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ErickwithnoK

Rebuilding my L20B

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You have my permission.

 

Might as well get a new manifold too.

 

I've legitimately never seen a used L series dual dcoe manifold for sale...would love to buy that part used.

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Maybe I'll shell out the cash for some new 40 dcoe's if that's really true. Is it an extra $600 true or just a caution? 

 

 

The hitachi seems complex but it's also a stock downdraft carb which makes it boring to me

 

Yeah double the complexity, ... at least double, plus tuning them with jets and air bleeds then syncing them. I might be wrong but there is no vacuum advance for them and shitty mileage. Unless you also add a cam most of this upgrade is a waste.... and it's a truck. You won't be bored.

 

Get a KA24DE and trans from a 2wd Hardbody and it will run circles around this for half or less. You won't be bored.

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Yeah double the complexity, ... at least double, plus tuning them with jets and air bleeds then syncing them. I might be wrong but there is no vacuum advance for them and shitty mileage. Unless you also add a cam most of this upgrade is a waste. You won't be bored.

 

What is considered adding a cam? An l18 cam?

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Just step into the rabbit hole and enjoy the ride.... build it how you want but build it right..

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No the L18 cam is the same as the L16. The L20B is the same cam as the L16/18 SSS and while a good cam for a 2bbl is not going to allow the engine to make use of multiple carbs. You would want something that opens the valves wider and for longer.

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It means regrinding your cam to a different profile... usually holds the valves open longer and other technical stuff I don't know...

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No the L18 cam is the same as the L16. The L20B is the same cam as the L16/18 SSS and while a good cam for a 2bbl is not going to allow the engine to make use of multiple carbs. You would want something that opens the valves wider and for longer.

 

It means regrinding your cam to a different profile... usually holds the valves open longer and other technical stuff I don't know...

 

This is probably in my Datsun bible "How to modify your datsun OHC engine", there are probably specs in there I could bring to a shop that would do the cam work for me. Someone mentioned earlier in this thread there's a datsun head guru in eugene? What about a shop in oregon/washington that any of you have used and liked for your stuff

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Engine strength is in the block. Engine power is made by the head. If the carb(s) intake, ports, valves, exhaust system is a symphony.... the cam is the conductor that brings it all together.

 

There are probably dozens of after market cam grinds available to choose from. From mild to wild. Keep in mind that the wilder the cam the less derivable it is at low speeds and idle. You will always be happier wanting more cam than have too much and wish you had less.

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Engine strength is in the block. Engine power is made by the head. If the carb(s) intake, ports, valves, exhaust system is a symphony.... the cam is the conductor that brings it all together.

 

There are probably dozens of after market cam grinds available to choose from. From mild to wild. Keep in mind that the wilder the cam the less derivable it is at low speeds and idle. You will always be happier wanting more cam than have too much and wish you had less.

 

So I should go with something mild and reap some small benefits of my side drafts? That sounds right up my alley, thanks Mike. I'll do some googling and see what comes up in terms of cams for sale.

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Duration is 248 but most cam makers agree to measure it at a 0.050" lift. I doubt that Nissan did. Duration at 0.050" is likely 220? but certainly less than 248. Anyone know what it is?The multiple carbs will gain you a little bit of power but you are working with a very stock and mild cam suitable for good all weather starts, idling, docile around town driving and emissions.

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Duration is 248 but most cam makers agree to measure it at a 0.050" lift. I doubt that Nissan did. Duration at 0.050" is likely 220? but certainly less than 248. Anyone know what it is?The multiple carbs will gain you a little bit of power but you are working with a very stock and mild cam suitable for good all weather starts, idling, docile around town driving and emissions.

 

I would like to know for the sake of comparison with the camshafts I find online, so that I can pick one with slightly more lift and duration to squeeze a little more performance out of my dual carb setup without sacrificing too much low RPM performance

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I would like to know for the sake of comparison with the camshafts I find online, so that I can pick one with slightly more lift and duration to squeeze a little more performance out of my dual carb setup without sacrificing too much low RPM performance

 

Call Isky. Pick their brains.

 

 

PM draker. Ask him about the Datsun head guru.

 

 

 

I'm with others about this...do a KA swap for $1000s less and still get twice the power you'll ever get out of an L. Er...usable power.

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Duration is 248 but most cam makers agree to measure it at a 0.050" lift. I doubt that Nissan did. Duration at 0.050" is likely 220? but certainly less than 248. Anyone know what it is?The multiple carbs will gain you a little bit of power but you are working with a very stock and mild cam suitable for good all weather starts, idling, docile around town driving and emissions.

 

General rule of thumb on cam design is that a "270" cam will be 220 at .050" lift.  If the stock cam measures at 248, it may be as low as 200 at .050", but the design is a little different for an overhead cam versus a pushrod cam.  I WILL measure it when I get the practice motor out of our race truck.  I made a tool to adapt a degree wheel onto a fully assembled engine.  There just isn't room to use it in the truck.  Since the cam in the truck literally has 1200 miles on it, the info should be precise.  

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webcamshafts

Schneider

Iskidiarian

CompCams

 

add the retainers, lash pads of correct size, new rocker arms$$$$ valve grind

sidedrafts carbs$$$$$$

all said and done on this youll be up to 750-1000$ just on this before the sidedraft set up

 

or bolt a 38/38 350$  matchbort the intake and throat of the intake, while you build the head on the side and maybe get another block

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Excellent, always wondered. I did hear 218 once.

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Call Isky. Pick their brains.

 

 

PM draker. Ask him about the Datsun head guru.

 

 

 

I'm with others about this...do a KA swap for $1000s less and still get twice the power you'll ever get out of an L. Er...usable power.

 

Isky makes cams? Will contact them, they probably could tell me what I want. Thanks!

 

It's not as much about the power as it is the vintage modified style I'm interested in, if I ever own a 510 that will get a KA.

 

 

General rule of thumb on cam design is that a "270" cam will be 220 at .050" lift.  If the stock cam measures at 248, it may be as low as 200 at .050", but the design is a little different for an overhead cam versus a pushrod cam.  I WILL measure it when I get the practice motor out of our race truck.  I made a tool to adapt a degree wheel onto a fully assembled engine.  There just isn't room to use it in the truck.  Since the cam in the truck literally has 1200 miles on it, the info should be precise.  

 

Thanks for the details

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Going back to the beginning, if your goals are within a $2k budget, get a valve job done, have your cam reground to a recommended "street spec, close to 280 advertised duration if you are looking for a lopey idle sound (Isky is great at this), and do as Banzai says with the carb and intake.  

 

If all this started because you need the bottom end rebuilt (burning oil, low to moderate oil pressure, etc...) then do the bottom end now and do the head later as money allows.  

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Going back to the beginning, if your goals are within a $2k budget, get a valve job done, have your cam reground to a recommended "street spec, close to 280 advertised duration if you are looking for a lopey idle sound (Isky is great at this), and do as Banzai says with the carb and intake.  

 

If all this started because you need the bottom end rebuilt (burning oil, low to moderate oil pressure, etc...) then do the bottom end now and do the head later as money allows.  

 

Definitely would love a deep lopey idle sound. 

 

I was just about to try to bring all this stuff back around to my goals. I've had a day at work to think about your recommendations, and maybe I should give up on side drafts at least for now. That sucks to admit because its a project I really wanted, but it's just a 620 and I don't need to spend so much on it. 

 

My current plan: 

 

Camshaft (Reground? Does that mean I can take my current camshaft into a machine shop that will modify it to specifications I provide them?) 

Valve job (What all does that entail?)

Port match the head (Can a dremel handle this?)

Rebuild kit (gasket set, timing chain/gear, bearings)

Hot tank the block

86mm bore with 280zx flat top pistons (Can I keep the same rods or do I need 280zx rods?)

Electronic distributor (Can't seem to find a used matchbox from a late model 620, other options?)

Weber 38/38 new (Is there an adapter to run my stock intake? Adapter for stock air filter housing?)

 

In general I respect all of your opinions more than I want to do whatever I want to do. Thanks again for all the help, even just planning for this kind of thing is a lot of fun  B)

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webcamshafts

Schneider

Iskidiarian

CompCams

 

add the retainers, lash pads of correct size, new rocker arms$$$$ valve grind

sidedrafts carbs$$$$$$

all said and done on this youll be up to 750-1000$ just on this before the sidedraft set up

 

or bolt a 38/38 350$  matchbort the intake and throat of the intake, while you build the head on the side and maybe get another block

 

Sounds pretty solid

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Go easy on the cam if just running a stock like carb. You won't see much change with it.

 

A dremel will work but  little slow going. Put the gasket on the studs and spray paint it. Take the gasket off and grind away and aluminum with paint on it. Now do thew intake. Smooth in 1/3" or so. A '78/'79 intake would be better than an L16/18... they have lagher runners all the way to the carb.

 

All L series pistons will fit all other L series engines except for the diameter.

 

The '78 and '79 A10 200sx, the '79 A10 (HL510) and the '80 720 all had EI distributors. Non California '80 S110 (200sx) and A10 (HL510) with single plug heads also had them.

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A 280 duration cam would be a good option with a 38/38 synchronous Weber "Outlaw".  Not common in imports, very common in all American cars.  Ed Iskendarian would be happy to regrind your cam if he has a pattern he can use for it, and he probably does.  

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Go easy on the cam if just running a stock like carb. You won't see much change with it.

 

A dremel will work but  little slow going. Put the gasket on the studs and spray paint it. Take the gasket off and grind away and aluminum with paint on it. Now do thew intake. Smooth in 1/3" or so. A '78/'79 intake would be better than an L16/18... they have lagher runners all the way to the carb.

 

All L series pistons will fit all other L series engines except for the diameter.

 

The '78 and '79 A10 200sx, the '79 A10 (HL510) and the '80 720 all had EI distributors. Non California '80 S110 (200sx) and A10 (HL510) with single plug heads also had them.

 

Is a 38/38 a stock like carb? 

 

It's ok if it's slow going, I'm a patient guy. I'll get some carving bits for aluminum and go from there. When you say smooth in 1/3" or so what do you mean?

 

Good to know about the pistons. Looks like new 280zx flattops are about 50 bucks a piece. 

 

I'll check out some local junkyards and see what they have in terms of a distributor.  Thanks Mike.

 

 

A 280 duration cam would be a good option with a 38/38 synchronous Weber "Outlaw".  Not common in imports, very common in all American cars.  Ed Iskendarian would be happy to regrind your cam if he has a pattern he can use for it, and he probably does.  

 

If I send an email to Isky camshafts (assuming that's connected to Ed Iskendarian) saying I want to take a stock l20 camshaft and have it reground to a 280 duration cam thats all the information he would need?

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A 32/36 is a bit more performance than stock. A 38/38 is bigger and opens up at same time, unlike 32/36 which is synchronous.

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Meant 32/36 is progressive and 38/38 is syncorous

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