40hp heads... help

[Shredder]

Got a set of really good used heads,mine was junk....my issue is this, the replacement ones have studs for the rockers, and they are tapered so the rocker arm Assy will not seat on the head bosses. They have a stamp.."Mexico" on them.My heads used a bolt and fastened down into a steel insert, looks like a case saver configuration. What can I do to fix this? Do I grind away the taper so they seat on boss, and use a nut and washer? The stud is larger in the head,so a "new" bolt will not go thru block and shaft. I surely don't wanna be cruzin and have it fall off. I'm sure someone has been here....your help is greatly appreciated....Thx!

[Mr. Motorhead]

The Mexico 40hp square boss heads have a stepped stud like a 1300/1600 head for the rocker assembly. Two very simple ways to solve the problem. #1 on my list would be get a pair of 1600 rockers and change out the old 40hp set. You will have just changed to a larger ratio rocker. Or #2. If you wish to use the old 40hp rockers (I don't know why you would) just take the mounting blocks off the 1600 set and put them on the 40hp set. It's as easy as that.
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[Shredder]

Mr Motohead,
What happens when I use the 1300/1600 rocker arm Assy? You say it is a larger ratio? What is it that happens for performance? Do I need to do anything different in setting valves? .006? .008? Just not educated in this ...apologies

[glutamodo]

Short stud engines get set to .006" valve lash. Here's a very old thread discussing this, the "short stud" or "square boss" heads and the original style:

http://www.thesamba.com/vw/forum/viewtopic.php?t=103248

You'll have another issue changing from round-boss to square-boss heads, the upper cylinder head studs need to be longer. And the exactly correct size studs can be difficult to locate - the thread above talks about this.

1200 engines had straight ratio rockers. The 1300-1600 engines had a slight ratio to them, 1.1:1. Usually you can use these without any concerns at all. They don't really make any noticeable difference in how it runs, I've changed back an forth a couple of times over the years and never noticed any change. 1.1:1 ratio rockers have two ribs cast into them like #22 in this image:

You see two 34bhp (40HP) rockers listed there, VW changed them slightly at that engine number and went with slightly longer studs at that time. You're only supposed to use the longer studs with the square-boss heads.


-Andy

[spencerfvee]

sorry guys I posted this on the wrong forum lol .the easy way to get dual carbs on your motorwith out spending a lot of money . is to install a set of 1300 heads .and use kadron carbs . that's the easy way since you have to replace your heads any way. there are not a lot of dual carb kits out there for a 40 hp motors . when you do find a vintage 40 hp dual carb kit they will hit your pocket book hard. that's .if you want to keep the 40hp look if you don't care go with the 1300 heads.or you can go all out and find a pair of dual port 40 hp heads from over seas . good luck on your build . just my two cents spencerfvee

[glutamodo]

Personally on a small engine like that, if I used 1300 heads to go with dual SP carbs, I would use dual Weber 34ICTs and not Kadrons.