Changing 40hp round boss to square boss

[Glenn]

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.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
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[Glenn]

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?
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
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[Chickensoup]

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.
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[Glenn]

[67rustavenger]

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
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[Glenn]

It actually broke the boss, so no timesert.
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Glenn
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"You may not get what you pay for, but you always pay for what you get"

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[67rustavenger]

[Dan Ruddock]

[RWK]

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

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73 Type 181
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[RWK]

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?
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73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[Glenn]

[Dan Ruddock]

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

[Glenn]

Here's the head.

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Glenn
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[Dan Ruddock]

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

[Glenn]

The insert was ripped out so there's nothing left.
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Glenn
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[Dan Ruddock]

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.

[Glenn]

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

[Glenn]

So new heads, 8 top studs and drill the rocker pedestals for the larger rocker studs is all that needs to be done.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

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[Dan Ruddock]

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