spitNL Posted April 8, 2010 Share Posted April 8, 2010 Has anyone thought about making an advance/retard mechanism for the spitfire/gt6 camshaft? Came up with this: An pair of wheels/gears that can slide from side to side thereby advancing and retarding the camshaft. My guess is that shouldn't be to hard to make. Need to enlarge the cover of course, and find a way of actuating it. Megasquirt/Adaptronic to steer it. Thoughts? Cheers, F. Link to comment Share on other sites More sharing options...
AJ.Lintern Posted April 8, 2010 Share Posted April 8, 2010 How would that work though? Surely there can only be a set number of links between the two sprockets - only way to alter the timing would be to jump a link? Or have I misunderstood completely? :-/ Link to comment Share on other sites More sharing options...
toofast2race Posted April 8, 2010 Share Posted April 8, 2010 So in effect get rid of the tensioner , worn chain condition = retarded cam , new chain condition = advanced cam Would you be able to measure this effect tho' and is it not more effective if you only play with the inlet advance, which I defy you to retro engineer Link to comment Share on other sites More sharing options...
GT6Steve Posted April 8, 2010 Share Posted April 8, 2010 You're talking about the very common "phase variator". We used to have them all over the place in my past life. It's way too early in the morning for my brain to be working yet but as I recall they just changed the effective distance between the two sprockets. Interesting idea for a dyno day! Link to comment Share on other sites More sharing options...
Nick Jones Posted April 8, 2010 Share Posted April 8, 2010 Interesting idea. Might be able to get a reasonable amount of swing if you use a long timing chain. Andy does have a point about this being less benefit that adjusting inlet only but that doesn't mean it's useless (especially if a cam is ground to take advantage of the effect) and we have to stick with the possible for now at least Nick Link to comment Share on other sites More sharing options...
GT6Steve Posted April 8, 2010 Share Posted April 8, 2010 Here's a link to the ones we initially used. They were fragile. http://www.candycontrols.com/PhaseVariator/PhaseVariator_PO.htm Link to comment Share on other sites More sharing options...
JohnD Posted April 8, 2010 Share Posted April 8, 2010 Would this work? A rotating adjuster would be easier to actuate than a sliding one. And it has to tighten in one side as the other is loosened. John Link to comment Share on other sites More sharing options...
Nick Jones Posted April 8, 2010 Share Posted April 8, 2010 That would work if both top and bottom sprocket were the same size, but I think the different sizes would mean you don't maintain tension with that rig. It's making my head hurt trying to reason it through properly though : Nick Link to comment Share on other sites More sharing options...
oviwan Posted April 8, 2010 Share Posted April 8, 2010 hi, had once this one in my hand but to short to figure out how it works: can be found in c-class merc, but others should have something similiar. harry Link to comment Share on other sites More sharing options...
DaveNotSoSideways Posted April 8, 2010 Share Posted April 8, 2010 Not much room between them sprockets, you'd need something on the end of the cam, a mech, like the VVC mech. Link to comment Share on other sites More sharing options...
spitNL Posted April 9, 2010 Author Share Posted April 9, 2010 Sorry for the late response, was out yesterday. Would you be able to measure this effect tho' and is it not more effective if you only play with the inlet advance, which I defy you to retro engineer I have read somewhere a manufacturer uses a 2 camshafts, one hollow so the other can rotate in it. Found it; Dodge Viper employs this. http://www.sae.org/automag/technewsletter/070402Powertrain/04.htm Would be to expensive to make for a Triumph, I guess. John, like others mentioned not a big amount of space to make that fit. Looks to big to me. :-/ I wanted to link the two extra gears so like on your idea one gear tightens as the other loosens, keeping lash constant. Found one of those merc phasers on ebay, not overly expensive, but you're right maybe better find out how much difference it would really make. http://cgi.ebay.co.uk/OEM-Mercedes-M119-Engine-Camshaft-Solenoid-A-1190510177_W0QQitemZ110504394419QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item19ba933eb3 Cheers, Frederick Link to comment Share on other sites More sharing options...
Nick Jones Posted April 9, 2010 Share Posted April 9, 2010 Heey.... that hollow double cam thingy is proper clever..... I like that Susepect you are right about the costs though.... Nick Link to comment Share on other sites More sharing options...
Harry Posted April 9, 2010 Share Posted April 9, 2010 Porsche 968 Vario cam Cheers, Harry Link to comment Share on other sites More sharing options...
AJ.Lintern Posted April 9, 2010 Share Posted April 9, 2010 Which apparently leads to prematurely worn cam sprockets and a BIG bill for two new camshafts :X Link to comment Share on other sites More sharing options...
mk2vitesses Posted April 9, 2010 Share Posted April 9, 2010 A few years ago now, a chap I knew was into BIG yank cars. He had a Oldsmobile 88 or 98 BIG Limo not sure, anyway he rebuilt the engine and fitted vari cams to it. At the time I had know idea what that was, I still don't know how that replaced the standard fixed cam, anybody? Link to comment Share on other sites More sharing options...
GT6Steve Posted April 11, 2010 Share Posted April 11, 2010 That Porsche setup is nothing more than a phase variator. Lengthens one chain whilst shortening the other side. Unless it was active, that's a whole new can of worms. I've been doodling Fredericks idea and I see it's entirely doable. Probably not in the original cam cover but if incorporated with the belt drive I've been noodling on FOREVER it could be done. Just the thing to make the project take longer.... Link to comment Share on other sites More sharing options...
spitNL Posted April 11, 2010 Author Share Posted April 11, 2010 Just the thing to make the project take longer.... Sorry Unless it was active, that's a whole new can of worms. What do you mean unless it was active? That it changes the timing with rpm? That it did and that was what I was contemplating, otherwise a vernier gear would be much easier. Belt drive would make it easier to incorporate, but a lot more work I think, and not so easy to DIY. (at least for me) If you're going to all that trouble you might as well go OHC. Cheers, Frederick Link to comment Share on other sites More sharing options...
spitNL Posted April 11, 2010 Author Share Posted April 11, 2010 Just the thing to make the project take longer.... Sorry, Steve Unless it was active, that's a whole new can of worms. What do you mean unless it was active? That it changes the timing with rpm? That it did and that was what I was contemplating, otherwise a vernier gear would be much easier. Belt drive would make it easier to incorporate, but a lot more work I think, and not so easy to DIY. (at least for me) If you're going to all that trouble you might as well go OHC. Cheers, Frederick Link to comment Share on other sites More sharing options...
GT6Steve Posted April 11, 2010 Share Posted April 11, 2010 Sorry, Steve What do you mean unless it was active? That it changes the timing with rpm? That it did and that was what I was contemplating, otherwise a vernier gear would be much easier. Belt drive would make it easier to incorporate, but a lot more work I think, and not so easy to DIY. (at least for me) If you're going to all that trouble you might as well go OHC. Cheers, Frederick I did not think of changing the phasing with RPM! Cute. That's a whole new set of doodles ;D I was pondering it being externally adjustable for dyno testing. On the Jag sites there's a fellow who's building a variable cam setup for his E-Type like the Hondas do. I'll bet it's finished by now... Here's the link, it's not quite what I thought...http://www.jcna.com/library/tech/tech0016.html Link to comment Share on other sites More sharing options...
spitNL Posted April 11, 2010 Author Share Posted April 11, 2010 On the Jag sites there's a fellow who's building a variable cam setup for his E-Type like the Hondas do. Have you got a link? edit: is this it? http://www.jcna.com/library/tech/tech0016.html http://www.jcna.com/library/tech/tech0025.html 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