For years now I haven't been able to get my Sprint to rev much past 6000rpm, maybe up to 6250rpm. Not that it's worth going past that figure as the engine has passed it's peak BHP by 6000rpm. In that time I've swapped blocks, chokes, replaced the uprated valve springs for standard ones & fitted a Megajolt system. I would expect this engine to rev to 7000rpm quite easily.
So I am wondering how much difference would be made by changing the valve timing by a couple of degrees?
The engine:-
Standard bottom end with Mahle pistons.
TT10106 equivalent camshaft by Newman cams.
Weber DCOE 45s with 40 or 42 chokes.
Head has been ported & polished.
Sports exhaust including larger bore stainless downpipe.
Cam Timing
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Mad Mart
- TDC Member
- Posts: 8534
- Joined: Tue Oct 03, 2006 5:48 pm
- Location: Winscombe, North Somerset, England
- Contact:
Cam Timing
Sprintless for the first time in 35+ years. 
... Still Sprintless.
Engines, Gearboxes, Overdrives etc. rebuilt. PM me.
2012 Porsche Boxster 981 S
... Still Sprintless.Engines, Gearboxes, Overdrives etc. rebuilt. PM me.
2012 Porsche Boxster 981 S
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jeroensprint
Re: Cam Timing
My yellow sprint revs to 7300rpm and has max power on the wheel of 139hp. Hans can state this but he still doesn't know why 
Maybe i will tell him once the secret of a good STD engine 
STD mahle pistons.
STD hs6 carbs
STD airfilterbox
STD camshaft
BELL sport exhaust
Ported head
Lightened std flywheel
Lightened std rods
All std and not new but good enough to had it re used.
I think in your case it's the ignitiontiming and it's importand to have all balanced very well. All rods the same weight and the rotating and translating weight also in balance. There are also lots of different clutch covers from aftermarket suppliers and these like the LUK or Valeo are much (1,5kg!!!) lighter than the original heavy ones.
Jeroen
Maybe i will tell him once the secret of a good STD engine STD mahle pistons.
STD hs6 carbs
STD airfilterbox
STD camshaft
BELL sport exhaust
Ported head
Lightened std flywheel
Lightened std rods
All std and not new but good enough to had it re used.
I think in your case it's the ignitiontiming and it's importand to have all balanced very well. All rods the same weight and the rotating and translating weight also in balance. There are also lots of different clutch covers from aftermarket suppliers and these like the LUK or Valeo are much (1,5kg!!!) lighter than the original heavy ones.
Jeroen
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Mad Mart
- TDC Member
- Posts: 8534
- Joined: Tue Oct 03, 2006 5:48 pm
- Location: Winscombe, North Somerset, England
- Contact:
Re: Cam Timing
Good point Ken, but I got similar rpm readings on the dyno so I hadn't looked at that.
Sprintless for the first time in 35+ years. ... Still Sprintless.
Engines, Gearboxes, Overdrives etc. rebuilt. PM me.
2012 Porsche Boxster 981 S
... Still Sprintless.Engines, Gearboxes, Overdrives etc. rebuilt. PM me.
2012 Porsche Boxster 981 S
-
jeroensprint
Re: Cam Timing
idem.Mad Mart wrote:Good point Ken, but I got similar rpm readings on the dyno so I hadn't looked at that.
Jeroen
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paulsprint
Re: Cam Timing
Cam timing will make a difference. A couple of deg advance (much more than 5 deg adv and the valves/ pistons get a bit close) won't but say 10 deg retarded will cause it not to rev. Also what is your ING map like. My engine was making best power at 27 deg advance. If you want I can email you a copy of my ING map.
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paulsprint
Re: Cam Timing
You can check the tacho by plugging the laptop into the megajolt. The rpm on there is 100% right. On the rolling road was the furling right at 6000rpm or was it leaning off