| Author | Message | |||||
     Jeff Martin Experienced User Username: jeff_r_1 Post Number: 198 Registered: 07-2018 |
Car number B297LH, 1951 Standard Body Mk VI Camshaft part number on my car is RE 19517, other numbers CC39 and C835. Numbers in parts manual, High Lift RE 5157, and Low Lift RE 6885 Mine are none of these and in the manual it says that the high lift shaft should be replaced by the low shaft, I find this statement confusing. Why would you want to replace the high lift with the low lift, would that not reduce the air into the engine and make it run poor ? But I guess it's the ramps on the shaft that make a difference too. There was also an article somewhere or info in one of the manuals that talked about the different camshafts and there were some different ones there to, and I can't find that at all, if someone here could point where this is please. EDIT: Found the answer, the RE 19517 is the same as the RE 6885 low lift, the difference between the two is that the cam shaft gear is retained differently, 8 set screws are used instead of four studs. This was taken from this service bulletin, section E, under Valve Timing. http://rrtechnical.info/mkvi/r/bull/4.pdf . | |||||
| ChristopherCarnley Unregistered guest Posted From: 5.62.43.200 |
Camshaft RE5157 the "high lift", was replaced from chassis B2DA by RE6885 the"long duration" type, and the cam wheel cover stamped "C". The high lift had .060" removed from its "toe", at a time when the very high rates of wear of both cams and tappets was causing an increase in engine overhauls, the 50 degree cut away of the lobes to aid rotation was a major mistake . The flat tappet valve gear was always flawed, and multiple attempts using all sorts of pre-start up lubricants to minimise "cold welding" were of little avail. The S1 cam shaft is very similar but with full width cam lobes, and rethreaded BSF for later MK VI/R Type overhaul replacements, and numbered RE23639 (Message approved by david_gore) | |||||
| Jeff Martin Experienced User Username: jeff_r_1 Post Number: 199 Registered: 07-2018 |
That's interesting, maybe that's why the idle on the car is so finicky to achieve, the lobes are worn and the cam is not allowing enough fuel in or all of the exhaust out. Given that though, the compression is all very even, but with that said my brother in law had this Chev Beaumont with very worn cam lobes. it had good fairly even compression, but the engine was being choked off because all of the exhaust could not escape and it would not run well at all, even more so under acceleration. It had hydraulic lifters of course so I would imagine that made things even worse. However when I did my engine, I'm sure the cam was measured and was with in spec, and given what the cam looks like, it doesn't look worn, or maybe it is, the first photo certainly has some weird wear marks on it. The lifters are certainly not scuffed. With that said, with out the 50 degree cut away, how does the new cam from the S1 rotate the lifters ?   | |||||
| Jeff Martin Experienced User Username: jeff_r_1 Post Number: 200 Registered: 07-2018 |
Introcar has RE23639 on for £600.00, not too bad and the cam for the S1/Cloud 1 for only £200.00. The part number for that is UE3736. Will the cam from the 4.9 litre engine fit in the 4.25 engine ? I know the block is longer in the 4.9, but I have to ask. | |||||
| ChristopherCarnley Unregistered guest Posted From: 159.242.227.16 |
Jeff, The UE part at £200.00 is a mistake, that is the surcharge on a reconditioned one. C. (Message approved by david_gore) | |||||
| David Gore Moderator Username: david_gore Post Number: 3896 Registered: 04-2003 |
Jeff, Christopher has forwarded the following image and comment for posting on his behalf:  This relates to Jeff's query and shows camshaft RE23639 removed from an R Type engine last July 2020, during conversion to 3 3/4" pistons and an S1 head. UE3736 is the S1 camshaft but the set screw holes are tapped 1/4" UNF whilst the same part RE23639 is tapped 1/4"BSF specially for use in the MKVI/R Type engine when all the earlier ones had been used up. The main physical difference apart from the cut off is that the exhaust cam has a higher lift, and gives better breathing. I suggest that he checks the heel to toe measurement of his inlet camshaft lobes, 1.517" when new. I have had camshafts of between .065" and .083" wear on the same part, and the car has run OK, before dismantling.  | |||||
| Jeff Martin Frequent User Username: jeff_r_1 Post Number: 201 Registered: 07-2018 |
Thanks Chris and David, this information is priceless. Yes, that makes sense, I thought £200.00 was too good to be true. | |||||
| Jeff Martin Frequent User Username: jeff_r_1 Post Number: 202 Registered: 07-2018 |
Chris, what do you think about the Flying Spares cam where they have improved the inlet cam profile, what have they done to that cam when compared to RE23639, if anything ? This is for an S1, but I don't mind using 1/4 NF bolts. "-The inlet profile is improved from the original factory profile" https://www.flyingspares.com/camshaft-ue3736sxr.html | |||||
| Jeff Martin Frequent User Username: jeff_r_1 Post Number: 592 Registered: 07-2018 |
Looking at the different camshafts and what's available, and I noticed this odd thing from post 6 here on this thread.  If you look at what's in the red box, you will see that the lobes' cut off's are facing each other; the offset is different too, which would allow the tip of the lobe to come in contact with opposite side of the lifter. This in turn would also rotate the lifter in the other direction when compared to the other lifters. This assumes that all of the other cut-off's are facing in the same direction, with the one exception talked about here.  We have RE19517 with the same two lobes now with the cut off's both facing in the same direction and a larger spacing in-between the lobes. All the cut-off's on this cam are all facing forward and all the spacing is the same _ all lifters rotate in the same direction. Why did RR want the one lifter (I think I3) rotating in the opposite direction from the others ?  Here's a comparison of RE19517, and UE3736 from Flying Spares showing the offset of I3 and it was assumed by FS that the block was changed to accommodate the new position of I3, but this assumption appears to be incorrect. (note that cam UE3736 is from an S1 and is of the straight lobe type) This is based upon the comparison of 3 blocks from a 4.25, 4.5 and a 4.9 litre, where the castings in all 3 blocks are the same when it comes to the position of the lifters. The lifter positions in all three blocks are spaced at 1.75 inches for each cylinder, or as close to that to make my point. The different offset of I3 is rotating the lifter in the opposite direction of the others on UE3736. . | |||||
| NormanGeeson Unregistered guest Posted From: 81.98.117.162 |
Jeff First your assumption that the lifters will rotate in a certain direction from the position of the lifter cut off, is not correct. There is quite a lot of R-R archive material on that very subject.(lifter rotation) Lifters can rotate in any direction even when the centres are off set. Don't forget the lifter can be under the influence of an angled push rod for instance. The lifter centres on straight lobe engines (S1 engines) are off set except for number three inlet which was positioned different to the others to make it easier to hob that nearby ignition / oil pump gear. (Message approved by david_gore) | |||||
| Jeff Martin Frequent User Username: jeff_r_1 Post Number: 593 Registered: 07-2018 |
I'm sorry Norman, I need to understand what you mean by "hob" in your statement ? "easier to hob that nearby ignition / oil pump gear" But the actual lifter position hasn't changed on an S1 engine on I3, (they're grouped the same too) it is the same space as a 4.5 litre block sitting in my basement and what Jason measured on his S1. I asked Jason to measure them for me, and he said "Bit hard to take a pic and hold the verniers, but my spacing is 1.75 also. Checked multiple times. Did not my lifter sockets look a bit different though". I found that all the spacing on intake and exhaust are all at 1.75 inches on my 4.25 and 4.5 engines, the lifters are the same too on the intake, all have the same part number across the board from the MK VI to the S1's. The offset of the lobe is simply moved towards the front of the engine on I3 _ I guess to make room for the ignition / oil pump "gear" as you said.  However, the result of the offset of I3 being moved, will result in the lifter turning in the opposite direction from all the other lifters; it's the only one that has been changed, hence the spacing is closer to E3 (about 1/2 inch) as apposed to all the other lobes spaced at 1 inch (approximately).. I don't agree with your statement here: "First your assumption that the lifters will rotate in a certain direction from the position of the lifter cut off, is not correct". Lifters will turn in a specific direction depending upon the position of the lobes, their design and the convex shape of the bottom of the lifter. I think you answered my question though, it's not about changing the rotation of the lifter, it was about the location of I3 to make clearance in the 4.9 block. All of this inquiring was to make sure that the straight lobe cam will function in my 4.25 litre block, and I believe it will now. Flying Spares brought to my attention of I3 being closer together to E3 and the block was changed accommodate this, but the block is over-all the same when it comes to the lifter casting holes. The only difference in cam lobe positions in the drawings from Flying Spares is I3. In the end it doesn't really matter which way the lifter turns, the lobe being moved on I3 will be on the other side of the offset of lifter I3, that's all. I thought there may have been some majour casting change, but according to Jason's S1, there hasn't been when it comes to fitting a different cam. . | |||||
| ChristopherCarnley Unregistered guest Posted From: 165.120.5.199 |
Jeff, The oil pump gear was created by the use of a cutter called a "hob". These days, gears are created by planing, shaving and hobbing. The camshaft shown above, kindly inserted by David, from a picture that I sent is actually an S1 type UE3736, with the cam gear threads machined 1/4" BSF, and renumbered RE23639, for later MKVI / R Type rebuilds. The dark marks in the red boxes, are not cut offs, but are minor grinding marks to imitate the previous 50 degree cuts. The cut offs/ shadow marks are to rotate the tappets, but only to even out or minimise wear. The Flying Spares, Introcar camshafts are remetalled and profile ground to reclaim a worn S1 camshaft. I have 2 off new RE23639 camshafts, if you are interested. (Message approved by david_gore) | |||||
| Jeff Martin Frequent User Username: jeff_r_1 Post Number: 596 Registered: 07-2018 |
Thanks for clearing that up about those shadows on the lobes, also what the meaning of "Hob" is. Flying Spares also says "The inlet profile is improved from the original factory profile" What did they do, change the ramp so it opens sooner and/or stays open longer then the original profile ? | |||||
| David Gore Moderator Username: david_gore Post Number: 4250 Registered: 04-2003 |
Norman Geeson has requested I post the following information here on his behalf:
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CAM DETAILS
CAM SHAFT SECOND