TR4 cam discrepancy -advice please

[Graze]

New engine, hi spec performance, suspected cam wear or machining fault

 

Specially ground cam from noted cam grinder used to TR's was fitted to car about 2000 miles ago. I am told by the guys who installed it that they ran it in ( 2 hrs at 2000revs is I understand the protocol but I need to confirm this is what they did)

 

Tiapets were noisy and I had a few goes at setting them. Couldn't get them right and also found that after working through them if I went through a second time a few needed further adjustment. I thought it was me doing an inexperienced job.

 

I took it to a local shop where one of the guys is a specialist performance engine builder and asked him to have a look. Same problem for him and he suspected the cam backs were out of round. So he pulled the rocker gear and tested the cam backs with a dial gauge and tells me No 4 exhaust, No 3 exhaust and No 2 inlet were out by up to 5 thou.

 

So my issue is what caused this, premature wear due to poor setup or poor grind?

 

Have decided to put it back together and drive it for another 500-1000 miles and see if it gets worse

 

My theory is if it gets worse, then it is wear, if it is stable it's the cam grind

 

Any thoughts or suggestions welcome

 

Graze

[RogerH]

Hi Graze,

I believe the normal running in for a new cam is 20 minutes at 2000rpm. Your 2hrs, if this what it was, shouldn't have done anything silly.

 

Roger

[TR 2100]

Hi Graze,

 

I would set out the situation in detail, in writing, and

send a copy, registered, to the "noted cam grinder"

and to the engine rebuilder.

 

Set out exactly what you have done, what has happened,

what you propose to do, and ask for their comments.

 

If you don't, it's so easy to say "Ah, well, you shouldn't/

should have done something else".

 

Did the engine rebuilder provide the cam? Big difference

if YOU provided the cam.

 

I'm not sure from the details you give the exact chain of

events. Was the engine rebuild under someone elses

ownership/instructions?

 

AlanR

[Graze]

Alan

 

It's a long story. Goes like this

 

Experienced TR engine builder (has built numerous race and hi performance engines for Targa Tasmania etc) built the engine and ordered the cam from the best cam grinder in Brisbane. They provided a race cam when a fast road cam was ordered. Engine built up, all good except you needed 2500 revs to start off so not really a car you could drive on the street.

 

Engine builder got diagnosed with pancreatic cancer mid build but managed to finish engine. When we worked out that the cam was wrong we got a replacement from the grind shop (no charge). Started to help him strip down the car to change the cam over when he got sick and passed away a few days later

 

Found a jaguar and classic car guy to finish the cam replacement and paid him another $2500 to do that work. Car ran well, revved well, was very happy till I thought it was a bit noisy and started on the tappet adjustments.

 

Took it to a third party who I know that is close by because I thought it was just a simple adjustment I couldn't get spot on. Jaguar guy is an hour away on other side of town - a nuisance or minor tweaks

 

So I'd be keen to try and target the cause so I can go to either the cam grinder or the second builder with my problem and begin to negotiate their contribution to the fix

 

Roger -I am sure you are right -20 minutes will do - my error

 

Graze