Type 4 VW heads

[HapHazard]

Purely out of interest, has anyone ever tried converting a Type 4 VW head to dual plug? I am not looking at the merits between a Type 1 and 4 head, I simply would like to know if anyone has done it before? If so, where was the 2nd plug fitted?

HH :ban:

 

[Autodidact]

Howdy, HH; On the VW forums, such as The Samba, there are threads that talk about dual plugging type 4 heads, and they invariably talk about the need for some welding to be done. I have a set of Type 4 heads and they seem to have enough space next to the existing plug to drill another plug hole without getting too close to either the existing plug or the cylinder stud, but there is a boss for some kind of sensor on one of the cylinders very near to where a plug could go, and this looks like what may need to be welded up (I had thought about screwing a plug into it, but welding would be better?). I may be wrong, but because of the location of the exhaust, and the pushrod tubes, it doesn't seem to me to be enough room to drill the plugs on the bottom side - I might be completely mistaken, though. I think your best bet would be to get on the Samba and ask those folks.

 

[HapHazard]

Thanks for the info Auto d. I assume that you were looking to use a type 4 case as the stud spacing for the barrels in slightly different to the type 1 casing. Also the pushrod tube holes look to be spaced entirely differently on the type 4 head as well. As I was looking at the possibility of having to go for a 1/2 VW project for weight reasons, then I may have more scope as I am using only part of the head, but I think that the amount of modifications would be too great (no doubt the reason as to why nobody else has done it already!). Shame, as the type 4 has some distinct advantages over the type 1 heads, running cooler, and not as prone to cracking between the valves, not to mention the exhaust coming off the bottom, which is a far tidier arrangement.

I may just try and get an old T4 head to play about with and get a better idea on how things would stack up for modifications....

Ho hum....

HH

 

[Autodidact]

Thanks for the info Auto d. I assume that you were looking to use a type 4 case as the stud spacing for the barrels in slightly different to the type 1 casing. Also the pushrod tube holes look to be spaced entirely differently on the type 4 head as well. As I was looking at the possibility of having to go for a 1/2 VW project for weight reasons, then I may have more scope as I am using only part of the head, but I think that the amount of modifications would be too great (no doubt the reason as to why nobody else has done it already!). Shame, as the type 4 has some distinct advantages over the type 1 heads, running cooler, and not as prone to cracking between the valves, not to mention the exhaust coming off the bottom, which is a far tidier arrangement.

I may just try and get an old T4 head to play about with and get a better idea on how things would stack up for modifications....

Ho hum....

HH

I was thinking the same as you! A half VW using Type 4 heads could be an 87ci engine with 103mm pistons and an 86 mm crank. Some of the schemes I was considering were a) making a completely new crankcase - flat sided, like a Corvair crankcase for simplicty, b) cutting the rocker boxes off entirely and bolting on new ones - machined or cast; that would take some careful design c) also, refering to (a) above, the Corvair has a bore spacing of almost exactly the same as the Type 4 and it may [or may not] be possible to use a Type 4 crank in a sawed-off Corvair case a la 1/3 Corvair - a new front cover with the additional bearing could be made and the Type 4 crank snout modified to better take the loads from the prop. But the stud spacing of the Type 4 would be the problem, here... d) how about cutting away everything from a VW case except the cylinder decks and the bearing webs and then surrounding it fore, aft, top and bottom with new [and simpler to make] pieces, The top and bottom covers could be structural and aid in holding the front an rear covers on. I think there are VW cases that can be drilled for the Type 4 stud spacing.

Happy experimenting!

 

[Brian Clayton]

Maybe you could look at the scat individual heads for ideas, dont they fit either case? I was thinking they fit either case, and that you bought the corresponding pushrod tubes they sold.

 

[HapHazard]

BC the Scatt individual heads are apparently no good as they run much hotter due to the vastly reduced fin area. Mosler used these heads apparently, and was a source of one of thier problems. Im not sure why they still make them, as for a race engine, they must kill the engine prematurely if they run them at the max.

Auto d, if the T4 needs too much mods to use, it isnt worth it. If one end of the head push tubes match approx the spacing of a T1, and the stud problem could be overcome, then yes. No..... its back to a good ol T1 head..... If you are talking about new cases etc, its a massive job, and you will probably end up with years of tears and expense..... If you were going to go that route, why not get a Scatt killer case, and build a big bore stroker at 90mm stroke?

If you contact them, you may find that they could leave the studs in the case undrilled, that way you may be able to use T4 barrels and heads? This would be far better route, and one I would consider as the case is so much better than both the type 1 or 4 (but probably heavier. It is a pretty good price however). I dont have enough knowledge of the VW to be able to say what other problems may be lurking if you went this route however?

HH

P.S. BTW Brian, love your 'Flying Rules'! Hope you dont mind, but I nicked them and stuck them on my FB post, got loads of likes!

 

[Brian Clayton]

BC the Scatt individual heads are apparently no good as they run much hotter due to the vastly reduced fin area. Mosler used these heads apparently, and was a source of one of thier problems. Im not sure why they still make them, as for a race engine, they must kill the engine prematurely if they run them at the max.

Auto d, if the T4 needs too much mods to use, it isnt worth it. If one end of the head push tubes match approx the spacing of a T1, and the stud problem could be overcome, then yes. No..... its back to a good ol T1 head..... If you are talking about new cases etc, its a massive job, and you will probably end up with years of tears and expense..... If you were going to go that route, why not get a Scatt killer case, and build a big bore stroker at 90mm stroke?

If you contact them, you may find that they could leave the studs in the case undrilled, that way you may be able to use T4 barrels and heads? This would be far better route, and one I would consider as the case is so much better than both the type 1 or 4 (but probably heavier. It is a pretty good price however). I dont have enough knowledge of the VW to be able to say what other problems may be lurking if you went this route however?

HH

P.S. BTW Brian, love your 'Flying Rules'! Hope you dont mind, but I nicked them and stuck them on my FB post, got loads of likes!

I meant just for the stud spacing, not for the actual head design. I thought the head would fit either case, so maybe looking at how they overcame the spacing issue might be helpful. I had seen the cooling issues a while back. I was thinking they could be drilled for dual plugs too, maybe the location would help you?


No problem on "flying rules", I stole them myself from someone on another forum.

 

[HapHazard]

Had a picture of a 1/2 VW T4 sent to me....nice looking bit of kit, but the front of the case has a lot of real estate attached to it!

 

[Autodidact]

Had a picture of a 1/2 VW T4 sent to me....nice looking bit of kit, but the front of the case has a lot of real estate attached to it!

Any chance you could share that with the forum? :lick: