Barksavon
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| posted on 17/1/11 at 08:51 PM |
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Setting Up a Camshaft
Hi ive just fitted a Newman fast road cam and followers and set the valve clearances on a Pinto. Ive seen a video on you tube from vulcan engines
about 'Dialling In' a Pinto camshaft. The bloke gets TDC with a push rod in No 1 cylinder and a Dial Indicator, he then moves the gauge
onto the spring cap on no1 inlet valve and turns the engine to tdc and measures how much inlet valve lift there is at tdc (.215 inch) he then checks
exhaust valve lift at tdc (.096 inch) adds both figures together, divides total by 5 then multiplies that by 3 giving him 0.186 inch. He then turns
engine over until the inlet valve is open 0.186 inch slackens the vernier cam pulley and turns the crank until tdc and retightens the vernier
pulley.
Couple of questions, what is the value of doing this, whats all the business of multiplying by 5 and dividing by 3 about.
Also ive checked what inlet valve lift ive got on mine at tdc and there doesnt appear to be any, which appears to make sense because tdc is the top of
the compression stroke isnt it so if either inlet or exhausf valve is open the compression wouldnt be there.... am i understanding this correctly.
The you tube video is 'How To Set the cam timing on a Ford Pinto engine'
[Edited on 17/1/11 by Barksavon]
[Edited on 17/1/11 by Barksavon]
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rusty nuts
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| posted on 17/1/11 at 08:58 PM |
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Multiplying and dividing is probably down to the rocker ratio. The Burtons catalogue gives clear instruction on cam timing, probably worth a look?
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ianclark1275
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| posted on 17/1/11 at 09:24 PM |
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Some tips that i do:
i always check TDC before starting
get an old spark plug and weld a small bolt on the end and round off.
insert at BDC and "SLOWLY" turn engine over both ways.
it will "CLUNK" when the piston touches the bolt head before TDC
mark this on the crank pulley either side of TDC, the actual TDC will be exactly in between.
its usually pretty close.
as for timing it, i use crank degrees at full lift after TDC. (dial indicator on valve cap etc..)
dads locost 1.3 Crossflow is 111.5-------but this is on a keyway so just fitted as standard. (not sure what it should be actually? anyone any comments
appreciated)
if in doubt then more advance is better than more retarded.
one final rough "have i made a nutsack of this" check is at TDC after compression the valves should both be closed and just rocking (int
opening and ex closing depending on cam overlap) this is probably what the vid was about?
measure twice, cut once, scrap it, start again.
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mcerd1
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| posted on 17/1/11 at 09:26 PM |
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have a read at this one aswell: http://www.burtonpower.com/tuning-guides/tuning-guide-pages/camshaft-fitting-timing.html
basicaly as I understand it (feel free to correct me or explain it better) there is two ways of doing it with a vernier pulley and you could do either
with a pinto....
1 - you find TDC, then set the valves to the lift they should have at that point
(this means working out how much lift your ment to have at that point and how that relates to where you can measure it.....but its easier this way on
twin cam engines)
2 - you find TDC and zero your timing disc, then turn the engine over till you measure max lift on the valve (dial gauge on the spring retainer or
similar), at this point you read off the angle from your timming disc - if its not where its supposed to be at max. lift then you slacken off the
vernier pulley turn the bottom end to where it should be on the timming disc while holding the cam still - then just tighten it back up
(this ones means ther isn't much working out, but lots of fiddling to find the max. lift point)
-
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snapper
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| posted on 18/1/11 at 06:27 AM |
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Just a couple of points......
The camshaft rotates at half the speed of the crank so 1 TDC has all valves closed and the next does not
TDC has a dwell period as the piston completes the up stroke and before the down stroke.
To find true TDC find TDC with a dial gauge, mark on timing disc, Cary on rotating crank until dial gauge moves again, mark on timing disc, true TDC
is the middle of the 2 marks.
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I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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