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Fri Dec 14, 2018 2:36 pm

I’m putting together a 2028cc (78.8 x 90.5) for my street Manx.

- Eagle 2246 Cam (260 @ .050, .452” lift w/1.1s)
- .045 deck, 9.4:1 CR
- 40x35 heads, AJ Simms mild ports
- 1.5” merged exhaust
- 010 distributor
- 40mm DRLAs, 34mm venturis

A local enthusiast has a pair of 45mm DRLAs, and I’ve been planning to swap my 40s plus parts ($) on my end for his 45s. I just found out that the venturis in his 45s are much larger than the stock 38mm though, and to work well for my combo I’d have to put new vents and jets ($$$$) in them.

I think my 40s will work great for my application (6K RPM limit), but I like idea of getting the larger 45s for inevitable future upgrades. At the same time, I’m not really excited to put out money for a set of Dells that I need to buy vents and jets for right away.

Would you swap the 40s for 45s? What vents (36mm?) would you run for my current setup? Or would you just hold onto the 40s?

Fri Dec 14, 2018 3:34 pm

45's are monster carbs. If you want any bottom end stick with the 40's If you're after maximum horsepower up around 5000 or more RPM then increase bore to at least 92mm preferably 94 to run the 45's. Maybe run 42mm or 44mm intake valves. I am looking for some Dell 40's myself.

Fri Dec 14, 2018 6:19 pm

45's will only help at WOT... At the end of the drag strip.

Very few engines can support 45's.

I run 40's on sandrails off road with a much bigger engine, and they give the best overall performance.

If you do trade, I might have the parts you need.

- Joe

Sat Dec 15, 2018 2:20 pm

Thanks, engine setup is staying the same - I have all of the listed parts already on hand, I just have to put it all together on my winter break. Carbs are easy enough to swap around though.

Any other input?

Sat Dec 15, 2018 2:59 pm

2028cc (78.8 x 90.5) for my street Manx.
- Eagle 2246 Cam (260 @ .050, .452” lift w/1.1s)
- .045 deck, 9.4:1 CR
- 40x35 heads, AJ Simms mild ports
- 1.5” merged exhaust
- 010 distributor
- 40mm DRLAs, 34mm venturis

Sounds like a really strong running engine! Have you had it running before that way?

Sat Dec 15, 2018 3:59 pm

Danwvw wrote:
Sounds like a really strong running engine! Have you had it running before that way?

Thanks, I think it should be. I had it running before with a slightly different setup for my early baywindow bus (cam, CR, exhaust, ignition):

- Engle 110 w/1.25 rockers
- 8.4:1 CR with .070" deck (I didn't setup the deck / chambers very well, live and learn)
- 1.5" exhaust with 1.5" heaterboxes
- 034 SVDA distributor, Mallory Hyfire 6A CDI

It was a rocketship compared to the 1776 it replaced, but I only put a couple thousand miles on it before putting the bus into storage years ago. I pulled the engine out and tore it down to change it up for my manx, and that's where I am. Had my heads flycut from 57ccs w/the step to 52.5, rebalanced the whole crank / flywheel setup (as it hadn't been balanced correctly the first time), along with some other changes. I have everything already, I just need time for the build process.

My manx weighs 1480# w/me in it, and has a close-ratio swingaxle (1.48, 1.04). It should be fun.

Sat Dec 15, 2018 4:21 pm

Well seeing as the carbs are going on such a light vehicle, if the carbs are a bit big you may not even notice.

If you are going to buy vents anyways you can get 36 vents for the 45s as that would be a nice compromise and still give you head room if you ever want to put them on a larger engine in the future.

I think either way you go you will be fine. I would be tempted to get a set of the 45s in addition so I can play around when time and budget allowed.

Sat Dec 15, 2018 5:42 pm

So you ran 34mm venture Dells in a bus? 2028cc? How was that? Hard to take off in?

Sun Dec 16, 2018 11:04 am

J-dub, thanks for the input.

Danwvw wrote: So you ran 34mm venture Dells in a bus? 2028cc? How was that? Hard to take off in?
Danwvw,

It was great, lots of effortless power, and wasn't hard to take off in at all. The bus was so much more fun to drive! Hills were of no concern whatsoever with that engine.

I'd been running a 1776 (110 cam/40x35 heads/36drlas) in the bus before that, and while the 1776 engine was powerful over a stock 1600, going to the stroker crank was a considerable improvement overall.

I have all of the parts for my current build, and I'm trying to justify spending more money to get a set of used carbs that will require more money and effort to work, and are realistically a little big for what I'm putting together. Just so I can say I have 45s? So I can immediately begin justifying more upgrades in the future? Bah, I *should* just run what I've got.

Sun Dec 16, 2018 11:20 am

stevemariott wrote: J-dub, thanks for the input.

Danwvw wrote: So you ran 34mm venture Dells in a bus? 2028cc? How was that? Hard to take off in?
Danwvw,

It was great, lots of effortless power, and wasn't hard to take off in at all. The bus was so much more fun to drive! Hills were of no concern whatsoever with that engine.

I'd been running a 1776 (110 cam/40x35 heads/36drlas) in the bus before that, and while the 1776 engine was powerful over a stock 1600, going to the stroker crank was a considerable improvement overall.

I have all of the parts for my current build, and I'm trying to justify spending more money to get a set of used carbs that will require more money and effort to work, and are realistically a little big for what I'm putting together. Just so I can say I have 45s? So I can immediately begin justifying more upgrades in the future? Bah, I *should* just run what I've got.

I would run the 45's

The biggest problem with carbs too big is the lack of throttle modulation (anything past half throttle feels the same unless you are at peak rpm).

If you low end goes away then the carbs are not tuned right.

Dan

Sun Dec 16, 2018 1:51 pm

stevemariott wrote:
I have all of the parts for my current build, and I'm trying to justify spending more money to get a set of used carbs that will require more money and effort to work, and are realistically a little big for what I'm putting together. Just so I can say I have 45s? So I can immediately begin justifying more upgrades in the future? Bah, I *should* just run what I've got.

So if I read this right, you are going to put back together an engine you already liked but with a bigger cam, tighter deck height and the step in the combustion chamber removed.

Heck yea! Put it together as it and have fun with it. The possibility of more carb is always there.

Sun Dec 16, 2018 5:34 pm

Thanks for your response, Dan.

j-dub wrote:
So if I read this right, you are going to put back together an engine you already liked but with a bigger cam, tighter deck height and the step in the combustion chamber removed.

Heck yea! Put it together as it and have fun with it. The possibility of more carb is always there.

Yep, plus a few minor changes (Berg fan, 2 qt. Scat sump, OE 911 swivel feet) for reliability. Thanks again for your input.

Mon Dec 17, 2018 6:22 pm

Aren't 45mm Dells on par with 48mm IDF's?
You need to match things, for example, if you had a stock head that is about 30mm at the intake port then the manifold needs to be 30mm at the head and the carb needs to be not too much bigger or things slow down and air-fuel ratios become difficult at lower RPM. I think that a 40mm intake valve probably needs an intake port at the manifold, not more than the 40mm valve would be about 85% of it thus 34mm maybe a little more on larger bore engines like 92mm or 94mm.
The carb venturi probably should not be larger than this as that will reduce airspeed and the ability to properly mix fuel at lower RPM's.
If you had 42mm intake valves and 94 bore to support that you could have 36mm ports and venturi's But even still a 45mm Dellorto carb is bigger than needed and the car just becomes difficult to drive around town because you can't use much of the throttle at lower rpm. Probably a 44mm IDF Weber would be about all you could do before the driveability of the lightweight buggy is crap.
What happens and the reason people run these big carbs is the power actually is low enough with them because of the poor airspeed below about 4000 RPM that the car is not so insane on take off yet feels like it's got a lot of kick once it gets up above 5000 rpm but it really just the contrast.
I am not an expert on this and have not tried this combo but this is how I understand the relationship between CC's - Valve Size - Porting - Manifolds - Carb size and Venturi.

Mon Dec 17, 2018 8:04 pm

If you change the heads to CNC Los Panchitos or something similar and upped your merged header to 1 5/8" I would then run the 45 Dells.

Tue Dec 18, 2018 4:10 am

Interesting thread. I like your contribution here Danvw.

I am (with some assistance this time) rebuilding a 2187. With new panchitos, this exact cam, 40 dells and 1.3 rockers, 1 5/8 extractors . Street motor in a full weight beetle. I have been grappling with this upgrade to 45 dells as well. From what i understands, all carbs "are tuneable to the application" but how much time do you have ... and how much effort will you exhaust? [pun not intended]

It never ends eh! : )

Tue Dec 18, 2018 4:26 am

Hello, a little input here on my end.. I run a 2180 in a Super Retro German Looker. And yes it is full weight and plus is a daily driver.

I run 40 DRLA's w/34 Vents on CB Street Eliminator Heads I got for a deal. They have 37.5mm x 42mm Valves as well... And also since I am in Virginia were it gets seriously cold in winter I wanted Heat and ended up with another deal on a 1 3/4" Header Exhaust w/Heater Boxes. Now I know this is not the best matched set-up but this is a learning engine plus my first "Real" Supped-Up Street VW.

But this is what I like, the Streetablity of the 40 DRLA's for the throttling of them is spot on as you drive.. This is in the mountains of Va., and yes, plenty of power for going up the mountains plus not a seriously high RPM engine, which I was not looking for, why, well to me High RPMs will just kill a street engine and take away from the longevity.

The engine will hit 5,500 RPMs, but after that it runs out of breath in a big way, but, up to lets say 4,800 RPMs man is it a nice and fun car to drive. Has plenty of pep, plus can get some great gas mileage but also bad at times. I do 3 hour one way trips so makes for a 6 hour round trip and on these trips I do not get into the throttle. I can average on these trips around 28 mpg. And on the flip side, if I am at home in the mountains, I can get as bad as 13 mpg if I am flying, and man do I mean litterly. And this is with in that 4,800 RPM spectrum. Oh, by the way, I am running an old school Engle 120 cam with 1 to 1 rockers, so not to crazy on valve train wear. So this engine was set-up to hopefully get at least 80, 000 miles on+ with valve jobs and see how long it last. But yes, I have been looking at my next build already for my engine builder, something that is concrete, like Glenn Rings 2180 which he runs 44 IDF's and also 48 IDA's on, I would just be putting on maybe 45 DRLA's for I like Dells...

By the way, Glenn Rings engine is a nice and superior build, you can find his engine build on his Distributor site, Glenn-ring.com... RB

Tue Dec 18, 2018 1:48 pm

Danwvw wrote: Aren't 45mm Dells on par with 48mm IDF's?
You need to match things, for example, if you had a stock head that is about 30mm at the intake port then the manifold needs to be 30mm at the head and the carb needs to be not too much bigger or things slow down and air-fuel ratios become difficult at lower RPM. I think that a 40mm intake valve probably needs an intake port at the manifold, not more than the 40mm valve would be about 85% of it thus 34mm maybe a little more on larger bore engines like 92mm or 94mm.
The carb venturi probably should not be larger than this as that will reduce airspeed and the ability to properly mix fuel at lower RPM's.
If you had 42mm intake valves and 94 bore to support that you could have 36mm ports and venturi's But even still a 45mm Dellorto carb is bigger than needed and the car just becomes difficult to drive around town because you can't use much of the throttle at lower rpm. Probably a 44mm IDF Weber would be about all you could do before the driveability of the lightweight buggy is crap.
What happens and the reason people run these big carbs is the power actually is low enough with them because of the poor airspeed below about 4000 RPM that the car is not so insane on take off yet feels like it's got a lot of kick once it gets up above 5000 rpm but it really just the contrast.
I am not an expert on this and have not tried this combo but this is how I understand the relationship between CC's - Valve Size - Porting - Manifolds - Carb size and Venturi.

48idf vs 45 del, no they are not on par. The 48idf has the potential to make more HP simply because it's bigger. I use to think about sizing the way you do but trial and error taught me otherwise.

You want both the intake and exhaust to be like a funnel, relatively small under the valve seat and slowly grows in size as you move away from the seat. This is why there are stepped headers and the carbs and vents that tend to be bigger than the port under the valve seat. When I see performance heads with great big exhaust ports around the guide boss area I know they are clueless.

The carb is not is not needed to be an air speed improver (the head port does that) but there must be enough air speed for the carb to accurately supply the right amount of fuel. The weber venturi chart is a good starting point. I have run different carb sizes on engines and had big top end improvements with the bigger carb choice without a loss of low end.

Dan

Tue Dec 18, 2018 7:14 pm

Thanks, Dan for the added information.