Wanted: Distributor block-off / blanking plug
- Thread starter Dr.Jeff
- Start date
bringing up an old thread here - if one were to cut down a DOHC version to fit the SOHC motor, what method would you use? Lathe would be great of course, but I don't have one. I'm temped to scribe a nice reference line and use a cutoff wheel and then finish on a grinder or sandpaper or both. Thoughts?
Dr.Jeff
True Classic
I think that method will work. Just be sure to note the dimensions needed, as posted earlier in this thread....posts #16 and 19.
So I actually made a modified version of this plug this week. I was curious about the hole in the engine end. That isn't necessary right? If I remember right the oil pump gear is flat on top. I'm guessing the plug just needs to keep it from coming out of the engine?
Also, in the drawing there isn't a dimension for the depth of the hole.
Also, in the drawing there isn't a dimension for the depth of the hole.
So after looking at this last night I don't think the depth of the plug (or wether it is hollow or not) is critical at all. I really think it just needs to plug the hole to keep oil in and junk out.
In the photos I show my distributor next to a stock DOHC plug. Drawings show to remove 5mm or so to fit SOHC. Nothing really on the distributor would be in that area, and the black cone on the distributor wouldn't really be strong enough to hold anything down anyway.
Also, it looks to me like this gear is spun by the aux shaft and the aux shaft is spun in the direction of engine rotation by the timing belt. That means the gear mesh would be pushing down on the oil pump gear, not up. The bushing shown in the drawing looks like it is under the gear as well, supporting that theory. Also, no real wear on the top surface of the gear, etc etc.
So I haven't cut my plug yet, but from what I see, the length really isn't critical at all, as long as it is "short enough". Maybe the shape is to help drip splashing oil back down on the gear instead of letting it run down the side of the block.
Is my thinking correct?
In the photos I show my distributor next to a stock DOHC plug. Drawings show to remove 5mm or so to fit SOHC. Nothing really on the distributor would be in that area, and the black cone on the distributor wouldn't really be strong enough to hold anything down anyway.
Also, it looks to me like this gear is spun by the aux shaft and the aux shaft is spun in the direction of engine rotation by the timing belt. That means the gear mesh would be pushing down on the oil pump gear, not up. The bushing shown in the drawing looks like it is under the gear as well, supporting that theory. Also, no real wear on the top surface of the gear, etc etc.
So I haven't cut my plug yet, but from what I see, the length really isn't critical at all, as long as it is "short enough". Maybe the shape is to help drip splashing oil back down on the gear instead of letting it run down the side of the block.
Is my thinking correct?
Jeff Stich
True Classic
Yes & no.
The black plastic bushing on the distributor shaft isn't there to hold anything down, it's an "oil slinger" meant to keep oil from roping up the shaft & into the distributor body while the shaft is spinning.
If you physically fit the DOHC plug into the SOHC engine block, you'll find that the extra length of the DOHC plug prevents it from sitting all the way down into the hole on the SOHC engine block (the bottom of the plug hits the top of the oil pump drive gear). That's WHY the SOHC plug is shorter, & why the DOHC needs to be modified to fit.
No special tools are needed to modify the DOHC plug; a tape measure or ruler, a pen/pencil, a hacksaw & a sheet of sandpaper taped down onto a flat surface will suffice. Measure your cutting line on the plug, mark it, cut it & sand the (just-cut) base flat holding the plug vertical on the sandpaper & doing figure-8's to sand it flush.
Last edited:
Yes, thank you. My point about the distributor oil slinger is that it clearly couldn't hold the gear down!
Therefore, the length overall of the plug is not really critical, since it doesn't need to replace something that was holding the gear down when the distributor is installed (nothing is holding the gear down with a distributor installed).
So yeah, I agree, cut the DOHC plug short enough, remove any rough edges and shavings created by cutting, and roll.
Therefore, the length overall of the plug is not really critical, since it doesn't need to replace something that was holding the gear down when the distributor is installed (nothing is holding the gear down with a distributor installed).
So yeah, I agree, cut the DOHC plug short enough, remove any rough edges and shavings created by cutting, and roll.
Dr.Jeff
True Classic
I think the question being asked is not IF it needs to be cut, but how critical the actual length is after its cut.
It probably isn't extremely critical to get it to an exact dimension. But although the gear may not tend to walk upward, I'd still feel more comfortable having the plug close enough to it that it can't come off the oil pump no matter what. A loss of oil feed isn't good.
It probably isn't extremely critical to get it to an exact dimension. But although the gear may not tend to walk upward, I'd still feel more comfortable having the plug close enough to it that it can't come off the oil pump no matter what. A loss of oil feed isn't good.
I measured the DOHC one I had (before I cut it). The hole was about 68 mm deep.
Well I decided to use my bandsaw (portaband in a stand so it's vertical). It was very easy to do. Cleaned up with a bit of sandpaper and spray of carb cleaner and we should be done!
Also, plug weighed in at 3oz and the distributor at 2lbs 2oz, so we can call this a 2lb weight savings! Haha.
Also, plug weighed in at 3oz and the distributor at 2lbs 2oz, so we can call this a 2lb weight savings! Haha.
Ics19
belle macchine!
I think the key part is the step in the distributor shaft (i.e. the change from the larger outer diameter down to where it's machined before the splines) - this locates into the recess in the drive gear. While the gear may stay in place under normal circumstances, it would be stopped from coming up when it hits the step of the shaft (in your picture you can see a shiny half-moon section where there's been possible previous contact). I don't think it's always in contact, it's not a bearing surface, but the amount of allowed play is more like 1mm I'd guess, so this is what you should aim for with the blanking plug (whose contact point will now be on the top face of the drive gear instead).
budzinsk
1987 Bertone X1/9, 1986 Alfa Romeo Graduate
Hi have one for a SOHC if you need one. $10 plus shipping. It is midway down on my page:
sites.google.com
Rob
Fiat Parts
Updated on Friday, September 8, 2023 I have a lot of Fiat X1/9 Parts I am looking to get rid of. I am based in Central PA and you are welcome to pick up in person or I can ship. Prices below not include shipping. I will do quantity discounts. I do not have any wheel sets or new parts. I do
sites.google.com
Rob
I'll take it!!Hi have one for a SOHC if you need one. $10 plus shipping. It is midway down on my page:
Fiat Parts
Updated on Friday, September 8, 2023 I have a lot of Fiat X1/9 Parts I am looking to get rid of. I am based in Central PA and you are welcome to pick up in person or I can ship. Prices below not include shipping. I will do quantity discounts. I do not have any wheel sets or new parts. I do
Rob