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7.4l TBI timing


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Hey guys,

 

Quick question, well first, the scenario...

 

So, a few months back I bought my '95 2500 with 7.4l and 4:10 full floating 4:10 rear end. This is my daily driver and to pull my 9000 lb travel trailer. When I bought it, it had several failed sensors, distributor issues, etc... I repaired all, timed it and shortly after set off to Florida with the trailer. It ran/runs well, but is a real dog up hill. It sounded as if the timing was retarded pretty bad. During the trip I changed the timing module with no difference.

I made it down and have since played with the timing. Timing was set to 4 degrees btdc. Milage was approx 16.5 (not horrible), but I have to play with the pedal getting on the freeway to get the most out of it. If I advance the timing to say 8 or even 10 degrees, it seems to run better all around and really wakes it up from a power standpoint, but the milage drops like a rock. Not sure if one of the previous owners put a cam in or not, they did put a k&n air cleaner on.

Does make sense that with more power, the fuel economy suffers? Thoughts?

 

Thanks in advance!

Lorne

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TBI works on velocity, that big engine is sucking that TBI unit like a straw.

it is a lot like the old carbs, a little bit smarter.

 

if this gets really frustrating, slap a big holley with a plate... msd has digital controls for any ignition.

 

Any errors at all straining that timing on that little TBI...

kaboom.

 

staying retard time is safe.

 

I just got the mpfi fuel injection in 2015. Went a long time with carbs.

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Thanks for the responses. EGR checked ok back when I got it a few months back.

 

It just seems so strange to me the the performance is so much better, but it seems that for every degree I advance I lose 2 mpg. The improved performance made me think a bigger cam may have been installed. Timed normal it even sounds retarded as the RPMs climb. Can't argue with the fuel economy, but pulling up large hills I feel like I should get out and push and max speed is 40-45 mph.

 

A carb would definitely supply more fuel. There's a way to fool the computer?

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