Valve Adjustment
Orig. Posting Date | User Name | Edit Date |
Jan 8, 2017 03:01PM | Rosebud | Edited: Jan 8, 2017 03:32PM |
Jan 8, 2017 01:37PM | 1963SV2 | |
Jan 8, 2017 10:48AM | Dan Moffet | |
Jan 8, 2017 09:54AM | h_lankford | |
Jan 8, 2017 08:07AM | tsumini | |
Jan 8, 2017 07:00AM | Alex | |
Jan 8, 2017 06:44AM | tsumini | |
Jan 8, 2017 05:55AM | dklawson | |
Jan 8, 2017 02:07AM | Alex | |
Jan 8, 2017 12:14AM | 1963SV2 | |
Jan 7, 2017 10:10PM | Rosebud | Edited: Jan 7, 2017 11:03PM |
Jan 7, 2017 09:48PM | tsumini | |
Jan 7, 2017 09:11PM | Rosebud | Edited: Jan 7, 2017 10:59PM |
Jan 7, 2017 08:34PM | tsumini | Edited: Jan 7, 2017 09:15PM |
Jan 7, 2017 08:18PM | Rosebud |
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Best accuracy for what??? You're only interested that the valve being measured is closed... and this is indicated by the corresponding valve being "more or less" open. How open, as long as its "mostly" is totally irrelevant.... Rosebud is only asking about "how open" due to misunderstanding about how the system works..
".....For anything but a full-race engine where you are setting the tappet gaps individually to chase every tenth of a horsepower, this is more than adequate...."
And it seems its important to point out that while Alex talks about individual gaps being relevant on a race engine, he's talking about the size of the gap......not how its measured...
Cheers, Ian
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I tend to put the car in gear and roll it forward from the passenger side by rotating the front wheel while watching across the valves for movement.
By 'proper sequence' I observe which valve opens next in sequence and use the rule of 9 to determine which valve to adjust. (uses a lot less driveway!)
.
"Hang on a minute lads....I've got a great idea."
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I tend to put the car in gear and roll it forward from the passenger side by rotating the front wheel while watching across the valves for movement.
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For anything but a full-race engine where you are setting the tappet gaps individually to chase every tenth of a horsepower, this is more than adequate.
Think about it, even a 320° full race cam has the follower sat on the base circle for over half the time...
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It's actually a very easy and very effective way of performing the task. The rule of 9 isn't complicated.
When a valve is fully closed, the cam follower is on the base circle which generates the maximum free play in the valve train - the tappet gap. A few degrees either side of this isn't going to make any difference as the cam follower is on the base circle for a long time.
To establish when the follower is on the base circle, you observe the other valves to determine when theey are fully open - a much easier thing to do.
With the engine stone cold, wind it round until one of the valves is fully open. Count which valve it is (you ought to count right to left, but it doesn't really matter as long as you stick to the same side) and subtract that from nine. If No 6 valve is down (inlet on 3) then you adjust valve number 3 (inlet on No2), if 4 is down you adjust 5, and so on.
It isn't difficult.
I tend to put the car in gear and roll it forward from the passenger side by rotating the front wheel while watching across the valves for movement. With practice, it can be done start to finish in 10-15 minutes.
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While the valve is only fully open for a relatively short time it is fully closed for at least 1/2 the cam rotation (basic geometry will demonstrate this). And you're setting the gap with the valve closed...
So don't sweat it. If 1 "looks like" its at full lift then 8 is measurable....
Cheers, Ian
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I just do it the practical way which is good for all engines. BMC recipe is specific to those 4 cyl engines with that valve arrangement.
Quote:
I would guess that it is a progression such that turning the engine is minimized. i.e. when #1 valve is set then a slight engine rotation will bring up #3 etc.
Actually, Haynes' method requires a lot of engine cranking to get through all 8 valves. So, I think there's something else at work here.
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I just do it the practical way which is good for all engines. BMC recipe is specific to those 4 cyl engines with that valve arrangement. I would guess that it is a progression such that turning the engine is minimized. i.e. when #1 valve is set then a slight engine rotation will bring up #3 etc etc. The best way i know to show valve is fully open is to put a dial indicator on the rocker arm and set it at max indication. If i were following that i would still just look at the piston and find where it changes direction. Some put a screwdriver on the piston for a better visual of piston changing direction. A few mm either side should not affect gap setting.
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