How do I know if I have a Q420 cam

[bronco]

I am rebuilding my twin cam engine out of my 1971 Lotus Elan Sprint DH. I am just about to start working on the valve clearances.

In 1985 the engine was rebuilt by QED to Q420 spec' through a previous owner.
How can I be sure my cams are Q420's? There seem to be no identifying marks.

I understand the valve clearance will be different to the standard .005 to .007 and .009 to .011 using a production camshaft.
Assuming they are Q420's what should the clearance be?

[garyeanderson]

Take a look at to rear of the cam, the end that doesn't have the cam sprocket on it. May give Ken at QED a call and ask for the clearances but the clearances you gave would be a good start i would think.



Gary

[SimonH]

Bronco,

I have no idea about the markings to identify but this post has a data sheet for them courtesy of OEW.

Cheers
Simon

[SimonH]

But Gary does! Must type faster next time.

[bronco]

No such markings on my cams......... unfortunately.
I wonder if they weren't stamping them that long ago?

I remembered I had a dyno test done when I first got the car and I managed to find the data sheet, it made 138BHP at 6500rpm (1990ish)
The engine analysis sheet from QED, when the engine was rebuilt, recorded 148BHP at 6500rpm.
A standard Sprint is, what, 125BHP at 6500rpm so it seems likely they they are Q420's.

Thanks for putting me onto the data sheet Simon.
QED Data Sheet: Exhaust 0.007 to 0.009 Standard 0.009 to 0.011
QED Data sheet: Inlet 0.004 to 0.006 Standard 0.005 to 0.007
There seems so little difference I am not going to get worked up about it. I will work on the tight side of the standard figures.

Thanks for the help.

[CBUEB1771]

Take a look at to rear of the cam, the end that doesn't have the cam sprocket on it. May give Ken at QED a call and ask for the clearances but the clearances you gave would be a good start i would think.

Gary - good photo, Did Beau hold you by your ankles to get the upside-down shot?

[SimonH]

No such markings on my cams......... unfortunately.
I wonder if they weren't stamping them that long ago?

Could it be that they are reprofiled ordinary cams and so they dont get marked up as such?

Simon

[garyeanderson]

Hi Bronco

Your welcome.

Gary


Hi Russ

I had the photo in stock, there was no running around to get it. I did have to remember where the hell it was on the computer so that I could edit it and turn it 180 degrees in MS photoed and then send it off to photobucket where most of this trash gets hosted from. Yes, its free account that they will give out to anyone all you need is a 100 dollar camera and a dial up line (15.99 a month, 28k bps, a screamer - as thats what I do when the pop-ups take over) an you can be a ace spewbag too.

The cylinder head is the Kenny Duclos built head from the rebuild of 26/4597 from 1996. When it went on the dyno all was going well and it was making 100 hp at 4k (from 1700cc) and at that point Kenny noticed that it was pissing oil out of the spark plug valley from the cross feed oil gallery and shut it down. A phone call to me was made and a suttle statement was made "I'm done with your engine, You need a new head. Come pay the bill and pick it up or buy a new head and we can finish it."

So this is the old head that was eventully repaired when Kenny had the time and it been on the shelf since 2000 waiting for the next project. It was to go atop the AX block that you have now along with a set of 85mm JE pistons that I have but as you know, finances got in the way of that plan. It will probably will make 170 hp with 1760 or a bit larger displacment and was to get dropped into a Cortina for a bit of old fart at play fun. It's still going to happen, if by the time I can afford to finish the project I can remember which way to turn the stupid wrench (what the hell is this cold piece of steel and why am I holding it?).

This is the Kenny head on the floor in the kitchen next to the trash bag, there is good light there so I take lots of phots near this location.


DJ, is this how you like your thread drift? or should we start discussing round caps here?

[bcmc33]

FWIW, my QED 420 cams are identified exactly like Garry's.

[bronco]

I suppose they could have been reprofiled.
I am not sure how I could tell.

I think the biggest clue is the BHP, I think it's unlikely they're standard cams.

[garyeanderson]

I suppose they could have been reprofiled.
I am not sure how I could tell.

I think the biggest clue is the BHP, I think it's unlikely they're standard cams.

Hi Bronco

How much valve lift do you have? If they are reprofiled to qed420 specs they should have .420 inch of lift minus the valve clearance or .414 on the intake with.006 inch of clearance. This is measured with a dial indicator with the indicator mounted above the tappet and the indcator at the same angle as the valve (27 degrees from the centerline)
For a rough idea with the cam out of the engine and in your hand, measure the cam lobe from the heal to the nose of the lobe. Then measure at 90 degrees and subtract that figure from the first. That figure should be damn near .420 too.

Gary

****************************************************
04:00 pm EST

Hi Bronco

I took a look at the QED cams in the head. I got out the 2" micrometer and measured the cams (in the head so I may not have gotten the exact figures but they are close) and got 1.475 heal to nose and at 90 degrees I measured 1.050 for a gross lift of .425 if you take away the .004 to 006 for the intake thats .420 inch of net lift. I looked up the stock base circle of the Lotus B cams and that is 1.20 inch with .350 gross lift vs the 1.05 of the QED 420 so take a look at your and let us know.

Gary

[Dag-Henning]

"LP 039"...????? Wow, that must be a very early head..??!

[bronco]

Thanks Gary.
I should get my new shims thru the post on Saturday so I will be out in the cold over the weekend. I will measure the lift to see what I get.