Head/Cam/Carb Combo Questions for a Bus Engine Build

[Tusk]

Hello all!
My buddy and I want to build a motor for his '61 Splitty (no RGBs)
We already have a machined case and are pretty set on building a 1641 as the cylinder spigots are not bored for anything larger.
But we've got some concerns on the head, cam and carb combo...
We have some brandy-dandy new big valve DP heads from AA on the shelf, and we were considering a CB cheater cam, but because of funding were probably going to stick with a single Solex 34/3. The concern here is that the carb won't be enough for those heads and that cam.

I called CB, because I haven't been able to get AA to answer the phone or emails for three months now, and the gal on the phone said that this setup should be fine though without really knowing anything about AA's heads, she couldn't say for certain...

Which brings me here! What say you? Is this setup useless? What do ya'll suggest?

This Bus will be daily driven and I know he'd like to be able to charge up hills and at least do 70 on the highway. Again, the RGBs have been removed and (so we're told) a '68 Beetle swing axle was put in.

Thanks in advance,
/T.
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1956 Beetle - Lisbeth - Sold
1979 Bay Window - Betty - Sold
1975 STD Beetle - Lucille - Sold
1964 Beetle - Rita - Restoration in Progress
1971 Squareback - Joanie - Sold
1961 Beetle - Daphne - Sold

[Dan Ruddock]

[Brian_e]

Sorry ..... but I can't think of a much worse combo for a bus without reduction boxes.

If you refuse to bore the case, sell/trade the big valve heads for some correctly ported stock valve heads. Ditch the slip-in egg shell 87's, and run some thick wall 88's. They will go in the stock case bores, but you will need to get the heads bored.

Run the cheater cam with the stock carb, 1 3/8" header, and 8.0-8.3cr, and a tight deck height.

Even better, just make it a 1776cc with all the other parts the same and it will be about the perfect small, stock carb bus engine.

Out of the box "Big valve" heads flow worse than slightly cleaned up stock valve heads. I have tested them on my flowbench many times, and they have some terrible choke issues just under .400" lift.

Brian
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www.type-emotorsports.com

[Tusk]

[Tusk]

[Clatter]

Doing 70 on the highway in a bus with thin-wall 87s..
It'll happen (maybe), but not for very long.

A bus motor is best built with a careful eye to details and the right combo.
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Bus Motor Build

What’s That Noise?!?

[Brian_e]

[evanfrucht]

Just build it stock if you can't put more time in money into building a well thought out performance motor.

If you don't do it right (with a lot of thought, time, care, and workable budget) it will run shittier and have more problems down the road than a stock one would.

Theres no way he will have it done in a month if the car is stripped and there's no engine, That's what they call "slapping it together."
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1967 Bug ( the daily rod )
1964 Fury Wagon ( the pavement shredder )

[chrisflstf]

As a bus owner, I would strongly advise following Brians advice. He has the experience and data to know what works well. You dont need big valves.
A straight axle in a bus with a small motor isnt a good combo either

[Tusk]

[sled]

[Alstrup]

Busses in general are/were underpowered from the beginning... The "lucky" part is, that the splitbhus is actually not that hard to push through the air. But, with which succes depends a great deal on what transmission was used for the straight axle swop. A 4,375 and a nice 1600 will do the job nicely. A 4,125 and it will soon loose its arm on even small hills. A 3,88 slightly worse again. If/ when the engine is out the easy way to figure out what final ratio you have is to lock one wheel, put it in 4rth, turn the inputshaft 100 turns and have another person count the revolutionbs the other wheel is taking and then calculate bacwards.
A purpose built 1600 will do the job nicely if youre not in a hurry, even with a 4,125 transmission, as long as youre understood with having to downshift even on smaller grades.
A nicely designed 1600 engine will soon pull 15-20% more torque than a stocker, also through a 34 Solex. And while that´s not a lot in real life power it does make a significant difference in the driving experience.

I agree with the rest. 87 mm barrels are not the solution on a bus engine. I would also rather stay at stock 85,5 and bump the compression instead. - or go larger on the displacement like 90,5 bore. A 1776 with a nice cam like the CB 2280 or the 2232 can make for a nice engine for a bus, even with a slightly modified stock carb.

- Ohh, I´m basicly repeating what Brian wrote up north. Ahh well, He´s right
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[Tusk]

[Brian_e]

Yes its worth it, and make sure the compression is at least 8.0 with a tight deck. Use the cheaper cb1512 lifters.

Little 1600's more than anything....all the little details start to add up.

Also, don't underestimate the benefits of spending 15min per head blending the valve bowls, and have your local engine shop do a REAL 3angle valve job on them.

Brian
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www.type-emotorsports.com

[Alstrup]

Just to show what a little TLC can do along with being meticules with a stock engine.
Here is a 1600 type 1 i built some years back for a ´72 convertible.
Totally stock internals apart from my standard balance job, along with rods lightened 30 grams along with 356 piston squirters and the balancing.
Case decked for 1,05 mm deck height. stock pistons, balanced +/- 0,5 grams.
Cylinderheads cleaned up in the bowl, casting flashes smoothed, rounded off edges in the exhaust, guide boss trimmed. NO MORE. Stock intake valves trimmed (smoothed) on upper side along with a 30 degree cut back. Radius cut on intake seats (Formula Vee style) regular 3 angle on exh. Non plug side of chamber laid back slightly. Cut for 8,2 CR.
1,25 rockers on intake, stock on exhaust.
Stock heater boxes. Stock Leistritz muffler. CSP large ID end pipes. (You can´t do it with the stock mufflers of today)
Rebuilt stock 1600 SVDA distributor set up for 10/30/38 advance. Pertronix coil.
Stock intake. 34 mm Solex with 27,5 mm venturi.
That´s basicly it.

Here is another 1600 with the CB 2232 cam, nice heads, 8,5 CR. CB Centersection along with a little work in the end castings.
34 Solex with 28 mm venturies. Initially an SVDA distributor, but it had a tendency to ping under load at specific rpms, so I swopped to a CB Black box and programmed my way out of it - without loosing power!
1½" CSP heater boxes and CSP Super comp exhhaust.

With this cam in a 1600 the idle is a tad lopey, but with the BB I could improve that significantly, down to it being barely noticeable unless for the trained ear.
With stock heaterboxes and say a VS muffler the power will be around 75 hp and a little over 130 Nm. At least that´s what I typically see.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[Tusk]

[Matthew]