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Dalecook321
Samba Member
Joined: February 23, 2025
Posts: 12
Location: Hampshire
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 Posted: Wed Feb 26, 2025 4:44 am Post subject: Jetting help? |
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Hey everyone, i have recently bought a 1973 fastback with a 1700cc type 4 engine, it has a webber 32/36 progressive carb, i wondered if anyone knew of about what jets i would need as at the moment its lacking alot of power (only making about 60mph). If anyone had any setyings and would knoe of the best place to buy the them it would be appreciated!  |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 23132
Location: Oklahoma City
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| Posted: Wed Feb 26, 2025 8:18 am Post subject: Re: Jetting help? |
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So.....fastback type 3 or type 4.?
Just asking because far too often "fastback" is a type 3 term and plenty of them have been converted to type 4.
No matter in the long run though.
You may not find much help here in the 411/412 forum even if you have a 411 or 412....because most of us use either the tactory injection systems or twin carbs ranging from factory to aftermarket.....and using a center mounted progressive is probably the worst carburetor choice you could make.
Long, unheated manifold runners make for very poor atomization. Typically you can optimize a center mounted progressive to have decent starting and run best down at lower speeds like for in-town traffic....or with less good starting and better performance at highway speeds with richer sloppier running down low at light to light driving. Without manifold heat it's very hard to get it to run both ways.
Also, which version of the 1.7L do you have? Very early (1968- to early 1970) European versions had slightly lower compression and hp but were designed around twin carbs and ran pretty well. But with that lower compression and hp they will run even worse on a center mounted progressive.
Most US 411 and 412....1971 and later....had D-jet fuel injection, higher compression and about 10 more hp and would run a little better with a center mounted progressive....but still quite poorly in comparison to twin carbs.
But.....all of that being said.....you would get better answers by posting this in the bay window bus forum. Ask a samba member named Wildthings as he has quite a bit of experience with type 4 engines and center mounted progressive and probably has a few tricks up his sleeve. For sure you can get these to run much better than 60 mph.....just do not expect perfect starting in all weather, best hp or fuel mileage.
There probably are a couple of people in this forum who can help you as well. I hope they chime in.
Ray |
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Dalecook321
Samba Member
Joined: February 23, 2025
Posts: 12
Location: Hampshire
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| Posted: Wed Feb 26, 2025 1:22 pm Post subject: Re: Jetting help? |
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| raygreenwood wrote: |
So.....fastback type 3 or type 4.?
Just asking because far too often "fastback" is a type 3 term and plenty of them have been converted to type 4.
No matter in the long run though.
You may not find much help here in the 411/412 forum even if you have a 411 or 412....because most of us use either the tactory injection systems or twin carbs ranging from factory to aftermarket.....and using a center mounted progressive is probably the worst carburetor choice you could make.
Long, unheated manifold runners make for very poor atomization. Typically you can optimize a center mounted progressive to have decent starting and run best down at lower speeds like for in-town traffic....or with less good starting and better performance at highway speeds with richer sloppier running down low at light to light driving. Without manifold heat it's very hard to get it to run both ways.
Also, which version of the 1.7L do you have? Very early (1968- to early 1970) European versions had slightly lower compression and hp but were designed around twin carbs and ran pretty well. But with that lower compression and hp they will run even worse on a center mounted progressive.
Most US 411 and 412....1971 and later....had D-jet fuel injection, higher compression and about 10 more hp and would run a little better with a center mounted progressive....but still quite poorly in comparison to twin carbs.
But.....all of that being said.....you would get better answers by posting this in the bay window bus forum. Ask a samba member named Wildthings as he has quite a bit of experience with type 4 engines and center mounted progressive and probably has a few tricks up his sleeve. For sure you can get these to run much better than 60 mph.....just do not expect perfect starting in all weather, best hp or fuel mileage.
There probably are a couple of people in this forum who can help you as well. I hope they chime in.
Ray |
Thank you, yes its a type 3 with a type 4 engine, was a show car in the 80s but hasnt been looked after the best so im trying to bring back some of its glory, (i have some pics uploaded of it if you wanted to see)! Its a w code engine which as far as im aware that means it was originally the 1971 fuel injected engine you were speaking of. I was aware of the problem of the single carb (also aware that many people hate them for that reason  ). But thank you very much for your reply, i will have a go in the bay window forum and will be sure to message wildthings. Thanks! |
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wagen19
Samba Member
Joined: November 16, 2007
Posts: 673
Location: germany
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| Posted: Mon Mar 10, 2025 12:50 pm Post subject: Re: Jetting help? |
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| Dalecook321 wrote: |
| raygreenwood wrote: |
So.....fastback type 3 or type 4.?
Just asking because far too often "fastback" is a type 3 term and plenty of them have been converted to type 4.
No matter in the long run though.
You may not find much help here in the 411/412 forum even if you have a 411 or 412....because most of us use either the tactory injection systems or twin carbs ranging from factory to aftermarket.....and using a center mounted progressive is probably the worst carburetor choice you could make.
Long, unheated manifold runners make for very poor atomization. Typically you can optimize a center mounted progressive to have decent starting and run best down at lower speeds like for in-town traffic....or with less good starting and better performance at highway speeds with richer sloppier running down low at light to light driving. Without manifold heat it's very hard to get it to run both ways.
Also, which version of the 1.7L do you have? Very early (1968- to early 1970) European versions had slightly lower compression and hp but were designed around twin carbs and ran pretty well. But with that lower compression and hp they will run even worse on a center mounted progressive.
Most US 411 and 412....1971 and later....had D-jet fuel injection, higher compression and about 10 more hp and would run a little better with a center mounted progressive....but still quite poorly in comparison to twin carbs.
But.....all of that being said.....you would get better answers by posting this in the bay window bus forum. Ask a samba member named Wildthings as he has quite a bit of experience with type 4 engines and center mounted progressive and probably has a few tricks up his sleeve. For sure you can get these to run much better than 60 mph.....just do not expect perfect starting in all weather, best hp or fuel mileage.
There probably are a couple of people in this forum who can help you as well. I hope they chime in.
Ray |
Thank you, yes its a type 3 with a type 4 engine, was a show car in the 80s but hasnt been looked after the best so im trying to bring back some of its glory, (i have some pics uploaded of it if you wanted to see)! Its a w code engine which as far as im aware that means it was originally the 1971 fuel injected engine you were speaking of. I was aware of the problem of the single carb (also aware that many people hate them for that reason ). But thank you very much for your reply, i will have a go in the bay window forum and will be sure to message wildthings. Thanks! |
Hello from germany. Since when have you problems with your engine? Suggest to do a complete maintance first, if not already done.
Is your dizzy still working, or seized?
Found out, the center mouted carb on which I have worked on, had the vacuum channel on wrong position, so not corresponding properly with any original VW dizzy.
But... for ex, a good old original Bosch 009 or any other non vacuum based ignition system can bring a lot of power and fun, after been carefully adjusted. Check also for leaks in manifold system. Good luck. |
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