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Rb26 Cam Lobe Clearance

drew6

By drew6,
in Engines & Forced Induction

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drew6 Rookie

drew6

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Hi guys,

Quick question, what tools are you guys using to notch the lifter bores to allow for large camshafts? I've heard of guys using milling machines, CNC machines, belt grinders, ect ect. The reason I'm asking is because I was planning to use a die grinder with a carbide cutter (same stuff I use for port/polishing).

Does anyone see a problem with this?

Thanks.

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dorifticon Community Regular

dorifticon

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What do you mean by "lifter bores"?

There is a precision tunnel bored surface in which the actual cam journals sit, but if you're literally just wanting extra room in the cylinder head to swing the taller cam lobes, it's not actually the bores that need to be relieved, it's kind of just a sharp lip between the cam towers - are you actually looking at the head?

As the head is alloy, it is as soft as puppy s--t for cutting through, a die grinder with a carbide bit will tear through it like nothing. It's not a precision job, you just need to releive the lip a bit, just be careful when you're doing it as the carbide bit will chop really fast, and also make your movements against the rotation of the cutting bit, if that makes sense, so you can control it better, don't want to slip and cut off a cam tower.

Obviously teh head is dismantled when this is happening and cleaned througoughly of swarf after.

Hi guys,

Quick question, what tools are you guys using to notch the lifter bores to allow for large camshafts? I've heard of guys using milling machines, CNC machines, belt grinders, ect ect. The reason I'm asking is because I was planning to use a die grinder with a carbide cutter (same stuff I use for port/polishing).

Does anyone see a problem with this?

Thanks.

Beer Baron Grand Master

Beer Baron

Posted
Posted

yeah, I think you need to take a look at the head again and see where the lobes will foul. there is not much material that needs to be relieved (well obviously varies a bit on just how big you want to go with cams). and as above, be careful it's pretty tight in there and the last thing you want is to f**k it up and have a throw away head.

drew6 Rookie

drew6

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Posted

Hi guys,

Thanks for the replys. What I was refering to as the "lifter bore" would be the bore that the actual bore that the valve spring and the lifter sit in. I'm in Canada, perhaps you guys call them a diffrent name in Australia.

I guess what I'm asking is: Does this require actual machining or will "play it by eye" method work?

Thanks

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