Timing question #1 vs #4 cyl

[Meatloaf326]

I’ve got an 89 NA idi in a van with a reman in it as well as new injector lines for the truck with no timing adapter. I figured the engine didn’t know it was in a van and timed it on the first cylinder to 7* btdc. Result was tons of white smoke and no power so I checked the timing on cylinder 4 which read a negative reading (I can’t remember exactly there were so many readings but I think it was -4*). I now have it set now to 10.5* btdc on cyl #4 and it feels pretty good too me. I’m going to try and retard it a degree or two tomorrow. My question is basically why is this happening? Previously I thought either 1 or 4 would work but I know little on this topic.

Also if anyone wants to chime in on timing preferences for NA idi vs turbo. I’ve read 7.5-8.5 btdc for all idis but have also read closer to 10* for NA.

 

[notenuftime]

Just ask your pump rebuilder they will know best.

 

[Big Bart]

I’ve got an 89 NA idi in a van with a reman in it as well as new injector lines for the truck with no timing adapter. I figured the engine didn’t know it was in a van and timed it on the first cylinder to 7* btdc. Result was tons of white smoke and no power so I checked the timing on cylinder 4 which read a negative reading (I can’t remember exactly there were so many readings but I think it was -4*). I now have it set now to 10.5* btdc on cyl #4 and it feels pretty good too me. I’m going to try and retard it a degree or two tomorrow. My question is basically why is this happening? Previously I thought either 1 or 4 would work but I know little on this topic.

Also if anyone wants to chime in on timing preferences for NA idi vs turbo. I’ve read 7.5-8.5 btdc for all idis but have also read closer to 10* for NA.

Meatloaf,

Guessing you know but make sure you know the right cylinder chart. Ford is different than Chevy. Number 1 is closest to radiator passenger side.

I do not have a van so not sure about if 1 and 4 will both work. Recall some van owners saying they use #4.

Most suggest 8.5* or 9.5* btdc at 2,000 rpms. Your choice.

Hope that helps.

 

[parkergn]

Getting some strange timing readings using #4 on my van, almost like -5* btdc if I could guess (meter doesn’t go negative)

Then I switched to #1 cylinder and seems to be close to 8*, (at least adjustable +- 2*)

Should I just time off of #1 moving forwards. On Facebook someone says those cylinders should fire at the same time and get same readings?

 

[FrozenMerc]

IDI Firing order: 1 - 2 - 7 - 3 - 4 - 5 - 6 - 8

Diesel timing meters get one pulse off of the crank dampener every 360 degrees of crankshaft rotation. Engine RPM is calculated internally by counting the number of pulses over a certain time period (1 or 2 seconds), and then usually averaged over an even longer time period (5 or more seconds) to smooth out the pulses and variation that naturally occurs. They also receive one pulse from the injector line, every 720 degrees of crankshaft rotation. Engine Timing is calculated by measuring the time difference between the injector pulse and the crank position pulse, dividing by the calculated RPM and converting to degrees. All that to say, you should see the same timing reading off of #1 or #4, provided the timing meter doesn't have any other advanced functions that would reference the meter to the full 720 deg cycle. This is true for any 4 stroke diesel, 4, 6, 8, or more cylinders. However, there will be a tolerance stackup, and you can expect to see a couple degrees of timing difference between pairs cylinders that operate 360 degs. apart.

 

[Cant Write]

@FrozenMerc that makes sense. If the above is true, the piece I’m missing is why do they designate #1 (pickups) or #4 (vans) then? Is it out of convenience (access) or is there something more.

This is coming from someone who has yet to play with my timing meter. So please excuse my ignorance.

 

[IDIBRONCO]

Is it out of convenience (access)

This is my guess (access). I don't recall on the Internationals, but I do know that the vans have the alternator in front of the #1 cylinder which makes it more difficult to reach.

 

[FrozenMerc]

I am sure access was the reason, however IH liked to do things a bit differently. The SV line of gas engines (304, 345, 392) built by IH were all timed off of #8, not #1....

 

[parkergn]

Getting some strange timing readings using #4 on my van, almost like -5* btdc if I could guess (meter doesn’t go negative)

Then I switched to #1 cylinder and seems to be close to 8*, (at least adjustable +- 2*)

Should I just time off of #1 moving forwards. On Facebook someone says those cylinders should fire at the same time and get same readings?

I found out the other day I was timing off #2 thinking it was #4 being opposite #1! Figured out my mistake and good to go now. Other then getting the Gunson pulse adapter to ****’n work

 

[IDIBRONCO]

The SV line of gas engines (304, 345, 392) built by IH were all timed off of #8, not #1....

Plus they use the same firing order and a small block Chevy.

 

[Old Goat]

I am sure access was the reason, however IH liked to do things a bit differently. The SV line of gas engines (304, 345, 392) built by IH were all timed off of #8, not #1....

There was also the IHC 266 V8. I bought a 64 Step Side PU when I got out of the Navy in 66.
Took it to a shop to have the timing checked. They tried to time it like a Chevy off #1 and said it was so far off didn`t know how it ran. That I better get it fixed or I`d ruin my engine....


Goat