Idle surge after injection head o-ring replacement and fdc bypass

[MultifuelM35a2]

Hello all I’m new to this and appreciate any and all help. I have a 1970 m35a2 with a LDT 465 and I’ve owned it for about a year and a half now. No problems with it at all. Ran like a top from day one and was very dependable. However I had recently discovered that my deuce was “making oil” and found out it was the injection head o-ring was leaking pretty good. But I had heard that the problem could also include the FDC leaking and the booster pump seal leaking. The engine was rebuilt in 90 according to the tag on the engine and nothing has been into on the injection pump before me because everything was still all wired up and painted with no chips. So I lined all my timing marks up with the correct LTD 465 mark on the harmonic balancer and took of the injection pump. I replaced the booster pump seal and both injection head o-rings and watched a video on how to adjust the fuel shutoff pin screws and wired the screws. It moves freely. I also bypassed the FDC. It took a while to start but a rag with fuel on it by the intake did the trick. Once started it doesn’t want to idle at all. It does when you have your foot on the throttle. It will idle very roughly after it warms up a little. It drives with a slight roughness but seams to get better after a little bit. However once you shut it off and let it cool and then start it again your back at square one and it doesn’t want to idle at all or nearly dies trying to idle. The idle smooths out at 1000 rpms but then as they go up it seams to get rougher again. I’m not sure what to look for in terms of fixing it because it started this problem after a did all three things at once. All the lines were bled by the bleeder valve at the top of the secondaries. I tried searching stuff but couldn’t find the exact problem I have to do me any help. Any and all help is very appreciated. Thanks
-Nick

 

[MultifuelM35a2]

Hello all I’m new to this and appreciate any and all help. I have a 1970 m35a2 with a LDT 465 and I’ve owned it for about a year and a half now. No problems with it at all. Ran like a top from day one and was very dependable. However I had recently discovered that my deuce was “making oil” and found out it was the injection head o-ring was leaking pretty good. But I had heard that the problem could also include the FDC leaking and the booster pump seal leaking. The engine was rebuilt in 90 according to the tag on the engine and nothing has been into on the injection pump before me because everything was still all wired up and painted with no chips. So I lined all my timing marks up with the correct LTD 465 mark on the harmonic balancer and took of the injection pump. I replaced the booster pump seal and both injection head o-rings and watched a video on how to adjust the fuel shutoff pin screws and wired the screws. It moves freely. I also bypassed the FDC. It took a while to start but a rag with fuel on it by the intake did the trick. Once started it doesn’t want to idle at all. It does when you have your foot on the throttle. It will idle very roughly after it warms up a little. It drives with a slight roughness but seams to get better after a little bit. However once you shut it off and let it cool and then start it again your back at square one and it doesn’t want to idle at all or nearly dies trying to idle. The idle smooths out at 1000 rpms but then as they go up it seams to get rougher again. I’m not sure what to look for in terms of fixing it because it started this problem after a did all three things at once. All the lines were bled by the bleeder valve at the top of the secondaries. I tried searching stuff but couldn’t find the exact problem I have to do me any help. Any and all help is very appreciated. Thanks
-Nick

I figured out the problem. To anyone who may read this with the same problem. My FDC bypass wasn’t the problem. The timing was the problem. All I had to do was take off the injection pump gear cover on the driver side front of the engine. The gear has elongated Holes to adjust for timing. You can tell where your timing is when you take the bolts out and see where the injection pump bolt holes are in comparison to the space in the elongated holes in your gear. Mine were all the way to the right side of the elongated while when looking at the truck from the front. I took a 22mm socket and put it on the center but and turned it a hair to get the bolt hole about a 1/16 to a 1/8 of and inch away from the farthest right side of the elongated hole and bolted it all back together. The truck fired up no problem just like it use to and runs like a top. To anyone who is looking for timing problems always check the injection pump gear to see what your timing is.

 

[Recovry4x4]

Did you get in there and loosen those while doing the head orings?

 

[MultifuelM35a2]

Did you get in there and loosen those while doing the head orings?

I had taken the injection pump off the engine and replaced everything and then put it back on my truck and it ran like garbage. Then I went back in and loosened the gear and found that the holes adjusted the timing and then I advanced it a 1/6 to1/8 inch and it ran beautifully.

 

[Floridianson]

Sound more like you got the timing off when you installed the IP back in the engine and did not check the timing at the Head. Looking over and reading the TM's can be worth it. Injection Pump Timing | SteelSoldiers

 

[NY Tom]

Thanks for replying to your post with a resolution.

 

[MultifuelM35a2]

Sound more like you got the timing off when you installed the IP back in the engine and did not check the timing at the Head. Looking over and reading the TM's can be worth it. Injection Pump Timing | SteelSoldiers

That’s for sure. I honestly went into this thinking I knew more than I did but a little more research and some backtracking and I was good to go. But yes I would recommend looking at the TM’s and making sure you know everything first. I just got lucky I guess

 

[MultifuelM35a2]

Thanks for replying to your post with a resolution.

I wanted to make sure I updated for anyone who else might need help and stumble across this thread

 

[Floridianson]

Understand. But if the IP gear has never been taken off or IP removed then to check timing we do not need to check the gear. HB on correct mark, advance window on it'd mark then the Head red / scribe mark will be just about one tooth off to the rear. That is correct IP timing. When we install the IP the three gear bolts are left loose and with the slots open. We install the IP with the advance window not quite on it's mark but the Head red / scribe mark is on it's pointer. Then after IP bolted down we rotate the center IP bolt clockwise to where the advance window is correct and Head is just about one tooth off to the rear. Then tighten the three IP gear bolts to spec.

 

[MultifuelM35a2]

Understand. But if the IP gear has never been taken off or IP removed then to check timing we do not need to check the gear. HB on correct mark, advance window on it'd mark then the Head red / scribe mark will be just about one tooth off to the rear. That is correct IP timing. When we install the IP the three gear bolts are left loose and with the slots open. We install the IP with the advance window not quite on it's mark but the Head red / scribe mark is on it's pointer. Then after IP bolted down we rotate the center IP bolt clockwise to where the advance window is correct and Head is just about one tooth off to the rear. Then tighten the three IP gear bolts to spec.

Ok hunny hats great to know. I watched a few videos and from m understanding they said for the red mark to be perfect on the pointer with the HB perfect on its mark and the mark under the inspection plate on its mark or very close. But I’m glad to have found out the correct way to do it thank you