Piper Cams fast road reprofile review.

sdibbers

Well-Known Member
Back in late April I fitted the Piper cams reprofiled fast road camshaft. You supply a good standard camshaft to Piper in Folkstone, they take it, check it to make sure it’s up to the job then reprofile to give 10.41mm lift and 260° duration for both inlet and exhaust. This is over the original 9.41mm and 240° for the stock camshaft.

Before fitting I would strongly advise that you’re sure the rest of the engine is ready. In my case I knew the main bearings, big end bearings, bores and piston rings had very little wear. I’d also just had new valve guides and seats fitted, checked the cylinder head for flatness and crack testing of the head. In case you’re wondering, I got the head tested for flatness and chose not to have it skimmed because I’ve seen heads excessively skimmed to the point the timing chain is too loose.

Changing over to the new cam requires some preparation. Check the tappets for any wear on the contact surfaces. They should be perfectly flat. Remove the camshaft following the manual specified route. Measure each stack of shims. Add about 1mm (0.040” for those watching in black and white) and replace shims and tappets.

I filled the camshaft with fresh high zinc 20w50 oil. Used assembly lube on the bearings and carefully fitted the new camshaft. We add the extra height to the shims to accommodate the material removed during the reprofile. They gain that extra 1mm of lift by reducing the cam’s base circle diameter. Refit the sprocket and turn engine over two full revolutions to check clearances. Now measure all valve clearances to Piper’s specs. Inlet 0.010”, exhaust 0.012”. Calculate the correct shim heights and change as needed (hint: they’ll all be wrong at first!). Rinse and repeat camshaft removal and shim placement. Once back together measure valve clearances again to be sure.

Now you’ve got the clearances set it’s time to adjust the valve timing. Piper recommends 106° for EP. So using the timing marks on the flywheel set it at 106°, make sure you have tension on non tensioner side of the timing chain and adjust the sprocket so the cam key and slot are perfectly aligned. There’s a good guide setting valve timing here.

Ok, two last turns of the crankshaft by hand to check nothing is hitting anything else and then it’s time to prepare for the first start.

With flat top tappets such as ours it’s especially critical you use an oil with ZDDP added such as VR1 race oil or any of the classic blends. The zinc lubricates the high pressure areas of the cam touching the tappets.

Piper is very clear on how you need to have higher revs straight away at start up. Lower revs increase surface forces on the new lobes and destroy it in seconds. With that in mind use the priming lever on the mechanical fuel pump to fill both float chambers of the carbs. Ensure everything is ready for a clean startup. Turn the key and as soon as it starts raise revs to 2,000rpm (I hated this bit - it seems so wrong!). You now have to hold the revs for 20 minutes to bed everything in. Be prepared to apologise to the neighbours afterwards (better to ask forgiveness than permission). If you find a leak or have issues, stop the engine immediately. When you start again go straight back to 2,000rpm.

So now we’ve bedded in the new camshaft. You’ll most likely find you’ll need to adjust mixture, and possibly needles for the carbs. I’m running a 2000TC engine bored out to 2200 with twin HIF6 carbs. I’m running BBZ needles and the car seems happy with them across the range. Interestingly enough I found that the rear carb now is exactly the same for mixture as the front, this wasn’t the case with the std camshaft with no visible wear. I’m running idle a little faster at 750-800 rpm now, possibly because of the extra duration. I also checked and adjusted balance on the carbs to
ensure all was right. Ignition I set to 8° BTDC on the dissy I had rebuilt and recurved to match the engine when I rebuilt it as a 2200.

Road test: So first impressions when set up? Idle is smoother, as is power delivery. Torque is a good bit higher, you can pull away at idle in first easily. The torque curve stays there all the way up the revs. That and power really come on at 3500rpm and above with the car not running out of puff at redline (before it was pretty much done at 5,500rpm). This means it’s very sprightly above 70mph, overtaking at highway speeds are easy and it feels much less stressed and thrashy at higher revs. Most of this is from my butt dynometer (as a friend over here calls it). But I can tell you on the track that last year on the main straight at Lime Rock Park I’d hit 90mph before turn 1. This year I’m hitting 95-97mph on the same straight.

One unexpected bonus: When I’m not driving like hooligan fuel consumption has improved by about 10%. Result!

Would I recommend the cost and time involved in this? Depends on what you want from your P6. I like sporty driving and this helps deliver just that.

The up sides are:

More power and a bigger torque band.

More relaxed driving because of power and torque increase.

In my case, better fuel consumption.

Performance matches or exceeds most modern cars, an important safety consideration.

The down sides are:

£220 is a fair chunk of change on top of the costs of fitting if not doing yourself.

You need a good std camshaft to supply. If you are using the one in the car expect 2-4 weeks turn around time from piper.

I knew it would take a while to fit and get setup correctly. Budget a full day’s work for this. You don’t want to rush it and make an expensive mistake.

shiny new camshaft
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Assembly lube on bearings
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Measuring valve clearances
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Realised I’d posted a lot of this a while back. But the last bit shows my impressions after a few months of motoring with it. Excuse my terrible memory!
 
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