3 injectors on a 6 cylinder engine MATH QUESTION please!

1950ChevySuburban · Post by **1950ChevySuburban** » Fri Jan 25, 2008 9:28 am

Hello all! Just got my 50 Burb Megasquirted, and almost running. I have a basic math problem though,
My intake uses siamesed ports, so I have 3 injectors. One for cyls 1+2, another for cyls 3+4, another for cyls 5+6.

If I do the math one way, I should be running around 39 flow rate, but thats discounting the fact I only have 3 injectors. Seems like MAYBE the rate should be halved? Or even doubled, since each injector feeds 2 cylinders?

I know each injector will fire 6 times per RPM

The injectors in it now are new, based on doubling (each one feeding 2 cylinders), so they're for a 7.4 litre Ford V8. However, I'm wondering if thats too much. I have no measurable run-time with this setup yet. (Engine ran great on the Dellorto carbs before)!

I'm running a mild cam, figure 200 HP for this 250 c.i. engine, with an automatic overdrive and A/C.

The injectors fire together, one batch. MS-I, V3.0 board.

Also, these injectors are 13 ohms each, so they're high impedence, even though they're banked together on one feed.

The engine setup can be seen in my avatar.
Thanks in advance!
John

Philip Lochner · Post by **Philip Lochner** » Sun Jan 27, 2008 7:06 am

There is a very practical way to find out and thats to start it! If those injectors are too large you will find it hard to find a reasonably lean (13) mixture at idle since your PW will approach that of the opening time of the injector. Then you could either drop the fuel pressure (undesireable) or fit smaller injectors.

EDIT: You could also reduce the number of squirts per engine cycle which would also increase the idle PW, should you find it becomes too short at idle.

1950ChevySuburban · Post by **1950ChevySuburban** » Mon Jan 28, 2008 4:59 am

Thanks for the reply, that's what I'll try then. Found out the parts store sold me a low pressure pump, instead of a high pressure pump. Ah well, minor setback. Maybe run it this afternoon???

Thanks again!
John

1950ChevySuburban · Post by **1950ChevySuburban** » Thu Jan 31, 2008 4:48 am

Thats a good point, I was concerned about that. Right now I've got it set up as a 6 cylinder with 3 injectors and it idles smooth. I plan on playing around with it, including setting it at 6 injectors (instead of 3) and seeing how that runs.
Either way, can't be any worse than carburetion which has no timing control at all, right? And I get instant cold starts HAHA!

I have a few hours after work tonight to mess with it, still dialing it in one step at a time.