Intake swap

[Earlybird]

I just got a 1976 280 SL twin cam. Is it possible to take the carbs and intake off an earlier single cam 280 and put them on the later twin cam 280? Are the intake bores on the same centerlines? I like the FI but want to go minimal with everything.

[Mark DiSilvestro]

Originally Posted by Earlybird

I just got a 1976 280 SL twin cam. Is it possible to take the carbs and intake off an earlier single cam 280 and put them on the later twin cam 280? Are the intake bores on the same centerlines? I like the FI but want to go minimal with everything.

I don't think so. The twin-cam has a crossflow head with intake & exhaust manifolds on oposite sides, while the single-cam has the intake manifold straddling the exhaust on the right side. You could probably use the intake manifold from one of the mid-'70s carbed twin-cam 280 or 280S cars.

Happy Motoring, Mark

[JimFreeh]

Also bear in mind that the 280SL in the R107 chassis has a different air intake than the sedans due to the low hoodline.

Even if you successfully install the carb manifold, you still have to deal with a clearance issue as well as changing out the fuel pump.

I've got a running W126 280S parts car, and the carb looks rather high for the SL application. But hey, if you're game, I don't have any need for the parts....

Jim

[Earlybird]

Wow/thanks, That sounds great. Even if I had to adapt some SUs or Webbers, it's worth a try. I have my own full size mill so if there is any kind of small alterations, I can do it. How much will it take for you to ship the parts to Washington state?

[Mike D]

Minimal? By adapting SU's or Webers to work? You sir, are in for a surprise.

Let's see, for starters; linkage, choke connections, jetting, wiring (if you go with an electric choke), water connections (for thermostatically operated chokes) or running a cable for a manual choke.

Mileage will suffer because if I remember correctly you have the higher compression head. You'll have to run it rich to prevent spark knock under load and at speed.

Since you have access to a machine shop, why not convert to a TBI using a Megasquirt ECU?

[ctaylor738]

Why would you do this?

Early K-Jet is about as simple and reliable as it gets. Parts are easy to find. The system works very well with minimal fussing once its adjusted correctly.

I can see that it would be an enjoyable challenge if you have the tools and equipment.

[Earlybird]

I am a Manufacturing Engineer with my own machine shop. I want a lighter simpler system.

[ctaylor738]

I understand that.

My point is that, IMHO, you will not achieve your objectives. The K-Jet system that you have is at least as simple as a pair of carbs, and way ahead techically in terms of accomodating driving conditions and engine temp. I don't think that there is much weight to be saved since the pieces are all aluminum with the exception of the fuel distributor, which is cast iron if you have the old style.

Having had several M110's with injection, and one with a carb, I can tell you that the injection has been 'way more trouble-free.

In practical terms, you will probably need to use the single carb manifold from a M110, because the M130 twin-carb manifold is very different. You will need to figure out how to mount a carb so that it has hood clearanance, probably a side draft arrangement.

Good luck, and please keep us posted.

[Earlybird]

I will probably adapt a 280Z or a Jag 6 twin SUs since Webbers are a little pricey.

[t walgamuth]

i agree that this is a poor concept.

having a good many years driving cars with carbs i can tell you that the fuel injeciton system on the 110 is much much simpler than a carb. now if you have the earlier system with the second set of points under the ignition points it might give better drivability if you were to swap to the later cis system. the cis is about bulletproof and dead reliable.

i dont know how tough it would be to convert it.

tom w