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Noisy top end gt6 mk3


Dolomitejohn

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Hi everyone. 

I am still getting to know my new gt6 but have noticed that from cold the engine sounds quiet. However as it warms up I can can hear the tappets ( I assume tappets). Its not just an isolated tap it's the entire top end.  

Is this a rebuild situation or an adjustment or an oil feed to top end job ( the extra oil supply pipe kit). 

Thanks all. 

John

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Don't fit an oil feed to the top! Starves the bottom end - there is plenty oil that get to the rockers if everything is as it should be.

First thing to do is adjust the tappets - but what you need to check is how smooth the rubbing pads on the rockers are as they can wear a grove and the feeler gauge bridges the gap so you get too wide a gap.

It could also be worn valve guides or even piston slap. 

Very hard to diagnose though!

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come to twiddle day  ???

old trick with it idleing use old feeler gauge to insert if it goes quiet you have a worn rocker pad 

this will might  mangle  a feeler dont use good ones .

rockers and shafts are a well worn area, they do a lot of work over the years , i would strip the assy down and study the shaft and oil ways including the pads 

worn camshaft bearing can give unsolvable tappet type noises , but do the simple first

 

pete

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As Mark says DO NOT fit an oil feed to the top end! It's not an additional oil supply, it's a diverted oil supply and you are robbing the bottom end. 

Worn rockers can go on for years it's just difficult to get the gap right. Wire feeler gauges would do the trick however, they are hard to find. I think Pete has some in his "Sunday Best" tool kit.

I did consider an alloy rocker cover to cut the noise down! :lol:  But be careful, there is very little clearance on the MK3 bonnet. Canley Classics say  "fits Vitesse and GT6  (except mk3)".

Doug

 

 

 

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It it really is an issue, have a feel of each rocker on the shaft I would expect to be able to feel some/all are quite sloppy. 

The simple remedy is to fit a new rocker shaft, and if the rockers have decent faces, that should get rid of the majority of any wear. 

 

The suppliers used to sell recon shafts complete with refaced rockers etc at a reasonable price. Not sure if that is still the case, but if so a decent plan B

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The valve train on my Vitesse was worn when I purchased the car, lived with it for a few extra years and then decided time for a change. Did an outright exchange with a new rocker and shaft assembly complete. Caught them with a sale and had the assembly taken to the NEC which saved on postage. Oh yes sale is currently on until 3rd March so tempting if the valve train is included - worth asking anyway if not shown discounted. Rimmer Bros are pretty good at discounting if you speak with them direct.

Fitted the replacement and the difference was a complete revelation - noisy to quiet instantly and able to set the rockers spot-on. Cost about £100 and worth every penny IMHO.

As mentioned above, do NOT go the route of the auxiliary oil supply to the valve train as the bottom end will suffer wear greatly. 

Good luck.

Richard.

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After I took into account pad face wear (doing the worn ones, by feel, comparing it to known good gaps), I eliminated tappet noise.

Some time after I noticed the first 6 or 7 rockers (front half on engine, furthest away from oil feed into shaft at rear) weren't dribbling oil from top holes at idle. stripped down rockers and the oil holes were clear, though shaft very worn at front of shaft, progressing along it to rear.

New shaft sorted the oil feed. Didn't appear to make any difference to noise (where the area of wear is on shaft, corresponds to where the load/pressure is on shaft/rockers due to the valve springs I think?, so maybe this also doesn't make it noisy/rattly with wear?.   .

I used my old rockers, as apparently the shaft wears more and new rockers may not be good quality, as isn't, probably the new shaft (£25.00), Better ones may be available for around £75.00, Chris witter I think supplies them, though maybe others?.

Dave  

Edited by daverclasper
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  • 3 weeks later...
3 hours ago, Guppy916 said:

then weld a new piece in and a lot of polishing

Came out nice - top job!

3 hours ago, dougbgt6 said:

Occasionally an SAH rocker cover with chamfered ends comes up on Ebay, but out of reach at £500+

I have one of these.  Don't like it.  Ugly and extremely heavy.  Bring on the lots of people with big money!!

Nick

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16 hours ago, dougbgt6 said:

I'll give you a fiver? 

 

19 hours ago, dougbgt6 said:

Occasionally an SAH rocker cover with chamfered ends comes up on Ebay, but out of reach at £500+

Oi oi! you had two more zeros in your original number...… I'd let you have it for that :P

  • Haha 1
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  • 10 months later...

     I  milled down the flies on the front three inches of the cover and installed the thin silicone gasket mentioned in another post. That along with the two factory studs with jam nuts on them and a hex head cap screw on the front hole solved the problem. All parts came from Moss.

 

Hope this helps,

 

Robbie

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       The problem I am having is on my 1972 GT6 MK 3. I replaced the rocker shaft and rockers with the kit offered by Moss that includes a hardened rocker shaft with 12 new rockers with bronze bushings installed. Moss claimed that the rockers have been fitted to the rocker shaft with a clearance of .002. After installing the shaft and rockers I took a black marker pen and painted the rocker pads and the valve stems with the pen. Then I turned over the engine three revolutions using a 15/16” Gearwrench combination wrench on the damper retaining bolt. Next I removed all the push rods so I could take a look at the wear pattern on the rocker pads and the valve stems. The wear pattern should be dead center on the valve tips but is halfway off center towards the intake/exhaust manifold. If the wear pattern was towards the rocker shaft side of the head then all I would need to do is to add a .010 shim to each rocker shaft pedestal. There are no spacer shims under the rocker shaft pedestals so I can not lower them to solve the problem. I also noticed that a couple of the push rods are rubbing slightly against the head. I have thought I’d reaming out the rocker pedestals mounting holes slightly larger along with matching up the oil feed port and then moving the complete assemble back towards the left side of the head.

     Is the kit sold my both Moss and Rimmer defective or did they both use the wrong rockers in their kit? Short of milling the bottom of the pedestals or the surface where the pedestals mount and installing different length push rods does anyone here have a solution to this issue.

 

Thanks in advance to all of you that try to help me with this issue,

Robbie
 

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Atro isnt this the wear pattern you want to see? The initial contact should be in the middle of the valve stem so that the impact is spread across its full diameter then the rotating action of the rocker will mean the pad tends to wipe across the outer half of the stem....

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Johny,

     Thank you for helping me with this issue. According to directions from Moss the pattern should be dead center on the valve top. They state that if the latter is closer to the rocker shaft then one needs to shim the rocker shaft to get the pattern centered. They state that if the pattern is like mine then see your machinist which tells me that the pedestals or the head need to be skimmed. 
 

     The old rocker bores were worn off center and from what the new centered rockers are showing I am afraid that this will happen to the new ones too. 
 

     If the experts here feel that the wear pattern looks good then I will re-torque everything and readjust the rocker clearance to .010 and call it a day. 
 

Thank you for your help,

 

Robnie

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From this drawing in the WSM I think if your rocker shaft was too low the contact wipe would tend to go to the outside of the stem face while raising it with shims the rocker goes further below horizontal so should move the contact inwards. It depends on the rocker resting position being as shown....

IMG_0366.JPG

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