trying to find what the dimension specs of XK camshafts…ie a new cam spec: mainly for the 3/8, C5717 and C5718 but would be nice to have for the 5/16 as well so all info in one place. For inlet, and exhaust if different between them: The heel to lobe tip, the round side to side diam ( off the lobe); and the bearing contact diameter which should be same for all. I have seen a few numbers in posts…but none that seem definitive/verified. This info would be useful in evaluating a used cam. Thanks Nick
Lift and duration aren’t really the whole story. You really need to know how it ramps up. I have no idea how to check this other than making a test piece along the lines of a radius gauge that you would hold up to both sides of the ramp at the same time.
In considering the heel to lobe tip remember to consider the running clearance specified. I think early cams were set to .006/.008 and later to .004/.006. Some said that was only for noise reduction.
ok info Art…and thanks, but not what I am asking…I know the duration specs, ramp up (they are extensively discussed in this forums archives) . so simply just looking for the dimension of a new cam on the bench…what you get when you put a caliper, heel to lobe tip. and 90 deg to that…just the round without lobe…and also what you get with a caliper on the part that is within the cam bearing/cap assy. But not on a used cam…the spec for a new one…so it can be compared to possible wear on a used one. I have some numbers but since unverified I do not want to post those.
Nothing to do with clearance, although you are correct for road cars. I use the 006, 008 on my 120, which happens to have non-oriinal to an SE, replacement 5/16 cams. I am looking to obtain a set of 3/8…don’t want “flat” used lobes.
Nick
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with a little lookin up…I could say exactly what clearances, when, what service bulletin applies, and to what cams, as well as the later E Type cams. It is all in the forum archives and TSBs etc. Don 't have to worry about “recall” or “somethin like”…What can one do with that? (sorry…pet peeve…if not sure, don’t know, can’t remember…why post it if it may be incorrect and will live on in the forum forever?
What I cannot find is definitive info as to the new cam specs for heel to lobe dimension, and the cam diameter at the bearing locations, for the cams…3/8, and 5/16, intake/exhaust. There are some posts of…well…I measured mine and…or add 3/8 to 3.1416 times X…
Nick
The last new (not reground) pair of Jaguar camshafts I bought came from Kent Cams in the UK. I would think they could tell you what the dimensions of the standard parts were.
http://www.kentcams.com/product-details/220/Camshaft/Camshaft/JAG4-Race/
Or ask Bill Terry. I have found him to be incredibly warm and helpful.
https://www.ttraceengines.com/about.html
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If you don’t want flat lobes hold a .100 radius gauge over the tip of the cam for the 3/8 or .200 for the 5/16. I’m holding to the .006/.008 spec for the 120 as per B63 of 120/7 book. 014 came a few decades later for a very different application not related to 120s. I’ll try to photograph a radius gauge held in place if necessary.
As to valve/cam/cam follower clearances there are quite a few Factory Technical Service Bulletins that state clearances as they changed back and forth over time. TSBs 65, 95, 95A, 109, 132, 142, 146…and even more that indirectly affect valve train set up, as guides, stems, valve head thickness changed that changed how the valve sits/seats. The starting point of stem to back of cam dimension plus the spec clearance is stated in the manual. How you achieve that with later parts is only in the TSBs. The short way of stating all this is the clearance for street use , 8-1 comp, started out as Int .006, and Ex .008, then changed as a factory spec to .004/.006. (with 006 or 008 intake and .010 exh for C Type and competition use only.), (and, but not per factory the 006, 008 can still be used), BUT NOTE BENE: So many specs/procedures in the Factory Service Manual are updated in the TSBs that almost nothing in the Manual should be used without a check for a relevant TSB or superceded part # and its implications, many of which are critical. If you have a later part (and how would you know that) that has to be matched with others (and how would you know that) , or installed with other mods, and you do not know it, be sure to have a hi limit on your credit card. Examples: A 3/8 cam can be installed in later cyl heads, but not in earlier ones without modification work. And, SB149 inlet valve, and SB185: valve guide: the inlet valve C8248 has a thicker head and requires a seat that will accommodate it,. The changes in distributors, and gap from .012, to .014-.016, and timing…all in the TSBs. IMHO no one should do much of anything without a set of TSBs. but ahhh I still cannot find a spec for dimensions of a new cam.
Nick
but ahhh I still cannot find a spec for heel to lobe, and bearing surface diameter dimensions of a new 3/8 cam.
Odd, given the passels of info this gang has…?
According to the Service Manual page B33…
“It is unlikely, except after very high mileages, to find wear in the camshafts and camshaft bearings. The camshaft bearings are of the precision shell type and under no circumstances should these be hand scraped or the bearing caps filed. Undersize bearings are not supplied.”
Journal diameter 1.0" -.001" -.0005" (25.4mm -.025mm -.013mm)
On page B47…
“…noting that the caps and cylinder head are marked with corresponding numbers.”
“If the same bearing shells are to be replaced, they should be fitted to their respective housings.”
That means put each one back where it came from.
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thanks…ood on the journal diam. I did replace cam bearings on mine…as I had a set of Vandevell VP907, C2288 on the shelf., at first baffled how to prise them out…but then once known it was easy to pop em out. I noticed that another set…not Vandervell did not fit quite as well . much care must be taken on the install. It is easy to damage the shell…and the sets come with no “extra” shell. Don’t ask how I know that. Yes…nice marks on the caps, corresponding to those on the cyl head inner border…for placement and orientation to be exact same on replacement. I noted that bearing cap torque is very slight 175 INCH lbs, and must be taken tight a little at a time across all. (same precaution for loosening) I have seen also that valve tappets and tappet guides were graded…A B C with this also on the head so as to fit letter to letter, but SB158 11/54 says this discontinued…
Now…to find cam heel to lobe as per new…nice to know for both 5/16 and 3/8…as that is where wear may be encountered on a used cam. Easy to measure a used one.but to compare to what new spec.
Nick
Maybe someone like Iskenderian Cams might have that info.
There won’t be any wear on the sides of the lobes, so the difference between the peak to foot and the side to side should be .3125" or .375"
Apparently the factory thought they would never wear so nobody would ever want that information.
OK Rob, …I understand that…so maybe that is the way to determine lobe condition. if it.is it still .3125. Wonder tho…is there a " base" below the lobe before the lift of 3/8 comes into play…does that make sense? So maybe now…for anyone with an exposed cam.,.engine or shelf…to obtain some heel to lobe measurements on used ones,see the range…with a precise micrometer., would intake and exh be the same? I have one set of int/exh 5/16 that I can access. Be interesting to see some measurements,
any takers…for either lift cams,.,?
Nick
Here are measurements from a pair of 140 cams, mileage and history unknown. Using a Starrett 1"-2" micrometer, calibrated on a 1.000" diameter Starrett gauge block, measurements of cam lobes peak-to-foot and side-to-side.
C.5717 Intake, front to rear
1.424" - 1.040" = .384"
1.424" - 1.040" = .384"
1.424" - 1.040" = .384"
1.424" - 1.040" = .384"
1.424" - 1.040" = .384"
1.424" - 1.040" = .384"
C.5718 Exhaust, front to rear
1.425" - 1.041" = .384"
1.425" - 1.041" = .384"
1.425" - 1.041" = .384"
1.425" - 1.041" = .384"
1.425" - 1.041" = .384"
1.425" - 1.041" = .384"
So the difference is not really .375" because I forgot to take into account tappet clearance. Plus there will be some tolerance allowance on the final dimensions, which the factory does not disclose to us.
So when they say cam lift of 3/8" they really mean within +/- a few thousandths.
At the bearing journals they were all .999" and I did not detect any ovality.
interesting, thanks…may have “typo”…? Special Equip (SE) C5717 intake, C5718 exh, referred to by factory as: 3/8th lift, .375, 3/8 = 9.5mm,
will measure my 5/16 soon and post.
it’d be nice to have a few others measure…for verifications “sample”,.
Nick
Yes, under a magnifying glass I can see the 8 on the exhaust cam was stamped twice and poorly both times, making it look like a 6.
Ha! Famous last words.
Here are measurements from a pair I just acquired in a stash of Mark V parts, with an anomaly.
C2444 Inlet cam stamped with 3/32" high numbers
1.360" - 1.044" = .316"
1.360" - 1.045" = .315"
1.360" - 1.043" = .317"
1.360" - 1.044" = .316"
1.360" - 1.043" = .317"
1.360" - 1.044" = .316"
Exhaust cam stamped with C2237 AND C2444 in 1/4" high numbers
1.360" - 1.042" = .318"
1.313" - 0.972" = .341"
1.359" - 1.042" = .317"
1.356" - 1.032" = .324"
1.359" - 1.041" = .318"
1.328" - 0.985" = .343"
I had to hold them both in position as per Plate B20 in the manual to be sure I was identifying them correctly as inlet and exhaust.
Make of it what you will…