17 replies to this topic

[Dusky]

Hi guys!

 

I've always been under the impression of owning a AEG 643 camshaft. ( quoted 7.62 mm valve lift)

Tho, I was a bit bored today and I measured the cam lift with my DTI on the pushrod

 

On the inlets this was around 8.03 mm and on the exhausts this was around 8.05 mm ( wich is basically all the same?)

this is the cam :

 

 

 

Anyone has any idea what cam it is?

I've thought about a KENT 649 too ( lift is around the same?)

Edited by Dusky, 14 September 2015 - 08:20 PM.

[Spider]

The Core is / was an AEG-643, genuine BMC / BL Grind. You'd best measure it completely to see if it's still that grind or been re-profiled to something else.

[Dusky]

The Core is / was an AEG-643, genuine BMC / BL Grind. You'd best measure it completely to see if it's still that grind or been re-profiled to something else.

So that will involve getting the timing disc out and measuring intake and exhaust durations etc? 

I think I know what I'll be doing tomorrow morning...

[nicklouse]

Really you need to measure without using pushrod. As you could be putting is some error.

As the real measurement is 7.77mm for the 544/643

[Spider]

Here's an ST Cam Sheet (from the Midget / Sprite - sorry it's the clearest one I have to post here);-

 

 

There are a number of methods for checking the cam profiles, all correct, it just should be noted how it was measured, ie, direct off the cam (with a follower) or at the valve.

 

The published ST sheets, like this one here, are at done with the head fitted and the Tappets set to either 0.016" or 0.019", in the case of the C-AEG643 they should be set to 0.016".

 

For the purposes of establishing what Cam / grind you have, there'd be nothing wrong with fitting the cam up, with followers and checking off a pushrod, you are not looking for academic resolution down to the 0.0001" only to get a profile shape, opening, closing and full lift angles.

[Spider]

Cam choices are a bit like interior decorating - everyone has different tastes.

 

I did have a 643 in a car a (good) few years back, fitted with Helical Close Ratio Gear Set and a 3.44 final drive. I recon it was a really great combination, it was - I felt - just about as far as you could realistically / comfortably go for a road going all rounder car (it was my daily driver for about 6 years), great performance and amazing mileage (at steady throttle), it came on the cam like a kick in the backside bang on 2500 RPM, below that, it was well 'off' the cam and not remotely tractable, but above that, had bags of power all the way to 7000 RPM. Our suburban speed limits are 60 kph and in top gear it was just on the cam at about 62 kph, so getting about in top gear was just possible, mind you, if it dropped down to 60, you'd be reaching for 3rd gear.  Looking back, I probably should have advanced the timing a few degrees just to make it a little more friendly at the lower end.

[Dusky]

I bought this cam 2 years ago to be honest, and I didn't have a real clue about camshaft designs, or I wouldve bought a 'tamer' cam

 

WHen I put a timing disc on the cam itself ( no crankshaft in the engine yet, that'll be for tomorrow) the inlet valve is opened for around 210° on the camshaft itself. Could thsi be realistic? Or should I try measuring it in a different way?

 

cheers

[hhhh]

210 in cam degrees? That's 420 crank degrees which is ridiculous, considering 320 is as high as was ever produced by BL racing. What clearance are you measuring at?

[Dusky]

210 in cam degrees? That's 420 crank degrees which is ridiculous, considering 320 is as high as was ever produced by BL racing. What clearance are you measuring at?

Thats my problem with it too, The number was outragously high ( and couldn't get my midn around it)

Tried measuring it at 0 clearance (hence the inaccurate figure probably ) , dont know at what clearance the ST cams are measured to be honest...

 

EDIT: think I just miscalculated. added 30° to 180° instead of substracting it, so must have been around 150° wich would be 300° duration, right?

Edited by Dusky, 14 September 2015 - 11:03 PM.

[nicklouse]

Again to add to spiders comments above. The bigger the engine the tamer the cam feels.
And modern ignition systems can also tame the engine. As can injection.

As you will notice from the table above many have the same lift with just duration being different.

Just to make my comment about measuring at the push rod yes fine if head with valves and rockers are fitted rather than a few standing push rod.

[Spider]

The C-AEG643 is a 288 degree cam.

[Spider]

Nicklouse's advice re: Ignition System and in particular, Injection is spot on I recon, Injection in particular can make HUGE Ports and Long Duration Cams quite user friendly, but only if set up right and for that in the first place, which includes very careful placement of the injector itself.

 

I bought this cam 2 years ago to be honest, and I didn't have a real clue about camshaft designs, or I wouldve bought a 'tamer' cam

 

 

So, reading between the lines here, you have driven with it and found it a bit too cammy?  You can re-fit it and advance it by 4 to 6 degrees, I think you'd like it much more.

Edited by Moke Spider, 14 September 2015 - 11:36 PM.

[nicklouse]

Nicklouse's advice re: Ignition System and in particular, Injection is spot on I recon, Injection in particular can make HUGE Ports and Long Duration Cams quite user friendly, but only if set up right and for that in the first place, which includes very careful placement of the injector itself.

I bought this cam 2 years ago to be honest, and I didn't have a real clue about camshaft designs, or I wouldve bought a 'tamer' cam

 
So, reading between the lines here, you have driven with it and found it a bit too cammy?  You can re-fit it and advance it by 4 to 6 degrees, I think you'd like it much more.

dont think it has ever been fitted.

[Dusky]

 

Nicklouse's advice re: Ignition System and in particular, Injection is spot on I recon, Injection in particular can make HUGE Ports and Long Duration Cams quite user friendly, but only if set up right and for that in the first place, which includes very careful placement of the injector itself.

I bought this cam 2 years ago to be honest, and I didn't have a real clue about camshaft designs, or I wouldve bought a 'tamer' cam

 
So, reading between the lines here, you have driven with it and found it a bit too cammy?  You can re-fit it and advance it by 4 to 6 degrees, I think you'd like it much more.

 

dont think it has ever been fitted.

 

tted ever since I had my 998

I must say I like it, but reading about it makes it sound too cammy for my 'target', so I would think a 266 orso could have been better :)

 

 

When measured @ 0.015" lift I get around 142-143°

Edited by Dusky, 15 September 2015 - 09:02 AM.

[jaydee]

Zero the wheel at TDC, both valves will be open, if you turn the crank backward and detect where the inlet opens, it will point between 30-35 degs on the wheel.

Now crank it, the wheel will go past the 0 and the 180 marks then the inlet closes with the wheel showing around 110 degs, you can do the math now.

Thats what i'd expect from a 288 degs cam.

 

Most standard road cams are between 230 and 250 degs, at 210 it will be way too short.

Edited by jaydee, 15 September 2015 - 10:00 AM.