l20b hits wall at 4500 - 5000 rpm, won't rev past help!

[HRH]

Cam timing and or a tooth off is my bet.  I just finally bought a degree wheel from Summit this past month.  However, I still did my base calculations with a protractor and straight-edge.  Got it dead nuts on, even for a poor man's method.  Only two degrees made a huge difference.  Even after the regrind shop told me to run it in position 3, it would probably be fine.  Made a 2 degree dowel pin and drilled out a cam gear.  Way easier than I thought it would be.

 

http://community.ratsun.net/topic/59762-my-new-ugly-betty-84-maxima-not-diesel/page-14

[Stoffregen Motorsports]

Never touched a dial indicator to be honest, I'm sort of considering getting a complete new setup that I know will work; cam with matching springs and lash pads, from a reputable place. I was thinking of looking at isky cams, but does anyone know some good places that do good datto stuff?

Rebello. They are the only shop on the planet still developing the L motor. There are three different cams I think you would like, but the 27C is probably the best for you. Mild but smooth and not hard on valvetrains. You can get one from Dave.

 

But if you get a new cam, you're still going to have to dial it in. Best thing for you would be to either learn how to set cam timing or install a stock cam.

[Stoffregen Motorsports]

This is probably the simplest example of how to set your cam timing using a dial indicator. http://www.classiczcars.com/topic/20414-how-to-degree-your-l-series-cam/

 

It doesn't hurt to have a dial indicator on a flexible stem - http://www.nationaltoolwarehouse.com/Rotor-RunoutBall-Joint-Gauge-Set-P6510.aspx?gclid=CJr-1ajKksgCFRBrfgodAXIIfg

 

and a degree wheel - http://www.summitracing.com/parts/isk-7-dw/overview/

[datzenmike]

From the vids... I'm not seeing or hearing anything wrong. You said it hits a wall and won't rev past 4,500- 5,000 and it clearly does rev past so... wtf?? Sounds like any L4 to me.... and better than some.

[Knox]

I thought I explained in my earlier posts; its not a rev limit anymore, its basically a horsepower redline, it CAN rev past 5000rpm in lower gears, but the power is completely over by 5000rpm or earlier; in, say 5th gear it will not budge past 5000rpm. Up until 5000rpm the engine is smooth and the induction sound is crisp, but as soon as it hits 5000rpm it doesn't sound 'in tune' or crisp anymore and starts running rough, not misfiring or anything like that, it just vibrates like crazy and just doesn't sound like it wants to go that high.

 

For what the engine is it should make power up until 6000rpm or higher, but it struggles to make any power past 5000rpm

[datzenmike]

Go to first post and click EDIT then click FULL EDITOR to access the title and change to something more meaningful. Saves reading 5 ages which I realize I should have but also saves other newer members.

 

 

All L series struggle past 5K, the cam just isn't up to it. The dropping off of engine torque is less noticeable in lower gears because of the torque multiplying of the gearing. They will rev much higher but you have to wait.

 

An O₂ sensor that gives you an air fuel ratio reading will point out any lean areas. SUs tend to lean out at top end. Try pulling the choke out slightly on one of these long third gear passes and see if this wakes it up. You can chuck the needles in a drill and sand them down thinner to increase the richness on the top end. 

[Knox]

Yeah I should probably do that, heaps has changed since I wrote the first post.

 

The cam should, in theory, be up to it, has 290deg duration with .490 lift, but there could be issues with the way its set up, but the problem was more or less identical with the previous cam, so I'm not sure whether they were both set up incorrectly or what, but it feels like it should be cam related.

 

I did at one point have a wideband o2 sensor set up, with the exact same setup I'm running now, with the same dellorto sidedrafts, jets, etc and it pretty much always landed at the high 12:1s at the HP redline, except when it gets bad vapour lock on hot days.