NOS 1,7 heads with strange numbers can I use them?, Now with photos! Options

[larss]

Have got two NOS heads which I hopefully can use for my stock 1,7 D-jet.
However they have an odd number "021 101 371 B" (the originals have an "Q" at the end) and also there is no ventilation tube (can be fixed) and no CHT hole (can be fixed).
The valves are the same dia but the holes for the pusrod tubes are slightly smaller (guess that can be machined).

What engine are theese heads originally made for and what are the issues for using them in a 1,7 D-jet?

/Lars S

[sean_v8_914]

http://www.tunacan.net/t4/reference/cylhead.htm

[sean_v8_914]

show us some photos, please

[larss]

Ok,
this image shows the NOS head "021 101 371 B" above the
original "021 101 371 Q" head below.
There is a groove in the combustion chamber opposite the spark plug hole in the original one which is missing in the NOS one, does that matter?
(IMG:http://www.914world.com/bbs2/uploads_offsite/www.lsmteknik.se-10787-1326823190.1.jpg)

Below is the NOS head, the brownisch is not burnt oil and dirt, it comes from the grease they put on the head at factory 40+ years ago ...I have not cleaned the whole head yet...luckily it seems easy to clean with degreaser...
(IMG:http://www.914world.com/bbs2/uploads_offsite/www.lsmteknik.se-10787-1326823193.2.jpg)

Below shows one hole for push rod tubes. It is hard to see but at the outer edge of the hole there is a "hump" which the O-ring will rest on (the outer tube end will not slip through the hole as it uses to do, but the inner end and the tube will pass).
(IMG:http://www.914world.com/bbs2/uploads_offsite/www.lsmteknik.se-10787-1326823195.3.jpg)


Any ideas what engine this head was ment for and what are the issues for using them in a 1,7 D-jet?


/Lars S

[904svo]

B heads are bus heads, Check the exhaust ports and see if they are square ports
or oval ports ( like 914 exhaust ports). If they are square ports you will have trouble finding exhaust manifolds to fit them if they are oval you should be able to use them with the stock exhaust system.

[Enzo]

Check the exhaust ports and see if they are square ports

I think its only the later 2.0 bus engines from 79 onwards that had the different shape exhaust ports, in the UK we call it the T25 but think it might be your Vanagon.

[larss]

Checked the exhaust ports, they are of the same type as the original 1,7 which is oval.
Is this head still a bus head and what issues are there when using it in a 1,7 D-jet?

/Lars S

[Enzo]

Is this head still a bus head and what issues are there when using it in a 1,7 D-jet?

The only problem you might have is if the combustion chamber cc is alot smaller, as will raise your compression ratio.

You could try and measure the cc of your existing heads (using a liquid and a syringe), and compare to these heads... if they are different then there are calculators online that you can feed the numbers into, along with bore, stroke, etc... and it will work out the compression ratio for you.

[904svo]

Some of these heads had a step in the combustion chamber. Those look like they don't there fore you have to install the head gaskets to get the CC right.

[Cap'n Krusty]

Early cars used pushrod tubes with a smaller OD on the outer end.

The Cap'n

[underthetire]

Ex ports are the same on a 1.7 on da bus. It was very late, like 78/79 2.0 bus heads that had the different shape.

[larss]

Early cars used pushrod tubes with a smaller OD on the outer end.

The Cap'n

Yes, guess theese are early 411 carb heads. Surprises me that any 1,7 engine had higher compression than the 1,7 D-jet...but possibly the early engines did not have the high compression pistons just flat ones...?


/Lars S

[sean_v8_914]

compression was lowered to cope with emission requirements. flat tops are higher compression. the lower compression pistons have a slight dish. I think its about 3cc volume. one point in compression is detectable with a calibrated seat dyno AKA your rump
that second head looks like a virgin, never fly cut.

I did not know about the smaller push rods, thank you.

[sean_v8_914]

here are the photos. good web site, hard to find this i thought
http://www.tunacan.net/t4/tour/heads.shtml

[larss]

compression was lowered to cope with emission requirements. flat tops are higher compression. the lower compression pistons have a slight dish. I think its about 3cc volume. one point in compression is detectable with a calibrated seat dyno AKA your rump
that second head looks like a virgin, never fly cut.

I did not know about the smaller push rods, thank you.

My original 1,7 D-jet pistons have a "hill" on top so there are possibly two low compression pistons compared to them: flat and dished.

The original heads have a cut out in the combustion chamber which the old NOS ones dont have so there is quite a few combination possibilities with all head and piston types...


/Lars S

[sean_v8_914]

early 1.7 had "the hill" on teh pistons. highr compr, power output was better too.

[HAM Inc]

Wow. That NOS head is real odd-ball. I have never seen one. The 'B' suffix is unique. It clearly has a 100mm register (like all 1.7 heads), but that sure looks a 2.0bus chamber (2.0 bus heads have a 105mm register). Typically the 1.7 and the 2.0 chambers have the same O.E. volume, around 49cc's.
I wonder what it was used for. Maybe a stationary application?

The common 1.7 chamber shape has the relief cast in to clear the piston dome some 1.7's used.
1.7 heads and 2.0 bus heads also share the same valve sizes, but the ports are shaped differently.

[Jake Raby]

Yep... Len is right, that "B" head is for an industrial engine application.

[HAM Inc]

I figured Jake would know!

I was 99% sure it wasn't from an automotive application. I'm pretty sure I've seen all of them.

[larss]

The common 1.7 chamber shape has the relief cast in to clear the piston dome some 1.7's used.

Thanks for writing that Ham inc, that means I have to grind the relief in the heads before putting them on.

Roghly measured the O.E. volume it seems to be a little, little less on the old NOS heads than on the original heads (with the relief) maybe just the relief volume differs.


/Lars S