camshaft identification

[gttjames]

Right guys confusion going on here, where im at...

Unknown engine, pulled cam out the other day, standard 'C' and 'U' markings on the end - assume standard...?

Went to see a forum member yesterday who had a piper 270 from his old build, i think he said was fitted by bbpt so was sure it was piper 270, has the same 'C' and 'U' markings on the end as my standard cam, but he pointed out next to the 4th came lobe (going 1 from timming cover) just to the right of the cam lobe it has stamped '270', now at work with my engine and see my cam has this '270' stamp aswell. Im thinking all the standard cams have 270 stamped on them?

They both have renault stamps on them the opposite side of the 270 stamp, so are they both standard, or are they both 270, or... possibly the 1 i bought is a piper 270, but a re grind with no markings.

I was under the impression the cams had 270 / 285 / 300 etc stamped on the gearbox end?

Rang CGB as i know they sell piper cams to see if they knew, there answer was they have sent cams there for a regrind and come back without any markings?

anyone help little bit stuck:(

[Brigsy]

Both sound like standard cams, all of the standard cams ive seen have 270 stamped in the middle.

[Kris M]

Both standard, as brigsy said they all have 270 cast halfway along, confuses alot of people ;-) all the piper ones ive seen have BP Followed by the number stamped on the end

[Sparkie]

ive seen a ktec one, with nothing at the end of it. - but if you compare with a std lobe, then its immediately obvious.

put a picture up of the lobes, we should be able to tell if its been reground.

[Fordy]

surely you could just measure the cam lobes and compare them against a stock cam or specifications of a stock cam?

[Ian S]

It's far from clear but here is stamped BP270:

http://www.rtoc.org/boards/picture.php?albumid=1507&pictureid=4366

http://www.rtoc.org/boards/picture.php?albumid=1507&pictureid=4367

[Ian S]

I've looked for my camshaft article but it appears to be gone!! :crap:

So here's the height of my BP270 from lobe tip to opposite side:

32.06mm

Measured all 8, they are the same, so no wear there :)

[gttjames]

Damn, there both at work, will get a picture tomorrow of both and post up.

With regarding looking at the lobe height, if its been reground couldnt it appear a smaller lobe, hence the reason for needing longer push rods, or putting the nuts on the other side to compensate:confused: - but yer looks to me there both going to be standard

the guy i bought it off said bb tunning fitted it for him, i never had any dealings with bbpt but they said its a piper 270... i wont say anymore

ian iv just got in - you have a PM

[Ian S]

I think I correct in saying that they leave the lobe height and grind off the other side.

This makes the lobe proportionally taller than the other side, hence a taller valve lift.

A re-pro, I presume, will have a smaller 'other side' radius.

I presume they can take the grind right up to the lobe so it can look more pointy.

They can shift the lob over a little bit too, but obviously that will make it a bit shorter and will need even more taking off of the other side.

As far as I know there are no "longer push rods".

"Nut's on the other side"? Not often. That would be a re-pro with a huge amount taken off the other side.

My measurement is the total span from lobe tip to other side.

[Sparkie]

As far as I know there are no "longer push rods"..

gordini turbo ones are longer

[Ian S]

That's a different head though. Am I remembering correctly that at one point you had an extra tall cam in your 5GTT? Did you use them in in that?

[gttjames]

I've looked for my camshaft article but it appears to be gone!! :crap:

So here's the height of my BP270 from lobe tip to opposite side:

32.06mm

Measured all 8, they are the same, so no wear there :)

right well measured the 2 cams i have here, and readings on my cam range from 31.94 to 32.06 across the 8 lobes

i also measured the cam i picked up at the weekend which is a 'piper 270' with no markings, the measureements from lobe tip to other side range from 31.90 to 31.98

So... my cam from vehicle has some lobes the same as your piper 270 and some slightly down to 31.94 (is this a big drop or within tolerance???)

what should measurements be on a truly standard cam, is it alot of difference im looking for here like a whole 1mm or is it minimal like iv found?

also both cams i ahve ehre have a section of red paint on in between 1st and 2nd lobe (from timing cover end) is this seen on normal standard cams?

[gttjames]

ive seen a ktec one, with nothing at the end of it. - but if you compare with a std lobe, then its immediately obvious.

put a picture up of the lobes, we should be able to tell if its been reground.

pictures as requested... my camshaft is on the left (out of unkown engine with no history) and on the right is the unmarked but with standard cam marks 'piper 270' picked up from a forum member at weekend.

both have standard cam markings, and red paint on them

http://i15.photobucket.com/albums/a371/sr50james/camshaft006.jpg
http://i15.photobucket.com/albums/a371/sr50james/camshaft007.jpg
http://i15.photobucket.com/albums/a371/sr50james/camshaft008.jpg

Also i have a graph from when it was rolling roaded agesss ago but it was with the unkown engine, but someone might be able to tell from the graph a guess weather its standard or not? mods are t25 .47, front mount, and 17psi and it made 187.5BHP @6565RPM (104MPH) 163.1 lbft / 5291RPM



sorry for bad quality pic

http://i15.photobucket.com/albums/a371/sr50james/rrpic007.jpg

[Sparkie]

they look the same to me.

[Ian S]

Right, I've got to the bottom of this conundrum.

I knew I had to find and measure my standard cam.

I found another cam but it was the one marked BP270. The one I measured the other day was the standard cam. I no longer know why I left it where I did with some of the removed parts from the modified engine but that was possibly five years ago and so I'd assumed, without looking at the end, that that was the 270. Maybe I'd retrieved the standard one to measure, sell, or put in for a re-profile and didn't put it away.

So, the BP270 measures between 30.67mm to 30.83mm.

Maybe there's wear there or maybe that's within Pipers tolerance.

The cam BB allegedly fitted was a standard came then. In lift at least.

My standard cam came from my original engine that I've owned since 1992 and had done about 80,000 give or take a few, and appears, buy my digital calliper measurement anyway, to have no wear.

These measurements, about 1.2mm taller for the BP270, concur with the camshaft graphs: http://www.rtoc.org/cam/?cam=std+GTT&lsa=&cam2=Piper+270&lsa2=&rocker=1.5&advance=0&vc=0.2

But they should. Those measurements are for this very same BP270 that I took and gave to Andrew Cooke for the previous version of that chart.

[gttjames]

Right, I've got to the bottom of this...

great work Ian. So your original measurements of 32.06 tie in with the 2 camshafts i have here, and this shows they're standard.

And your marked piper 270 gives measurements of 30.7/30.8 which is obviously different to the standard measurements i have here.

So despite the cam lobes being smaller in height, its still a 'performance' camshaft, regrind so the the lobes are smaller but the lift is faster etc, more adjust needed on tappets, correct?

Thanks again Ian, was well confused here.

[Ian S]

Yes :)
So despite the cam lobes being smaller in height, its still a 'performance' camshaft, regrind so the the lobes are smaller but the lift is faster etc, more adjust needed on tappets, correct?.They grind the opposite, not the lobes. Each lobe tip is the same distance from the cam shaft centre, but by cutting away the other side, the lobe is PROPORTIONALLY taller. Therefore by adjusting the tappets in to the smaller radius of the opposite side (back) of the cam, when the lobe comes around, the valve is opened further :)