Allowing for the inaccuracies of my equipment, my use of the equipment and the settings of the the tappet clearances, I am happy with this. Thank you for all of your help.
Regards,
Jamie.
