A trick to center pushrod tubes, for more clearance

[modok]

Pushrods rubbing tubes..... a common problem yes?
Sure is close. The 3/4 side was even worse too, trust me

actually looks oK with the close up photo, but that's < .030 clearance.

Trying to figure out how to get JUST a little more wiggle room, I thought.....if the pushrod tubes were just centered in the bores.....that would be enough.
Look how there is a big GAP where you can see the seal next to the pushrod, but the steel part of the tube is flat against the hole on the opposite side.
At that point i had a stupid? brilliant? idea.
You see, because the pushrods come at the head at an angle, tilted, that pushes the seal deeper in on one side, so that pushes the tube sideways.
Not a big deal, but it pushes it exactly the way you DON'T want it to go
So, I tried offsetting the 45 degree seat where the seal seats, .010 up, and 010 to the side.

Back together, now they are centered, and I have plenty of wiggle room

The downside is now the heads are right and left only, so that's the stupid part of the idea.
BTW why does CB use o-rings on the big mouth tubes when the stock seals fit fine?
AND, watch out for those.
I have a set of the CB big mouth tubes.....won't fit IN the holes. The hole is .940something, the end of the tubes are .980 , so it even looks ok if you don't notice, you don't know unless you try fitting them without seals. Ti's not going to compress the seal
The end of the normal tubes are .910 diameter where the seal goes, about 1mm clearance, and today I learned WHY, never did consider it before, but, it's like that for a reason! If it wasn't then it would not work OR, you'd need left and right heads

[Slow 1200]

what cam and rockers?

fans of narrow engines always talk about the advantages of shorter, lighter pushrods, which is true, but the more extreme angles work against everything else in my opinion (never though about the pushrod tube issue, that convinces me even more )

[modok]

heads, rockers, tubes, All CB stuff.
1.25 intake, 1.1 exhaust
One of their milder cams, can't remember the number at the moment

The pushrods are the big dual tapered aluminum, which is making it slightly worse as well.

[theKbStockpiler]

Maybe oval-ing the tube would work for you.
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[vwracerdave]

Yes I have always understood the heads are machined neutral for a universal fit and really need to be machined slightly offset making them a left or right head. If that were done than stock P/R tubes could be used on big cam. The downside is that the Jaycee big mouth tubes that work without leaking are far more cheaper then the machine work to fix the problem and offset them for left & right use.
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[UK Luke 72]

Once everything is bolted up I just roll a 3/8" extension bar around to massage the offending lips where I need them.
Not quite as elegant a solution as yours Modok but it works for me.
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[mark tucker]

every oe non effed with vw had 2 diferent heads on them, I presume a lefty and righty.. I dont wory or have any issues like this with the big mouth scatempijcee tubee's. and no leeks or rust either. I will not use the oe style tubes for any thing execpt for BBQ grill gass/air feed tubes.....just kidding.

[modok]

Getting things to fit properly in their holes, just feels good.
It's nice.
I never took the time before to really LOOK at it, but, it's works kinda like a ball joint.
The stock tubes having a flexy slinky at each end help the seals accommodate seating crooked, but if you remove that feature by using aftermarket tubes...you lose that, which makes machining the seats to line up nicely even more useful. It seems very simple now, but before I never did take the time to really look at how it works.....because the way VW did it, just worked.

[nsracing]

I just peen the top of tubing that 'rubs' the pushrod. There is always one that will be close. But I never had the need to machine the holes bigger. The only larger seals I know of are the ones for the Wasserboxer.

I have run pretty much all the larger cams and 1.4 ratio rockers and peening the tube is enough to clear.

[oprn]

[Cusser]

[67rustavenger]

[FeelthySanchez]

[Boolean]

JPM's mouse 2.0
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[bugguy1967]

He has plenty of clearance with those CSP/JPM tubes. That was done because of how narrow the engine is.
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[nsracing]

There is always a BIGGER tool someone is using. I love it!

Ain't machine work fun?

[modok]

It's not just about the size of the tool, but also how you use it.

I seem to be getting just as good surface finish with my slice of torsion bar on a stick. That's actually what that is, with an aluminum tube jammed on to reduce chatter.

[KROC]

[mark tucker]

mine are dry. you have to oil the orings and leave some oil inbetween the orings so they always have oil if you dont they will just wear out from no lube,I dont us greese as they willl push this way or that and be out of reach in the other area's . I also put the washer ends on and swedge the tubes to them so they wont come off.I have also put on bigger washers too so the seals dont go over them.( Imho the washers are too small od for the silycone soft seals) when using them use a little oil on the head seat so the seal slides into the proper sealing position eazely. dont oil the seals as it may end up at the backup washer area and...let the seal jump the washer. ( this go's for all pushrod tubes) the scat big mouth tubes are soft aluminum and can be deformed or formed eazely I open them up bigger the amount they need to go to fit the washer. always oil the inside of the tube the orings slide into. over 80,000 miles and no leeks.
on my first vw motor (1874cc) I used those old hard blue small tubes with springs...I had to oval them for pushrod clearance till i found the big tubes. if you fuck with them long enough even the ovaled tubes can seal with silycone seals..I dont think you can swedge the hard tubes bigger at the mouth they will just crack.
as far as pushrod holes in the ehads my 910's are left&right with the holes offset more on 1 head. and if your machining them do it at the proper angle...wll both angles tilt the head this way and that way mainly that way to match that sides angle.dont forget to number the heads.if you can assemble to find out of you need to move the tube location or not..if you havent noticed the seats in the mag cases are angled...not sure of the s,uminum cases are or not.. I did get a nice 53(I think thats it) cutter for recutting the seats. I wish the cams on the type 1 were like the type 4 with wiode lobes I would move the lifters a little more...Im gonna move them on my roller motors any way to ceneter each one better....just wish the amumnum cases had more meat in the lifter bosses..Im using the .874 dia jessel lifters..I would rather use the .937 but...that would require some extensive wellding...or the tf1 case that I wish I had...and a feather.

[modok]

Sharp guy, yes they should be cut at an angle for even better fit. i did realize that, and consider it, but decided to keep it simple this time.

.....it isn't so simple.
The 3/4 head I had to go .045 over, the right head only .020, i went .010 Up on both, and I'm not totally sure why that was, but that's how it was.
Using the CB big mouth tubes allows more offset to be used because the tube is bigger, so using the big mouth tubes and offsetting the seats you could get up to 3mm more clearance, but the big mouth tubes alone you really only gain 1mm.