Hi All, I am in the process of rebuilding an EJ motor for my FE I'm fairly sure it will come back from the machine shop with a bore of 3.125. I am planning to use the standard cam and my question is what jet sizes to use in my standard Stomberg? Thank Doug
51 main metering jet. Move up to 53 if it tends to miss or surge at cruise.
you can R n R the main jet with carby insitu with a standard manifold ,you need a special tool page 193 of service manual item 6A12 .Vern
an adjustable one will fix hesitation on take off
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Quote from: ipg on May 11, 2021, 08:07:06 AMan adjustable one will fix hesitation on take off
Not sure I agree with this. Hesitation on takeoff is often due to the accelerator pump washer being tired (can also be blocked pump circuit, timing etc). An adjustable main jet serves only the main metering circuit. There is no sudden increase in flow in this circuit when you moosh the accelerator (the opposite occurs - throttle opens, manifold vacuum drops, less suck on the main metering jet, less flow through the main metering circuit). The only way an adjustable main would cure that would be if the jet was open waaaaaaay too far (so that there is heaps of fuel to mask the vacuum drop). You would then have a very rich (and fuel hungry) car.
Not a big fan of adjustable jets (I think I own three or four). They were once described to me (perhaps by Ken or Doctor Terry?) as being really useful for taxis. Wind them in until you get awesome fuel economy, then drive until the valves are burnt and crispy :(. Would not recommend them unless you are either VERY good at reading spark plugs with modern fuel, or have access to a wide-band O2 meter.
Cheers,
Harv
Thanks for the info, I will let you know how it goes once I have the engine back together and fitted. Doug
Just to let you know the outcome of my J Series engine rebuild, block was bored out to 3.125 i.e. 142 cu in, and rebuilt with standard J series cam and BXOV-1 carburetor (.051 main jet). All went well, however, the car was surging slightly when cruising or under prolonged load, changed up to a .053 main jet and all is well. Marvelous what two thou can do. Thanks Doug
;D
Cheers,
Harv
Yep.
That's exactly my experience with a 3-1/8" bore J-motor. With a 51 main jet it's a little flat-spotty and surge-y just off idle, but I get 33-34 mpg on long trips. A 53 main jet smooths it out nicely.
Rob