Geoff Dixon Posted January 31, 2001 Share Posted January 31, 2001 Am in process of upgraded my cylinder head. As part of this project I am fitting solid followers - retaining the existing hydraulic followers, taking out the hydraulic gubbins and fitting custom made shims. How do I set the cam and cam follower clearances and to what. I assume I have to machine the shims to set the clearance but dont know what this should be. Link to comment Share on other sites More sharing options...
Mike Bees Posted January 31, 2001 Share Posted January 31, 2001 The cam supplier will tell you the clearances. Probably something like 10 thou on the exhaust side, 8 thou on the inlet side. Yes, you need to grind the shims. You need to do each one individually before bolting down the cam carrier. It is very tedious! Mike Link to comment Share on other sites More sharing options...
Geoff Dixon Posted January 31, 2001 Author Share Posted January 31, 2001 Mike, thanks. Those the clearances I have been given by Piper. Are these clearances between the cam shaft lobes and the cam followers when the cam shaft is just sitting loose in the carrier ie. not tightened down at all? Link to comment Share on other sites More sharing options...
EFA Posted January 31, 2001 Share Posted January 31, 2001 Geoff You can do them with a grindstone or some wet an dry. The trick is to get your selection of tappet inserts optimised (like find the insert to tappet arrangement combination that requires the least grinding) The good K engine builders should have a range of insert sizes available to make this task easier - they do for the VX! Arnie Webb Organiser- L7C Le Mans Trip To book for this years Le Mans Trip see The Le Mans Trip Website It really is very very very very full now!!! Edited by - fast arnie on 31 Jan 2001 13:53:25 Link to comment Share on other sites More sharing options...
Mike Bees Posted January 31, 2001 Share Posted January 31, 2001 Geoff - it's the clearance between the base circle of the cam and the top of the follower. You don't need to bolt down the cam carrier to measure it. Work on just one follower/shim pair at a time (so no followers in place except the one you are currently shimming). Lay the cam in place, orientated so that all of it's bearing surfaces are in full contact and so that lobe on the one that you're shimming is pointing away from the follower, lean on the cam and measure the clearance. Mike Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted January 31, 2001 Share Posted January 31, 2001 Was talking to Warren at 'Piper' today and finding out about a new ish cam suitable for 'K' use. It is slightly milder than the '740' (to the tune of about 5 BHP), but if used with a limit of approx. 7,600 RPM it can be used with hydraulic (std.) followers. Any thoughts ? Link to comment Share on other sites More sharing options...
Mike Bees Posted February 1, 2001 Share Posted February 1, 2001 If you're not going to go solid then it souns like a good choice, the 740 is producing some really good results with well-ported heads. If you're going to do a significant amount of track work then solid followers are strongly recommended. Mike Link to comment Share on other sites More sharing options...
Rob Walker Posted February 1, 2001 Share Posted February 1, 2001 Piper now produce a hydraulic version of the grind 740. Its the BP285H could be a good choice for those not wishing to fit solid lifters Link to comment Share on other sites More sharing options...
Tim Seipel Posted February 4, 2001 Share Posted February 4, 2001 One thing you must do when setting tappet clearances on a K. Bolt the head down!! It is also better to fit a full set of tappets and shims of nominal size close to that which is required then bolt the carrier down and measure all the clearances. Knowing what the clearances should be and the size of all the shims are, move them round as much as possible to match actual sizes then grind others to suit. A time consuming process that is essential to get right. Link to comment Share on other sites More sharing options...
Rob Walker Posted February 6, 2001 Share Posted February 6, 2001 Bolting the head down can`t do any harm but measuring the clearances with the cam carrier bolted down against the valve spring pressure will give you very unreliable results. Edited by - Rob Walker on 6 Feb 2001 19:01:31 Link to comment Share on other sites More sharing options...
Roger King Posted February 7, 2001 Share Posted February 7, 2001 Tim Seipel is spot on with his advice. Many a person has been confused to find that the valve clearances mysteriously change after the head is torqued down on final assembly. It is simply due to distortion and happens on every OHC engine that I have ever worked on. Likewise, I would always fit valve springs and tighten the cam carrier down too. It's a horribly slow and tedious process, but you are after all trying to set the valve clearances under the conditions that the engine will see when it is finally assembled. Link to comment Share on other sites More sharing options...
Rob Walker Posted February 7, 2001 Share Posted February 7, 2001 Thats rather simplistic Roger. The cam carrier when new has a tolerence of .0023" to .0037" and a service limit of .0059". When the engine is running the oil film will also play its part. Also trying to measure clearances accurately with the cams influenced by spring pressures from all angles has a perverting influence especially if there is some wear in either the cam carrier or the cam. I have had no problem in setting clearances with the cam carrier off and simply holding the cam down against the head measuring the clearance between base circle and follower on two valves per operation. Then remove the two followers and on to the next two. When completed refit the cam carrier and recheck the clearances. I have not seen a clearance that has been more than .002" too loose. Repeated torquing of the cam carrier which is very flimsy would also worry me. To each his own as they say. Link to comment Share on other sites More sharing options...
Tim Seipel Posted February 10, 2001 Share Posted February 10, 2001 If you follow my process (how the engine was designed by the way), and accurately measure things, you probably will only ever do it once because the clearances won't move! Link to comment Share on other sites More sharing options...
Peter Carmichael Posted February 11, 2001 Share Posted February 11, 2001 On my K none of the clearances changed by more than 2 thou. Tim is sort of right and I will be measuring the ones I have before I dismantle in order to get everything spot on with reassembly. Link to comment Share on other sites More sharing options...
Rob Walker Posted February 11, 2001 Share Posted February 11, 2001 Tim/Peter not wanting to tell your father how to suck eggs, but its a sod of a job to get your feeler gauges between the base circle of the cam and the follower with the cam ladder in place. Suppose one could cut down some feelers into little bits in order to present them parallel with the surfaces to be gapped. Anyone out there devised a simple method. Link to comment Share on other sites More sharing options...
Peter Carmichael Posted February 12, 2001 Share Posted February 12, 2001 You can get feeler gauges with an appropriate angle in them. Link to comment Share on other sites More sharing options...
Tim Seipel Posted February 21, 2001 Share Posted February 21, 2001 I use straight feeler gauges and bend them. Not difficult! Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted February 21, 2001 Share Posted February 21, 2001 The angled end feeler gauges I use came via 'Snap-On' tools. Expensive, but they feel 'right'! Link to comment Share on other sites More sharing options...
EFA Posted February 23, 2001 Share Posted February 23, 2001 If you had a Vauxhall engine you could use cheap "normal" feeler guages and you wouldn't have to bend them. Adv VX. Arnie Webb The Fat Bloke blush.gif in a Slow Old Vauxhall wink.gif Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted February 23, 2001 Share Posted February 23, 2001 Cheap feeler gauges for cheap V/X's I guess!!!biggrin.gif Link to comment Share on other sites More sharing options...
Tim Seipel Posted March 3, 2001 Share Posted March 3, 2001 You've been reading my mind! Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now