I'm building up a slant-6 with 1.70/1.44 valves, 260 cam, 0.100 milled head, + .060 pistons.

I purchased a refurbished GM TBI from a 4.3L. Will it be adequate for this case or will I need larger injectors? I believe the stock injectors are typically 45#.

Thanks - TJ

I would run it with the 45# injectors at 12lbs fuel pressure. If you run out of fuel go to 15lbs....if you run out then move up to 55# injectors at 10 lbs.....

Dont let anyone try to convince you you need more than 55# ....

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Depends on how hot his motor is. My '64 is close to maxing out two 85lb injectors at 6000 RPM (80-85% duty cycle).

But, for normal modified 225 use, 55# is probably perfect.

Lou

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Home of Slant6-powered fun machines since 1988

I run 55lbs on my build, honestly I tip in a little bit at WOT and would recommend going with the 4.3L injectors at 15PSI cause like the carbs it's sometimes better to go smaller and be able to tune it easier.

This is just one of the sites to find out more about mods and replacement parts for GM TB's: http://www.tbichips.com/305mods.htm

One thing I have done to both my Caprice and my GMC conversion van is called the Quarter-Mod. When you need alittle more fuel pressure or in my case it helped achieve a better spray pattern, you take the cover off to access the regulator and place a Quarter on it, replace the cover and you just turned the pressure up!

Another great site is the Impala SS forum. You can search around without joining.

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Chris'
Autobody
Restoration
Service

Thanks all for the information and links. I have a much better idea where I stand. I'm still just getting my feet wet with EFI.

-TJ