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6vE Samba Member
Joined: February 14, 2005 Posts: 64
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Posted: Tue Feb 22, 2005 12:09 pm Post subject: Long Studs and Valve Adjustment, (Stud Kit?) |
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So I finally adjusted the valves on my '65 the other day. Turns out I have the long studs, so I set the intakes at .008" and the exhaust at .012" per the instructions in Muirs book.
He recommends to have a "stud kit" installed, but doesn't really explain why.
What problem will I have if I don't do that? After all, the engine has been ok for 40 years....
Should I just keep an eye on the valve settings, or should I really get the kit installed? |
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glutamodo  The Android

Joined: July 13, 2004 Posts: 26448 Location: Douglas, WY
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Posted: Tue Feb 22, 2005 12:55 pm Post subject: |
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Okay, here's the story on the 40HP heads. For whatever reason, when VW redesigned their engine in 1960, they decided to redo the heads so that the studs passed through the rocker "chamber" pass under the fins on the underside of the head, and screw into threads tapped just behind the combustion chamber. Not a good idea. The heat stress, added to the constant stress/vibration of the valvetrain, caused many of these to fail - the studs would snap off, or would pull out of their threads. VW monkeyed with this layout from 1961 models to the 1964s. They changed the size of the threads in the head and the shape of that rocker shaft, but the problems continued. Also, the heating differences of this style required that huge valve adjustment, as the clearances usually decreased from a cold engine to a hot one. Depending on what VW literature you read, they were either .008/.012 cold or .008/.008 cold.
Now, the earlier style 36HP heads, the rockers bolted onto studs that were screwed right into the rocker chamber. These didn't have that problem with breaking studs, or with wildly changing valve clearances, that were set to .006/.006. So when VW engines started having problems with the long studs, VW issued orders to retrofit them to the short studs. There were several companies that produced kits to do this. The most common one was one that drilled a large hole where the rocker fit, then a large slotted insert was screwed into the rocker chamber. The rockers were now secured with BOLTS, these are amercian bolts too, by the way, they have 1/2 inch head on them (although a 13mm fits OK) So if your engine has BOLTS holding down your rocker arms, you are converted to "short studs", and can set your valves to .006.
The other style fixit kits out required you drill out the rocker stud holes, then tap them for a giant "step stud" - these were metric kits, at least any that I've seen were, and have a M8x1.25 nut that holds the rockers on. The only way to tell for sure whether you have long studs or not on engines that have STUDS holding the rockers down is to look under the engine for where the rocker stud hold emerges on the under/backside of the head. If it ends there, short studs - .006 valve adjust. If it continues over to the combustion chambers side of the head - long studs.
In 1965, VW finally decided to fix all the problems with the 40HP heads , and designed a very strong, beefy head that is much like the 1300-1600 single port head. These have a square shaped embossment under where the rockers bolt to the head. I have these heads on the 1385cc 40HP in my 62 bug, and they are great! (but since they are beefier heads, they require longer upper studs than the other 40HP heads used) Now, after 1965, VW put out a "universal" replacement head that would fit the 1961-1964 engines, that looked more like the earlier heads, including a rounded emobssment under where the rockers bolt to the head, but had short studs. These usually have a casting part number that ends in "F".
As far as your engine in particular - your 1965 has the Long Studs? Well, there's very few VW's with their original engines out there anymore anyway. Most of the old "long stud" heads have been converted years ago, not many of the old ones remain. What I'd do, if you truly do have long studs, is do this test. Set your valves to .008/.008, COLD, of course. Then run the engine around for a while til it's nice and hot. Then come home and put on some cloth or leather gloves and a heavy long sleeve shirt to protect you from heat, and pop those valve covers off. Then check your valves and see how tight the clearances have become. IF they are are all about the same, and none are on zero clearance, then go with the 008/008 setting. If the exhausts are down around or past the zero clearance, go to .010, or .012.
As far as getting the kits installed - it's best to have the heads off the engine. Also, I don't think you can BUY the kits any more, although I have a couple of the US style ones laying around, enough to do like 4 or 5 heads I think. However, they require special size drill and tap to put in, and not many people have them around any more. I know I don't have the tools, although I do know of a retired machinist that has the tools for the kits I have.
-Andy
Edit, a good reference picture of the two style heads:
Last edited by glutamodo on Mon Oct 29, 2007 8:14 pm; edited 2 times in total |
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6vE Samba Member
Joined: February 14, 2005 Posts: 64
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Posted: Tue Feb 22, 2005 1:25 pm Post subject: stud kit? |
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What I'd do, if you truly do have long studs, is do this test. |
I doubted it myself, but the rockers are held on with nuts, not bolts, and I definitely feel long studs coming out the other side, on both heads.
Thanks for the scoop! I'll try your test next weekend.
Just out of curiosity, what could happen to an engine with the valves set with too much gap?
BTW, before I reset them, the gaps were VERY tight. Who knows how long it's been, or if a previous owner set them to short stud specs? |
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glutamodo  The Android

Joined: July 13, 2004 Posts: 26448 Location: Douglas, WY
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Posted: Tue Feb 22, 2005 1:57 pm Post subject: |
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Setting valves too loose won't really hurt anything, but it might limit your power somewhat, due to reduced flow from valves that aren't opening all the way. Really REALLY loose valves are not good to have though, they are very noisy and would pound the heads of the valve stems, or even the pushrods could pop out of the bottom of the rocker arms.
BTW, you can usually SEE the long studs coming out of the back of the head, even installed on the car, if you angle your head right and aim a flashlight correctly.
I happen to have one of those "F" series replacement short stud heads here, did a scan of it which I'll attach. You can see on these heads that they retained the "block" that the long studs originally would screw in to, but on these heads there is no hole there. The studs just screw into the rocker chamber. The circle I drew is where you'd see the long stud if it was in place on this head.
One other thing about 40HP heads, early ones had a 32mm opening at where the intake manifold attaches, late ones had a 34mm. (I prefer the larger ones, espeially since I run the big bore pistons on mine.) So you can see there's a large variation on 40HP heads.
andy
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6vE Samba Member
Joined: February 14, 2005 Posts: 64
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Posted: Tue Feb 22, 2005 6:36 pm Post subject: studs |
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Whew... I've got a lot to learn!
I didn't see the studs, but I'm sure I could have if I had worked at it, but there is a tin plate in the way. I'm positive they are there, though, because I felt the threads and put my fingers around em to be sure, and that's the place, (per your drawing, thanks!).
I think I'll run with em, since it seems strange to change something that has worked for 40 years. But I will try .008" on the exhaust and see how it holds when hot.
She does seem a little sluggish today, but it's hard to tell because I've been babying her so my dying clutch will last awhile longer.
Thanks again! |
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gerg a.k.a. 6volt65

Joined: April 25, 2003 Posts: 5454 Location: Monroe, LA
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Posted: Tue Feb 22, 2005 10:21 pm Post subject: |
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I was able to find the conversion kit at the local off road shop and installed it with no problems while the engine was in the car. I used the press in type and just sucked them into position with a bolt and washers. These required no drilling and pressed into place just like a wheel stud on an american car. I believe they were BugPack. Super cheap too . . .like <$5 per head, although I only needed one side - I had a long head on one side and a short on the other.
And >.008" is just to fricking loud for me! I run .004/.004 and keep a regular check on them.
Andy - are you running the 1.25 rockers with your big bore kit? I have a set and am fixing to buy the same big bore kit for my 40. I want to stealth in some extra power while maintaining the original look. How is the power increase? What carburetion are you using? _________________ Gerg
. . . I got 99 problems and my bus ain't one . . .
'65 Sunroof Beetle
'65 Vert
'60 Singlecab |
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glutamodo  The Android

Joined: July 13, 2004 Posts: 26448 Location: Douglas, WY
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Posted: Wed Feb 23, 2005 9:16 am Post subject: |
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I've not seen any stud kits except the ones I mentioned in my post. I worked at a VW parts/service shop for several years and never heard of the ones you talk about. Sounds like a good deal.
I have worked on stud kits in the car before, but only to try to repair ones that had already been installed. I had the metric "step stud" style on one of my engines, and one of them worked loose and started to wallow out, fortunately I had been able to locate some replacements. But those heads eventually wore out and I went with different heads.
Later on, I had the slotted US-style kits on a different head wallow out on me. I Didn't know what to do, but I did have a few of those giant "step stud" style replacements on me, so I drilled out the rocker hole a little bit (it was almost the right size) Then I took one of the step studs and cut a couple of sharp slots across the threads, making a home-made tap out of it. Then I lubed it up, and started working in and out of the hole to cut new threads. Cleaned up all the pieces, and put in a fresh step stud, and it was fixed! The engine itself overheated a few months later though, so I never found out how well my half-assed fixit job would have held up. On my current engine I went with the superior 1965 heads.... they are great!
That 008/008 spec was only if you had long studs, otherwise 006 is fine. I used to run mine 004 for a while, but I had so many problems with eroding valve seats and stud kits getting loose,etc, that I stopped feeling comfortable with that tighter spec. Too many times I'd get to zero clearances, so I've just gone with 006. And on this current engine with the beefy 1965 heads, they don't sound very clackety to me.
As for what rockers I run. 40HP came with straight ratio rockers. I'm running the later stock 1.1:1 rockers on there. I have thought about the 1.25:1's but never did anything. With those small exhaust valves, the 34mm intake manifold/intake ports on the head, and stock exhaust, I think any further high performance mods would be wasted. The car runs very good now. This car has only had big-bore 40HP engines in it since I bought it in 1989, and this current engine is the best running one I've had yet. Oh, the carb, I have a Bocar 30PICT-1 on there. Can't remember what jets I'm using, I set it up on an exhaust gas analyzer and kept changing the jets out til the mixture at 3000RPM was as ideal as possible.
You might have problems going with Big Bores on your 40HP, they are no longer made. I got lucky and found a set on eBay, the guy didn't know what he had, someone had written something like 1964 Karmann Ghia on the box so that's what he listed them as. But I could tell from one of the pictures that these had the thinner cylinder walls of the 83mm. So I bid, and won the auction. I think that with shipping I paid less than 100 bucks for the set, complete and new in the box. They were brazillian Cimas with a date in the early 1980s. Good stuff, that set is what's in my car right now. For spare parts, I also bought a zero mile engine that had been sitting in a garage in Arizona for years. The engine was seized due to the heat turning the assembly lube into tar, and when I tore it down I found that whomever line bored the engine chose the wrong block, it was warped and should have been scrapped. However it wasn't a total loss, as it had a new set of 83MM's on it, again 1980's-era Cima. My point is, there still are 83mm sets out there, but you really gotta dig to find them.
Oh, and having those larger intake port heads - not a lot of people realize that 40HP's came with two different sizes. The manifolds were different sizes as well. VW claimed the same HP rating throughout the whole 40HP era, but I think the small changes they made from 1961 to 1965 did likely result in slightly more HP, they just didn't talk about it.
andy |
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gerg a.k.a. 6volt65

Joined: April 25, 2003 Posts: 5454 Location: Monroe, LA
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Posted: Wed Feb 23, 2005 11:39 am Post subject: |
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Thanks for the info! There has been a recent limited run of Mahle 40Hp big bore kits running about $200 a set. I know BFY had an add here for them, as well as another shop in Arizona.
Thanks Andy! _________________ Gerg
. . . I got 99 problems and my bus ain't one . . .
'65 Sunroof Beetle
'65 Vert
'60 Singlecab |
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glutamodo  The Android

Joined: July 13, 2004 Posts: 26448 Location: Douglas, WY
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Posted: Wed Feb 23, 2005 1:12 pm Post subject: |
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you're welcome!
I hadn't heard about a new run on 83mm kits, I guess I been away from the business side of things too long now. Thanks for the info. And 200 bucks was what Motorworks was selling them for back when they were still available - I think that's about what I paid the last time I bought some. (But those came in a Cofap box - but aren't Mahle and Kolbenschmidt and Cofap all the same compnay now??)
If you can - get a set of the 1965 style heads if you go Big Bore. I recently found a cleaned up, barely-used set that was made in Mexico on eBay. Only paid 60 bucks plus shipping for the pair, and the valve guides are still tight. I'll probably just lap the valves, putting in new exhaust valves since I have some here, and they should be good to go.
The hardest part in using the 1965 style heads is finding the right length upper cylinder head studs for them. I ordered a set from a Formula Vee parts company online and they turned out to being too long. Well, one of them was the right length, but the rest were longer, I think they might have been 1300 style. So I had to double-washer most of the nuts, which I wasn't really happy about, but so far the heads seems to have stayed tight.
Anyway, also get yourself a good 34mm manifold that has a clear preheat tube if you go that way.
andy |
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gerg a.k.a. 6volt65

Joined: April 25, 2003 Posts: 5454 Location: Monroe, LA
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Posted: Wed Feb 23, 2005 3:26 pm Post subject: |
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Andy - is the 34mm intake specific to any paritcular year or is it aftermarket?
Thanks, _________________ Gerg
. . . I got 99 problems and my bus ain't one . . .
'65 Sunroof Beetle
'65 Vert
'60 Singlecab |
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glutamodo  The Android

Joined: July 13, 2004 Posts: 26448 Location: Douglas, WY
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Posted: Wed Feb 23, 2005 4:17 pm Post subject: |
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The larger intake manifold was a production change. It's discussed in the bentley 1200 book. I'll go look it up, heck, since my scanner is fired up I'll just do some more scans. looks like the small manifold was 61 and 62, but I've seen them migrate to other year 40HPs.
Oh, while looking through it, I came across this factory modification to the pre-1965 heads. This is a mod I've done on all the heads I've used of this style. don't know if it helped any, but I figured it didn't hurt either.
Here's the info on the intake manifold change.
It was a fairly early change in the 40HP series, but I've seen plenty of early heads and manifolds lying around through the years. The special adapter 32/34mm gasket they mention, I remember special ordering a pair of those about 10 years ago, and they still were available! I never used them but I still have them around... just in case. 40HP gasket kits are supposed to come with both size intake manifold crush seals, 32 and 34mm. I've also seen some of the larger 34mm come in certain brand engine gasket sets for the 1300-1600 engines. I remember one time I wasn't able to find ANY spare 34mm gaskets. I had a bunch of 32's but they are too small to use. Then I found someone on the net that was selling off a lot of old stock stuff and bought me a dozen. That was the same guy I bought the metric "step stud" style "short stud" hardware from.
andy |
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glutamodo  The Android

Joined: July 13, 2004 Posts: 26448 Location: Douglas, WY
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Posted: Wed Feb 23, 2005 5:57 pm Post subject: |
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BTW - speaking of the nice 1965 VW heads, I think I just spotted a good deal on some used ones on the classifieds page. I mostly use theSamba for the classifieds, the message boards usually just seem too busy for me to keep up. But I do like going through the ads once or twice a day.
anyway, the guy says these are 1300-1500 heads, (and I think one pair might be out of a very early type 3 1500 - they have the round boss rocker hold downs with the US-style slotted stud kits in them, but with the angled SP style intake ports) , but I think these other heads he has pictured are the good late 1200 40HPs. They are square boss and have the 90 degree intake ports - In this ad -
http://www.thesamba.com/vw/classifieds/detail.php?id=50893
http://www.thesamba.com/vw/classifieds/detail.php?id=50893
andy |
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6vE Samba Member
Joined: February 14, 2005 Posts: 64
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Posted: Wed Feb 23, 2005 6:26 pm Post subject: longstuds |
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So, in a nutshell, are you guys saying it would be worthwhile to pick up some replacement heads just in case, or for the rebuild I'll eventually have to do?
If/when my motor dies, I'll probably go with a 1600 anyway. |
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glutamodo  The Android

Joined: July 13, 2004 Posts: 26448 Location: Douglas, WY
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Posted: Wed Feb 23, 2005 7:17 pm Post subject: |
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Well, if you plan to lose the 40HP, don't worry about picking up any spare heads. The ones I got off of ebay were probably from a euro-spec car, as they weren't set up for stale air, but they looked so nice, and was such a good deal when no one bid against me. I'm running a stale air but have the parts now to put together a spare big-bore motor, which I will make as a fresh air, one of my "somday I'll get around to it" projects.
andy |
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gerg a.k.a. 6volt65

Joined: April 25, 2003 Posts: 5454 Location: Monroe, LA
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Posted: Tue Mar 01, 2005 6:54 am Post subject: |
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Andy - I am pretty sure I have a real good set of the heads you describe above. My part number is 113 101 373, and I read that they are the '65 40Hp heads with square rocker boss that requires no stud repair. These are the heads right? A one year only 40 Hp part. I bought a 40Hp here on the Samba for $30 down in Phoenix - wound up being a parts engine but had these heads on it and they look fine! _________________ Gerg
. . . I got 99 problems and my bus ain't one . . .
'65 Sunroof Beetle
'65 Vert
'60 Singlecab |
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glutamodo  The Android

Joined: July 13, 2004 Posts: 26448 Location: Douglas, WY
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Posted: Tue Mar 01, 2005 9:05 pm Post subject: |
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Yep, those are the good heads! You just have to make sure you get the upper studs that will fit them. Like I mentioned above, I had to put double-washers under the upper nuts on my engine or they'd run out of threads before they'd be tight.
andy |
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gerg a.k.a. 6volt65

Joined: April 25, 2003 Posts: 5454 Location: Monroe, LA
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Posted: Sat Oct 08, 2005 7:18 pm Post subject: |
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glutamodo - I went to assemble my engine today with the 373 square boss '65 heads and have apparently run into the head stud length problem. I have 2 sets of upper head studs - one set is 8" long, and they came off of the same engine I got these heads from. I don't remember spacers or double washers on them when I disassembled. The other set is 7" long. Look at this picture with the 8" studs in place:
I am several threads short and overall length is too long. Is this what you had?
If I put the seven inch studs in the tips of the studs are right where the threads start on these. So they are far too short in length.
Here are the studs I have
The lowest in the picture is the 7" upper studs that came off of an engine with early 40hp heads
The middle stud is the 8" stud that came off a 40Hp with the 373 heads
The top stud is what goes on the bottom row of head studs.
I am thinking that I need 7.5" studs to be right. I may just go have 8 of them made.
Also, how much would you expect the 'new' push rod tubes to compress when heads are torqued? I put the 4 tubes in place and let the head down and the head is like 1/4" or more from seating onto the cylinders. These are the correct part number for 40 Hp engines and are NOS / unused. Do you think this is normal or is there a different part number for the push rod tubes on the 373 heads? Different length in other words. Here is the gap with the head sitting on the tubes:
You can see the shiny gap between the cylinders and the head. _________________ Gerg
. . . I got 99 problems and my bus ain't one . . .
'65 Sunroof Beetle
'65 Vert
'60 Singlecab |
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Steve22 Samba Member

Joined: March 05, 2004 Posts: 1389 Location: the wild unknown
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Posted: Sat Oct 08, 2005 10:03 pm Post subject: |
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Greg,
Did you expand the tubes before you put them in? It looks like they are still pretty compressed (the accordians on the ends).
I didn't hear anyone mention that Serrano had the Mahle kits... I just got mine a couple of weeks ago from him.
I'm almost to the point where I can start my rebuild, broke ground on the new garage last weekend... hoped to do the final leveling on the foundation this weekend, but it rained today... maybe I can get to it after work this week and later this week I can actually have the concrete poured! _________________ '65 Karmann Ghia 'vert
'73 Super Beetle
'59 Beetle ragtop
'73 Sunroof Transporter |
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glutamodo  The Android

Joined: July 13, 2004 Posts: 26448 Location: Douglas, WY
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Posted: Sun Oct 09, 2005 2:56 am Post subject: |
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Those look about the same length as the ones I had.
According to the Bentley manual, the correct length for studs to match the 1965 heads is 193mm. That's just under 7.6 inches - or 7 19/32" As I found out, these are near impossible to find.
Expanded pushrod tubes will be just long enough for "correct" length studs to just start the nuts on them when you go to bolt the heads on. From your pic, if those aren't squished yet, the ones you have are probably fine. All 40HP heads use the same pushrod tubes. I probably mentioned this before, but you should use the longer 40HP push rods, the ones with the little knurled pattern on them, which are 2mm longer than the early 40HP.
andy |
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gerg a.k.a. 6volt65

Joined: April 25, 2003 Posts: 5454 Location: Monroe, LA
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Posted: Sun Oct 09, 2005 7:40 am Post subject: |
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Sounds good. Has been a while since I built a VW engine so I could not remember the amount of 'squish' for the tubes. I can press down on the head and the tubes definitely squeeze and spring back up. They look compressed in the pic but are actually the correct uncompressed length and have never been used.
As far as the studs go I guess I'll look at maybe getting a set made or just some spacers.
Come to think of it, the engine I got these heads off of was not a '65 case - it was an early case with the late model heads on it. So now I wonder what the studs I have in the case are for? The shorter ones in the pic above are for early 40 HP heads, I am missing the 7.6" ones for the 373 heads, but what up with these 8" monsters?
I never even thought to crack open the Bentley - been too long.
Thanks! _________________ Gerg
. . . I got 99 problems and my bus ain't one . . .
'65 Sunroof Beetle
'65 Vert
'60 Singlecab |
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