Cam timing 4.2 engine

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phoenix
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#1 Cam timing 4.2 engine

Post by phoenix » Tue Nov 22, 2022 11:51 am

Hi.can the two vernier type adjusters on the camshaft sprocket be adjusted in situ .
.e. just by removing the two large circlips .
S1 4.2 RHD Bryan

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mgcjag
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#2 Re: Cam timing 4.2 engine

Post by mgcjag » Tue Nov 22, 2022 3:33 pm

Hi...not sure what your trying to do here......typically you set the camshafts to tdc...put on the chain and sprockets......then fit the serated plate, bolts and clip....so the serated plates are bolted to the camshafts.....fully detailed in the service manual....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#3 Re: Cam timing 4.2 engine

Post by phoenix » Tue Nov 22, 2022 5:38 pm

What we did was remove the head after putting safety nuts on the camshaft sprockets .When we reassembled the cams were not in the correct position assuming the chain did not move ? . When crank moved about 7mm on pointer the cams are oth lined up. Obviously chain must have moved a cog but I didn't think it would.
S1 4.2 RHD Bryan

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#4 Re: Cam timing 4.2 engine

Post by mgcjag » Tue Nov 22, 2022 6:05 pm

I wouldnt rely on the pointer to set crank TDC unless you know its set correct.....but beware turning crank if cams arnt set correctly....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#5 Re: Cam timing 4.2 engine

Post by abowie » Tue Nov 22, 2022 9:49 pm

To answer your question directly, no.

To move the camshaft sprocket you need to remove the two bolts.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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Allrand
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#6 Re: Cam timing 4.2 engine

Post by Allrand » Wed Nov 23, 2022 5:17 am

phoenix wrote:
Tue Nov 22, 2022 11:51 am
Hi.can the two vernier type adjusters on the camshaft sprocket be adjusted in situ .
.e. just by removing the two large circlips .
Yes you can. With the crank accurately on tdc, remove the sprockets, set the cams in the correct position using the timing guage. Replace the sprockets on the cams without bolting them & tighten the upper chain. If the bolt holes don't line up, remove the circlips, pull the serrated plates out & reposition them where the holes line up exactly, refit the circlips & bolt up again.
Randall Botha
'64 3.8 fhc & '51 Mk 7

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#7 Re: Cam timing 4.2 engine

Post by mgcjag » Wed Nov 23, 2022 8:44 am

Hi Randall....your explenation is ok but not what the OP asked......he asked if it could be done just by removeing the large spring clips.....no....as they are bolted in place so the bolts need to come out......Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#8 Re: Cam timing 4.2 engine

Post by Allrand » Wed Nov 23, 2022 11:11 am

Yes you are correct Steve, but reading into his question it seems he wants to change the position of the camshafts. To do that he'll have to remove the bolts and sprockets.
Randall Botha
'64 3.8 fhc & '51 Mk 7

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#9 Re: Cam timing 4.2 engine

Post by phoenix » Wed Nov 23, 2022 11:40 am

Thanks guys. I will remove bolts on upper gear wheels put crank on TDC then remove large circlip and move the cams into position. Is that correct ?
The only thing I can think of that happened when we removed the head before was that the upper chain moved a cog . I did not think it could though and yes we did fit nuts to the upper gear wheels .
S1 4.2 RHD Bryan

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#10 Re: Cam timing 4.2 engine

Post by Allrand » Wed Nov 23, 2022 6:07 pm

Hi Bryan, remove the sprockets completely from the cams, reset the cams then press the sprockets back onto the cams, then remove the circlip & serrated wheel, reposition the serrated wheel in correct postion, replace the circlip and bolts.
Randall Botha
'64 3.8 fhc & '51 Mk 7

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#11 Re: Cam timing 4.2 engine

Post by phoenix » Wed Nov 23, 2022 11:21 pm

Big thanks guys.
S1 4.2 RHD Bryan

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