Real world experience with this 40 Horse Big Bore Setup?

[mbliss13]

One of the best running engines I ever built from both a reliability and performance perspective was a big bore 40hp. My config was:

1. 83mm P&Cs
2. 8.3:1 static compression
3. Stock 1200 exhaust
4. 30 PICT carb (no mods)
5. stock rocker arm assys

and....

6. Engle 110 cam.

With the stock gearing in my 63 bug i could go 70 mph all day long, got decent mileage (25+mpg), and had no idle issues.

Engine went 110,000 miles before it was pulled out for a rebuild, and went back together the same way after a refresh.

-Mike
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1951 Standard Beetle (German Delivery)
1954 Beetle, L275 Light Beige Survivor
1960 Beetle Convertible, L41 Black
1962 Beetle, L87 Pearl White with Judson/1200 power
1967 Beetle, L282 Lotus White

[dougallison]

I have some similar questions about setting the timing on my '62 with a fresh rebuild. I'd like to get some feedback on timing and the stock jetting for the carburetor (28PICT with 28PICT-1 top for the 12v choke). The carb is freshly rebuilt by Tim at Volkzbiltz. I am still breaking in a newly rebuilt (by a local machine shop) big bore 40HP 1385 (AA's with Grant rings) which is otherwise stock. I have a VW BOSCH 205/034 distributor that came on the car when I bought it and put a new vacuum advance (I've been told this dizzy is from about 74 and I know it has been on the car for at least the last 22yrs/30k miles).

I first set static the timing at 7.5 BTDC and idle about 900RPM. So far I've only run it 20mins at 2k sitting and then another 30mins driving 20-50MPH. Changed oil between and set the valves cold at .08 per Haynes. By the time I got home it seemed to be idling faster for some reason. When I shut it off, it dieseled once or twice. I started it a few more times since then and it does the same. Pulled the plugs and they look like they have a lot of carbon to me which I think means it may be running too rich.

I then used the degree template to mark 28 and 32 BTDC on the pully and bought a cheap timing light at Harbor freight. With the vacuum plugged I first set the timing to 7.5 BTDC at idle but at 3-3.5k it seemed to advance beyond 32 BTDC. I then lowered the idle to about 5 BTDC and at 3500 it still seems to hover around 32 BTDC. In fact it seems to occasionally bounces around from 29 to 34/36. Turned it off and - it dieseled once.

I know I don't really know what I'm doing, but this is getting frustrating.

Questions:
1. Could there be an issue with this dizzy?

2. Perhaps is this timing light too cheap and not to be trusted?

3. What is the stock jet size ok for a reliable driver? (Spensorfvee1946 said "a stock 28pict carb jets a 55 or a 50 idle jet. 122 main jet a 130 air jet . a 125 main jet with a big bore kit should work." - I'm not sure, but this sounds like the existing jets are either too small or too large??

4. Any other thoughts about tuning/timing on this engine?

[glutamodo]

First of all, 28PICT is NOT A MATCH for an 034 SVDA distributor. You need a 1960s vacuum-only advance distributor. That's what I run on the 1385 in my 1962 Beetle.

Second, looking at spark plugs with just a bit of idling and bopping around town will not give you an accurate indication.
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Andy T.


IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox.

[dougallison]

I’m Very willing to consider getting a different dizzy, but your answer doesn’t really address either the fact that this one has been been working for the last 22yrs on the original 40hp - Or the the other questions about the timing when the vacuum was plugged and not connected to the carb at all.

[glutamodo]

Okay, if you've not seen it, go here for my comprehensive discussion of how vacuum advance works: https://www.thesamba.com/vw/forum/viewtopic.php?t=185095

In a nutshell, the 034 needs a specific vacuum signal for the advance. It will not get it from a 28PICT. It will run almost entirely off of the centrifugal advance. And on a 1200 series engine, that is OK actually. But the vacuum advance might kick it at higher RPMS, but that is totally when you DO NOT WANT IT. You would be better off running a decent 009 or just leaving the vacuum line disconnected and plugged.
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Andy T.


IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox.

[dougallison]

[spencerfvee]

[dougallison]

Thanks using he 034 plugged is only temporary until I can get another. I’m guessing the 4R5 is still best one for my setup?

[glutamodo]

I been largely away from the computer the last couple of days.

As I said above, I would not use the 034 with the vacuum advance hooked up. Inside of it, is a centrifugal advance very similar to the 009. Now Bosch themselves said that 009 was not intended for dual port engines, but was okay to replace single vacuum-only distributors in the 60s. And I found that to be true. I had a German 009 on my 1385 in the late 80s and early 90s and when I changed it to a proper ZV/PAU4R5 it ran the same, great either way. (why is this? good fuel atomization I think. 1200 cylinder heads have tiny intake ports and valves, so the velocity of air being sucked through them into the engine is very brisk. That's how VW got away with originally setting the idle speed only at 550RPM back then! Although they later retconned that to 750-900 RPM, and with today's fuels I would go that way.)
_________________
Andy T.


IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox.

[spencerfvee]

[dougallison]

Thanks glutamodo & Spencerfvee for the help and recommendations on a dizzy. I picked up a 4R5 from Bill at Sparxwerkx.com based on a recommendation from [email protected]. With only 16 degrees of advance, he recommended I may want to set the initial at 12 rather than 10 so the full advance will be at 28. So far, it seems to be working great.

[glutamodo]

I just noticed this... only 16 degrees of engine advance? I've run a number of 4R5 distributors over the years and never saw that little from the advance canister on them.

Keep in mind that advance in distributor degrees and crankshaft degrees are different by a factor of two. So the degrees in this chart need to be doubled for what you're going to see at the pulley with a timing light. So, 7.5 to 10.5 means 15 to 21 degrees, so expecting 16° is kind of low, and in my experience I usually saw around 20-21°.

What I'm trying to say is, don't assume anything until you test it in action.

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Andy T.


IMAGE NOTE: It has been noted that Chrome based browsers may have issues in displaying my vast image library, which use non-secure links and are on an FTP server. Images should still be viewable if the link is clicked though.
I do not know how to fix this. All I can say is it all works fine for me with what I use, Firefox.

[Sebastian Gaeta]

UPDATE:

I am glad this thread has taken on a life of its own, it has been very informative for me.

The engine is built, I used the AA P&C's with Grant rings and all is good. The low end improvement is very noticeable between 2500 and 3500 rpms which is where it really needed it. While it is by no means a slingshot, it keeps up with traffic much better now and I feel much safer on the city streets.

My plan was to reassemble the engine using the stock carb and distributor and adjust from there. The engine runs so well that I am not going to start chasing after bigger carbs and a different distributor because it has given me just what I was looking for right off the bat. I don't see any upside to messing with it. If I want to go any faster in an old air cooled car I'll jump in a 356!

Thanks to all for the advice, it has been greatly appreciated.
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Sebastian Gaeta

'63 Beetle Turkis
‘64 Karmann Ghia Coupe Manilagelb/Black Roof
'64 356C cabriolet Signalrot
'65 356C coupe Rubinrot
'66 Single Cab Velvet Green
'67 Karmann Ghia convertible Heliosblau

[fl59bug]

Spencerfvee (Jack), well it has taken me forever to get the car running again, but I have your '67 PICT 30 installed. I swapped the 125 jet out for a 127 since I'm running the stock exhaust just to get the car back on the road, but have a 40hp 4 into 1 NOS header to be installed as soon as I get it to fit.

Initial impressions are good. Engine started right up with the "new" carb. I drove it up and down my street and it seemed to run fine. I need to take it to the store and see how well everything plays together now that I have done the following:

1. had passenger side head exhaust valves, guides and seats replaced

2. swapped metal adapter plate used to mount '61 trans in '59 body for a bus nose cone

3. changed worn trans input shaft seal and throwout shaft with new parts

4. swapped stock rocker shafts with mismatched 40hp 1:1 rockers and later 1.1:1 rockers for new CB solid shafts with new 1.1:1 rockers and elephant feet adjusters

5. switched out Empi 30 pict1 carb with OG '67 30 pict 1

6. bled brakes with pressure bleeder (a real PITA since my brake fluid reservoir is mounted below the gas tank directly on the upgraded dual circuit MC)

7. had work, covid19 (didn't catch it but just like everyone else suffered through society grinding to a halt) and lots of other junk get in the way!