Tom928

I am looking into changing from the stock to Euro cams on my 81 and have a couple questions;

Lift on the Euro's is higher and duration is longer. With US pistons - does this mean the engine becomes interference?

Ignition timing - the 79 and 84-86 cams show a different timing. 79 is 31 degrees, 84-86 is 20 degrees. I presume the timing changes with the cam?

What issues if any do you run into with Euro cams?

Many thanks,

toofast928

So ignition timing spec follows to cam, not the distbutor?

Lizard928

total amount of timing advance will go with the distributor not the Cam, the camshaft simply drives the distibutor.

look at there base ign settings, the US may be 6 deg where the euro may be 10 with no vacuum advance and at idle.

Tom928

So after installing Euro cams I stll set the timing to 23 degrees (US 81)?

Garth S

That is a reasonable place to start, but may not be optimum: while you have euro cams, you do not have euro pistons, their compression, etc ... so the optimum point will likely reveal itself with some experimentation.
The stock 23 deg ( @3000rpm) is a summation of static timing (x deg) + centrifugal (y deg) with vac advance and retard lines disconnected. The total is taken at 3K rpm to assure that the centrifugal portion is maxed out as the weights swing out to advance the 'advance plate': When in service, vacuum actuators further act on this plate to advance or retard it depending on engine load at rpm ( which varies vacuum).
All of this conspires to shape the advance curve vs. RPM .... and by changing the cams, the engine often ( but not always) optimizes on another curve.
Your mission, yungtomgrazhoppa, is to find the new curve ...

While the distributor applies the advance curve, it is the compression, cam lobe profile, cam timing, and a few other things that define what that curve should be .... re a previous query.

mark kibort

I did this, first one that i know of, and it worked fine. 83 euro on a US 84 motor. with the intake, 243rwhp up from 200whp. the engine is alread a interferance engine from the beginning.
the piston valve reliefs hit the valve at .3". most of the cams are in the .4" range


mk

JP Rodkey

I transplanted my '79 Euro cams into '84 US heads and set timing specs for a '79. Engine idles great, correct temperature, no pinging........no problems at all. Don't have dyno results, but it worked well for me.

Jim bailey - 928 International

Yes..."I did this, first one that i know of,.." which only points out that you do not know.

LT Texan

the '81 has a 9:1 comp ratio? with the longer valve timing, would cylinder pressures be too low? I'd think you'd want to raise the comp ratio along with doing this.

mark kibort

the hp curve showed no peak torque gains, but only HP gains. (but no losses either)

mk

Lizard928

Mark K,
since when is the 16V 84 US car interference?
I just helped a friend who just got one and the nose of the camhaft broke off, we just swapped the cam, I looked at the valve stems and they all appreared proper (ie no bent valves holding them open).
We finished bolting it all up today and it fired up first crank, and ran beautifully.