27 replies to this topic

[Cooperman]

The big question is whether the engine builder did a proper trial build or spring calculation/measurement to check coil clearances at full lift.
It does look like coil binding on at least two valves.

[sledgehammer]

The big question is whether the engine builder did a proper trial build or spring calculation/measurement to check coil clearances at full lift.
It does look like coil binding on at least two valves.

 

I suppose that could cause the wear on the journal as well

 

lobes definitely seen some excessive wear - not just bad material 

[ACDodd]

Point to note, cams are not hardened after grinding.

Ac

Edited by ACDodd, 25 March 2016 - 10:36 PM.

[MRA]

Your camshaft has been seriously overloaded due to mechanical error, as above spring bind or similar.

 

refit the cam and a push rod (straight one) and with a DTi determine your cam lift, then ascertain rocker ratio (I think you said 1.5) this then gives you the valve lift and now you need to measure the maximum movement that the valve will move down, remember inlet and exhaust will invariably be different, now here is the magic .... 

 

(cam lift x rocker ratio) - valve max lift = ?

 

Now if the answer is negative you have your problem, if it is positive.... HINT  it won't be positive, or at least not if you use the camshaft manufacturers cam lift ( yours is knackered and measurements will be way down)

 

When you come to put it together again thie above calculation MUST result in a positive only figure that also gives you a minimum of 0.030" (0.762mm) minimum.

 

ok now the really bad news..... 

 

Your camshaft is scrap

Your pushrods are scrap

Your followers are scrap

Your valves may be scrap - check the keeper/collett groove and the valve stem top.

Your springs are scrap - well the outer are anyway

Your valve spring caps are scrap

Your valve colletts - are probably scrap

your cam bearings are scrap.

 

The whole engine will need a full strip, clean, clean again and rebuild

 

Don't forget to remove the oil way gallery plugs and brush through to remove all traces of swarf.

 

Alternatively speak to the engine builder and if they built and fitted the head then they need to consider rectification

[Spider]

Point to note, cams are not hardened after grinding.

Ac

 

I've bought Camshafts, new and Re-ground from all over the world and a great variety of supplies, even some local ones.

 

I'll say some are and some are not. The original Cams fitted by the factory were, at least until the early 80's. After that, I'm not sure as I haven't had many here to check. The original ST ones were also hardened.

 

I'll add here that from my experience, those that have been hardened last well and give a very good life.

 

Here's one after market supplier who does supply Hardened Cams (56 - 58 Rc):-

 

https://dl.dropboxus...Spec266_276.pdf

 

 

These guys also include Hardening as part of their standard process;-

 

http://tighecams.com.au/different.htm

 

 

These days - generally speaking - if I'm looking for a performance Camshaft, I will only get them from the USA, if I'm having one reground, I send the cam and followers to Tighe as I agree with their process.

 

by the way, the 'roots' of Tighe go back to the Repco-Braham F1 engines and beyond.

 

<Edit: All the factory Cam Followers and most replacement ones have at least a hardened face. I would think it not a good idea to run these on a 'soft' cam. >

Edited by Moke Spider, 26 March 2016 - 07:53 AM.

[ACDodd]

The a-series factory cams are hard enough after reprofiling not to need it.

I agree other cams may need hardening. The biggest problem with bad wear after low mileages is usually the first start and spring poundage/rocker combination, and looose/slack followers. Its the break down of oil film that damages the material not the material itself.

Ac

[sledgehammer]

When I worked at Kent Cams (summer job) -

 

we Parkerized (bonderizing, phosphating) them after profiling

 

the a series were parkerized , but bearings were taped up to stop it , then they were polished

 

it would hold the cam lube on the cam at start up , the coating lasts a while

 

the vauxhall cams of the 80's & 90's should have been induction hardened - they were made of chocolate

 

loved that job

Edited by sledgehammer, 26 March 2016 - 05:16 PM.

[MRA]

When I worked at Kent Cams (summer job) -

 

we Parkerized (bonderizing, phosphating) them after profiling

 

the a series were parkerized , but bearings were taped up to stop it , then they were polished

 

it would hold the cam lube on the cam at start up , the coating lasts a while

 

the vauxhall cams of the 80's & 90's should have been induction hardened - they were made of chocolate

 

loved that job

 

You can't induction heat chocolate...... lol

[MRA]

A camshaft that is not hardened is not worth fitting.

[Cooperman]

 

When I worked at Kent Cams (summer job) -

 

we Parkerized (bonderizing, phosphating) them after profiling

 

the a series were parkerized , but bearings were taped up to stop it , then they were polished

 

it would hold the cam lube on the cam at start up , the coating lasts a while

 

the vauxhall cams of the 80's & 90's should have been induction hardened - they were made of chocolate

 

loved that job

 

You can't induction heat chocolate...... lol

 

   . 

[sledgehammer]

 

When I worked at Kent Cams (summer job) -

 

we Parkerized (bonderizing, phosphating) them after profiling

 

the a series were parkerized , but bearings were taped up to stop it , then they were polished

 

it would hold the cam lube on the cam at start up , the coating lasts a while

 

the vauxhall cams of the 80's & 90's should have been induction hardened - they were made of chocolate

 

loved that job

 

You can't induction heat chocolate...... lol

 

 

You can if it is still in the foil 

[MRA]

Lol, apparently, after talking to a "chocolate" expert (not somebody made of chocolate but ....) they say that if you melt shop chocoate it does get harder when it sets !!!  lol

[jamieburke17]

Baught the cam from minispeed think, along with the cylinder head, the head is off to get stripped and checked, I suspect it's valve guides jamming up since there was loads of gold flakes at the bottom of the sump, that would explain the pushrod and cam damage wouldn't it? Also the tappets wernt adjusted but they wasn't far off, and I had been reving it highl a couple of days before.. I'll keep you posted, head should be back soon!