newdean0 0 Posted February 12, 2006 Well, since I'm taking the head off my mi the temptation to throw money at it is becoming too great . Has anyone had just a 3 angle valve seat done on these heads? Did it make a big difference? Do you think it was worth the money? Also is there a standard cut angle or it is a proprietary thing i.e. is it worth taking it to a big name or is this a job any engine builder with a bit of competence should be able to do? I don't really want to fork out for a full porting at around £500 but it would be nice to see some benefit from all the work apart from a smoke free exhaust. Cheers Dean Share this post Link to post Share on other sites
Guest davebxgt Posted February 12, 2006 Well, since I'm taking the head off my mi the temptation to throw money at it is becoming too great . Has anyone had just a 3 angle valve seat done on these heads? Did it make a big difference? Do you think it was worth the money? Also is there a standard cut angle or it is a proprietary thing i.e. is it worth taking it to a big name or is this a job any engine builder with a bit of competence should be able to do? I don't really want to fork out for a full porting at around £500 but it would be nice to see some benefit from all the work apart from a smoke free exhaust. Cheers Dean Unfortunately the original 45 deg seat is quite wide and doesn't leave enough material in the inserts to make a bottom cut. So to cut a proper 3 angle seat you need to a) replace the inserts - expensive or get larger valves - which allows the angles to be cut but is also expensive. Dave Share this post Link to post Share on other sites
maturin23 10 Posted February 12, 2006 Try a search - this is a well-discussed topic! Share this post Link to post Share on other sites
jonD6B 0 Posted February 12, 2006 Have a read of www.Pumaracing.co.uk if you haven't already. Share this post Link to post Share on other sites
dee205 3 Posted February 12, 2006 Bigger valves and 3 angle seats is the way to go. That's what I intend doing. Damien Share this post Link to post Share on other sites
petert 587 Posted February 12, 2006 (edited) Bigger valves and 3 angle seats is the way to go. That's what I intend doing. Damien Have you read the pinned Big Valve Thread thoroughly and digested all the results? If I had spare money to spend on an Mi16 I'd put it towards decking the block and liners. Increasing the CR to 10.8:1 and optimising the deck height gives far more impressive results. Edited February 12, 2006 by petert Share this post Link to post Share on other sites
dee205 3 Posted February 12, 2006 Has anyone on here done this? What kind of results? Share this post Link to post Share on other sites
petert 587 Posted February 12, 2006 Has anyone on here done this? What kind of results? I do it regularly: http://www.aussiefrogs.com/forum/showthrea...7760#post307760 With one of my inlet cams I can get 180hp with a std. inlet manifold. Share this post Link to post Share on other sites
dee205 3 Posted February 13, 2006 Have you read the pinned Big Valve Thread thoroughly and digested all the results? If I had spare money to spend on an Mi16 I'd put it towards decking the block and liners. Increasing the CR to 10.8:1 and optimising the deck height gives far more impressive results. Excuse the dumbness, but what does that involve? What's the work and cost involved? It's the first time I've heard it mentioned. Share this post Link to post Share on other sites
petert 587 Posted February 13, 2006 (edited) Excuse the dumbness, but what does that involve? What's the work and cost involved? It involves milling the deck of the block and turning down the tops of the liners, so that the pistons are flush (or just proud) with the top of the bores at TDC. It's a reasonably labour intensive job, as the liners have to finish square with the deck, and protrude a few thou. It costs me AUS$400 for a friend to do it. Edited February 13, 2006 by petert Share this post Link to post Share on other sites
Super Josh 4 Posted February 13, 2006 (edited) Why not just fit high compression pistons? No read to remove the engine from the car then. Josh Edited February 13, 2006 by Super Josh Share this post Link to post Share on other sites
petert 587 Posted February 13, 2006 Why not just fit high compression pistons? No read to remove the engine from the car then.Josh Because it wouldn't work. Assuming they were forged, you'd have to hone the liners a few thou. anyway. Even if they were cast in that spec., you'd risk disturbing the liners. Too dodgy for me! Share this post Link to post Share on other sites
base-1 17 Posted February 13, 2006 Original question - MattSav at QEP can do it on his super-tastic valve magicmachine, and it isn't that expensive, given the benefit alot of people decide to not bother lapping the valves and just get this done instead Share this post Link to post Share on other sites
pug309twin40s 1 Posted February 13, 2006 yep. QEP did 3 angle vavle seats on mine and a mates mi16 cyl head. and was very good work and good price. Share this post Link to post Share on other sites
Super Josh 4 Posted February 13, 2006 Why not just fit high compression pistons? No read to remove the engine from the car then.Josh Because it wouldn't work. Assuming they were forged, you'd have to hone the liners a few thou. anyway. Even if they were cast in that spec., you'd risk disturbing the liners. Too dodgy for me! Peter, I'm not sure what you are saying here. Are you saying that high comp. forged pistons don't deliver the goods? Or that you think that they are too risky to fit? Surely decking the block is alot more risky than possibly disturbing the liners? Josh Share this post Link to post Share on other sites
dee205 3 Posted February 13, 2006 I know this is getting off-topic but it's getting interesting. Would the higher compression from both mentioned methods not put more strain on the engine. And how would the higher compression from decking or high comp. pistons affect later modifications to the engine. ie. different cams, tb's.. Damien Share this post Link to post Share on other sites
