Head Modifications For High Lift Cam?

[Cactus 1]

Can anyone point me in the right direction for a thread detailing cutting clearance slots for high lift cam lobes? I have been searching the forum last night and this morning but can only find occasional references to it.

 

I only realized there was a clearance issue when I went to set the timing having rebuilt the engine. Although I realize it would be prudent to do so I am reluctant to pull the head off to do the work if I can do an adequate job with a die grinder and burr

 

Are there any issues I should be aware of before I start removing metal Is there anything I need to watch out for or is it straight forward? The last thing I want is another disaster with this build. ( I will cover that nasty experience in another post)

 

Any thoughts would be welcome thanks

 

[Tom Fenton 1,541]

In my opinion the head needs to be off and stripped. Grinding material out will fill all the head with swarf, if one single piece of this gets round the engine then your crank brgs will be scrap shortly afterwards. its not worth the risk.

[Cactus 1]

That's good advice Tom and I know in my heart it is the right thing to do but Its just so tempting to leave the head on. I will wrestle with that dilemma a bit longer but i think in the end he head will be off again.

[GilesW 41]

Tom is right.

 

Yes it's a total pain, but nothing compared to a bit of swarf getting picked up. And due to what you are doing I would say this is VERY likely regardless of how careful you are.

[Tom Fenton 1,541]

 

That's good advice Tom and I know in my heart it is the right thing to do but Its just so tempting to leave the head on. I will wrestle with that dilemma a bit longer but i think in the end he head will be off again.

Would you pour swarf down the oil filler pot? If the answer is no then you need to pull the head!

[petert 586]

You need to be able to spin the cam without any valves in the way. Impossible job without stripping the head.

Edited October 9, 2014 by petert

[Stu 18]

^^^^^^ What he said...

 

Plus, you're bound to get some swarf in a gallery that supplies a lifter, so it'll either tap its tits off (best case) or knacker the cam (worst case).

 

Bite the bullet, get it off

[Cactus 1]

Ok despite my super human ability so control swarf, lol, the head is coming off again. It would be a nightmare to attempt in situ and as Peter states being able to spin the cams I think is a must.

[2052NV 24]

^^^ thats the best plan! With my head i just did a cut and test method

[pip470 61]

Cant the cam be reground so that the lift stays the same but you just reduce the base circle. Im running nearly 13mm of lift and it hit the head at first but after the second regrind they were fine.

[Cactus 1]

Ok update - got the head sorted out the cam is spinning nicely and if anyone else thinks it may be possible to do without stripping the head forget it Read the advice above - the swarf was all over the place. I think I spent as much time getting rid if the stuff as i did doing the modification.

 

So the next question is do i go with solid lifters?

 

The engine is being built on a tight budget so I have picked up various components as and when bargains have presented themselves and I am in no hurry which is a good thing as i dont get much time to spend on it.

 

Anyway with this approach over months and months I have ended up where I am today with the following bits and pieces. xu10 head omega pistons 4 branch exhaust manifold longman inlet manifold gsxr throttle bodies piper vernier pulleys and this piper pt 1603 cam. .Almost forgot, ages ago I built a megasquirt to run it.

 

I don't know where this will end but I thought perhaps i should consider sorting out some solid lifters for it. what do you think? If I do it i will be converting the existing hydraulic ones

[petert 586]

There's nothing cheap about solid lifters unless you have the skills to build them and shim yourself. I've recently helped a friend modify an OEM set and they've worked out well. He has the machinery and ability to make them himself. There is literally hours of work involved. If paying someone, you'd be better off buying aftermarket solid lifters. Even then, you're up for a few hours in shiming over the cost of building a hydraulic head. The end result is well worth it if you plan to do any motorsport work.

 

If it were mine, I'd regrind the PT1603's into a suitable solid profile.

[Cactus 1]

Thanks Peter,

 

It was another post that got me started with going solid and i do need to dig into the forum again to refresh my memory regarding camshafts. I think I read somewhere on here that the that the standard exhaust cam was not too bad and changing the inlet was more worthwhile. Hence i have only one pt1603.

 

Its wierd how this all started - I got the oportunity of a recently rebuilt head which was the only thing i intended changing but then the unused pistons came along for next to nothing and i before i knew it i was building a performance engine.

 

In an ideal world I would have been able to choose more suitable parts, i probably would have used a different inlet manifold for example, but since its not I carefully need to decide where i spend. I have no idea how much regrinds cost but perhaps I should do it. The engine is getting a bit special i guess so it would be a shame to spoil it.

 

I have a lathe so i thought i could turn some inserts up to convert the followers, Again the is idea came from a post on here and I think there was a diagram on the thread that was probably lifted from a k series website. Time isnt too much of an issue; this engine has been ongoing for years I wont lose sleep if it takes another year or so lol.

[petert 586]

It's possible to grind something very worthwhile on to the std exhaust cam, if going solid. The base circle doesn't matter as much, and you don't need as much lift on the exhaust. You can replace the internal pieces of the hydraulic lifter, with one piece made from OD14mm silver steel. Turn the outside to a taper like the original, then hollow out the centre. Make a dummy set, without hollowing out, from mild steel first however. The length of the internal is used to set the valve clearance. It's not a difficult process if you're handy with the lathe.

[SweetBadger 94]

Newman do an adjustable lifter, current catalogue has them listed at £272.00 for a set.

 

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I was considering these for my engine build but decided to stick with the hydraulic lifters as I should be keeping the power band below 7600rpm.

 

They use a hardened grub screw with a locking nut - this would be a damn site easier to set up than converting the hydraulic lifters and using shims, but I've no experience with their reliability.

[petert 586]

The best lifters to convert are actually the crappy Piper ones. They only have a 12mm bore and are considerably lighter.