BC847

So, . .. . I understand it's common for our mess to start sounding like a Chebby diesel's clatter with a bit much IP timing advance.

So, . . . . . how loud is too much Chebby clatter?

I often see reference to those who've shoved the pump to the head.

I've run out of IP mounting bolt slot and can't advance the timing anymore with the current cog indexing. As such, I've got about 3/16" till the pump touches the head.

With a cold (overnight) start, and the KSB doing it's thing, the heap rattles pretty good with a light throttle and less than 10psig boost. Once up to full normal operating temp, the clatter is gone. (I DON'T run more than 10psig boost when below the start of the normal operating temperature range).


Drifting more . . ...

When I ran the PDR 190 injectors, with 2.10mm plunger lift, thing's sounded kinda funny. Backing it up to a flat 2.00mm had it much better.
With the larger DDP4s, I figure more injection advance is in order (if it don't work, back it up). With pushing it to it's max available static advance Wed. night, Thursday I ran an eighth mile in 8.87 @ 75.48 (60' 1.86), 8.87 @ 75.87 (60' 1.89), and 8.81 @ 75.86 (60' 1.85) (this also includes the KSB advance FWIW).

I didn't actually measure the current timing with the gauge (estimated at 2.4mm or so lift). I just marked where it was on screw-up . . . . Excuse me, "Start-Up" of this round of tuning.


So when does the SOP gauge read ~ That's About Enough! . .. ?


Barring rain and a bad bald man's comb-over wind, I'm running for fun at The Rock tomorrow.

apwatson50

I know when I had my pump advanced pretty far, when it was cold it would rattle pretty good. So I retarded it just enough to where it didn't rattle really bad when cold.

After I retarded the timing I noticed that the turbo seemed to spool a little faster also.

Now today I just got my "mess" started with my custom modified pump. The modified part that pertains to this thread is the timing piston that is now 2mm shorter on the retarded side. Thus I advanced the pump drive gear 1 tooth and set the pump just about stock to the case. All i've done so far is get it started but it starts nice and is very smooth. So i'm hoping that once its going i'll have more dynamic timing advance than before, not sure how much but we'll see.

Aaron

wannadiesel

I ran mine up a little too high after I jumped the gear a tooth and the truck started bucking under light load. I backed it down 1/8" and that's how the truck was set when it made the numbers in my sig. I ran it like that for a while but it just sounded spooky to me, so I'm another 1/8" back from there - which is still about 1/16" more timing than I had when I was at the end of the slots with the gear in the stock position.

mhuppertz

Who modified your advance piston? I have been too chicken to take my pump apart in order to get at the piston. The great, late, Pastor Bob told me in a PM to cut it down 2mm, so that tels ya how long I have been thinking about it...

mhuppertz

More fuel takes a little longer to burn, especially at higher RPM's.

wannadiesel

More advance gives the fuel more time to burn. More air would help the EGT, but it won't give the big dyno numbers most of us are seeking.

DIS's strategy is solid for their application. Those engines need to be able to actually work for a living and run for a million miles. We can get away with the spooky stuff we do because we aren't working the engine very hard. My current setup wouldn't last 5 minutes at full load. If you are building your truck to pull heavy all the time I encourage you to follow Bruce Mallinson's formula - lower compression, plenty of fuel, and more air than you need. You won't be king of the dyno, but you will be able to flat-foot it up the side of a mountain (assuming you can keep the the trans cool).

BC847

Thanks for the replies folks.

Based on that and the engine's general performance as of late, I'm thinking I'm approaching this side of too far (meaning I'm OK).

The 'ol heap ran it's best 60', 1/8 and 1/4 times yesterday at The Rock. I hope I get the forum member name correct saying that was UnrulyNFS in the right lane.







I need a bigger hair drier as it's blowing a bit of black at the top end. Did I mention HOT!

Alwaysworking

nice, what turbo do you have?

BC847

An off-the-shelf PDR HX35 Hybrid, and thanks.

Alwaysworking

now if i could do that with my 5speed that would be cool.
does it really rattle bad or is set right now?

BC847

It only rattles when stone cold and only with a mild part-throttle. When at full standard operating temp, there's no rattle even with the KSB energized.

SMOKE' EM

do you have a hard time starting it in the cold? mine was hard to start since i advanced the timing so much but its only on cold nights

BC847

Nope, fires right up.

wannadiesel

Congrats on getting it into the 13's!

apwatson50

I had a buddy with a mill cut it down. only took a few minutes. The piston itself is aluminum with a steel insert in the middle. And it must be anodized.