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Cam upgrade


710wagon

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I'm getting motor work done on my stock L20B (head and block resurfacing). I recently put on dual sidedrafts and now that the motor is apart, this would be the time to do the cam. My question is, is it worth messing with the cam to get some more power or just to leave it be? Also, if it's worth changing, and suggestions?

 

Any help would be appreciated. Thanks.

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I would do it myself.

Key is finding the lash pads and retainers

 

Isky has cams and stuff but lash pad sizes is a best guess size. usually 150/160 on a new cam.  regrind around 180/190.

 

partsgeek sell a compittion cam 460/280 duaration. You can run stock springs with this but still need retainers and lash pads.

 

best to get new rockerarms also.  these maybe expesive

 

 

also hop the machinist has the valve seats and the valves all close as possible so you don't need different lash pad sizes as if one valve is sunk mor then you need a different size

 

 

hope this helps or maybe confusses you more

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Personally it makes a big difference.... especially if you have dual side drafts.... I'd stay with a mild grind If your staying on the street...

This is what I did on my L16..

20160225_201946_zpscyihhlxa.jpg

I went through Schneider racing cams.... they list about 12 different grinds, and they will do a custom one if you ask.. they regrind your cam for about $120 and can supply the correct lash pads to suit.

You'll probably wanna upgrade the springs and retainers too, the rockers are recommended too.. i think you can recondition the ones you have, but I decided to do brand new rockers, which you can still get through the dealer ... I think all total it cost around 500 for every thing....

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Also now that everything is apart and being upgraded there's lots HP to be gained from porting and larger valves. That power would otherwise be lost even with a larger cam, because the head can only flow so much air. Everything done together creates one hell of a beast.

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Actually you can do the cam any time. Engine doesn't have to be apart.

 

I'm getting motor work done on my stock L20B (head and block resurfacing). I recently put on dual sidedrafts and now that the motor is apart, this would be the time to do the cam. My question is, is it worth messing with the cam to get some more power or just to leave it be? Also, if it's worth changing, and suggestions?

Any help would be appreciated. Thanks.

 

710? The U67 head which has the co joined intake and exhaust.... what exhaust are you using if you have side drafts?

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Rockers will wear a pattern in them. I've seen a few but if you can see it, they are pretty much toast. The majority you can't see anything. I suppose if they have a 'pattern' on them they will wear into the new can. If that's the case it sure won't be much. You can 're-new' the rockers with very fine wet sand paper and a small sheet of glass. Use the kitchen sink and gently rub the rocker across the sand paper till smooth. I would run an oil with a ZDDP level same as when Datsuns were new and not the crap they sell today. I use Shell Rotella T 15w40. If your rockers (or cam lobes) have a gouge in them it's probably today's oil formulated for roller rocker cams and low in ZDDP..... But I digress.

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Don't know the cost, haven't called them yet, but most likely a drop in the bucket compared to new.

 

Only thing about reconditioning, is what is it going to do to the lash cap thickness requirements ??

But I'm dealing with a 280-ish cam out of Japan anyway, so I'll deal with that when the time comes.

 

Wish I could find the old style rockers that did not use the brazed on wear pad, but had just a hard chromed surface.

They are lighter, but every time I find an engine with them, the chrome is wore through.

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Well $6 or $7 ... thats not to bad...

 

when I got my cam done, they supplied everything to go with it.. lash pads retainer and springs assuming new rockers. So I figured new rockers was the easiest way to keep the geometry correct.

 

Whatever works to keep them running....

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Doctor you like Delta?

Delta in Tacoma Washington.?

I got 3 cams from them and they were not per spec. I gave them away  I gave my cores and they sold me their cams for like 40$ apc which I thought was way too cheap.

Maybe machine is out of spec

 

they listed .450 and one was .460lift.  Using a good Digital Mitoyo Mic they showed only like .400 lift.

 

Schneider does only regrinds anymore. No more new cams what they told me.  but they have lash pads in various increments. Have to search site.

 

 

I have the cam Crashed shows on my 521. I would get the longer duration one as the 521 has a low gear ratio and maybe put it on Cam dowel number 2 or leave on number 1.

 

I ran one nissanmotorsport spring and one stock. so I didn't need a lot of pressure as its a daily driver and the lift is .460 minus the lash .  Plus Scheider is asymmetric meaning has faster opening and slower closing.

 

 

personally best to get cam they gets most power in at 6500 as the distributor will be the leak link and go out of time anyways

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personally best to get cam they gets most power in at 6500 as the distributor will be the leak link and go out of time anyways

 

Distis go out of time after 6500rpm?? Any idea how much? Maybe its not a big deal NA but with a power adder that sounds dangerous.

 

MantisX

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Also now that everything is apart and being upgraded there's lots HP to be gained from porting and larger valves. That power would otherwise be lost even with a larger cam, because the head can only flow so much air. Everything done together creates one hell of a beast.

You don't even need to do a full porting to realize some big gains (depending on which casting you start with). A lot of cheap power is available in the area just under the valve. Some people call it "pocket work" or "bowl work".

 

Valve sizes are the engine's firewall. Without large enough valves, it doesn't matter what else is done, the engine won't be able to move the air.

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It's not complicated. It's just that there are a few steps that shouldn't be overlooked.

 

Valve spring tension and installed height are important to make sure the valves don't bounce and also so the springs don't bind.

 

Proper rocker geometry is important to make sure (at the very least) that the rockers stay put and don't wear out.

 

I always suggest having a custom cam installed by a pro. If it's your first time around, pay attention to what they did so that the next time you can do it yourself. Having an assortment of lash pads is reason enough to have a shop do it.

 

There are upgrades that don't require mods, but they usually net very little gain.

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If the rockers are in good shape (no scoring or wiggly appearance on the wear surface) I would just run them. You can scuff your own rockers on some 220 grit paper, lubricated with WD40, to get a clean, fresh surface. But if they are not pitted or scored, I would leave them alone.

 

Most L series cam grinders are aware of the conditions and will harden the cam accordingly.

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If the rockers are in good shape (no scoring or wiggly appearance on the wear surface) I would just run them. You can scuff your own rockers on some 220 grit paper, lubricated with WD40, to get a clean, fresh surface. But if they are not pitted or scored, I would leave them alone.

 

Most L series cam grinders are aware of the conditions and will harden the cam accordingly.

..........

Not to keep mentioning Schneider but I know they do harden the cams...

As far as the rockers, and to who ever wants to do a cam.. Its your engine do what you feel comfortable, replace what's needed, reconditioning what you can....

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Stock lift for the L20B cam is 0.413" at the valve. I think when the lift gets near 0.470" the spring is near stacking.

 

I have an Iskendrian 0.490 laying about and a spare U67 to try it on....

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