12v no Rattle!!!!

J

jmoritz

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May 4, 2014
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ok im at my end of strings on my engine build! i need advice/help figuring this thing out..... my build specs are in my sig line for refrence, but to start it off when i first got the engine built i pin timed the engine and the pump, started the truck and it ran but as i tried to increase the rpms it started to sputter and run crappy, it was hazing (blue)and just wasnt happy. so the next morning i went out and timed it up to 17*, still hazes (blue) at idle a bit but now runs ok. truck has very minimal low end torque, but has good top end. builds about 38 psi of boost granted it is a 16cm hot side. the thing that bothers me is the lack of low end and the lack of "rattle" per say. i swear ive never heard a cummins run as quiet as my truck does and i feel like the lack of combustion noise could also be whats causing my lack of low end. the engine now has 6000 miles on it, not any real noticable crank case vent fumes, i rechecked the timing and the valve lash all are still in spec. ive done a ton of searching and havent came up with anything that pointed me in a good direction. any help would be great!!! any questions are welcome!
 
your HX40 and the timing are causing your lack of "low end"

I'm guessing it doesn't really come alive until 2000rpm or so?
 
Yep, but then engine wouldn't hardly rev past 1300 rpm when it was timed at 12.5* and yes the turbo sucks
 
It still hazes at 17*, it should still run proper at 12.5*, there's something that's odd. It's almost like it has low compression or something. Timed @17* on other trucks I've heard, they have almost a sharp rattle to them. On mine the grill vibration noise is almost louder than the engine rattle.....
 
I disagree on running proper at 12.5* Especially with a larger turbo.

You might have your injectors pop tested
 
You are correct, there are more issues here. The engine timed at 12.5 should still free rev just fine. Did you check tdc with a dial indicator just to make sure? I would verify timing. make sure you have the correct timing chart for that pump.
 
Correct timing chart? 12.5 was pin timing. I wasn't aware there was different charts?
 
different pumps degree at different angles referenced from TDC.

how did you verify TDC on the #1 cylinder before you timed the pump.

they turbo is not your issue. does it ever pop or cut out when the engine is cold then go away after warm up?
 
When it's really cold out it has popped before. I find tdc using the cam gear pin and checking the in/ex valves. Use a blue point micrometer tool in delivery valve Hole to measure plunger lift to set timing. And also when it's cold it stumbles a bit for the first few seconds than clears up. I don't have the heat plate hooked up.
 
my experience has been if you have a factory timed HX35 truck (12.5* or so) that runs just fine and then you put a bigger turbo on it, it will break up/stumble/white smoke on free rev or under heavy acceleration in lower gears

my theory is that the added boost from the smaller turbo builds more heat in the cylinder and helps with the burn...

each pump cam has a different timing chart for plunger lift
 
So the engine was a 175hp factory, 5spd truck. Plunger lift is at 6.5 rite now witch from what I read is rite at 17*. The thing that seems to bother me most is the lack of noise at idle. It's almost like it lacks fuel at idle or something. Where would a guy find the different timing charts?? Thanks for all the input so far!!
 
The search function will find u the timing charts....to me its sounds kinda like my truck when I first got it and the timing was just under 8*
 
I'll jump on the search as soon as I get home and see where that takes me. Thanks
 
A good question is, where did you get the chart that you have been timing off of up to now?


Sent from my iPhone using Tapatalk 2
 
Ok so according to that chart, mine is the 175hp so at 6.5mm plunger lift I'm at 16.5* so that should be acceptable. Got my old timing chart off the net last year but I wasn't aware there is different charts. Learned something new today! Could the valves be leaking by bad enough to cause a loss of compression?
 
So Timing is good, under full throttle 37 lbs of boost it runs clear out the tail pipe, max egt is 1200* at the top of 5th gear. I know the injector spray angle is is wrong because the injectors are for a 95 truck and the pistons are the non intercooled pistons so the have a larger and slightly different shaped bowl. Could this cause any problems?
 
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