Author Topic: Pump timing (Read 5175 times)

jimfoo · « **on:** June 20, 2008, 07:06:10 am »

At first I was thinking my timing wasn't advancing, then I remembered if I remove the wire from the ALFV, the timing changes by 10 degrees. So is this an indication that for whatever reason, my timing is advancing as far as possible it idle? What is the total possible dynamic timing on an IDI pump?
If it is fully advancing, what are the possible causes, wrong spring, too high internal pressure, something else?

zukgod1 · « **Reply #1 on:** June 20, 2008, 07:38:25 am »

Quote from: "jimfoo"

At first I was thinking my timing wasn't advancing, then I remembered if I remove the wire from the ALFV, the timing changes by 10 degrees. So is this an indication that for whatever reason, my timing is advancing as far as possible it idle? What is the total possible dynamic timing on an IDI pump?
If it is fully advancing, what are the possible causes, wrong spring, too high internal pressure, something else?

This is a good point. I have a keyed 12v to mine as well.

I don't think we can advance the timing all the way with just 12v. I can see where we will get some but mechanically I don't think it's possible with internal pressures at idle.

I wonder if as you mentioned in your other post if we could put a switch in the throttle somewhere to activate it..?

I would think anything off idle would be the way to go.
I have seen and have one at home a double switch set up on the IP, I assumed one was to shut off the AC compressor at WOT but never understood the one it rests on at idle. maybe something like that would work, break the 12v signal at idle but as soon as your off idle it advances.?

jimfoo · « **Reply #2 on:** June 20, 2008, 07:55:02 am »

Removing power retards timing to what I assume is the static timing, I think by equalizing the pressure differential across the timing piston, but I could be wrong on that. Originally, it was supposed to be controlled by engine temp from what I have read, to reduce emissions of a cold engine.

jimfoo · « **Reply #3 on:** June 20, 2008, 12:36:01 pm »

Well, found one thing wrong, my case pressure is somewhere between 55 and 60 psi at 1k ish rpm. Guess it's time to make something to take the pressure regulator out.

jimfoo · « **Reply #4 on:** June 20, 2008, 01:41:25 pm »

Got the pressure back down to where it should be and the timing advances with engine speed now, though maybe a tiny bit quicker than I would like, but I have shims I can put in.
Question- will too far advanced timing cause smoke? #1 is now firing at 6* BTDC, but #3 is at 23* BTDC. So much for the guy I paid to calibrate them. :evil: I have to see if I can make another mark so I can check the others. Then again thinking about it, shouldn't 1 &4 fire at TDC and 2&3 at BDC on the flywheel? That means #3 is firing WAY early.

jtanguay · « **Reply #5 on:** June 20, 2008, 01:44:49 pm »

Quote from: "jimfoo"

Got the pressure back down to where it should be and the timing advances with engine speed now, though maybe a tiny bit quicker than I would like, but I have shims I can put in.
Question- will too far advanced timing cause smoke? #1 is now firing at 6* BTDC, but #3 is at 23* BTDC. So much for the guy I paid to calibrate them. :evil: I have to see if I can make another mark so I can check the others. Then again thinking about it, shouldn't 1 &4 fire at TDC and 2&3 at BDC on the flywheel? That means #3 is firing WAY early.

yep 1&4 @ same and 2&3 at same. that is utter crap that the #3 is firing so off.

btw i bought a ferret gauge and it doesn't seem to be working right. the timing light doesn't always work. i've even tried sanding down the injection line but nothing works. sometimes moving the clamp works, but its so hit or miss and doesn't flash consistently... hopefully the injector is ok, but i doubt that is the problem.

jimfoo · « **Reply #6 on:** June 20, 2008, 02:00:19 pm »

My light only fires with the timing light pickup on the loop one way. If I turn it around, it doesn't flash at all.

jtanguay · « **Reply #7 on:** June 20, 2008, 03:17:49 pm »

Quote from: "jimfoo"

My light only fires with the timing light pickup on the loop one way. If I turn it around, it doesn't flash at all.

ah good to know! thanks

jimfoo · « **Reply #8 on:** June 20, 2008, 04:14:34 pm »

I made a new mark appx 180* off of TDC and #3 is still 23 * before, but so is #2, so now I'm wondering if the cam plate is screwy as I can't see 2 injectors being that far off and exactly the same. The pump is off and draining.

jimfoo · « **Reply #9 on:** June 20, 2008, 07:37:23 pm »

Got the pump apart. The cam plate has a, well I'm not sure what to call it, erroded, chipped sort of piece near the top of a lobe, and a roller has a small one too. All the rollers and the cam have heat marks. Guess it makes a lot of heat at that many rpm.

jimfoo · « **Reply #10 on:** June 21, 2008, 08:08:34 pm »

Cam plate with galling on one lobe and heat marks on all lobes.

A roller with a small chip, and heat bluing like all the rest.

jimfoo · « **Reply #11 on:** June 21, 2008, 08:53:39 pm »

I haven't seen a speck of metal in it yet. Yeah, I think it is from the over revving. I don't see it getting that hot otherwise. Maybe from when I turned the key off and it was still screaming with no fresh fuel for cooling.

jimfoo · « **Reply #12 on:** June 21, 2008, 09:26:43 pm »

I was wondering if maybe a roller makes one rotation per 2 humps. That would make a difference for the one that has a pit, but yeah, I probably should get them checked, or finish my tester I started. I did make a quick case pressure tester out of a piece of aluminum rod, but it was a pain to use with lines and stuff in the way. I had to use the right thickness of copper washers so I could screw my line for the gauge in the side. Luckily I had some m12 1.5 bolts and a tap I could use to adapt it.