mark kibort

so, interesting enough, we saw 6 degrees (crank as you say) advance on the cam that shouldnt have any issues (driver side) and 3 degrees on the other side passenger. both were set at near 2mm with 20 degree crank advance.

so, Bill, did the tool point to 6 and 3 degreed advance based on 6 holes, so 6 degrees crank? I just want to make sure i understand what you saw, as i wasnt looking at that when you did it.

mk

PorKen

Which version of the 32V'r does Bill have? The V1, or the V2 which is in the picture I posted?

Because of different belt tension at different places in the rotation, the most accurate position to take a reading with the 32V'r is at TDC #1. Is where you were checking?

Bill Ball

V2 (just purchased from Roger after I mangled my original V2). I checked the tool's alignment too.

It was 6 holes advanced (+ side in your photo) on 5/8 and 3 holes on 1/4.

PorKen

The tool measures in CRANK degrees. It's range is -9 to +10, so it couldn't measure +12° CAM.

You might have seen a bigger gain if you had also moved the driver's side to 2.2 or so, then the cams would be close to syncronized when hot.

At the level of the V on the head, 2° equals 1.05 mm distance. As you go closer to the center, it's less, so at belt level it would be very difficult to tell with the naked eye.

mark kibort

I get it. now we know your tool is in crank degrees. the 12 degrees i mentioned was thinking that the tool was in cam degrees. SO, 6 degrees on the crank is 3 degrees cams, but we dont talk "cam degrees anymore"

so, 6 degrees is still a big diff. like i said, it would be over .5mm on the WSM adjustment method.

By the way, based on the WSM adjustment method, it is 1.6mm/2.0mm for passenger and driver sides, but did you know that the S4 is 1.8/2.0 mm? i wonder why this is???? also, that spec is +/- .1mm. SO, in spec, the S4 could be 1.9mm both cams.

mk

PorKen

Oops! Good customer!

Just to be sure, were you checking at TDC #1 for both sides? Counting in a up-down-zig-zag pattern, from zero, down 1, up 2, down 3, etc.?

So +6 was three upper holes left of zero?

mark kibort

So, what you are saying, is that with a new belt, we should see a similar differnce on the marks, as we would see with a hot engine.

I have the pics of a new belt and old belt. Let me see if you can visually see the diff.

anyway,, what do you think the reason is for the porken tool being so far off on my engine? variance in cams, brackets, heads, block, chains, sprockets.....etc?

mk

Bill Ball

Yes, TDC #1, counted holes in up/down zig-zag pattern. The tool was right on the money in Dennis's rebuild with S3 cams. The only difference is that we set Dennis's cams using the lobe center (max lift) instead of the WSM 20 degree lift because the cams had been ground (not changing the lobe centers).

AO

Mark it doesn't sound like it was that far off. You measured 6º crank (or 3º cam) advance. From the sounds of it you are 2º crank (1º cam) off.

PorKen

The S4 intake cam is not as aggressive as the S³, so the S4 lobe has less meat at 1.6 versus the S³, so the measurement is 1.8.

Cam| ¼ | ⅝
S³ | 1.6 | 2.0
S4 | 1.8 | 2.0
GT | 2.8 | 3.1
GTS| 1.83 | 2.08

All the different cam grinds have different lifts at 20°, but in degrees, all the 928 32V cams measure as below (±1°) with the V2 32V'r.

¼ | ⅝ Cold
-2 | 0

¼ | ⅝ Hot
0 | 0

In the range of error, but not purrrfect, when hot.

mark kibort

What do you mean? I measured the timing dead on for both sides 2mm. the passenger side could be off a degree or two based on it being retarded from the driver side, BUT the driver side was dead nuts on at 2mm at 20 degrees advance. So, the tool is 6 crank degrees off, no my settings. (3 degrees cam).

mk

mark kibort

If thats the case, explain the S3 vs GT cams........ .3mm vs .4mm diff. they are the same cam with the same duration and lobe profile. why the gap?

I think the answer here is just to a cam timing when the engine is hot.

I can verify this with a the marks to see if we are getting any of this kind of movement. 1-2 degrees seems like a lot of stretch, especially compared to the other cam setting which seems to have its offset caused by the engine growth geometry.

mk

AO

Sorry, I was thinking it but didn't write it...

It's not that far off if you account for 4º crank (2º cam) for expansion of the block (cold v. hot) and probably 2º crank (1º cam) for the stretching of the belt.

Sorry for not being clear before.

PorKen

Oops, 1.05 mm is not right, here are the precise measurements for 2°.

Top row of 32V'r holes - 1.408 mm

Bottom row of 32V'r holes - 1.384 mm

Top of belt (74.5 mm from cam center) - 1.298 mm

Remember, GT intake cams are advanced 8° versus S³ (open at 3° ATDC) so you are checking at a different lobe thickness.

S³ and S4 intake valves open at the same point, 11° ATDC. GTS open a little later, 13° ATDC, and the (cold) difference between banks is .25 mm.

Checking (with the 32V'r at TDC#1) with a hot engine is the ideal.

Louie928

A suggestion.... Don't get too wound around the axle on the initial cam timing settings. Ball park is good enough now. Once the engine is running, and the rings sealed, take compression with the engine hot. Both sides should be the same. The side with higher compression has cams advanced (intake valve closing sooner) with respect to the cams on the other side. You can use Ken's tool to take a reference cam timing setting when you get equal compression. After that, use Ken's tool to advance, or retard both sides an equal amount to get the torque curve you want. Mark is expert at figuring torque under the curve between the shift points he wants. Time the cams to get the best compromise for those shift points. I'd anticipate, he'll want his cams set 5 or more degrees retarded from the WSM specs.