Prepping a holden oil pump for performance use

**gaff3rp** · 19-08-2013, 08:24 PM

Great read. Will definitely be giving it a go when i get ready to start on my engine.
Would drilling a hole in the centre of the welsh plug so it acts as a restrictor but does not totally block the bypass passage help with collapsing filters or would that weaken the plug too much?

**EVL253** · 18-09-2013, 12:36 AM

I'm halfway thru doing this now. if u study a stripped pump u will see that from stock the pressure relief valve regulates after the filter. where that cup plug was where filter screws on is the passage.
as zok has said before thread this passage right thru screw a grub screw in down the bottom side with loctite. I used a 1/2 inch UNC as size was right n I had that thread tap. don't reinstall the small cup plug in top. this will reference the relief before the filter. this way if it opens it dumps back into the pump. stock bypass dumps it into the engine unfiltered.
get me a cup plug n gaskets n my pump will be done

**zok race carbs** · 18-09-2013, 07:21 AM

Originally Posted by EVL253

I'm halfway thru doing this now. if u study a stripped pump u will see that from stock the pressure relief valve regulates after the filter. where that cup plug was where filter screws on is the passage.
as zok has said before thread this passage right thru screw a grub screw in down the bottom side with loctite. I used a 1/2 inch UNC as size was right n I had that thread tap. don't reinstall the small cup plug in top. this will reference the relief before the filter. this way if it opens it dumps back into the pump. stock bypass dumps it into the engine unfiltered.
get me a cup plug n gaskets n my pump will be done

I'm glad someone listened to what I was saying or writing

I use a 20 mm brass plug

zok

**EVL253** · 18-09-2013, 08:27 AM

20 mm brass plug for where the bypass was? both bolt shops in this town which were full of engineering supplies said nope don't have welsh plugs I was like wtf! ran outta time in my lunch hour so I'll go chasing the plug n gaskets elsewhere.

**zok race carbs** · 18-09-2013, 08:28 AM

Originally Posted by EVL253

20 mm brass plug for where the bypass was? both bolt shops in this town which were full of engineering supplies said nope don't have welsh plugs I was like wtf! ran outta time in my lunch hour so I'll go chasing the plug n gaskets elsewhere.

yes
if you get stuck I can mail them to you

**EVL253** · 18-09-2013, 03:33 PM

thanks zok I rounded up both plug n gaskets this morning.give me something to do while its on stands till I get a new gearbox

**zok race carbs** · 18-09-2013, 06:23 PM

Originally Posted by EVL253

thanks zok I rounded up both plug n gaskets this morning.give me something to do while its on stands till I get a new gearbox

no worries

**EVL253** · 18-09-2013, 10:56 PM

pump all back together. put it on tomorrow after work.CBF tonight n don't think neighbours would appreciate the noise of my car running at this time of night. one day when I get old I might have a quiet exhaust....

**Hqtunna4me** · 05-10-2013, 10:46 AM

20mm welch plugs do not fit any of the oil pumps i have. First one i tried was an original pump. Popped out the bypass, grabbed a 20mm plug falls in and out. measured the bypass valve 20.4mm. New plug measures at 20.2 that was my practice pump. opened up the brand new jp standard pump. exactly the same as the original, bypass is 20.2mm. anyone else come across this problem? Tk says he uses 3/4? i seem to need one which is ore like 13/16. Whats the go here?? Only thing i can come up with is you guys are knocking it in past the lip the bypass usually goes in to. which wouldnt seem right to me. Yes its the right hole, and yes ive measured with 2 set of verniers.

**hsv08** · 05-10-2013, 11:18 AM

Originally Posted by Hqtunna4me

20mm welch plugs do not fit any of the oil pumps i have. First one i tried was an original pump. Popped out the bypass, grabbed a 20mm plug falls in and out. measured the bypass valve 20.4mm. New plug measures at 20.2 that was my practice pump. opened up the brand new jp standard pump. exactly the same as the original, bypass is 20.2mm. anyone else come across this problem? Tk says he uses 3/4? i seem to need one which is ore like 13/16. Whats the go here?? Only thing i can come up with is you guys are knocking it in past the lip the bypass usually goes in to. which wouldnt seem right to me. Yes its the right hole, and yes ive measured with 2 set of verniers.

I think the 1 I used was a 21mm bucket.

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**Hqtunna4me** · 05-10-2013, 11:21 AM

yep thats what i will have to use, just seems everyone else has used 3/4 or 20mm plugs. As usual i cant seem to get a 21 mm in town, can get everything else though.

**EVL253** · 05-10-2013, 11:29 AM

3/4 inch & knock it in place. I put bit of sealant round the edge socket & extension n few good hard belts with the hammer it went in.long as its blocked off n tight fit

**HPE PETE** · 05-10-2013, 12:58 PM

i have 2 genuine pumps here one is 18.1mm and the other is 20.4mm, im just going to make an aluminium plug to suit each one

**Hqtunna4me** · 05-10-2013, 01:58 PM

Originally Posted by EVL253

3/4 inch & knock it in place. I put bit of sealant round the edge socket & extension n few good hard belts with the hammer it went in.long as its blocked off n tight fit

3/4 will not fit my pump, thats my point. neither will 20mm. will need 21mm.

**zok race carbs** · 05-10-2013, 02:00 PM

Originally Posted by Hqtunna4me

yep thats what i will have to use, just seems everyone else has used 3/4 or 20mm plugs. As usual i cant seem to get a 21 mm in town, can get everything else though.

the steel pumps and aloys have different sizes i have 21 mm plugs pm me your address and i will send you one since i stuffed you up with the tap

zok