What is thread on fuel pump block-off plate?

[StewRat]

I reckon I need to add more pressure relief to my crankcase and the fuel pump blockoff seems a popular spot.

But I can't work out what the thread is on it - it certainly doesnt fit anything in my (growing through mistaken purchases) box of fittings.

Dont think I know what manufacturer it is but its pretty standard/common - looks like this googled pic:




TIA

Stewart

[Andy]

If it is an American part I would expect it to be  NPT thread .

1/4 npt is roughly 11-12mm internal diameter 3/8npt is about 15mm as a rough guide to see what you may have.

[Martin S.]

That thread looks way small for helping to vent the crankcase. Adapt a dash 8 (1/2") or dash 10 (5/8") or something decent otherwise you're wasting your time.

[richie]

That is 1/4 npt on that type block off

[andy198712]

That thread looks way small for helping to vent the crankcase. Adapt a dash 8 (1/2") or dash 10 (5/8") or something decent otherwise you're wasting your time.

That’s what I did with my one of these, drilled it out and fitted up a an10 fitting, just fits between the bolt holes 

[StewRat]

Cool - that all makes sense.

I have several BSP hose tail fittings that work with the 1/2" hose I've got so I'll drill it out for that .

Thanks

[StewRat]

That thread looks way small for helping to vent the crankcase. Adapt a dash 8 (1/2") or dash 10 (5/8") or something decent otherwise you're wasting your time.

That’s what I did with my one of these, drilled it out and fitted up a an10 fitting, just fits between the bolt holes 

Except that - having removed the plate now ... the hole underneath in the case is no bigger than the 1/4 NPT blank in the block off plate.
So without major surgery to enlarge that, it will be the limiting factor.

I'm looking at adding this in addition to breather connections from both rocker covers and the oil filler neck, trying to solve a problem where I am getting oil sprayed on inner wings after (say) 3rd run of the day but no obvious single source. And havent been able to replicate in the garage. Guessing at crankcase pressure combined with thinner hot oil.

[leec]

The only time I ever got oil spray from the engine was when I put too much oil in the engine and it came from the breather box breathers.
Maybe worth looking at where your oil is on the dipstick assuming you have a deep sump?

Lee

[StewRat]

The only time I ever got oil spray from the engine was when I put too much oil in the engine and it came from the breather box breathers.
Maybe worth looking at where your oil is on the dipstick assuming you have a deep sump?

Lee

Well that opens up a whole new can of worms

In that I am trying to work out just how much oil is circulating in any equivalence to a "standard' engine as measured at the dipstick.

With a remote filter and remote oil cooler and associated piping, its hard to work out how much of the at rest oil will be in transit through that system when running. So I tend to fill oil towards the top end of the "standard" markings to allow for that usage. If anything, I worry I dont have enough oil in circulation.

I dont have a deep sump currently .

Interested in your statement about your oil spray experience. From what I've read there is a real challenge around engine case pressure under race conditions, how to vent it, etc.

The StewRat is in a garage behind a row of houses so that does limit my testing due to noise. Maybe I should take the car to some remote location and do a few simulated full rev passes and see where the oil is coming from.

Stewart

[leec]

Sorry, didn't mean to open the can 

I have an empi 3.5 litre sump, and I run the oil level so it literally just wets the bottom of the dipstick. When I over filled it it was well above wetting the dipstick bottom.

Thought I would mention it, as if your oil level was too high am upgrade on your current breathing system may not show any improvement

Lee

[Martin S.]

A deep sump is a good idea on every VW engine. For a few bucks spent, you get a 'poor mans dry sump'. Most of the oil is moved to well below the crank where it is sheltered leaving less chance of the oil being thrown around. 

[richie]

That thread looks way small for helping to vent the crankcase. Adapt a dash 8 (1/2") or dash 10 (5/8") or something decent otherwise you're wasting your time.

That’s what I did with my one of these, drilled it out and fitted up a an10 fitting, just fits between the bolt holes 

Except that - having removed the plate now ... the hole underneath in the case is no bigger than the 1/4 NPT blank in the block off plate.
So without major surgery to enlarge that, it will be the limiting factor.

I'm looking at adding this in addition to breather connections from both rocker covers and the oil filler neck, trying to solve a problem where I am getting oil sprayed on inner wings after (say) 3rd run of the day but no obvious single source. And havent been able to replicate in the garage. Guessing at crankcase pressure combined with thinner hot oil.

Is it a EFi case then? never seen normal case that didn't have much bigger hole than that, are you sure its case that's that size not fuel pump bakerlite stand or a hard gasket?

[StewRat]

That thread looks way small for helping to vent the crankcase. Adapt a dash 8 (1/2") or dash 10 (5/8") or something decent otherwise you're wasting your time.

That’s what I did with my one of these, drilled it out and fitted up a an10 fitting, just fits between the bolt holes 

Except that - having removed the plate now ... the hole underneath in the case is no bigger than the 1/4 NPT blank in the block off plate.
So without major surgery to enlarge that, it will be the limiting factor.

I'm looking at adding this in addition to breather connections from both rocker covers and the oil filler neck, trying to solve a problem where I am getting oil sprayed on inner wings after (say) 3rd run of the day but no obvious single source. And havent been able to replicate in the garage. Guessing at crankcase pressure combined with thinner hot oil.

Is it a EFi case then? never seen normal case that didn't have much bigger hole than that, are you sure its case that's that size not fuel pump bakerlite stand or a hard gasket?

The hole I refer to is definitely on the top plane of the case, not anything sitting on it. The block off plate is similarly flat bottomed to cover that hole. I've never worked on std engines, but I assume it is the hole the fuel pump pushrod rides up n down in.

As to the origins of the case, that is a whole other story. Suffice to say it has RaceShack machined into the sides which I didnt know when I bought it.

[StewRat]

A deep sump is a good idea on every VW engine. For a few bucks spent, you get a 'poor mans dry sump'. Most of the oil is moved to well below the crank where it is sheltered leaving less chance of the oil being thrown around.  

Useful info - thanks - I have looked at deep sump but felt the extra depth was pretty minimal.

Guess it renders the dipstick even more useless ?

Edit - sorry, missed LEEC's comment on oil fill with deep sump.

[richie]

So nothing like this?

[StewRat]

So nothing like this?

No! To right of distributor hole, flat area top of case and a small circular hole that roughly equates to the 11mm or so the block off blank has.

Dammit - looking back at my spreadsheet I understood this to be a CB "super race case" it was ready for 94mm cylinders, clearanced, and though I forget the details now had the gusseting etc of a stronger case. But looking at pics online now I cannot see a case that has the small pushrod sized hole that mine has. And thats just googling cases, not even performance cases!!

Humph, not sure what is going on here now, will revisit tomorrow and double check I'm not going mad.

[StewRat]

Having said that

ahem

I just found a pic of my case that suggests there is a bigger hole there.

Car is in garage a few miles away and in my defence I nipped in quickly today to remove the block off - and could swear I was surprised to see the small hole underneath.

But I need to go back tomorrow and check all this before digging myself a bigger "hole".

[DaveN]

There’s a picture of your crankcase in your build up thread. it has the big hole where the stock fuel pump should be

[StewRat]

There’s a picture of your crankcase in your build up thread. it has the big hole where the stock fuel pump should be

Yeah thats the one I found - but I need to get to the car today to reconcile that with what I believe I saw yesterday. I could swear I was looking at the top surface of the crankcase but can only assume there is some extra plate there. But it was a flying visit, and neither memory or eyesight are what they used to be!

[DaveN]

You probably were looking at the gasket that has a small hole for fuel pump rod

[StewRat]

I've been able to check now and I only have 2 things to say:

1. Which of you left that gasket there? And made it all shiny so it looked like the crankcase metal. You may think it's funny but it's not big and it's not clever. You only let yourself down with this kind of prank.

2. If you need glasses to see properly, then WEAR them. Especially in half light.

I hope we've all learned something from this, in which case I will say no more about it.

Stewart

[andy198712]

I've been able to check now and I only have 2 things to say:

1. Which of you left that gasket there? And made it all shiny so it looked like the crankcase metal. You may think it's funny but it's not big and it's not clever. You only let yourself down with this kind of prank.

2. If you need glasses to see properly, then WEAR them. Especially in half light.

I hope we've all learned something from this, in which case I will say no more about it.

Stewart

 

[Martin S.]

Buddy's wife was having trouble getting a plug into a port in the back of his Mac Pro. So she got out the electric drill...   

[Martin S.]

Here is a picture of my fuel pump block off with -8 fitting attached.
It is for the turbo oil drain on my engine, but you get the idea.
Use -10 for venting or as big as possible.

[StewRat]

Thanks Martin - and for your separate note.

So phase 2 of this thread may turn into an AN tutorial ...

I haven't used AN fittings anywhere so far, and in spite of a good deal of reading on the subject, I'm still a bit confused on some points. For example:

Can AN fittings only be used with braided hose? As I understand it if you have the correct DASH-X where X translates to the OD of your hose it should fit? But will it work? I think AN hose end fittings have (left-handed) threads to cut into and secure the hose/pipe. Does that work on say std non braided oil/fuel hose? Or does it only work on metal (braid).

In this current example - where we are looking to essentially attach a hose via AN fitting to a plate - is this done by 1) threading the plate, or 2) by securing/sealing from behind?
If 1) Is this a std straight thread (albeit bigger than I currently have in tap set) or do I need an "AN" tap? And how many threads required to be sealed? I suspect not enough thickness in my plate.
If 2) I guess it would have to be secured and sealed and then ground down as back nut won't fit into the (even larger) hole in the block.


Sorry for all the questions - this is what happens when "knowledge workers" start working on cars. Too many basic gaps in my knowledge.

Thanks!

Stewart