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OKR
Jul 1, 2022 10:24:59 GMT
Post by dave1800 on Jul 1, 2022 10:24:59 GMT
That's odd and very frustrating. If I recall correctly, Tommy in Norway changed the camshaft on a Mk11 engine in situ by cutting a hole in the inner wing and taking it out through the wheel arch. David You do and I did but the oil pump shaft is still there and in the way. I think the later type should move up out of the way. Not happening! Given in and started pulling the gearbox off. Almost there just got to get the engine crane on it! Waste of an afternoon plus I will have to clean it and make new gaskets. Shall find out why it won't come out tomorrow hopefully. Nick I thought you had to pull the distributor drive shaft out? C.
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OKR
Jul 2, 2022 8:30:11 GMT
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Post by 1800heap on Jul 2, 2022 8:30:11 GMT
Ok the cam is out and did have a couple of lobes worn out. Didn't pull the engine apart for nothing at least. One is quite worn but I am surprised that the lobes are still polished, so no pitting or damage. They are just really stumpy!
I have most of the gear for assembly. Made all the gaskets today. I have the good cam back in now and a new oil pump fitted. No way this cam will come out with the oil pump fitted, that I could see anyway. Being a mk3 18H as far as I know it should have come out. Lucky me anyway! I would like to know about cams that come out and how. Is the WM lying to me?
I have decided to put all the valve gear back first to check out the cam. Do the gearbox when I am happy it is ok. I am in the dark as to the cam type at present. It is a crab cam I think, but has been reground and came out of a box that said MGB. MGB grind?
It seems to have a bit more duration than the old cam but very hard to ID on the bench. Hopefully I will be able to determine some numbers tomorrow. Also seems to have a touch more lift.
Nick
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OKR
Jul 2, 2022 12:31:23 GMT
Post by Penguin45 on Jul 2, 2022 12:31:23 GMT
The BMC cam should have a part number stamped onto the shaft itself. Aftermarket ones seem to have code letters stamped onto the ends as far as I can tell.
C.
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OKR
Jul 2, 2022 23:04:56 GMT
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Post by 1800heap on Jul 2, 2022 23:04:56 GMT
Ok I just looked at a Mk2 cam and yes stamped on the shaft as you say. No markings that I can see on the one I have put in. It has the fuel pump type end otherwise no stamps I could see. It has a different lobe profile to the standard. I will try to get some open close numbers today which will hopefully help. Nick The BMC cam should have a part number stamped onto the shaft itself. Aftermarket ones seem to have code letters stamped onto the ends as far as I can tell. C.
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OKR
Jul 3, 2022 0:55:02 GMT
Post by dave1800 on Jul 3, 2022 0:55:02 GMT
The manual isn't lying. I changed camshafts in both a Mk1 and Mk111 engine for Piper fast road versions with the engines out of the car but definitely still bolted to the gearbox. I can't remember there being any problems, so I am baffled. It will be interesting to know what caused the issue you have encountered. I assume you have a new set of tappets. David I have the good cam back in now and a new oil pump fitted. No way this cam will come out with the oil pump fitted, that I could see anyway. Being a mk3 18H as far as I know it should have come out. Lucky me anyway! I would like to know about cams that come out and how. Is the WM lying to me? Nick
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OKR
Jul 3, 2022 6:05:59 GMT
Post by andrewa on Jul 3, 2022 6:05:59 GMT
I used the Tommy method for changing the cam with the engine in situ without any problems. I also had the lobes worn at one end of cam issue (it was a new Piper cam) which I put down to not following the break in procedure they suggest - run engine at 2500 when first fired up with new cam for 20 mins, don't let it idle etc.
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OKR
Jul 3, 2022 9:30:04 GMT
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Post by 1800heap on Jul 3, 2022 9:30:04 GMT
I am dirty about it Andrew! I tried a few things, turn jiggle etc etc I even moved the crank. I gave up because I didn't want to damage the bearings. I suspect I have an old oil pump gear or something odd like that. I am going to try to pull the cam from one of the old engines I have just to see. If it comes out I might try substituting the gear before I put the gearbox back. David I am not using new followers. The cam is a good used unit anyway so I have gone through all the used followers I had and got 8 nice ones. I then resurfaced them with 600 grit on a piece of glass. Then finished with 1200. There is a method to the madness. The followers I chose from are well used sets but the exceptional ones I picked had barely any wear. My theory is that they must be good metal and should give me a good hard wearing set. Nick
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OKR
Jul 3, 2022 12:11:45 GMT
Post by andrewa on Jul 3, 2022 12:11:45 GMT
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OKR
Jul 4, 2022 7:42:09 GMT
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Post by 1800heap on Jul 4, 2022 7:42:09 GMT
Thanks Andrew Just proved it to myself today and pulled the cam from the Oz crab no problem. I will now pull the box off that engine to see if the oil pump gear is different! I would like to substitute the gear if that is all it is before the box goes back on OKR. Nick
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OKR
Jul 4, 2022 16:51:39 GMT
Post by andrewa on Jul 4, 2022 16:51:39 GMT
Needless to say I went with the double lapped hi flow oil pump on mine!
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OKR
Jul 4, 2022 21:38:09 GMT
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Post by 1800heap on Jul 4, 2022 21:38:09 GMT
Ok there is no difference in the oil pump gear. I think the Oz engine has a recess in the cast opposite the oil pump gear. I can't look at OKR'S engine again as I put the new cam in already. I did notice something interesting though. The engine in OKR was cast in 1968! The Oz engine was 1970. Now why was there a 1968 cast engine in a 1973 MK3 ? This car has been with us since I was 14 ish. Doing the maths it was about 10 when we got it and had the original engine I think.
It had low oil pressure, which is why we got it cheap and my recollection is that I replaced the crank with parts from my dads car ALF which was an H reg 1969 I think. Perhaps my memory is not correct and we used the engine. Only trouble with that is dad still had ALF'S block with engine number to match. I am sure I would have remembered swapping the engine numbers!
Did the engine get swapped in the 1st 10 years. Was leyland using up old stock?
Who knows. Anyway my intention is to leave the engine more or less standard Andrew and the OZ car is getting a tweeked engine. On this I will use the crossflow head and fuel injection. If I ever get time! I will just have to remember not to bother trying to swap the cam on OKR!
Nick
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OKR
Jul 4, 2022 23:29:50 GMT
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Post by 1800heap on Jul 4, 2022 23:29:50 GMT
Ok the numbers for the cam regrind now fitted to OKR
Inlet Valve opens - 22°BTBC Inlet Valve close - 71°ABDC
Exhaust Valve opens - 54°BBDC Exhaust Valve close - 27°ATDC
Inlet Valve peak at - 76°BBDC Exhaust valve peak at 78°ABDC Inlet Duration - 273° Exhaust Duration - 261° Lift - 0.354"
So what do I have and is it going to be ok as a road use cam as the numbers are bigger than an S cam?
Nick
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OKR
Jul 5, 2022 1:16:36 GMT
Post by dave1800 on Jul 5, 2022 1:16:36 GMT
Hi Nick I'm sure you appreciate that trying to compare cam profiles from one manufacturer to the next is a minefield. Did you use the crab tappet clearance to measure the inlet and exhaust openings or what seems to be a more common 0.050". For what it is worth here is a list of common MGB cam profiles. It would appear your cam grind falls into the mild road category with possibly some fall off in torque at the bottom end compared with the standard crab cam. You know I can't not mention ignition timing change needed with a non standard cam. I assume you will be using the twin carbs so the maximum advance of the standard crab distributor may well be quite a few degrees too many and that is definitely not good! It may also need a little more advance at idle to get it running smoothly but my experience with a fast road Piper cam using a single carb didn't require any more advance at the lower end. Hope this helps David
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OKR
Jul 5, 2022 2:48:05 GMT
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Post by 1800heap on Jul 5, 2022 2:48:05 GMT
Thanks David this does help greatly. It gives me somewhere to start. This is the first non standard cam I have touched so the more info the better.
Checked the cam with the clearance roughly set to standard so that is good news as the cam will be a little more towards an S cam.
I shall have to see what I have advance wise I have no idea. I do have another electronic distributor I believe that may be better suited. I will change the clearance and recheck.
Thanks
Nick
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OKR
Jul 5, 2022 3:23:34 GMT
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Post by 1800heap on Jul 5, 2022 3:23:34 GMT
Ok a very rough check with 0.050" as valve clearance gave roughly
5 in 45 in
15 ex 48 ex
I just noticed a value of 0.020" in the WM that says "Timing" is that what that means for cam timing?
Nick
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