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Mon May 23, 2022 5:53 pm

Have an engine that had the rocker stud insert rip out of a 40hp short stud round boss.

It seems like the best option is to replace both heads with square boss heads.

But are the rocker assemblies the same? If not what needs to change?

Just want to know what i'm looking at before I go that route.

Mon May 23, 2022 6:05 pm

Did a search and it looks like the following are issues:

Round boss heads to square boss heads

Rocker assemblies
Head studs
Pushrods
Intake manifold

Can someone confirm?

Mon May 23, 2022 6:08 pm

im not sure you have to change the rocker assemblies. they are both 1.0 ratio unless the shaft blocks are different.

why not just buy a 10 dollar repair kit? easy and permanent fix. be aware tho. there are two styles.

If you must have different heads, buy some 1300 heads. bigger valves. both are 1 year onlies.

Mon May 23, 2022 6:24 pm

Chickensoup wrote: why not just buy a 10 dollar repair kit? easy and permanent fix. be aware tho. there are two styles.
Links?

I work mostly on 1600 based engines which is why i'm asking before moving forward.

Mon May 23, 2022 6:54 pm

Time-sert or heli-coil.
I like the time-sert. You can buy them online. Or rent the tool and buy the time-serts from ACN.

This is an example. Not the specific tool for the round boss heads you are working on.
http://vwparts.aircooled.net/Time-Sert-Tool-Rental-5-16-24-0562-p/time-sert-rental-0562.htm

Mon May 23, 2022 6:55 pm

It actually broke the boss, so no timesert.

Mon May 23, 2022 6:59 pm

Glenn wrote: It actually broke the boss, so no timesert.
Well that kinda changes things, doesn't it?

Like you, I only work on 1600 based packages. Good luck searching.

Mon May 23, 2022 7:56 pm

Glenn wrote: Did a search and it looks like the following are issues:

Round boss heads to square boss heads

Rocker assemblies Drill the bottom hole on the cube shaped rocker blocks bigger
Head studs I should have the two that are different
PushrodsSame
Intake manifold will fit the square boss heads

Can someone confirm?

Measure the length you need for the head studs. The manifold will fit if it's a square boss 40hp head.

Dan

Mon May 23, 2022 8:08 pm

FWIW, I pulled 40 hp rockers off a 1776 with CB big valve heads, one of the smaller problems it had!
ratios are different from 40 hp to 1300-1600, some 40 hp rockers, some if not all 40 don't have the oil hole to adjusting screw, and as you can see some are not welded shut, 40 hp arms don't have the 2 ribs on the top center of arm

Mon May 23, 2022 8:16 pm

Notice also the arm main beam on screw end is thicker on late arm then 40 hp arm, this was done to have room to drill oil hole through. May also have to change head studs for later heads (13-1600), Isn't there 40 hp sq. boss heads? or is that what your talking about?

Tue May 24, 2022 2:54 am

Dan Ruddock wrote: Glenn wrote: Did a search and it looks like the following are issues:

Round boss heads to square boss heads

Rocker assemblies Drill the bottom hole on the cube shaped rocker blocks bigger
Head studs I should have the two that are different
PushrodsSame
Intake manifold will fit the square boss heads

Can someone confirm?

Measure the length you need for the head studs. The manifold will fit if it's a square boss 40hp head.

Dan
Dan,

Which studs are the problem? Too long or too short?

Tue May 24, 2022 4:53 am

Not sure but I believe it is the two top row studs near the exhaust ports. A pic of the square 40hp head would help.

Ahh found a pic. all of the uppers are longer.

www.thesamba.com/vw/classifieds/detail.php?id=1714853

Tue May 24, 2022 6:16 am

Here's the head.

Tue May 24, 2022 7:18 am

Are there threads in the bore missing the mount on the left? If no threads, tap to size and screw in a mount like the one on the right. The one on the right has been converted.

FYI, when this conversion is done the valve clearance changes from .008" to .004"

https://www.thesamba.com/vw/classifieds/detail.php?id=2479064

Dan

Tue May 24, 2022 7:40 am

The insert was ripped out so there's nothing left.

Tue May 24, 2022 8:06 am

Wow, I find that hard to believe. the threads are very large coarse threads. Somebody must have hacked it up when they taped it. I do have a set of early 40hp heads with the conversion already done. The engine was running when I pulled them off, but I have not done a thorough inspection of them. I have never seen a 40hp pull out the inserts, and yes I have rebuilt a number of them back in the day.

Tue May 24, 2022 8:12 am

After some searching it seem the round boss has 177mm top studs and the square has 193mm. Assume both are 10mm.

Tue May 24, 2022 8:14 am

Glenn wrote: After some searching it seem the round boss has 177mm top studs and the square has 193mm. Assume both are 10mm.

Your assumption is correct.

Tue May 24, 2022 8:15 am

So new heads, 8 top studs and drill the rocker pedestals for the larger rocker studs is all that needs to be done.

Tue May 24, 2022 8:24 am

Yes, you could also just put some 1500 1.1 rocker assemblies on it or swap out the rocker block for late ones.