KA plans change again... DeviousKA, your advice would be appreciated again.

[Veriest1]

So with the new addition to my family (See M3 in sig) I've decided not to turbo my SOHC 240sx since I'm already missing the Z3's ability to just floor it around corners.

After I'm rid of my bike (It should be picked up next week sometime) I'm going to tear into the 240's engine bay. Currently I have my Koyo radiator, and walbro 255lph pump installed, and a nice big puller fan on order. I've also ripped out (and plugged) most of the extraneous vaccum hoses and emissions junk.

I'm seriously considering going the side draft carb route with PDM's race profile cam or maybe even the one from Nissan Motorsports. If I use Hybrids solid lifter will I still need to get the cam towers milled? I know Hybrids website says the lifters negate the need for this work on his camshaft. Also, when will the hybrid KA race cam be out, soon?

PDM's cam is Intake 268 degrees duration, .441 valve list, Exhaust 272 degrees duration, .447 valve lift. While Nissan Motorsports is .550"/288 Degrees & .563"/292 Degrees.

With the carb setup is there an easy way to set a rev limiter? I was thinking cutting power to the fuel pump might be the way to go. But I'm not sure about where to take the reading from other than, maybe, the tacometer. I haven't bounced off a rev limiter in a couple of years but I like the added insurance against grenading.

My reason for wanting the carb setup is because it (at the moment but I could be misinformed) seems easier and cheaper to setup compared to MS or AEM on ITB's and fuel injection. It seems cheaper because I won't need to buy a computer and injectors. Or in the case of MS it should come out close to the same price with less fabrication work on my part. Just the throttle cable assymbly (and maybe a revlimiter which I don't have to setup). I'll also get to ditch a ton of wiring and further simplify the car.

Can I get away with using the valve train parts (springs and valves) the turbo guys use or do I have to use the Nissan Motorsports parts?

I noticed Courtesy doesn't seem to be selling only the rebuild kit for the Mukini carbs. What carbs are recommended the Mukinis or Weber? I've heard mention of both being used. And can you still get a good price on the Manifold for this set up Devious?

Thanks in advance.

[deviousKA]

The only set of new carbs you are going to find are S&K, maybe if your lucky some NOS webers. Used mikuni 44's or weber 45+ dcoe go for about 700 minimum per set, unless you find a deal. A good place to watch is the race-cars.com classified.

S&K (weber copies) are available new from Rebello racing, or you could source from japan. These are nice carbs, they retain all weber compatible parts so maintenence is easier.

The solid adjustable lifters can compensate for reduced base circle, but on wilder cams you should machine the towers some to correct the geometry. The lifter adjusters themselves can extend .100" or more with full strength and integrity. Unfortunately I do not have a time frame on the race cam.

As far as rev limiter with carbs, you will want to implement this into your ignition system. You can use a variety of electronic distributors, with different control unit/coils to achieve this. You can simply set them to retard advance to x degrees at certain rpm or similar.

Valve spring wise, you dont have lots of off the shelf options. The intake valves have a much better weight/spring rate ratio than the exhausts. So a mild upgrade on the exhaust side is an option sometimes used. You can use L/Z series performance valve springs, and lightweight retainers on the ka24e exhaust side. Spring free length should be within .080" of ka24e on a new after market l/z spring.

If your interested in the ka24e sohc carb manifold, contact BC Gerolamy for the best deal. They are cast in-house.

[SSS]

Gabe, so the L series exhaust retainers will work fine in the SOHC in conjunction with the L series valvesprings?

[deviousKA]

Gabe, so the L series exhaust retainers will work fine in the SOHC in conjunction with the L series valvesprings?

Correct, or even with ka valve springs.

[Veriest1]

This may be a retarded question as well.

If I buy a used GT3 engine with 13.5:1 compression and drop it to a more standard ratio like 11.1:1 (the pistons with DE head ratio) will I need to do anything more to make it practical for long term use.

Does anyone know how long these engines normally last at GT3 spec? Both the ones I've found have less than 2 hrs on them.

I also need to call some machine shops, etc, to find out how fiscally prudent buying the engine outright would be. Yadda, yadda, research, yadda, yadda....

[deviousKA]

imho your money would be better spend building your own. Those old malcom garrett engines have been sitting for years and would need to be torn apart and freshened up anyways. You could build the same thing with similar components for ~3500

[DjPantsSpecR]

devious mainly covered this, but to elaborate on your rev-limiter issue, Bee-R makes a really nice rev limiter that just cuts spark, real easy to use and easily found at http://www.takakaira.com sorry i'm not cool enough yet to have some side drafts...

[Veriest1]

That's ok DJ. It doesn't bother me if you're not cool. Thanks for the link though.

That's pretty much the conclusion I came to Devious. Other than needing to freshen them up. I also decided it would be better and more enjoyable to do this in stages instead of all at once out of the car on top of being cheaper.

What kind of power band will the wild cams have? I'm hoping for decent power from 4500 up to redline. I intend to call PDM and stuff but I would like to hear others experiences. With this type of setup.

EDIT: I wasn't really planning to retain my ECU and the Bee R setup uses it. My plan was to use an MSD or Mallory (See Summit Racing) ignition box. However, further thought has made me wonder if this is possible. Does the fuel pump rely on the ECU and if I eliminate it will I just make it harder to set up the auxilory systems such as lighting? I personally don't see why they would even run through it though.
Modified by Veriest1 at 3:40 PM 7/5/2005

[Veriest1]

So bah... I hate decisions.

I could pick up a DE and drop it in with some new bearing yadda yadda, a megasquirt, and my sohc pistons. I don't care about power steering and I don't have AC anyway so all the complications of the swap are really out the window.

What are the advantages of having two cams? Does it rev faster? More tuning capability? Obviously the DE has more stock horsepower and supposedly it has a better head design.

Anyone have some info on the fuel pump question above?

Yadda yadda, I search now.
Modified by Veriest1 at 2:12 PM 7/8/2005

[deviousKA]

Dohc advantage,Cheaper/easier high compression setup because of lower chamber volume (other advantages go along with that as well such as quench, piston weight etc.)

Disadvantage,decent cams expensive, valvetrain is more expensive and harder to work with.

Sohc advantageCams/valvetrain simple and affordable to produce good assembly.

Disadvantage,High compression difficult to obtain

That is extremely over-simplified, as there are other points to make in a comparison. Imho, it boils down to that when making a decision. If your pocketbook is large enough, dual cam is the way to go. Upgrade the valvesprings and order some billet ground cams from Colt (~$800-900 all said and done).

[InsanityInc]

The advantage to DOHC is twofold. For one, you have a CFM advantage simply because you have more valve area. Second, you can tune the cams independently (eg retard the intake advance the exhaust or what have you).