Stock type 4 bus engine.

[E4ODnut]

My son is in the final tuning stages of his fully restored '76 Westy. This thing is heavy, and to top that off he pulls a little utility trailer with more stuff in it. A couple of years ago he built a T4 2258 for it. Unfortunately he got some bad advice on the build and made a few less than perfect decisions himself and the engine proved totally unsuitable. Last fall we went back to the drawing board to decide what conditions he would be driving under and what he really needed out of the engine. He lives in Saskatchewan, with extremes in temperature. Heater boxes are essential, chokes are preferable. The trailer hitch severely limited his choice of exhaust. He would like to drive faster, but in the interests of economy and reliability we decided to design for a cruising speed of 100 KPH with a maximum speed of 100KPH more or less. His tires and gearing put his cruising speed at 3270 RPM which is relatively low. We decided to design a cam for maximum low to mid range torque. Anything above ~4500 RPM wasn't important to us. We figured with air flow in that RPM range we should be able to use a set of Solex Brosol 34s that he had as long as we installed the 28 mm venturis. Because economy is important, and there are very few options for vacuum cans on SVDAs we decided to go with CB Performances "Black Box" ignition using a Pertronix trigger and a locked distributor. This winter I spent the Christmas season with him and helped him assemble the engine. We spent a lot of time and attention to detail on it.

So far, the results are everything we could have hoped for. The engine is quiet and smooth through the full power band. It starts well and there are no flat spots. It pulls like a Peterbuilt from idle to ~3500. By ~4000 it's starting to pant and by ~4500 it's given pretty well all it's got. Even on a long hard pull he hasn't seen head temps over ~370F and oil temps have never gone above ~180F. Under average driving conditions he is getting ~ 21 MPG Imperial.

Even with this displacement the Brosols work well for us, but if you have to rev higher, with more corresponding air flow, they might limit what you could do.

[cliveawn]

Ok,What were the specs of the pistons,barrels,valves and cam.
Did you end up just using the stock exhaust?
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Green 78 Westfalia Helsinki,

2056 with 41 x 34 valves,ported heads
Fully balanced
8,5:1CR
JPM Custom made cam
JPM 7075 dual taper pushrods
IDF 40's with 28mm venturi's
Python CSP 42mm exhaust.
115 HP

Daily driver 2017 Volvo V60 D5 hybrid
Rica stage 2 tune 345hp.

''Funny thing about common sense is that its not very common''

Seismic gun mechanic

[udidwht]

Want a solid runner go with the following.

96mm AA biral P/C's
42x36mm heads new AMC castings with all new hardware (Headflow Masters)
Porsche swivel adjusters
Solid spacer rocker arm assembly
71mm stroke
73 Web cam with Web solid lifters
Dual 40mm Webers
72-74 exhaust
Quiet pack muffler
Thunderbird or S&S 4-1 header
Bosch SVDA or CB blackbox
Pertronix flamethrower coil & Pertronix points replacement module
091 trans

I'm running that setup and its a very strong engine and can easily hold 70 mph with pedal to spare. I just returned from a 2,925 trip (Seattle - Huntington Beach, Ca.) And the bus ran flawlessly. I barely consumed 1\2 qt of oil the entire trip. Average fuel consumption was 17.3X - 24.5X when taking into account traffic, wind, road conditions. Dialed carbs in using LM-2 for low 13's at WOT and under load.

Now just over 13,000 miles on engine and its power is still growing.
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1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires

[E4ODnut]

Bore: 96mm
Stroke: 78mm
Rod length: 131mm
Heads: Brothers mild port, 44mm intakes, 37.5mm exhaust
Compression ratio: 8.1:1
Carburation: Dual Solex Brosol 34s, 28mm venturis, 55 idles, 160 mains, 130 airs (at this point, tuning continues)
Ignition: CB Perf "Black Box", Pertronix module, locked distributor
Exhaust: Stock heater boxes with Monza muffler
Camshaft: Steve Long Racing 248-252-108
IVO: -4
IVC: 32
EVO: 35
EVC: -1
Idur: 208
Edur: 214
Icl: 108
Ecl: 108
LSA: 108
Overlap:-5
I lobe lift: 0.321
E lobe lift 0.306
Rockers: stock 1.3:1 ratio (nominal)

We kept the large valve heads only because he had bought them for the initial build. We figured they wouldn't do us much if any good with the restrictive exhaust, but they shouldn't do much if any harm either.

Theoretical torque curve is quite flat, peaking at ~3500 RPM. In theory in the same engine, a Web 73 would probably develop a bit less torque but move it up to peak ~4000 RPM for a slight increase in HP.

[udidwht]

For something on the street going any bigger than 42x36mm in the valves will make for a difficult combo.
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1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires

[E4ODnut]

In theory I would have to agree, but in real life, this engine doesn't appear to have a problem with it. If we were design this engine again from scratch we probably would have kept the stock heads and valve sizes. As I mentioned, they were retained only because he had them and had considerable money tied up in them. Trying to sell used specialty parts in his part of the world can prove to be very difficult in most cases.