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1986 GMC Brigadier
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By twoleftear - Wednesday, January 29, 2020 5:18 PM
I bought a 1986 GMC Brigadier with a 855 cummins it has No plate on the engine any idea what the horsepower and series this big cam engine would have. Thanks, Joe.
By Geoff Weeks - Thursday, January 30, 2020 6:46 AM
If it has an aftercooler, I would guess a 300 hp, if not, then 290 or less.
Coupla things can help. LOok on the fuel pump and post the tag number off it. Also look on the left rear of the block for a pad stamped with the engine serial number.
By twoleftear - Thursday, January 30, 2020 3:06 PM
Truck is in storage for the winter but will look at it soon thank you for the info. It has a miss engine kinda bounces at fast idle, no smoke to speak of, done a few tests on the engine. Number 5 cylinder seemed like the culprit, pulled injector, dirty cleaned screen bouncing went away miss is more tame. I did not get number off injector thinking may need to replace injectors.Truck has sat with very little use in the last twenty five years.
By Clayton Hoak - Friday, January 31, 2020 1:52 AM
The 1986 Brigadier brochure lists the NTC 300, NTC 350, Formula 300, Formula 350 and L10 as the Cummins engine options. The Detroit 6V-92TA with 85 mm injectors was the "standard" engine.

Check the passenger side visor to see if the truck's component information is still there and legible. The code to the left of the engine listing defines the engine model and horsepower.

KZG - Power Option - NTC-350, 350 HP (2100 rpm)
LPD - Engine - Cummins NTC Series (301-350 HP)
LRB - Engine - Cummins NTC Series (240-300 HP)
LYA - Power Option - Formula 350, 350 HP (1800 rpm)
LYB - Power Option - Formula 300, 300 HP (1900 rpm)
LYC - Power Option - NTC-300 , 300 HP (2100 rpm)
LYH - Power Option - Formula 300, 300 HP (1800 rpm)
LYK - Power Option - NTC-300 , 270 HP (1800 rpm)

There are other Cummins option codes for the NTC-400 and L10.
By Geoff Weeks - Friday, January 31, 2020 1:58 AM
Run it under load before making more diagnoses, it just may need to "seat in" things. If after running under load you still have a miss, then we can look at other things.
By twoleftear - Saturday, February 01, 2020 2:01 PM
Truck was bought then drove 400+ miles it never got better or worse making that trip. After the trip is when my buddy and I started to go over it number 5 cylinder was off compared to the other cylinders using a heat gun. Winter came and its a far as we got cleaning number 5 injector. Truck is going to be used as a farm truck short hauls moving hay and grain.
By twoleftear - Saturday, February 01, 2020 2:04 PM
Ok, Thank you Clayton. I will check that out. and yes it does have an aftercooler.