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Timing issue maybe?


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My dad rebuilt his 93 350 with 16.5 compression to the higher horse 15.3 kit. Went with stage 2 injectors and a bigger turbo, the. BW S475. 75/96mm 1.32ar. It has the same specs as the 171702 that the 60 series guys love. And the blixxton he's had since he bought the truck. 

Here's the issue. It smokes (unburnt fuel greish color) until it gets up to operating temp but then clears up mostly. We don't have an A-B light that mack says to use for adjusting the timing but my dad has it somewhere around 10.5-14 he's not 100% sure where. 93 was a change over year so we've been having difficulties finding out if we have the +10 econovance or the +20 econovance? It almost seems like the timing is too far retarded. Between gears its a trail of black longer than the 53 footer. Even on a steady pull it leaves a steady stream. 

 

From Binghamton NY to Boston mass there's some good pulls on I88 and 90 and the fan never came on once and coolant never got above 180. Pyro got up to about 925-950ish. Seems to me if it was advanced too much it would run hot but it doesn't. I'm thinking it could need to be advanced some more. Or could it be that it has a 350 file in it still and we need an ecm off a vmac1 427 or 454 to get it to run right. 

 

Mack doesnt support vmac1 anymore right? And if we updated to vmac2 the dealer would put a low NOX file in it which we dont want that bs installed. 

 

Maybe someone here has dealt with a similar problem? Seeing 40 psi and wont go over 950 on the pyro compared to 1100+ before the inframe with the blixxton

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I think its either the timing is not advanced enough or the 350 file is messing up. Today my dad bumped it up to around 16 so will see how it runs. Gonna re-torque the heads and set the overhead

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Let us know how it goes kind of an interesting issue if it don’t solve you problem maybe check the compression wrong pistons can lower your intended ratio!

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  • 2 weeks later...
12 hours ago, masterwelder said:

How’s you’re dad like the section of I88 between Oneonta and Cobleskill? To say it’s rough would be  kind!

I was just up there last weekend actually... in my car tho. Completely different ha

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