73 1.7 Heads Interchange

[sallittjob]

Morning Guys,

So my beautiful (new to me) 73 412 has finally been receiving some long overdue maintenance on my behalf. The engine has 80,xxx original miles on it and is completely stock.

I noticed recently that after a cruise around town, the idle had a slight misfire. I broke out the leak down tester and found that #3 had a massive exhaust valve leak. So I popped the valve cover and found the exhaust valve was tight (zero lash cold). I readjusted and then my leak down went to 2%. I pulled the plug and check the valve in the cylinder expecting to see a hammered out seat. To my surprise, the seat looks perfect, so I'm assuming the valve is stretching and about to break. It is a sodium filled VW valve that I set to 0.006".

I want to repair the engine so I was trying to think of some options. I have a 0 mile VW Canada remanufactured 1.7 bus motor in my collection. I was wondering if I could steal the heads off of that motor and use them on the 412? From my research, it looks like the combustion chambers are the same size, only difference might be the temp sensor and smog ports since the bus motor is for a carbed vehicle. I was hoping maybe I can drill and tap the temp sensor hole and add the smog ports, then swap them on the 412 and be on my way. Any thoughts?

Other option would be to send the OG heads out to get a valve job. The castings appear to be in excellent condition still so I think that is a viable option.

Thanks!
_________________
57' Beetle Deluxe
1192cc SP

71' Super Beetle
1968cc DP

73' 412 Sedan
1679cc FI

75' Westy
1800cc FI

[Pelle]

Buss heads have smaller intake valves. As already noted there´s no threaded boss for the temp sensor and the crank case vent pipes are missing.
Buy a set of NOS heads https://www.thesamba.com/vw/classifieds/detail.php?id=2355062 These are correct for 411/412 with D-jet.

[raygreenwood]

A few items:

1. The 1.7l bus and the 411/412 1.7L....both have the same valve size (39mm x 33mm).

2. If it's still in factory form, it should not have sodium filled valves unless you or the previous owner installed them.

3. Do you need the smog system where you are living? If not, I would deactivate the air pump and plug the holes in the head.

4. In the 411, 412 and 914 cars ....it would be very rare to have a valve seat drop out unless the engine were subjected to repeated "near over heating" like you get in the bus. Lighter weight, better gearing etc.....so what you found is not surprising.
But....the worry is that yes....your valve is stretching. On some of the earlier 411 and maybe early 412, there was a limited batch of engines made that had the issue of exhaust valve being overly stretchy and snapping a valve early in life like 30-50k miles. It was limited and kind of handled like a dealer recall and not much info was ever out there.....but in the late 70s and early 80s there was the short term reputation/fear of 1.7L engines snapping exhaust valves.
It came and went pretty fast but it's vaguely possible maybe you got one of those.

But, no vw type 4 to my knowledge ever had sodium filled valves except for 914 2.0.

5. The head casting and combustion chamber of the bus and 411/412 1.7L are the same.

I would not install/drill ports for the smog air system unless that is required in your state. It's horrible for the engine.

Also, heads from a bus engine....even though the 1.7L bus engines were probably among the most robust....will still have some level of abuse that the equivalent mileage 411/412 head does not. I would use them for moderate to short term while you properly rebuild your original heads.

At this point in time....it's wise to have new seats and guides installed. Ray

[heimlich]

[sallittjob]

Thanks for the help guys. So this might be a stupid question, but what's the opinion on just replacing the exhaust valves? The seats looks good and if the guides check out, couldn't I just install new exhaust valves and lap them in? Again this is a 80k 412 head that looks to be in good shape other than a stretchy exhaust valve on #3. If I went this route, I'd change all 4 exhaust valves.

I'm thinking about just using the rebuilt VW Canada 1.7 bus heads but if swapping the valves in a reasonable option, that would be ever easier.

Thanks-
_________________
57' Beetle Deluxe
1192cc SP

71' Super Beetle
1968cc DP

73' 412 Sedan
1679cc FI

75' Westy
1800cc FI

[raygreenwood]

[sallittjob]

Update:

Got the engine pulled over the weekend. I have to say, compared to my Type 4 bus, this was a smooth operation. I tilted the transmission and slid the engine right out the back. No need to remove any of the fuel injection parts or tin ware.

Does anyone have shops they recommend to work on the heads? I was thinking of contacting Head Flow Masters but I'm open to recommendations. I'll also take the opportunity to send out the injectors for a cleaning/rebuild since they probably could use it with their age.

_________________
57' Beetle Deluxe
1192cc SP

71' Super Beetle
1968cc DP

73' 412 Sedan
1679cc FI

75' Westy
1800cc FI

[Pepperbilly]

Not sure what to tell you about the heads in your area.

I had my original injectors cleaned and flow tested. I still had problems though. I did have some continuing fuel contamination problems which did not help. I gave up on my injectors after looking at the spray patterns. I opted for new SMP injectors through Rock Auto. The performance is outstanding and I have not looked back. I don’t think it is worth the time and money to try and revive old injectors.

Bill

[raygreenwood]

[sallittjob]

Thanks for the info on the injectors. I'll probably just buy the new ones as you guys suggest. I don't really have any reason to believe there is anything wrong with the OGs, but I just thought with their age it could be a point of concern. I'll post some pics up of the injectors when I pull them this weekend.

Still no decision on the heads. I called headflow masters and left a message, no reply yet. I don't mind shipping to a highly recommended shop. I don't want to have to mess with the heads again so I'll pay to get it done right this time. I'm going to add a DD CHT gauge too while I'm at it since I have one in all of my ACVWs and like the peace of mind.
_________________
57' Beetle Deluxe
1192cc SP

71' Super Beetle
1968cc DP

73' 412 Sedan
1679cc FI

75' Westy
1800cc FI

[raygreenwood]

[Pepperbilly]

On the injector side of this discussion, make damn sure your fuel tank is clean. I did have mine out and thought I had cleaned it really well. I spent alot of time on this. Well, it turns out that there was still some very fine sediment remaining. You can see the photos in my wagon, the problems thread. So I fiushed the tank several times again while it was back in the car. It got much better, but I am changing out fuel filters every so many miles just to be on the safe side. So far it has not caused me any grief with my new SMP injectors and the fuel filters are showing less and less contamination with each change.

Bill

[Hawker]

Hello,

Rock Auto have the correct Bosch 028150007 / SMP FJ119 fuel injectors for the 411 with D-Jetronic for sale at $70/£59.

Rob

[sallittjob]

The fun continues:

So I finally got the heads pulled. A few things I noticed during teardown:

1.) The intake manifold gaskets didn't match. It seemed like the #3/4 side was a carb gasket (thicker). The nuts also seemed too loose on that side.

2.) The engine isn't totally original like I thought. The pistons and cylinders are flat top AAs and you can still see cross-hatch. No rust at all on the cylinders. This explains the excellent leak-down numbers I recorder (2%ish per cylinder pre teardown).

3.) Here is where things get funny but the big picture comes into focus. The heads on #3/4 don't match the #1/2 heads. Both are 1.7 heads but the #3/4 (problem child that started this teardown) have sodium filled exhaust valves (like I stated in my first post). So I'm assuming the PO had a head problem and brought it somewhere to have the engine "repaired". Looks like they just grabbed some bus 1.7 heads with sodium valves and slapped them on there. Did P/Cs for good measure and tossed the unobtanium domed pistons.

4.) Further evaluation of the #3 exhaust valve found a chunk of guide missing in the port. Also, the valve stem is visibly reseeding below the level of the other 3 valves on that head. Seems like I had a bomb waiting to explode in the form of a stretched valve and worn out guide. Good thing I decided to tear into it.

I made some calls and all the good well-known head rebuilders are busy right now. Tims told me 2+ months before he can touch them. So I'm going to roll the dice here and shift back to my original plan. I plan to pull the VW Canada rebuilt heads off my longblock and see what they look like. I added some pics for reference just because I think it is super cool that a VW Canada Rebuild from the early 80s is still in the wild, unrun. If this works out, I'll save the shortblock for a future engine build for my bus. I recently did a top end job on it and it's running nice but this will be my insurance policy.

Thanks
_________________
57' Beetle Deluxe
1192cc SP

71' Super Beetle
1968cc DP

73' 412 Sedan
1679cc FI

75' Westy
1800cc FI

[raygreenwood]

The 1.7L heads...to my knowledge.... were never made with sodium filled valves...at least not in the US. I do not know about Europe. Your engine was rebuilt in Canada so no telling what their normal spec is.

Those also look like so many other fairly common valves with a divot from the machining center in the head. I have some older valves that look just like it that are either TRW or ATE and are not sodium filled.

It would be interesting to find them sodium filled. You should cut open the stem of one and see.

The carb gaskets should be thinner. The correct fuel injection gaskets are about 8-9mm thick and are made of phenolic plastic.

All of the 1.7's and most of the other engines came with 9mm exhaust valve stems. From my long ago experience, sodium filled valves are even slightly bigger. Ray

[Pepperbilly]

As far as I understand the bus heads, they eliminated the breather ports. The whole crankcase breathing system was much simpler, but I don’t think better. I would really look into correct breathing heads as the engine was designed for the 411/412s
I am a stock kind of guy and I like to keep things as they were designed. You may find less difficulty down the road. I could be wrong…

Bill

[sallittjob]

[raygreenwood]

[Pepperbilly]

Chris,

Two different types of intake manifold gaskets. The 1.7 heads had 4 studs for mounting. 1.8 and 2.0 had 3 studs for mounting.

Bill

[raygreenwood]