1969 cummins serial number location hunt!

Truck Shop said:

That engine is a 335 with a 350 pump. all NTC 350's were after cooled, 335's were not after cooled.
335's had the cartridge filter up front, 350's had either a canister or spin-on

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I think i read somewhere that some of the early 350s did not have the aftercooler.
Just reay hard to say at this point. As old as most of this is and all things not adding up it can be a hienze 57 mix and match special built from a junk pile for all I know lol! Guess i will never really know without a serial number! Thats one area cummins really dropped the ball on being consistent with serial number location!

Truck Shop said:

That engine is a 335 with a 350 pump. all NTC 350's were after cooled, 335's were not after cooled.
335's had the cartridge filter up front, 350's had either a canister or spin-on.

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if that eng has a taper nose crank its a 335 for sure . was also rated as nta 380 for which I have an after cooler that fits it

petepilot said:

if that eng has a taper nose crank its a 335 for sure . was also rated as nta 380 for which I have an after cooler that fits it

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Cool another clue! How do i tell which nose it is? I assume i need to pull the harmonic balancer off.

Whats the difference between nt and ntc? I have been told it was a nt350 and also a ntc350 based on that pump cpl

Oh also i dont know that i need an aftercooler. The truck its going in has a carge air cooler. I thinks thats a more effiecent way to do it anyhow. May upgrade from that antique turbo though lol!

workshoprat92 said:

Cool another clue! How do i tell which nose it is? I assume i need to pull the harmonic balancer off.

Whats the difference between nt and ntc? I have been told it was a nt350 and also a ntc350 based on that pump cpl

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the crank will have 1 large I believe 1x1/4 ' bolt in center instead of 6 smaller

Can't see the end of that crank, but some 335's that were late production had the late blunt nose crank
using six bolts instead of the single gland bolt. Water pump is another different item, I don't see a idler
pulley for the water pump.

really not

petepilot said:

the crank will have 1 large I believe 1x1/4 ' bolt in center instead of 6 smaller

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Truck Shop said:

Can't see the end of that crank, but some 335's that were late production had the late blunt nose crank
using six bolts instead of the single gland bolt. Water pump is another different item, I don't see a idler
pulley for the water pump.

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can`t tell for sure but that looks like the older concentric pump.

petepilot said:

really not


can`t tell for sure but that looks like the older concentric pump.

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Lol this is funny i was just gona add that it has the old style screw in pump. Dont know if that means anything. I will look at the crank nose when i get home.

It's a 335.

Truck Shop said:

It's a 335.

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Is that based on the water pump? If its a 335 i am a bit disapointed lol. Guess it really dont matter. It will do what i need it to do!

Really the only huge difference between a 335 and 350 other than the crank was the after cooler. Technically a after cooled 335 is a 350. That was Cummins up-grade to reach 350 hp.
Other than the water pump and oil filtering there is not much difference. Most 335's that broke a tapered nosed crank were over fueled and because of that there were alot of pistons
that got cooked. That's where the after cooler came in play. The 335 was a good engine in it's day. That turbo-without seeing it up close could be a old Schweitzer those turned up slow.
But most any turbo back then was slow, that's why a driver needed to not let the rpm fall below 1700 on the up shifts. To much turbo lag below 1700, it was hard for them to recover.

Well I guess the pic answers that question lol! Definatly a tapered nose. So im gathering that couples with the ecentric pump makes it a nt350 for sure.
Ok so some thoughts. Thats all assuming it was built to original cpl right? I mean we already know its got a 350 pump on it. So if i knew things like what cam, injectors, turbo, engine timing and so on then it could be built to a 350 cpl right? One bobble i do know of is that my dad rebuilt this thing back in the 80s. When he did they screwed up and put 400 pistons in it. I know that by the old recipts from when he built it. I had to figure out why it smoked so bad at idle back when i ran it in 92. Long story short i did some custom hot timming to get it to stop smoking. Basiclly i have been told with the 400 pistons it makes it a low compression 350. Or now i know 335 lol! Anyhow so it sounds like an aftercooler is good for 45 hp. Im sure thats with some different timming and fuel setting i would bet though????

The truck its going into. Its replacing a siezed 3306b. Cat says it was a 310hp engine when it went out thier door!

The stock timing for a NTC350 was 36, IIRC the 335's were 33. With NTC350 non top stop injectors, pump, turbo and correct pistons with a after cooler you have a 350.

Tag on the turbo!

workshoprat92 said:

Lol this is funny i was just gona add that it has the old style screw in pump. Dont know if that means anything. I will look at the crank nose when i get home.

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You know the pump is excentric and turns in the block to adjust the belt. They often started leaking after adjustment. We cut the old belt off and rolled a new one on. Stayed with the same brand and number. Never turned the pump after installed.
A touch of fuel and that charge air cooler will wake it up a bit.

Tenwheeler said:

You know the pump is excentric and turns in the block to adjust the belt. They often started leaking after adjustment. We cut the old belt off and rolled a new one on. Stayed with the same brand and number. Never turned the pump after installed.
A touch of fuel and that charge air cooler will wake it up a bit.

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I changed that pump back in 92 when it was in the truck. Truck was overheating but everything in the system looked good. No leaks and system was hokding pressure. Changed thermostat and same thing. I just happened to notice that when the cap was off and it was up to temp the water was not moving! I pulled the pump and found it had a phenolic impeller that fell off the shaft! That one was a head scratcher to find! Who would expect an impeller to come off?

that water pump is still available but must be ordered cummins will not have it in stock the 743 cube 220- 262 uses the same pump as does some of the 855 cu 250s

Guys more than anything i would like to see this engine run again! Main reason for me is that my dad bought the truck it was in back in the early 80s! It put food on the table for me and my 2 brothers for many years. It was rebuilt and shortly after that in about 92 i built a dump box and put it on the truck. I sold all my lawn mowing equipment i amassed in high school and paid for the materials to build a box. The box was also built out of a salvaged underground fuel tank. I ran the truck for about a year and paid cash to go through colorado areo tech to be an aircraft mechanic! No student loan debt at all! Thank you old freightliner! In the end the aircraft career was a fkn nightmare and probably a huge contribution to my alcoholism! I have come full circle and am most happy dump trucking and enjoy the people i meet doing this far more than the aircraft crowd! Still the aircraft education made me tbe person and technician that i am today. There are principals that apply no matter the machine and what mode of earth it operates on! I want to see this thing go again because its a special part of my history that made me what i am today and gave me the knowledge and abillity to provide for my family even in a pathetic worn down physical state that im in! Its would be an honor to wield this nobel machine one again! Does that sound crazy? I will keep up on this thread as i get it back to life!

Good for you!