'85 Z24 rebuild

[RPM28]

Any advise on an aftermarket cam? The head is ready for re-assembly. I would like a small amount of pop corn if there's a cam availible without much loss of bottom end.

-Rod

[seang]

You could probably back-cut the valves. Even without porting these are almost always a flow improver, and I have yet to hear about a case where it hurt flow - this being the ports themselves can flow enough to facilitate them.

Your motor has 8.3:1 static compression. The bigger a cam is, and the more overlap there is, the less dynamic compression there will be. Dynamic compression is ALWAYS lower than static because of valve overlap.

Sometimes, you can do a number on performance by using too big a cam if you aren't going to increase compression/head flow along with it. Hotter cams have less dynamic compression than mild ones.

There are some available. Comp cams, Shneider cams, and maybe some others.
Modified by seang at 4:19 PM 1/24/2010

[breadbox]

So if the grind is to aggressive you could start slapping valves together right?

[seang]

So if the grind is to aggressive you could start slapping valves together right?

That's what I hear about the NAPS-Z motors, yeah. I don't know how much lift and overlap it takes before this happens.


Modified by seang at 1:07 PM 1/23/2010

[RPM28]

Saeng, Do you know the oem seat/valve angle for the Int. and Ex.?

-Rod

[seang]

No, I don't know anymore. It's in the service manual, though. Maybe someone else here knows?

If all else fails, there is always

[Aven]

The valve seat angle for the Z24 is 45*30'.

[RPM28]

Thanks,It look's like 30/45. but was wanting confirmation.

I'll look at the book....... It's at the shop.

Although I have the proper equipment, these engine are new to me.

I've build race specific kart engines for ~ 20 years.

Thanks

-Rod

[Aven]

My memory sucks, I looked it up.

[RPM28]

Thanks Aven,

I picked this truck up for $400 with 293,000 miles on with it running strong. After ~ 30 minutes of run time it would get a little hot and stumble at idle. Replaced theromostate, plugs and wires. Checked water pump....... good condition. Then suspected head gasket failure after very little condensate out the exhaust. Valve head angle is straight with slight pitting. My intent is to re-surface (I have a old B&D valve refacer that runs true), or would you guy's suggest new valves with this amount of milage? The seats still have sufficient meat, so I'll grind them with my Sioux. Again, my experience is with mostly Briggs & Stratton single cylinder flat & ohv.

Again - Thanks for the info......... Great forum.FWIW- I have a 08 Amarda and love it. I will recommend.

-Rod
Modified by RPM28 at 6:44 PM 1/25/2010

[dogred]

Had that problem also with idle, replaced my plugs with E3's problem disppeared. Redoing the valves won't hurt anything if you know what you are doing. If you paid $400, and your intent is to run it until failure as a daily driver then I suggest resurface. If your intent is to hop up performance then go with new valves.

[85NIS720]

Comp makes two cams for the Z24, which I hear are pretty good. I'm probably going to end up buying one for my 720.

http://www.compperformancegrou...Z2024 <- Check it out.

[RPM28]

Yea, it's just something i'm going to knock around in. No long trip's for sure. Perhaps a ride to work.......... ~ 20 miles a day depending on performance after rebuild.

The body is perfect - Bed has no dents or scratches.

Again, thanks for the info.

-Rod

[85NIS720]

Keep us updated. I'm hopefully going to start doing power add-ons to my 720, once I get it back.

[flinterman2000]

Yea, it's just something i'm going to knock around in. No long trip's for sure. Perhaps a ride to work.......... ~ 20 miles a day depending on performance after rebuild.

Once you intend to go with the cam I advise the new valve instead of the grind due to the milage of the truck. If you could get any rebuild info from the PO it would help determine if changing the valves makes sense.