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+--- Thread: Re-profiling Cam Followers (/showthread.php?tid=3015)
RE: Re-profiling Cam Followers - GK5268 - 02-07-2019
I fitted these on my Ruby about a year ago now, a definite improvement in performance and the most noticeable tweak I made, more so than when I changed from a LC to HC head!
I found that under load the engine revved less at a given speed, which makes for slightly quieter driving (haha), getting more bang for your buck.
Fuel consumption is around 35 - 38 mpg depending on driving, but as the roads are fast and heavy with traffic most of the time around where I live I need to keep up with modern cars so as not be seen as a nuisance and the car is much more usable than before (now my daily driver this year), so I have been very pleased with the flatter tappet blocks.
With my close ratio gearbox, I have quick acceleration off the mark, quite a respectable performer!
All I need now is better road surfaces...
RE: Re-profiling Cam Followers - Jack in the Box - 02-07-2019
Evening Gary,
I am struggling with your second sentence. You seem to be implying that your gearing has changed, or am I missing something?
Thanks Alan
RE: Re-profiling Cam Followers - Ian Williams - 02-07-2019
Is there any advantage/disadvantage of flatter radius tappets with a standard camshaft?
Absolutely! better power and torque, at the expense of slightly greater wear of the cam gear.
RE: Re-profiling Cam Followers - GK5268 - 02-07-2019
Alan, there is more power, so the engine needs less revs to give the same output, it was very noticeable at first (going up local hills), but not so now as used to it as it is still noisy! And since fitting the c.r. gearbox the car is much more usable and much better hill climbing.
RE: Re-profiling Cam Followers - Chris KC - 03-07-2019
Has anyone ever tried different combinations of follower radius / cam profile on an engine dyno? Some objective data to compare (i.e. torque / power curves) would be a wondrous thing.
RE: Re-profiling Cam Followers - Bob Culver - 03-07-2019
Few make one change at a time so all observations are clouded. And for most Seven owners what happens beyond 4000 or even 3500 rpm is of little interest so gains beyond that not relevant to them.
There are a myriad timing gears about and I often wonder what actual timing is on other cars.
RE: Re-profiling Cam Followers - Greig Smith - 03-07-2019
It might be helpful if someone could post side by side pictures of a standard follower & a modified follower ??
Logic says a flatter radius would give a slightly longer open duration at the same cam lift & clearance, which would allow a tiny bit more mixture into the cylinders.... more mix = a bigger bang = more power
Aye
Greig
RE: Re-profiling Cam Followers - Charles P - 03-07-2019
Same duration but faster rate of opening, so the total charge that can be ingested is greater.
RE: Re-profiling Cam Followers - GK5268 - 03-07-2019
(03-07-2019, 09:34 AM)Greig Smith Wrote: It might be helpful if someone could post side by side pictures of a standard follower & a modified follower ??
Logic says a flatter radius would give a slightly longer open duration at the same cam lift & clearance, which would allow a tiny bit more mixture into the cylinders.... more mix = a bigger bang = more power
Aye
Greig
Spot on, the re-profiled tappet blocks are shorter (obviously as originals are ground down!!!), which is why the bronze tappet guides need to be cut down so that the locking nut has room to do its thing. With the shorter guides there is more room in the chamber to fiddle about, which makes re-assembly that much easier compared to the standard set-up.
I did have a photo showing the difference, but can't find this now, but there was a post on the Forum awhile ago with photos showing the difference, should come up on the search facility, if I find it I will post a link.
RE: Re-profiling Cam Followers - Ian Williams - 03-07-2019
Anyone who is considering playing around with followers would also be well advised to look at removing any material from valve which hangs below the seat. Think about it, you do not want anything shrouding the port opening once the valve lifts from the seat, every small gain counts, and coupled with re-profiled followers the effort is very worth while.