A new belt will retard about 2° after it's normal break-in stretch. This might also explain the 2° advance.



It's going to be close to 100° here this week, and I need to do an intake R&R to put in my crank breather system, anyway, so I'm going to wait on the dyno until next week.

 

I'm confused, but that's not unusual.

MY 1-4 5-8

'93 +2 +2

Belt is broken in and engine cold.

Is this what you would set for street use?

 

For an auto, +2 gives you a torque advantage. (Autos can't really use the HP peak very often, anyway.) I am going to adjust my auto to this, soon.

With a cold engine, 1-4 should be 2° retarded of the 5-8. Measured hot (painful to do), both sides will be equal.

I would change to the following - retarding the 1-4 is much easier than the 5-8.

MY 1-4 5-8

'93 _0 +2

 

Going to make these to see if adjusting can be easier. The 'socket' will locate on the big hex washer -and- the 5mm bolt heads. Hopefully the extra torque provided by the gear hub, plus the regular 32V'r spacer, will allow the cams to be rotated (CCW) w/o having the cam bolt come loose.

The wrench should at least make R&R'ing the cam bolt easier.

I'm also going to replace the 10x55mm cam bolts with flange head bolts for more grip.

 

So on my 90 S4 auto I did 1-4 -2 and 5-8 0 with new belt and engine cold. Is that correct?
What should my 91 GT 5 sp be set at with the belt having 3k on it?
Thanks
Bilal

 

With a new belt I set the 1-4 to 0 as the belt stretches about 2° after a few hundred miles. So, 1-4 0, 5-8 0. Recheck after a 1000 miles or so.

With a used belt, -2/0 cold (factory setting), would be fine for the GT. Or, you might want to go -4/-2 cold.


Here is the GT timing dyno from Ott's Performance which shows a HP advantage with 3° retard.

I like -2°, as this is timing the cams 'straight up', in line with the cam key. I am going to dyno my '86.5 5-speed with this as soon as I finish R&R'ing the intake.

 

i saw a 3-5hp gain with a 6-8 degree retard.
i think the real effects are the loss of peak torque traded for the gain of high RPM hp and the duration of HP at the top rpm.
kind of the basis for the GT cams vs the 85 cams.

 

If you need any "seed money" (read: Early purchase) on that tool set Ken, let us know. I have at least three engines I will need to use it on.

 

B - I am ordering the laser cutting tomorrow. I have to see if the socket fits, and if it helps. Then I'll see about making more of those.

I don't think the wrench needs to be hardened? It is close tolerance, and closed loop, so it doesn't need to be super strong, IE it could be a fairly inexpensive item. Maybe I should put a 17mm on the other end?

 

Hello All

I would like to issue a big congratulations to Porken on the 32 vr , I have just finished a cam adjustment on my 5 litre engine , and could not believe the ease at which it could be done with this tool .
I have been one of the old school and used the manual method to do this in the past , which guarantees a complete days work on the adjustment alone . With the tool I can get it acucrately down to 2 degrees where I wanted it , this accuracy can be nowhere had with the manual method . I thoroughly reccomend it to you all .
The ingenuity of humanity never ceases to amaze me as opposed in contrast to the stupidity of the global warming religion .

Thanks Porken for this great tool .

 

^^^^Yeah, what he said. I had never timed cams before and it was super easy.
Now what i want to know is what can I do to the timing to get more off the line grunt. I am talking CLK 63 AMG grunt like I drive at work. We have a bunch of AMGs and after driving them my car feels like a snail.

 

Jeff,

If you want AMG grunt in a 928 you need an AMG type of engine! When Marc Thomas developed the Devek White car a lot of folks forget that this vehicle was a "torque monster""and torque off tickover was immense. Indeed tuners who built these motors generally had to "push'' the tune to the top end power to prevent low end torque ripping apart the manual tranny they were invariably mated to. The auto box does not have these limitations.

No amount of tuning will get you that kind of grunt and doubtless you are well aware of that. So, your options are a stroker kit [presumably about $20k by the time it is built by a pro or a twin screw at about $10k+ when installed. I have always believed the twin screw would be awesome on an automatic if correctly engineered and well sorted, and such kit would completely transform the machine to reestablish the 928 as a modern day supercar in most respects- I am sure Tony and others will attest to that.

Regards

Fred R

 

Fred. Yeah I know. It is frustrating though to have a freight train under your foot and then get back into your freight train and it feels like the little engine who could in comparison. I am exploring ideas on what to do for more power, Murph, TwinScrew, Turbo, stroker, LS1. They all have their devils.

 

The new tools worked great! The dimensions were not quite perfect, but the prototypes still made adjusting -both- sides trivial.

I was able to retard the 5-8 on Keith W.'s GTS in minutes, instead of hours. Freshly installed replacement cam gear was 5° advanced, was able to retard to 0 by just turning the cam CCW - bolt did not loosen. Awesome. (Pics tomorrow.)

 

Ken:

Put me down for a set of these tools when you have some more made.

Thanks,