Triple Carb

[red_dog007]

Hello all. I have been looking around for a Z car for about 2 years now to purchase. I have finally found one that I am 99% positive that I am going to end up purchasing. It is a 1971 240z. I was thinking about dropping in an LS1 into this beast, but since the engine and tranny have been rebuilt, I dont really have a good reason too. Plus I was only thinking about doing that if I got a newer 240z, or a 280 n/a. But instead I got an older 240z that is still all stock, in great condition so I am going to pretty much leave it this way.

Though I would like to get a little more power out of it. I was thinking about getting a triple carb. I was looking at getting a DCOE 40 triple carb kit for it. (three carbs, all the little pieces and the manifold)

Would this be a pretty good kit to get? Are there any others out there that would be any better? Can I talk the dual carbs off, put on this triple carb kit and be ready to go? Also, what sort of power increase could I be expecting from a carb upgrade?

[beandip]

Adding triples to a stock engine will not do much for you . Triples are for big cams and high revving engines . With out going all out on the head , big valves and porting and headers plus a 2 1/2'' mandrel bent exhaust system . You are much better off with the Stock SUs . Find a good ZX ignition for this engine and get away from points . You will be vary glad you did and will like the improvement it makes to the driveability . It's hard to improve on the performance of the SUs , I am running them on a '82ZX engine in my 240 and and am VARY happy and I am running a cam and the rest . Another thing larger exhaust piping on a stock engine will lower the low end torque at least any thing bigger than 2 1/4 '' . The triples look cool though . Gary

[red_dog007]

Well, good thing that I didnt spend $1.5k on a kit then. What would be some good upgrades that would get me a few more hp. I would like to get the car to be in the 6 second range without adding a turbo/super charger and I dont think that I wouldnt need all that much more power to get this.

The triple carbs and the exhaust was all that I could really think of, but I guess it wont do much after all.

I still like how the Triple Carbs look though, so if I ever get that much $$ lying around, I still might just do this mod anyways.

[jmortensen]

Adding triples to a stock engine will not do much for you . Triples are for big cams and high revving engines . With out going all out on the head , big valves and porting and headers plus a 2 1/2'' mandrel bent exhaust system . You are much better off with the Stock SUs . Find a good ZX ignition for this engine and get away from points . You will be vary glad you did and will like the improvement it makes to the driveability . It's hard to improve on the performance of the SUs , I am running them on a '82ZX engine in my 240 and and am VARY happy and I am running a cam and the rest . Another thing larger exhaust piping on a stock engine will lower the low end torque at least any thing bigger than 2 1/4 '' . The triples look cool though . Gary

Once again I have to disagree with you beandip. My experience contradicts your recommendations. The original Mikuni advertisement suggests a 25% gain in power from adding Mikunis. The first engine I put Mikunis on had a VERY mild port job and was an L28 with dished pistons and an E31 head with 280Z valves, at roughly 8.3:1 (stock for L28E) compression. It had a medium sized cam about the equivalent to the Schneider/MSA Stage IV. It had 2.5" mandrel bent exhaust and a header, and 280ZX EI with no vacuum advance, but that was about it for all intensive purposes. When I put the 44 Mikunis on my wife went from getting a little sideways getting on the freeway to being absolutely terrified of the car. I suspect that just by adding the carbs I gained 40 whp. While I never tested the carbs with the SU's, I did test hp once with the triples and according to the drag race trap speed/mph calculators the car was putting down about 240 whp, so the 40 hp estimate that I made beforehand still sounds reasonable to me. This got even more credibility when Dan Baldwin posted about his experience when he went from his Jag SU's to Mikunis. I think he did something else other than just adding the carbs, but IIRC he put down another 50 something whp after the swap.

The couple suggestions I have are that the cam will help (if you've got high rpm induction a high rpm camshaft helps), get a big enough cam, and get big enough carbs. 44's or better on the cam, and MSA Stage IV or better on the cam. Also a reground cam will cost about $65 from one of the cam grinders, vs $180 from MSA. Why pay more?

[beandip]

Jon , you might have misread my post . this is about a bone stock L-24 and adding triples . On a 280 with some moderate mods , this is another matter . Over carbreating a engine will loose drive ability . Unless your are going to be driving in the upper Rs all the time like on the track again another matter . As you stated you added headders and head work as well as a cam. Gary

[Bruce Palmer]

Hey Dog,

Exactly what is it you're wanting this car to do in 6 seconds?

[jmortensen]

Jon , you might have misread my post . this is about a bone stock L-24 and adding triples . On a 280 with some moderate mods , this is another matter . Over carbreating a engine will loose drive ability . Unless your are going to be driving in the upper Rs all the time like on the track again another matter . As you stated you added headders and head work as well as a cam. Gary

A bone stock L24 would benefit from triples. It would benefit even more from triples and a camshaft. The rest of it, the headers and the mild port work is not necessary to get the benefit of the triples. If I were putting triples on an L24, I would go with 44s and forego the 40s. This advice comes from my experience with a friend's L16 who ran 40s then 44s. 44s made a lot more power.

Again, I drove my 8.3:1 compression L28 with no vacuum advance, a medium cam, a 12 lb flywheel and an ACT clutch in stop and go traffic every day for years. Never had a problem, although I will say that I wish I had lower rear gears. I was running 3.70's, but would have been much happier with 4.11s.

[zguitar71]

My experience going from worn out SU's to Ztherapy SU's was huge the power increase was very noticeable. Then a year later I went to tripples and the difference was even bigger. Tripples do make a difference! The other great side effect of the tripples is the intake sound, very nice.

[Carl Beck]

I originally put the triple Webers on my 72 when I had the original L24 in car... around 1975 as I recall. Then transferred them to the L28.. They just looked and sounded so neat... Originally getting them jetted correctly was a trial and effort taking place over a couple of years... and tons of money spent on them... over and above the original cost...

The main problem with the triples as far as I am concerned - is finding someone that really knows what they are doing - to tune them out at your location. If you learn to do it yourself - expect to spend a lot of money on the learning curve.

Today - I'd never recommend triples for a street car ... Spend your time and money and add a good after-market Fuel Injection system. There will be learning curve there as well - but it will transfer to most other modern cars anyway... Other than that I'd stick with a good set of SU's..

just my experience...

FWIW,

Carl B.

[sblake01]

Hey Dog,

Exactly what is it you're wanting this car to do in 6 seconds?

1/8th mile? Not sure you'd make that with just Webers and exhaust.

[jmortensen]

Today - I'd never recommend triples for a street car ... Spend your time and money and add a good after-market Fuel Injection system. There will be learning curve there as well - but it will transfer to most other modern cars anyway...

FWIW I think this is pretty good advice. An aftermarket FI that uses a stock FI intake and eliminates the restrictive stock AFM would be a good upgrade. I don't think that there is as much ultimate power capability out of the stock manifold as in a triple manifold, so for ultimate NA power a individual throttle body setup on a triple manifold with aftermarket FI is the probably the ticket, but they cost a LOT of money, probably 3x what the triples will run. On the upside you can run a 50mm throttle body and still have more bottom end than a triple carb setup with 44s. Then there's custom manifold stuff like John Coffey, which again is even more expensive.

For those who want the triples, the Mikunis are a lot easier to tune than Webers. There are less parameters to mess with, so they'll be less dialed in, but they hold their tune for a long time and with just occassional synching they'll continue to run right.

sblake01 - I think the original poster was talking about 0-60 in 6 seconds.

[geezer]

It all depends on what your expectations are. You say, you would like a little more power out of it. Triples will do that for you, at a price. You had better become an expert just to bring them to the point where they work well together and be able to maintain peak performance. Otherwise you can count on a fair share of downtime and frustration. Or you can pay someone to do this for you (not cheap). Even then expect downtime. They are not in the least bit, practical for a daily driver. Another thing that will come into play, is all the other parts you will want and need to complete the package, in order to reap the benefits. There really is no end to it. Now, if it's not a daily driver, I say great, go for it, learn all you can by reading books and talking to others running similar setups and have fun with it.