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Thu Aug 20, 2015 8:40 am

Hi all,

I need some advice for my first stoker build, there are so many variations of components to choose from. This is a budget build and will be using parts from my current engine, i'l list these below. The engine is for my bus the current 1600 doesn't cut it fully loaded up with kids,bikes, camping equipment. My goal is to achieve around 100hp build with plenty more torque than a stock engine.

Current engine parts

AS41 cases - will be machined for lager bores and fully flowed

Engle 110 cam and original lifters if within spec, they havn't done many miles

30mm melling pump - will change this

041 heads with 39 inlet 32 exhaust

Autocraft rocker shaft with standard rockers

Petronix billet distributer with ignighter 2

standard exhaust and heater box

webber 32/36 progressive carb.

New parts I think are suitable:

counter weight crankshaft 76mm stroke

i beam rods - not sure of size?

27mm oil pump

90.5mm p's and c's

I am willing to change exhaust and carburettor but need help to choose a good overall package that works well together. I don't see many builds with 041 heads why is this?

Thanks in advance for your help

Rich

Thu Aug 20, 2015 9:01 am

The much larger intake valve with stock exhaust valve on the 041's give them a reputation for running hot and cracking. If you're set on using those heads I would increase the exhaust valve size to 35.5. But really, a set of properly ported stock valve heads would do fine for your build. They will also allow you to use a standard header with heater boxes to keep costs down considerably.

Loose the progressive carb. Dual 36-40mm Weber's or Dellorto's.

I would use a 74mm crank with 5.325" rods for an easier build and to keep engine very close to stock width so a standard header fits properly and your tin fits without gaps.

Consider 94mm bore, 94x74 is 2054cc.

Thu Aug 20, 2015 9:17 am

Hi

Wasn't aware the 041 heads had problems, ok need to think a bit on that

duel carbs agree, but wot the standard heater boxes be to restrictive?

Will the 94mm bore be any less reliable than the 90.5?

the rod size makes sense to me, I don't need this to be any more difficult then it needs to.

Thanks

Thu Aug 20, 2015 9:25 am

76mm crank with 5.5" SCAT i-beams and B-pistons -- assembles almost like stock, very minor case clearancing, if any.

It's a bus? I'd consider the 92mm thickwall cylinders that fit in the 90.5mm case and 94mm heads -- 2021cc.

Stan

Thu Aug 20, 2015 9:51 am

stan_tichomirov wrote: 76mm crank with 5.5" SCAT i-beams and B-pistons -- assembles almost like stock, very minor case clearancing, if any.

It's a bus? I'd consider the 92mm thickwall cylinders that fit in the 90.5mm case and 94mm heads -- 2021cc.

Stan

VW or Chevy journal?

I agree that thickwall 92's are a better option than 90.5's, and safe choice.

Thu Aug 20, 2015 9:53 am

VW journal. I still have the 76mm crank (CB 4041) and 5.5" i-beams (SCAT), I may use them in this Type 3 I just got at some point. I was mocking it up with 94mm B Pistons, case bored for 94mm. It spun fine without any clearancing to the case at all (no cam, but I doubt that would have made a difference). Deck height was almost at 0 without shims. In same case, with same pistons, 82mm crank with 5.4" h-beams, I need .070" worth of shims to be at .040" deck. With a good amount of case clearancing, and we clearanced the cam too though it did fit as-is.

Stan

Thu Aug 20, 2015 10:19 am

stan_tichomirov wrote: 76mm crank with 5.5" CB I-beams and B-pistons -- assembles almost like stock, very minor case clearancing, if any.

It's a bus? I'd consider the 92mm thickwall cylinders that fit in the 90.5mm case and 94mm heads -- 2021cc.

Stan and keep the 30mm pump, add the extra oil gally,slot the lifter bores,use 1.25 rockers,40x35 valves.slight porting& chamber work, .040 piston to head clearance.total seal rings. pretty simple.

Thu Aug 20, 2015 10:25 am

I'd also go for the shorter (74mm) stroke, and either 92 mm or 88 mm thickwall pistons. I would stay with the 88s if you plan on running stock valve sizes and heater boxes.

-I would lose the progressive, dual singles will do fine, if you also:

-Lose the cam. If maximum low-end torque, and power at stockish RPMs, you can do better. If you want to keep the engle 110, you'll need dual dual carbs.

This will not get you 100 hp, more like 75 to 90, depending on skills. Your first stroker?

Thu Aug 20, 2015 11:28 am

yes first stroker

will be a slow careful build, i have leaned a lot from other engine builds on here. I just want to get the right combo of parts to make it all work nicely. the machine shop has a rolling road, so ill book some time on it when the builds finished.

Thu Aug 20, 2015 1:06 pm

there realy isant a right combo as much as a rong one,even then a rong combo can be made to work. just try to keep the parts you get are for the application you want/need. and remember need;s and wants are not always the same thing. build it right the first time the way you want it,dont skimp or cut corrners.use good quality name brand parts from a trusted sorce. and ask questions when ever you want some help and or entertainment.

Thu Aug 20, 2015 5:13 pm

78 stroke, stock length rods, and AA 90.5 B pistons is an easy combo, should require no spacers.

Mahle B pistons are 1mm shorter, so if you use mahle B pistons then use 5.5 rods for 76 or 78 stroke.
If 74 stroke just use A pistons with stock length or 5.325 rods and some spacers.

nobody likes the odd valve heads, but they will work Ok with stock end castings on them. I'd get better heads if using dual IDFs

Thu Aug 20, 2015 8:16 pm

Budget build? is there such a thing. I'll be waiting quite a while saving to buy parts. John of aircooled, has said he can get a progressive to run very well, its just most dont know how to set them up properly he said. I might end up using a stock carb with bored ventury to 28mm on my 78stroke / 88pc set for around 1900cc. I dont like fooling with dual carbs plus no carbs to remove before pulling the motor.
I have the 041's and will use them but if had to buy again would get the stock dual port heads to be a better match with stock header. I'll have compresson at or near 8 to run cooler and not worry of ping, just seems right for a bus but some say higher is good for power, I want torque?

Thu Aug 20, 2015 8:19 pm

Progressives can run well, but they retain the stock end castings, so you are flow limited by those and not the carb. Duals do not have this restriction, which is why they make so much more power in mid-range engines and wilder.

I tell people don't bank on more than 90hp with a progressive. If you want more, then you need dual carbs, preferably dual 2bbls.

Fri Aug 21, 2015 3:06 am

Thx Modak combo below looks good.

78 stroke, stock length rods, and AA 90.5 B pistons is an easy combo, should require no spacers.

@John whats the best carb to use for torque?

also any exhaust suggestions?

Thanks

Fri Aug 21, 2015 4:27 am

Very similar to what I'm building. 8)

I'm going with:
78.4mm Crank
5.4 Unitech rods
AA 92mm B Thick wall
(I think it's a nice Combo)

Hope this all works out for the both of us! :D

Fri Aug 21, 2015 6:29 am

Ive never seen 78mm that didnt need the cylinders cut or the case decked for usage with 5.4 rods. but I do like mine at zero deck with a .040 headgadget. as I recall mahle had diferent pin hights&cylinder lengths too for diferent bores&strokes.so to make it easy....a shim i& 5.5 rod is simples than cuttunng the cylinders or case to get to where you want to be. or if you dont care yup them 5.4 rods will work in all of them....as will just about any deck hight as long as you have some piston to head clearance so it will spin over.
and of corse there are different stroke 78mm cranks, so that also comes into play. :wink:

Tue Nov 17, 2015 1:37 pm

Ok budget went out the window.

I know have a scat engine kit-

Stroke 78.8
Bore 90.5
Cam C35
H beam rods
D port heads
44mm duel webbers

I'll get everything dynamically balanced, and get the intake manifold match ported.

I need some help choosing an exhaust that will work well for this set up. Remember its going in a bus.

Thx

Tue Nov 17, 2015 2:28 pm

Use 5.5" rods, and sleeve the 44s down to a 32-34mm venturi.

Tue Nov 17, 2015 2:49 pm

Hi John

What difference will the different sizes make? 32 or 34

Will one create more torque?

Tue Nov 17, 2015 3:43 pm

C35 will work best with 32mm venturis (my opinion)