Triple carbs and mild cam, head Q

[ra240z]

I have a L28 from a 83 280ZX for my 240Z. I have triple 45 from Top End Performance with TWM airbox and 3-2 headers in 2" with 3" exhaust in stainless steel. The head is N42 and will be ported to fit in/ out.

I am not a " motorhead " and I have read a lot about this but will also try to ask for some advice. My goal with this engine is good power also with low rpm - and the questione is what type of camshaft and spec should I go for. I feel that I am lost in a "technical" jungel with this cam issue:stupid:

This car will only be a street car.

Thank you for your time

rab

[jmortensen]

The benefit to the carbs is that they make more power at higher rpms. If you put a smallish cam in there, you will hinder the carbs ability to do what they do well. I would suggest a medium sized cam, something in the .490-.520 inch lift and 280-300 degree duration advertised numbers range. Any smaller and I think you're giving up hp.

That doesn't mean it won't work. I had a friend use 44 Mikunis on a L16 with a nearly stock cam. He followed the common "knowledge" that most people overcam an engine and went way too conservative on the camshaft. He also convinced me to buy my first cam for my L28 which was similarly tiny.

I got fed up with it and bought a .490/280 cam for my car which was running SU's at the time and he warned me that it would have no bottom end, would be impossible to drive in traffic, etc. After a ride in my car he immediately purchased a much bigger camshaft. Don't get me wrong, his car made more power than with the small cam and 44's than it did with the dual 36mm SU's he replaced, but not nearly as much as it did after he went bigger on the camshaft. As for me, I was wanting to go bigger again on the camshaft when I finally decided to do a V8 conversion instead. The .490/280 worked well on the street but I felt like it was a bit of a compromise on the track.

[ra240z]

Thank you Jon, I guess that a .490/280 cam will need other spring, arms etc. Do you have a input where to find this as a kit other then MSA.

With that duration what is the power band as I like it start around 2-2500 rpm

Thanks

rab ( lost in space feeling)

[jmortensen]

Not as a kit per se. But you'll need just a few things; springs and retainers and different valve stem seals. I would imagine you could ask a local machine shop and they could get parts for you. If not anyone who sells Schneider cams should be able to get their springs and retainers. For valve stem seals there is a common Ford part that works on the L series and provides the necessary clearance, more info here: http://forums.hybridz.org/index.php?/topic/25807-improved-l6-valve-stem-seals/

You'll need to get the right size lash pads as well, but I wouldn't take anyone's recommendation on lash pad sizes or buy them in a kit. Sizes will change based on where the valves are in the head, how many times the valves have been cut or how many times and how far the valve seats have been cut. Here's another resource for figuring out the lash pad size without having to order a whole bunch: http://forums.hybridz.org/index.php?/topic/42991-custom-cylinder-head-building-what%E2%80%99s-involved%E2%80%A6/

[ChrisZ]

If he want the power band to kick in at 2-2500 RPM, wouldn't a .490 be to big then ?

You could also choose to have a cam re ground, as an excample you could send Delta a mail, some cam info here

Chris

[jmortensen]

If he want the power band to kick in at 2-2500 RPM, wouldn't a .490 be to big then ?

You could also choose to have a cam re ground, as an excample you could send Delta a mail, some cam info here

Probably, but then SU's would be a much better choice than triples for that scenario as well. You can't have it all. You either get a high strung motor that makes a lot of power up top with the triples, or you get an L28 that runs out of poop at the top end with the SU's. That's my experience having run both anyway. SU's with the .490 cam works great at 2500 rpm on an L28, for the record.

I daily drove that L28 with that cam, 44's, 2.5" exhaust, light flywheel and ACT clutch for years and had no problems and stalled probably once a year when my foot slipped off the clutch or I just completely spaced out and didn't pay any attention to what I was doing. That combo is easy to drive IMO. It's not as though you can't drive at 2000 or 2500 rpm, that's just not where it's going to make the most power.

[ra240z]

Thank you for your replyes, I think that " You can't have it all " says pretty much. It seems for me that a medium cam such as .490/280 is where I need to be. I think that option will give me most in both low and high rpm with my set up.

The machine shop will take care of rest of it:)

Thanks again for your input.

rab