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HotRodMatt

Pinto cam problem or am I being paranoid?

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HotRodMatt    229

Hi all,

Got some rare time in the garage tonight and I was setting the valve clearances before refitting the head and I noticed as I was doing so that the ball stud on no1 inlet, despite being set to the same gap, is wound noticably further out than the others.

A closer look and the lobe's base circle seems to sit a tiny bit higher into the centreline of the camshaft than the others (hope that makes sense!).

I have had this setup running and don't remember there being an issue before, however I did set the clearances before with it in the car so may just not have noticed it and I probably wouldn't have noticed it this time were it not on the bench. But now I have seen it it's bugging me.

The cam turns over fine and the engine has only been run twice, no more than 45 mins total so should I just refit the head and forget about it? If it ain't broke, etc.d3fa950c86a50ace9c43482fa8039d13.jpg

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JP.    232

As I understand, its a new cam that has only run twice for about 45minuts??

 

Did you break-in the cam when fitted to harden the lobes ?? That means inmidiatly after first startup running it a minimum of 2500rpm for 20 minuts.
​If not, cam will be scrap within 700miles

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HotRodMatt    229

As I understand, its a new cam that has only run twice for about 45minuts??

 

Did you break-in the cam when fitted to harden the lobes ?? That means inmidiatly after first startup running it a minimum of 2500rpm for 20 minuts.

​If not, cam will be scrap within 700miles

Yes correct. The issue is with the heel of the cam rather than the tip.

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anglia58    65

hi,the problem will be that the valve won't come up as high as the other one's, you also will have more valvelift on that one ,

that's why your adjustment on the ball stud is so high, the top of the valve shout be from the bottom of the head 120mm,

if you have taken a 1mm of the head it shout be 119 mm and so on, if they are lower you get more valve lift, if they are higher

you get less valve lift, you can correct this by make the valve seat deeper, the cam will be alright, it just looks that way,

cheers marcel

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colr6    1,271

Plus if I remember correctly with the rocker pad been a different angle to the rest the valve opening time will be different to the others because of the angle the cam lobe hits the rocker. There was a discussion about ohc valve geometry a long time ago where people were using grp 1 valves and the stem were 1 mm longer so altering the ramp angle. There is a lot of power to be gained by ensuring the angles are correct.I remember an article on an engine that was produced by a well known London based company who also charge a lot for parts ( clue) they had a 2.0 pinto stage three head rally cam twin 45s and all the other gubbins to go with it and it produced less power than std RS and most of it was due the bad head geometry.

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