How much timing before I'm spraying out of the bowl?

R

rightwinger

New member
I currently have a P pumped 24V with SO pistons, and I am running the DAP 6X.013 sticks, set to 300 BAR with the 152* spray angle and stock copper washers . I'm currently running 26 degrees of timing and the truck starts up great, and runs great.....I would love to add some more timing but am curious if anyone knows at what point you are spraying outside the bowl. Any experience here would be greatly appreciated.
 
This is just a fun DD for me, I have 4K GSK but rarely will ever see anything past 3000-3500 RPMS. Mainly I was surprised at how well it starts & handles with 26* of timing, just figured a few more degrees might be fun as long as it is not spraying outside the bowls and remains easy to start. I'm still running a factory grid heater as well so that should help cold start ups.
 
I'd be curious what a timing light would show exact injection timing on your truck now.

not doubting you a bit its set at 26* by whatever method you used, just curious what a light would show.
 
You bring up a valid point, even though I believe I am using the most accurate method for setting the timing, I would still love to verify it with a timing light. Currently my pump was built by Seth Farrel and pin timed for 20*, I have the magnetic degree wheel from Power Driven Diesel and bumped it 6 additional degrees......However, I still have some doubts as to how accurate the wheel was being that the magnetic degree wheel is slightly larger than my stock harmonic balancer. I might invest in a diesel timing light just to know exactly what it is.......
 
It's funny you bring this up, my truck I just finished up is almost identical and I have the same question. P24v with westons 6x13s,180 pump built by Seth and timing set at 26 degrees using the pdd mag degree wheel. If you just breath on the starter the truck fires, which makes me wonder if I really have it set at 26. I haven't been around enough other trucks with this setup to be famialar with them.
 
rightwinger said:
You bring up a valid point, even though I believe I am using the most accurate method for setting the timing, I would still love to verify it with a timing light. Currently my pump was built by Seth Farrel and pin timed for 20*, I have the magnetic degree wheel from Power Driven Diesel and bumped it 6 additional degrees......However, I still have some doubts as to how accurate the wheel was being that the magnetic degree wheel is slightly larger than my stock harmonic balancer. I might invest in a diesel timing light just to know exactly what it is.......
Click to expand...
If you do, be sure to give us an update.
 
I don't know about the bowl pattern v. timing, but 26 is mild for 24 valve P pumped.
In my experience 30+ is pretty nice with no starting issues. If you have a good scope, you could look in the cylinder now, then bump timing up and check again after some run time.
 
Snedge said:
I don't know about the bowl pattern v. timing, but 26 is mild for 24 valve P pumped.
In my experience 30+ is pretty nice with no starting issues. If you have a good scope, you could look in the cylinder now, then bump timing up and check again after some run time.
Click to expand...

It only takes one more degree to confirm you're spraying outside the bowl. haha
 
Why exactly are p24v's so much more tolerant to high timing than a 12V? I have always known this to be true, but never known the exact reason.....I could assume it's the centered bowl & injector.....I'm guessing the increased airflow on the head is not part of it because there have been some 12V heads that flow much more than a 24V head.
 
Thatguy69,

Are you running a Waterman pump also? I realize it's overkill for my needs, but I was already using a billet front cover and planned to re-do all of my fuel lines with stainless braided lines & AN fittings, so I went ahead and got a Sprint 400......Currently I have about 500 miles on the truck, initially the fuel leak fairy was visiting me quite often, but once I got everything tightened down and the leaks stopped, I could not be more happy. I was dead set on a mechanical fuel pump, and had previously used a Fuel Boss, and that was ok.....but even with minimal tension on the cog belt it was still causing premature wear on the seals in the pump and some of this was likely due to how low it was mounted and the dirt & debris it was collecting from driving. At idle, I am seeing 60 psi, and while driving I am seeing 80-95psi.....It will hit 100 psi in higher RPMs, but normally driving is around 75-80psi typically. I am still running the factory fan, but simply spaced my fan about an 1/8 of an inch back further towards the radiator with a large washer and this has been good so far, clearance is tight, however I still have about 1/2 an inch between the pump & fan blades and have never had an issue with the fan blades touching. I am pleased with how well it holds a prime and starts up so far. I do plan to install a one way check valve in it once I have time, this was done on another build and was beneficial in keeping prime, but surprising I haven't really needed it yet. I have noticed that the increased FP has really helped with throttle response and even tamed the surging/bucking a little (stiffer throttle springs helped the most). I mention all of this because I'm not sure too many people are using a Waterman style pump on a daily DD and was curious as to what other folks experience has been.
 
Best I remember somewhere around 32*, but its also going to depend on the piston and spray angle of course. My Truck didn't start coming alive until 30* but this was also a HO Pistons
 
rightwinger said:
Thatguy69,

Are you running a Waterman pump also? I realize it's overkill for my needs, but I was already using a billet front cover and planned to re-do all of my fuel lines with stainless braided lines & AN fittings, so I went ahead and got a Sprint 400......Currently I have about 500 miles on the truck, initially the fuel leak fairy was visiting me quite often, but once I got everything tightened down and the leaks stopped, I could not be more happy. I was dead set on a mechanical fuel pump, and had previously used a Fuel Boss, and that was ok.....but even with minimal tension on the cog belt it was still causing premature wear on the seals in the pump and some of this was likely due to how low it was mounted and the dirt & debris it was collecting from driving. At idle, I am seeing 60 psi, and while driving I am seeing 80-95psi.....It will hit 100 psi in higher RPMs, but normally driving is around 75-80psi typically. I am still running the factory fan, but simply spaced my fan about an 1/8 of an inch back further towards the radiator with a large washer and this has been good so far, clearance is tight, however I still have about 1/2 an inch between the pump & fan blades and have never had an issue with the fan blades touching. I am pleased with how well it holds a prime and starts up so far. I do plan to install a one way check valve in it once I have time, this was done on another build and was beneficial in keeping prime, but surprising I haven't really needed it yet. I have noticed that the increased FP has really helped with throttle response and even tamed the surging/bucking a little (stiffer throttle springs helped the most). I mention all of this because I'm not sure too many people are using a Waterman style pump on a daily DD and was curious as to what other folks experience has been.
Click to expand...

You dont need near that much lift pump pressure for what your doing
 
I'm just running a hotrod factory 12v mechanical lift pump from pdd. So far so good but I don't have a ton of miles on it yet, sold my wheels and my new ones have been on backorder over a month. Truck has sat 2 weeks without losing prime so far, I'm also using a tork tek ofv
 
I'm fully aware that the waterman is more than I needed, but again, my reason for going with a gear mounted pump wasn't for performance nearly as much as wanting to get the pump mounted higher off the ground and to eliminate a cog belt. A factory 12V pump would of likely worked fine for my needs, but I had the billet front cover already and was already re-doing the fuel system so I figured why not? I do have a check valve that is supposedly suppose to open at 70 psi, but this might need some tweaking in order to lower my overall FP. I have been told by several people at PDD & Keating that a p pump can safely run 90-100 psi,, however I'll likely adjust it down to maybe 40-50 at idle and see where that puts me.

32* of timing seems like a lot especially on the HO pistons, I know you said it runs great, but does an engine still "run great" even if it is spraying outside of the bowl? My concern would be that I am causing premature wear or damaging pistons over the long haul. at 32* have you verified that it's not spraying out of the bowl or are you just basing this on the fact it seems to run great? I'm by no means a math wizard, but I feel like there should be a way to calculate this and come up with a rough idea of when we're spraying outside of the bowl. I'm thinking if degrees of timing could be converted to a specific height of the piston in the bore, we could get a relative idea.......hopefully someone much smarter than me will chime in....LOL
 
rightwinger said:
I'm fully aware that the waterman is more than I needed, but again, my reason for going with a gear mounted pump wasn't for performance nearly as much as wanting to get the pump mounted higher off the ground and to eliminate a cog belt. A factory 12V pump would of likely worked fine for my needs, but I had the billet front cover already and was already re-doing the fuel system so I figured why not? I do have a check valve that is supposedly suppose to open at 70 psi, but this might need some tweaking in order to lower my overall FP. I have been told by several people at PDD & Keating that a p pump can safely run 90-100 psi,, however I'll likely adjust it down to maybe 40-50 at idle and see where that puts me.

32* of timing seems like a lot especially on the HO pistons, I know you said it runs great, but does an engine still "run great" even if it is spraying outside of the bowl? My concern would be that I am causing premature wear or damaging pistons over the long haul. at 32* have you verified that it's not spraying out of the bowl or are you just basing this on the fact it seems to run great? I'm by no means a math wizard, but I feel like there should be a way to calculate this and come up with a rough idea of when we're spraying outside of the bowl. I'm thinking if degrees of timing could be converted to a specific height of the piston in the bore, we could get a relative idea.......hopefully someone much smarter than me will chime in....LOL
Click to expand...

Fuel pressure probably wont make as much performance difference as you think. On my 12v I had an airdog 220gph which ran 65psi at idle...WOT went down to 6psi, I replaced with a belt driven pump and now at 40psi idle and 65psi WOT (I've tested up to 100psi). Going from 6psi to 100psi I ran the exact same mph down the track, no power gains at all. Good fuel pressure just ensures that you have enough fuel bypassing to cool the pump. Pressure makes heat, so you don't want any more than you need to fill the barrels in time and overflow some for cooling.
As far as spraying outside the bowl or not..I would suggest trying running a few different timing settings and see which you like best. Performance should be the judge.
 
rightwinger said:
I'm fully aware that the waterman is more than I needed, but again, my reason for going with a gear mounted pump wasn't for performance nearly as much as wanting to get the pump mounted higher off the ground and to eliminate a cog belt. A factory 12V pump would of likely worked fine for my needs, but I had the billet front cover already and was already re-doing the fuel system so I figured why not? I do have a check valve that is supposedly suppose to open at 70 psi, but this might need some tweaking in order to lower my overall FP. I have been told by several people at PDD & Keating that a p pump can safely run 90-100 psi,, however I'll likely adjust it down to maybe 40-50 at idle and see where that puts me.

32* of timing seems like a lot especially on the HO pistons, I know you said it runs great, but does an engine still "run great" even if it is spraying outside of the bowl? My concern would be that I am causing premature wear or damaging pistons over the long haul. at 32* have you verified that it's not spraying out of the bowl or are you just basing this on the fact it seems to run great? I'm by no means a math wizard, but I feel like there should be a way to calculate this and come up with a rough idea of when we're spraying outside of the bowl. I'm thinking if degrees of timing could be converted to a specific height of the piston in the bore, we could get a relative idea.......hopefully someone much smarter than me will chime in....LOL
Click to expand...

I can't answer your question accurately, I'm just speaking from experience. I didnt worry so much about whether it was spraying outside the bowl or not, but just clean streetable power at that point with good starting manners. I don't know the specifics, but 12v VS 24v timing is not relative. I run 26* on a 12v with stock pistons @ 155 spray angle and it's clean and streetable... 145* could run more IMO.

All of these references were shot with a light and True TDC on the balancer.

In a 24v application it's going to take more timing for sure, I just don't know what that number is specifically. I would keep bumping timing until the truck started getting harder to start cold and back off a few degrees, that will put you pretty close.... and you can judge idle haze from there to clean it up as much as you want.
 
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