Charley B

I haven't reread the whole thread so this may be redundant, but do you have any other evidence of overheating? I'm guessing chances are at least 50/50 the gage is not correct. What kind of laser temps are you getting off the engine?

Mrmerlin

drive the car till the temp gauge gets to near the hot zone quickly open the hood and check the top rad hose and top of the radiator with your laser temp gauge if its in the neighborhood of around 185 to 200 degrees give or take , it sounds like your car coolant system is operating correctly

Louie928

Brian, I did a couple of tests on my (5L) GT with the cams advanced and retarded 6 crank degrees from stock. I wouldn't say that one way was better than the other. Retarded cams gave better top end above about 4300 and advanced cams gave better power below 4300. The stock setting was a good compromise. I notice in this thread that these cams were both set the same. I thought the right side should be set a couple degrees retarded as compared to the left side when cold. The right side will advance more than the left side when the engine heats up.

edco

Hey Guys,

I haven’t put a whole lot of miles on the car since Bill and I adjusted the timing after the Bonneville 100 ORR last month. I have driven the car just a hundred miles or so and everything looks normal. I was running hot on the driver’s side and that cam timing was advanced 5 degrees. We used Porken's slick little tool and I think the problem is solved. Just a note the one side was hot enough to slightly blister the paint on the bumper cover next to the rmb. I’ll have a better feel when we head up to run the Gamblers Twin 50 on Thursday I’ll try to post a report from the race.

H2

I checked mine on a lift and took my readings at a few points on both Driver and passenger sides. I think if 2 cylinders are running hot you would see a hotter side down before the H-pipe. Mine was hotter on the one side running advanced all the way back.

H2

Charley and Mr. Merlin,

I'm running about 188 or so degrees out of top hose and about 10 degrees cooler on the lower hose....and 210 degrees or so at the plastic resevoir... and that's OK....BUT...that's WITHOUT the AC going and NOT running it hard. It appears to be OK for regular easy driving but would not stay in the safe zone on the track or long uphills where I'm sure it would overheat. I'm looking at replacing the radiator with new just to eliminate that possibility. But I'll be surprised if that's the problem....but maybe? A good radiator is a good investment anyway I figure.

What's mystifying to me is that when I intentionally get it hot, it doesn't quickly cool off when driving down hills at 60mph or coasting like you'd expect it to. It takes a long time to stabililize temp at halfway mark. Also, when hot, and idling, after 20 minutes, it's still above the top white line. Compared to my '85s, something's not right. I just haven't figured it out yet. The gauge may be a bit off but I shouldn't be able to put it into the red so easily (when it's already hot as it should be) and it should cool down easily. Makes one think that it's not pushing coolant quick enough but it's a brand new Porsche WP and fluid certainly is circulating. BTW, the relatively small opening in the thermostat makes it impossible to push coolant beyond a certain speed. That's by design.

The air flaps are missing and that should help.

Harvey

edco

Just a follow up, I ran up to Elko, NV for the Gamblers Run and am happy to report that the problem has been corrected. Thank you Bill for helping me get this problem sorted out using Ken’s nice little tool….

H2

PorKen's tool wins again! It's a genius setup. I really like it. The above conversation does tend to confirm that a little timing maladjustment can contribute to overheating engine. Very interesting thread. Thank you.

H2

mark kibort

I have a hard time believing that this was even a problem. over heating at idle, or was it just the 50degree difference? running lean at idle is kind of a misnomer. the LH hunts with the fuel , full rich to full lean to average out to near stoich. as we belabored before, stoich is the highest temps, but under cruise, is best for fuel economy. any leaner, EGTs actually go DOWN. But, at the cost of rough running. 50f temp difference could easily be the difference in the heat disapation capability differences of the two sides. are they the same now, under the idle conditions?

Now, the porken tool. how does it know where 0 is? wouldnt 0 be the point where the driver intake cam , (#6) moves 2mm on a 20 degree crank movment off TDC? If "0" for the driver side is that, and the spec calls for 1.7mm for the passenger side, its easy to see that it would would need to be retarded by a few degrees, right?

On the holbert car where i have been "guestimating" settings, i ended up setting both sides to 2mm as was the setting for the holbert car before i removed the cams. does this mean that my passenger side is advanced now? and if so, would that side idle hotter than the other?? Ill do an IR test today.

I want to check things out, as i did notice on a full slightly warm compression test, that the passenger side was slightly lower by about 5psi ( ave 190s vs ave 185psi comparing left to right)

I think i should take porken up on borrowing the tool to check!

Mk

Bill Ball

The tool is based on the fact that the cams are machine ground to the same timing. There's no significant variation in timing from the cam in one car to next one. Unless you have shaved the heads or otherwise changed the valvetrain, the tool should be accurate. Ken can provide further explanation.

I can come over any time with the tool. If you want to pull the cam covers, we can compare it to the WSM procedure.

As regards the effect on exhaust temp, I think running advanced can change that w/o any mixture changes.

PorKen

The dial indicator is difficult to set up, and you are measuring off of the intake cam, driven by a chain from the exhaust cam. It is difficult to get consistent results. The 32V'r shows the position of the exhaust cam, and is much easier to repeat. Any way you do it, the cam timing is going to be ± something. The belt stretches at valve events enough for 1-2°, the temperature of the engine changes, etc., etc.

FYI: I have a couple of preorders for a new run of 32V'rs, but I need at least five orders to pay for the laser cutting, as I have to order at least ten at a time, so I'm going to start a new thread for more orders.

Correct, the V2 tool's zero is the #6 measurement, which turns out to be 2 crank° advanced of parallel key center (the V1 measures the key center). Measured cold, #1 is about 1° retarded from #6.

With both cams set to 2mm, your 1-4 cam is likely at least 1° advanced over the 5-8 when warm.

Shaving the heads will change the timing, but not what the 32V'r indicates. About the only thing that would change the measurement would be reqrinding the cams.

mark kibort

Thanks Porken!

So, if i understand this..... the "0" poisition is actually at a position 2 degrees on the crank or advanced of the center of the key position. 2 crank degrees is 1 degree on the cam pulley, right?
So, this means that the 1-4 cam being advanced by 1 degree would actually only be .5 degree advanced passed the 5-8 cam setting , for a total of 1.5 degree advance.

Will there be any compression test difference by variations in these settings? if so , i wonder if its worth checking the max compression cylinder on the 1-5 side cold and see if it changed vs the warm check i did. And, retard the timing back to stock on that side and see if it changes.

the tool looks pretty cool. Bill, i think i may take you up on doing a few tests with it.

thanks

MK

mark kibort

Here is a puzzle for you guys.

Just did a compression test cold (dont think i have ever done this before)

took the greatest passenger side hole and tested it . results 183psi, near the 185 warm test

NOW, the puzzle. took the driver side highest compression hole. Results: 177psi ( warm 195!!)
thought this was a fluke, so i did an adjacent cylinder, still 177psi cold , on a 190psi max on that hole warm.

Is this the dramatic effects of cam timing or just cold non circulating oil dry cylinders?
since they are dry, i should maybe go back and test the passenger side again, since it was the first to be tested cold. hmm??????

could this be the effects of the block expansion changing cam timing?

next test maybe to pull the passenger side cover warm and see what it is timed out at.

mk

Charley B

Mark, are you sure you want to head down this road. You may spend the next two years buying compression testors, spending all night in the garage and forgetting to go to races. The possible combinations that can affect compression by 10 pounds are endless and non-duplicatable on a DOHC engine. The last guy I knew trying to nail it down, was led away in a straight jacket and never heard from again.

Bill Ball

Mark, let me know when you have some time and I'll bring the PorKen tool over.

mark kibort

you are probably right. I think ill just go to the dyno and see if i am down on power and then chase it down from there. my 60-100 mph runs are not that far off, and could be slower due to the taller tires (305x35s)

This is what happens when there is more than a few weeks between races. the idle time gets me into trouble!

mk