78 replies to this topic

[imack]

Cam bearing oil pump end.

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[PACINO]

Hi imack. I don't see this notch on mine. Is yours a 1275cc engine?

[imack]

Yes, 1275.
The bearing at the timing chain end has the same notch.
I don't think the cam bearings in my current 1275 have these notches.

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[imack]

I was wrong, I've found pictures showing the notches in the bearings of my new engine, again 1275. This time bearings installed by KAD.

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Edited by imack, 19 March 2024 - 05:23 AM.

[KTS]

 

Front bearing as installed by MED about 10 years ago.

Thank you imack! Of the three (3) pieces that complete the 'front cam bearings' set, I distrust this one specifically. I think the other two are well placed.

 

 

Keith Calver makes specific mention of the front cam bearing (i.e the one at the timing chain end) being incorrectly fitted.

 

if you look at the image imack posted of that bearing in post #43 you can see the bearing is installed with the slotted hole lined up with the drilling at the 9 o'clock position (this is the feed from the crankshaft mainjournal, and is not central in the tunnel, hence the need  for a slotted opening in the bearing), and the round hole lines up with the oil feed that goes up through the block to feed the cylinder head

 

the image in post #41 shows the slotted hole in the bearing is lined up with the drilling that goes up through the block indicating the bearing is incorrectly fitted, with the likelihood that the oil feed into the bearing from the crankshaft main journal is blocked (..which also means you won't have any oil supply to the cylinder head either)

[super6al]

Hi 

Just looked PACINO's image #41 again and the builder has pencil marked on the block where the oil ways are so he can line up the bearing. It looks like he has installed the bearing so the notch (if there is one) would be on the inside of the block. If I'm correct this would mean the bearing oil holes would be in line with the oil ways. So provided they aren't shrouded it should be ok? Presumably if he marked the block he would have checked the holes were in line.

Alan

[PACINO]

Front bearing as installed by MED about 10 years ago.

Thank you imack! Of the three (3) pieces that complete the 'front cam bearings' set, I distrust this one specifically. I think the other two are well placed.

 
Keith Calver makes specific mention of the front cam bearing (i.e the one at the timing chain end) being incorrectly fitted.
 
if you look at the image imack posted of that bearing in post #43 you can see the bearing is installed with the slotted hole lined up with the drilling at the 9 o'clock position (this is the feed from the crankshaft mainjournal, and is not central in the tunnel, hence the need  for a slotted opening in the bearing), and the round hole lines up with the oil feed that goes up through the block to feed the cylinder head
 
the image in post #41 shows the slotted hole in the bearing is lined up with the drilling that goes up through the block indicating the bearing is incorrectly fitted, with the likelihood that the oil feed into the bearing from the crankshaft main journal is blocked (..which also means you won't have any oil supply to the cylinder head either)

Beautiful KTS. But here it seems that he marked where the oil hole goes. Therefore, it is difficult to think that it could be misplaced.

[KTS]

agree; the builder does appear to have marked the block to show the locations of the two oilways, but as Keith Calver noted the bearing has been installed backwards so although the holes line up with the drillings there is a very good chance that the oil feed to the cam bearing from the crankshaft main journal is shrouded/blocked.

 

have a close look at the image that imack posted in #48 - pay close attention to how the drillings in the block align with the holes in the bearing and you should see if they were reversed (as in your install) the lower oil feed is likely to be covered as the round hole is central in the bearing, but the oil drilling is offset in the tunnel

[PACINO]

I understand you KTS and I thank you for your explanation. You don't know how I'm filling without being able to move forward. But the problem is that after speaking yesterday with the engine builder, he told me that: "That is perfectly fittedt.The front cam bearings are SYMMETRIC, they do not have one lip that is thinner or thicker than the other. Therefore they DO NOT keep a specific position "The front cam bearings were machined, but for some reason (he says) the engine turns hard or with difficulty. Once turned on for 10 minutes, the engine will turn smoothly."

What I can do? I personally DO NOT want to try to turn it on like that. It could damage the camshaft, or so Calver says; A lot of oil accumulates under the rocker cover.

Honestly, I'm sick with all this.It's like a bad dream.

[KTS]

to help explain to the engine builder what is wrong means you need to understand exactly why the cam bearing has different shape holes and how that works with the camshaft to provide lubrication to the cylinder head

 

the front journal of the camshaft has a machined groove around around it's circumference and another short groove at one point that points forward.  The circumferential machined groove does not line up with the drilling that takes oil up to the cylinder head, but the short groove that points forward does line up once per revolution of the camshaft

 

with the cam bearing correctly fitted (elongated opening to side, round opening up), oil comes in through the lower opening and into the groove in the camshaft journal providing lubrication.

 

each time the camshaft turns, the groove that comes forward from the circumferential groove (which is filled with pressurised oil) lines up with the round opening in the bearing which allows a pulse of pressurised oil to be directed up towards the cylinder head.

 

With the camshaft bearing in backwards the lower oilway (high pressure oil from the crankshaft main journal) is permanently connected to the upper oilway (oil to the cylinder head) by the circumferential groove in the camshaft journal.  So instead of getting one pulse of oil for each turn of the camshaft, it gets a permanent feed of pressurised oil.

 

it is frustrating to find problems, but far better to spot them and fix them before they result in more significant/expensive problems down the line

[PACINO]

I was wrong, I've found pictures showing the notches in the bearings of my new engine, again 1275. This time bearings installed by KAD.

Fantastic! imack, thanks a lot for your help. Here you got a friend for whatever you need.
Luis

[PACINO]

And I have to say the same about KTS. A guy I didn't know but I have to thank him a thousand times for his great explanations.

I was able to talk for about 30 minutes with the guy who made the engine. He's 200% convinced that the front bearings are perfectly facing the oil holes. That this is what is really important. Whether the "notch" is in or outside,(he says) it means nothing. That the bearings do not have a direction of rotation.

[imack]

I think your front bearing (timing chain end) is fitted backwards. It's vitality important that the front bearing (timing chain end) is not fitted backwards. Even though the holes in the bearings align with drillings in the block the bearing could be fitted backwards. If fitted backwards, the rockers will be fed with a continuous supply of pressurised oil which will result in the rocker cover filling with oil.
When the bearings are fitted correctly, the rockers will be fed by a pulse of pressurised oil once every camshaft revolution via the groove and slot in the camshaft journal.
The oval hole in the bearing needs to align with the oil feed drilling from the crankshaft. The round hole in the bearing must align with the drilling that goes to the cylinder head and rockers.
Your engine builder 'appears' to have aligned the oval hole in the bearing with the oil feed drilling to the cylinder head which indicates that the bearing is fitted backwards.

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[PACINO]

Marvelous! This is what KTS said before. Thanks a lot imack. Then we can affirm from what we can see, that the bearing on the distribution side is incorrectly positioned. But what happens with the oil pump side, does it matter if the notch is on the inside instead of on the outside, or not at all, and is that cam bearing correctly positioned? These are exactly the ones I sent to the builder. I asked this company this morning if the bearing on the oil pump side has a notch on the side that is not seen in the photo. For now they have not answered me.
Kind regards
Luis

[Lplus]

I think your front bearing (timing chain end) is fitted backwards. It's vitality important that the front bearing (timing chain end) is not fitted backwards. Even though the holes in the bearings align with drillings in the block the bearing could be fitted backwards. If fitted backwards, the rockers will be fed with a continuous supply of pressurised oil which will result in the rocker cover filling with oil.
When the bearings are fitted correctly, the rockers will be fed by a pulse of pressurised oil once every camshaft revolution via the groove and slot in the camshaft journal.
The oval hole in the bearing needs to align with the oil feed drilling from the crankshaft. The round hole in the bearing must align with the drilling that goes to the cylinder head and rockers.
Your engine builder 'appears' to have aligned the oval hole in the bearing with the oil feed drilling to the cylinder head which indicates that the bearing is fitted backwards.

Considering the size and convoluted shape of the oilway to the rocker shaft and the comparable size of the return holes to the sump via the pushrod holes and the holes in the tappet section of the block, that seems incredibly unlikely.