what carbs?

[Ant-dat]

i'm looking to get a set of twin webbers for my 510 project.

I not sure if i should go for 40's or 45's and webber or delorto's

 

the engine spec,

L20B with 1mm over size pistons

A87 head ported and polished

fast road cam

vernia pulley

 

I think 40's will give more torque over 45's but 45's give more power?

what you guys think?

[DOnatello]

I think mikuni 44's would be your best shot. Try Todd over @ wolf creek racing. ;)

[Ant-dat]

do they fit on a webber manifold? sorry if it's a silly question but in UK don;t think we get Mikuni's never seen then or head of them untill i got on here

[MicroMachinery]

Yes.

[ggzilla]

Mikuni-Solex were sold by Nissan Competition. It's a French carburetor design made by Mikuni Kogyo. Not really 'better' than Weber DCOE, about the same. Same bolt pattern on the manifold side, just like Weber DCOE or Dellorto PHLA. The air cleaner side has a slight different pattern, and using off-the-shelf DCOE need to be slightly modified.

 

 

I think 40's will give more torque over 45's but 45's give more power?

Both will give the SAME power and torque (low speed power).

 

It DEPENDS on the chokes you put into the DCOEs. For a 2-liter with maximum power at 7000 RPM, 42mm venturis are probably right. Oops, those won't fit in the 40s. Oops. Won't fit in the 45s either.

 

If you want max power at 6000 RPM, fit 37mm chokes. Which will fit in 45s, but not 40s.

 

If you want max power at 5000 RPM, fit 30mm chokes. Fits both 40s and 45s, and either will give you the same power and torque.

 

[EricJB]

GG what size engine is that chart for? I am always tring to find carb/venturi vs displacment info.

 

I have a 1.mm over L20 (1998cc) u67 haed w/ Z intake valves, ports have been straightened, smoothed out, and intake/ exhaust match ported, .490 by 290 cam, shitty shorty header w/a 2 ft 2.500 straght pipe. Dual 40dcoe's with 36 chokes. When I launch it, I have to be really quick on the shifter or it's on the rev limiter (7000) It has no problem hitting 7000 rpm. It drove well on the street before being converted to track only use.

 

If your going to drive on the street, Head work, cam, and exhaust will be a deciding factor. Do you know the spec's of the cam? Stock valves? 41mm chokes with 42mm valves with a mild cam aren't good bed partners. Valves unshrouded in combustion chamber?

 

Over carbing it will make feel soggy at the bottom. untill you get the air speed up. Under carbed is just more drivable.

 

I used to have a street/ strip VW bug w/ a 1968cc big heads big cam (600+ by 324 ) 1 3/4 header w/ merged collecter. Weber 48 IDA's with 42 chokes. It didn't even start to wake up till 5000rpm's. redline was 9000 and i got 8mpg on the street. It barely Idled at 2200. Today the same motor is in my sandrail with a smaller cam and 44 IDF's with 36 chokes. Starts pulling at 4000 and redlines at 8000. I hope all this gives you some sort of baseline.

 

IMO I wouldn't take a set of Dells if you gave them to me. Italian Webers or Mik's for me.

[ggzilla]

That chart is from the weber book and is for ANY size engine. The CC per cylinder is listed along the X-axis.

 

The chart is to prevent over-carbing. Remember the carburetor bore size doesn't mean much. It's the choke size that matters. Weber "45" (45mm bore) can fit chokes of 32mm to 40mm.

 

A 45 with 32mm chokes is wimpy compared to a 40 with 36 chokes. Choose your tuning carefully.

 

Give me some good Italian carbs, like Dellortos. Better than Chinese Webers?

[EricJB]

When I first looked at the chart, thats what I thought. But with the vertical line at 325, that makes it a 1300cc.

 

I agree with you on the choke size, I think the 40 DCOE's came with 28 chokes out of the box. Maybe it was 32, I cant remember (I know the IDF's were 28). and the chinese Webers are complete trash. I have always steered away from the Dells, because way back when I started messing with this stuff, (the eighties) Dell tuning stuff was harder to find than Weber or Mikuni. I have a friggen tacklebox of Weber jets chokes and emulsion tubes. So I just stick to that. I have a complete 44 Mik set up with 34 chokes that I've never even tried, because I dont want to start over with tuning crap.

 

I guess I came off like a Dell hater. I have tweeked them for freinds and they worked fine. I just dont want 3 tackleboxes ha ha.

[Ant-dat]

thanks guys some good infor there,

reason i looked at webbers they are much easier to get here in the UK, Dellortos not quite so easy. But starting from scratch with the engine build i can keep options open and keep eye out for different ones. and if lucky pick up a set at a resonable price lol

 

when i ran my L20B in my 810 sotck with A87 head (stock) it used to run out of power around 5500 rpm, It would rev past it but really only making noise. I put it down to the head been restricted and not folowing well enough for the L20

 

I'm looking to get a good street car with maybe some track/sprints or even hill climb events

 

any one got handly pics of the mikuni carb setup?

[Ant-dat]

Head work' date=' cam, and exhaust will be a deciding factor. Do you know the spec's of the cam? Stock valves? 41mm chokes with 42mm valves with a mild cam aren't good bed partners. Valves unshrouded in combustion chamber?[/quote']

 

i will dig out the new head i have and measure the valves and grab some pics, not looked at it for a while. The cam i think is a 272 bought it from Datsport many years ago and never used it, only info i have is MCNL288R on the recipt I need to send email and double check specs with Baz.

Going to use the stock header with a longer runners on down pipe and 2" amybe 2.25" stainless system

[wayno]

An L20b with a stock cam will fall on it's face somewhere above 4500-5000 rpms, the L16 and L18 are made to rev, especially with a cam, I have heard guys talking about 7000rpms all day long, never heard them talk about an L20b that way.

[Ant-dat]

An L20b with a stock cam will fall on it's face somewhere above 4500-5000 rpms' date=' the L16 and L18 are made to rev, especially with a cam, I have heard guys talking about 7000rpms all day long, never heard them talk about an L20b that way.[/quote']

 

Yer thats exactly what mine did, A good friend of mine built a L20B using a cabstar block iirc and when he had his running it did exactly the same

 

I also want to lighten the flywheel as well as i'm using a flywheel from a L6 (only one i could find in UK to fit)

 

I have thought of swapping the L14 for L16/L18 to get a revy engine. But i have the L20B and i know the history of it well and it's only done about 45k miles

[wayno]

A cam will help with the higher rpms, but you will lose torque, the more power you have at higher rpms, the less power you will have at lower rpms(starting out), it's a trade off, it all depends on how you use your vehicle.

[Ant-dat]

i do have a few L4 heads

W53 Closed

A87 Closed

U67 open

and the head on my L14 (not sure what it is yet)

[wayno]

i do have a few L4 heads

W53 Closed

A87 Closed

U67 open

and the head on my L14 (not sure what it is yet)

 

 

All my drivers have the W53 head(there all closed), my favorite has 280Z valves installed in it(huge valves), and the intake is ported to match the sidedraft SU type intake manifold as I like SUs, but it still falls flat on its face at about 4500rpms, but it has lots of torque, and it will move a lot of weight at hiway speeds. We don't have the L14 block over here, must be a small head like the 210, not a sought after head over here.

[ggzilla]

A cam will help the engine run ... without it, it doesn't work. The L20B runs out of steam because it is so much bigger, it's maxing out the head and intake. If you get the right free flowing stuff, it'll do 7000 rpm too.

 

In other words, the L20B makes as much power at 5000 than the L16 does at 7000, given the same modifications.

 

 

The weber chart is for ALL size engines, the example line at 325 cc is just one example. Draw your own lines at the 500 cc mark.

 

 

Ant, you have the 1800 SSS, right? That uses the same camshaft as an L20B (non-USA).

[Ant-dat]

i used to have a 810 SSS coupe that had the L18t and i found out a while back that it uses the same cam as the L20B from the workshop manuals. I have emailed Baz from datsport to ask spec of cam i bought years ago, I know it is a better cam than the stock L20B one but i cant rememebr the exact specs.

i'll dig it and the head out and grab some pics

[ggzilla]

any one got handly pics of the mikuni carb setup?

 

Here's the Nismo 44s

 

Here's my A14. I like the way the fuel line go on the Mikuni PHH and the look of the round starters

 

[Ant-dat]

those looks ace,

Managed to get a set of dellorto 40 dhla's :)

[Ant-dat]

 

:)

[DOnatello]

 

 

 

 

 

 

 

 

[Ant-dat]

very nice,

spec list of the L20B? if you don't mind that is. Looks like it's in a B110?

[DOnatello]

Nope engine came stock in a 610 wagoon. Stock bore and stroke, stock everything actually except for isky cam (stage 3) and mildly ported head. and yes to the guy who was talking about the L20 and high rpms. I ripped on this l20b to 7k and higher every single day. Remember "no replacement for displacement" :cool:

[ggzilla]

These look very nice:

[EricJB]

These look very nice:

 

 

 

Man, That Redline mani is a sexy bitch.