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l20b DCOE fitment and tuning help


theeoracle

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I'm looking to buy dual 45 dcoe Webers for my l20b rebuild and i have a couple of questions.

 

Will i run into clearance issues if i run with this manifold or just need to get one smaller air horn to clear the master?

http://www.ebay.com/itm/Dual-Weber-40-45-DCOE-Intake-Manifold-for-Datsun-510-L16-L18-L20B-L-Series-NEW-/271751493275?hash=item3f45a6b69b&vxp=mtr

 

Also would i need different venturis if i get these?

http://www.ebay.com/itm/WEBER-45-DCOE-PAIR-TWO-WEBER-45-DCOE-GENUINE-EUROPEAN-/271430618319?hash=item3f32868ccf&vxp=mtr

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That a lot of cheese to lay out for an induction system. You won't reach it's full potential without a larger lift/duration cam, larger valves, porting and port matching, ignition up grades and some exhaust work. On a relatively stock L20B it will not make a huge difference without them.

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I don't really care if i have to choke then to start them. I just want moar power.

 

...and there we have it. You need to research more on this and start a plan. Everything affects everything else. Like a symphony everything has to be in tune and working together.

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Ok so if i'm not going to port/polish, bigger cam, new pistons, bigger valves, and only going to get a bigger cam. I should get 40s?

 

would these work good? This l20b is going in my 510.

http://www.ebay.com/itm/Dual-40-DCOE-Weber-Kit-Datsun-Nissan-L16-L18-engines-510-521-610-710-620-/271548920616?hash=item3f3993b328&vxp=mtr

 

And if i only get a bigger cam and stick 40s and not 45s will i notice a HP difference?

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Your best bang for the buck is a NEW direct replacement 32/36 Weber from Redline about $300. Includes gaskets, adapter, air filter and anything needed for the swap. Be sure to keep and use the cast iron exhaust header that is on your 510 on your L20B engine. This is way large enough for an L20B and then some. Now maybe a mild cam increase with mostly more lift.

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If you can make it out to this............

 

 

BBQaug1st_zpsakjrxygc.jpg

 

 

 

 

 

...........you could pick a lot of people's brains........

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I have this identical setup. Those 45's would be ok on a l20b i think, they come with 36 mil chokes stock, and i bet your jetting will be close out of the box.

I would still get a jet kit and play with it because going up or down a size can do wonders.

 

The runners in the cannon intake are kinda small so if they dont match your ports dont be scared to open it up.

 

Schnieder cams makes good shit, just dont go too crazy if your not changing springs and checking piston to valve clearance etc.

 

Your gonna run into some tightness with the last air horn, itll fit but theres no room for a filter. So you need shorter ones, or put remote caps that look like the ones on a datsun f10. Im looking into this to see if the wilwood ones will fit on a nissan master cylinder.

 

 

On another note, has anyone put dco/sp 55's on a cannon intake? I have 40 mil chokes in my 45's and i think theres more left in it with more carb

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I have this identical setup. Those 45's would be ok on a l20b i think, they come with 36 mil chokes stock, and i bet your jetting will be close out of the box.

I would still get a jet kit and play with it because going up or down a size can do wonders.

 

The runners in the cannon intake are kinda small so if they dont match your ports dont be scared to open it up.

 

Schnieder cams makes good shit, just dont go too crazy if your not changing springs and checking piston to valve clearance etc.

 

Your gonna run into some tightness with the last air horn, itll fit but theres no room for a filter. So you need shorter ones, or put remote caps that look like the ones on a datsun f10. Im looking into this to see if the wilwood ones will fit on a nissan master cylinder.

 

 

On another note, has anyone put dco/sp 55's on a cannon intake? I have 40 mil chokes in my 45's and i think theres more left in it with more carb

are you only running a bigger cam? is your head ported?

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The stock springs are close to stacking around .470" lift That's valve lift not lobe lift. Haines will know.

 

I have a cam I got at Canby a couple of years ago. It's a regrind. The lift works out to 0.4875

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Im running an lz2.3 with big valves, cam, tons of compression and lots of cubic dollars.

 

I have 45's on it, at the start i had the 36 mil chokes in it, and felt like it was running out of breath at 6000 or so, so i put 40 mil chokes in which are the biggest you can go in 45's. In the future i wanna sell these and get 50 or 55's.

 

I think if your cammed a little more than stock it will work well, hell if its all together you could bolt them on and give it a try.

They come with 36 mil chokes so on a l20b that will help your top end out alot, your not going to be able to lug it around at 1500 as much though. If you need it to be tractor then put a 32/36 on it and call it done,

 

You can also choke them down to a 32mm if it seems boggy.

 

As for hard starting, if theyre set up right itll take two pumps and itll be running, babysit it for 30 seconds and itll be happy,

Alot of guides ive read have said not even bother hooking up the "choke levers" as theyre not needed, and i agree.

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ok thanks scooter. I love to keep the car above 3k when i'm pooti'n around town.

 

 

The stock springs are close to stacking around .470" lift That's valve lift not lobe lift. Haines will know.

 

I have a cam I got at Canby a couple of years ago. It's a regrind. The lift works out to 0.4875

Could i get a .480 or just get a .460 cam? Will the 460 be enough for 45s with 36mm choke or should i get diff springs with a .480?

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Bolting dual carbs onto a stock L20B will increase horsepower. It will. But the gains are not worth the effort (and cost). If you are willing to tear into the cylinder head a bit, the true potential can be unleashed.

 

Just wanted to clarify that.  It's called splitting hairs.

 

Also, any size carb can be made to work with the proper chokes and tuning. Now this term "choke" is meant to describe the venturi inside the throttle bore of the carb, not the air/fuel enrichment device. Actually, smaller chokes in a larger bore carb can be beneficial. The shape and size of the venturi can help speed up the air right in the area of the fuel jets making the fuel atomization perfect. So in a nutshell, don't worry about the size of the carburetor so much as the size of the chokes.

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The runners in the cannon intake are kinda small? Yes

 

Yes they are but I dont think the casting can handle to much poerting out as it will be thin and maybe crack.

 

the Mikuni( short runners will fit not hit brake master) and Nissan manifolds(grind last airhorn) were already 1.5 in ports

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If I had a choice of intake manifolds, there are only two that I would use.

 

Mikuni manifold: Easy fit, nice and compact, quality casting, good port size and shape. But apparently are getting hard to find.

 

Nissan Comp manifold: Best performance, high quality, hard to find and hard to fit. You won't be able to run an air cleaner on this one without some work. I use a remote reservoir on the brake master whe I install this one, and even then you ned to notch the rear velocity stack (as banzai mentioned).

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I have this identical setup. Those 45's would be ok on a l20b i think, they come with 36 mil chokes stock, and i bet your jetting will be close out of the box.

I would still get a jet kit and play with it because going up or down a size can do wonders.

 

The runners in the cannon intake are kinda small so if they dont match your ports dont be scared to open it up.

 

Schnieder cams makes good shit, just dont go too crazy if your not changing springs and checking piston to valve clearance etc.

 

Your gonna run into some tightness with the last air horn, itll fit but theres no room for a filter. So you need shorter ones, or put remote caps that look like the ones on a datsun f10. Im looking into this to see if the wilwood ones will fit on a nissan master cylinder.

 

 

On another note, has anyone put dco/sp 55's on a cannon intake? I have 40 mil chokes in my 45's and i think theres more left in it with more carb

 

I run 50 DCO's w 46 chokes on my built 2.3 but on a comp manifold.  Not enough meat on the cannon manifold.

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It might be just me, but I always run isky cams. They will sell you a matched set of springs,retainers, etc. For your set up and will regrind your old cam to the spec you want/need. A reground cam is harder material and will last longer plus it'll be a little cheaper.

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I run 50 DCO's w 46 chokes on my built 2.3 but on a comp manifold.  Not enough meat on the cannon manifold.

Good to know! My cannon is probibly a 100 thou thick in alot of places due to hogging it out.

 

Thats basically where i was thinking of going with mine, along with a better header and go up to a 600 lift cam for a few more ponies.

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If I had a choice of intake manifolds, there are only two that I would use.

 

Mikuni manifold: Easy fit, nice and compact, quality casting, good port size and shape. But apparently are getting hard to find.

 

Nissan Comp manifold: Best performance, high quality, hard to find and hard to fit. You won't be able to run an air cleaner on this one without some work. I use a remote reservoir on the brake master whe I install this one, and even then you ned to notch the rear velocity stack (as banzai mentioned).

So i can run 45 dcoe webers on a short runner mikuni manifold?

and what parts would i need for the linkage? to my 510

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