Cam Followers

Simonpfhc · Post by **Simonpfhc** » Wed Jun 03, 2015 5:05 pm

Hi,

I'm in the middle of assembling the cylinder head of my 3.8. I was about to install the new followers and noticed that the new ones are significantly shallower than the old ones. I'm sure I read in one of the threads that the longer ones are preferred for quieter running?? The old followers seem to still be a good fit so could refit the old ones.

The part number of the new ones is C44010*. Any advice appreciated.

Cheers.

Simonpfhc · Post by **Simonpfhc** » Wed Jun 03, 2015 5:17 pm

Maybe I should have investigated before posting.....

I have just checked the SNG site and the correct followers are p/n C7213/1 which are showing as superceded with C44010.

The C7213/1 followers are listed as 'long skirt' but the 44010 ones are not! The correct ones are also a lot more expensive (almost ?100 a set) but that's what you pay for to get the correct ones I guess ;-(

I'm still tempted to use the old ones......

Cheers.

Post by **mgcjag** » Wed Jun 03, 2015 5:41 pm

Hi Simon..the 44010 do not show as e type parts...but for xj if they wear they go barrel shaped, thinner at the top and botton....measure them with a vernier gauge...Steve

MarekH · Post by **MarekH** » Wed Jun 03, 2015 5:49 pm

Go search the interweb for Dick Maury's article about cam buckets. That'll tell you all you need to know about the differences between the 1940s to the present day. From memory, it is something like "georgiajag.com" and Dick often posts on the Jag-Lovers.org site.

kind regards
Marek

Simonpfhc · Post by **Simonpfhc** » Wed Jun 10, 2015 7:26 am

Thanks Steve and Marek for your advice.

Indeed, after careful measurement, my old tappets are indeed very slightly barrelled. Consequently I have now ordered and received a new, correct set of tappets from SNG.

I have also read the excellent article that Marek suggested on the Georgiajag site:

http://georgiajag.com/Documents/Tappets/Tappets.html

However, it doesn't mention any issues using the shorter tappett??

Another slight issue is that the new tappets are extremely tight in the bores. I almost couln't get one out and had to wrap it with duck tape yo pull it out! They measure exactly correct in diameter and so I am planning on a quick polish to see if that helps with fitment.

I am sure that they should be able to slide and rotate pretty freely - the incorrect 'short skirt' tappets I have do! Anyone see any problems with me polishing the tappets?? Any surface coating to worry abput maybe??

Thanks..

Post by **mgcjag** » Wed Jun 10, 2015 8:05 am

Hi Simon a way to pop them in and out is to use a rubber suction cup on the top the type used on a stick to lap in valves....they should be a snug fit... have u put some oil on them...I wouldnt try to polish them....maybee swap them around and see what happens....my understanding is that if the shorter ones are slightly worn then the guide will also be slightly worn so using the longer ones makes them less likley to rock in the guide.....ideally the guides should be checked and replaced if there is any wear but if its only slight the longer ones can let u get away without fitteng new.....I had lots of tappet noise fitted the longer ones and now nice and quiet......Steve

abowie · Post by **abowie** » Wed Jun 10, 2015 8:56 am

Simonpfhc wrote: Another slight issue is that the new tappets are extremely tight in the bores.
Thanks..

When a head is rebuilt, it is usual to have the guides machined to fit new (oversized) cam followers. When we have this done the followers are fitted individually and marked. The clearances are usually about 0.5 thou. From experience I can tell you that these are scarily tight to fit the first time. I use a lot of oil and sweat a lot. Once correctly lubricated they will come out with a suction cup. When done like this though, the heads are virtually silent. We ran the engine on our current resto on Friday for the first time. There is NO tappet noise at all.

Just fitting new followers into worn guides without proper machining is going to be a bit hit and miss. If the guide isn't a good fit it will still be noisy, even if you set the shims perfectly. Polishing them is all very well but remember that the follower is designed to rotate in the guide and so needs to be perfectly round.

To be honest if it were me I'd have the guides all recut and use new long skirt, 20 thou oversized followers from SNGB or XKs. I recognise though that this costs a significant amount and requires you to remove the head.

If you can't do it this way, make sure that the followers rotate freely and move up and down easily with a suction cup. A loose follower will only make noise, but if one gets stuck and jams a valve into the top of a piston it'll make a mess.

Simonpfhc · Post by **Simonpfhc** » Wed Jun 10, 2015 5:17 pm

Well it's sods law that the first tappet I picked up to test is the only one out of the whole set that is a tight fit! All the test fit perfectly with each one a very snug fit but easily turned. I will give a very slight polish and it should be OK.

Anyway, I have now trial fitted the inlet camshaft and am going to need much thinner shims. I presume this is due to the fact that the valve seats have been machined when the new valve guides were fitted?? Anyway, I need shims as small as 64 thou going up to 72 thou. Do any of the regular suppliers provide shims in these sizes??

Cheers.

Post by **mgcjag** » Wed Jun 10, 2015 6:47 pm

Hi Simon.....have you trial fitted cam with new bearing shells.......also worth measuring the thickness of the new cam followers, from where the shims fit to where the lobe of the cam touch.....if they are all the same then fine but if they differ they will have to go back in the same position as where they were when you checked there gap...I numbered mine on top with an indelible pen.....

Simonpfhc · Post by **Simonpfhc** » Wed Jun 10, 2015 7:23 pm

Hi Steve, yes, trial fitted with new shells. I am also keeping the tappets in the order.

I have been reading up on shim sizes. Looks like it is not recommended to fit shims less than 85 thou due to several reasons - they may shatter, tappet could contact the spring retainer (noisy) or even dislodge the collets (disasterous!). One option is to use tappets from the X300 as they are identical in size but with a thinner surface-surface measurement. However, you then need to source much 'thicker' shims!

I've already bought 2 sets of tappets, am I going to need to buy a third???

Cheers.

abowie · Post by **abowie** » Wed Jun 10, 2015 10:13 pm

Simonpfhc wrote:Hi Steve, yes, trial fitted with new shells. I am also keeping the tappets in the order.

I have been reading up on shim sizes. Looks like it is not recommended to fit shims less than 85 thou due to several reasons - they may shatter, tappet could contact the spring retainer (noisy) or even dislodge the collets (disasterous!). One option is to use tappets from the X300 as they are identical in size but with a thinner surface-surface measurement. However, you then need to source much 'thicker' shims!

I've already bought 2 sets of tappets, am I going to need to buy a third???

Cheers.

I don't have any experience with the X300 follows. You can get custom made shims although as you say 60 thou is pretty thin. One solution is to get the valve stems ground down. This will work but there is the issue of losing the hardening on the tips of the stems.

Personally, again, I'd have the valve seats replaced and have them cut to the correct height. More expense I know, but then you only have to do the job once.

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