| Author |
Message |
steve souza (Stevebnut) (24.91.79.43)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 26, 2004 - 9:33 am: | |
can more power be gained by using different injector timing height adjustments?
For example say using 1.460 instead of 1.484 or vice versa?
Does it inject more fuel or does it inject it at a different time or duration?
What exactly does setting the injector timing (height) affect?
By the way, i have a 6v71 with n75's and standard timing with a two valve head.
It smokes black if i keep my foot in it under a heavy load like a steep hill but i watch my exhaust and lift the right foot to keep from cooking a cylinder or two.
Big increase in power from the original c 60 injectors that were in it!
thanks-- Steve |
Bill Gerrie (209.50.74.33)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 26, 2004 - 4:07 pm: | |
Steve
I've asked that very question before and the answer I got was that the engine was made to run at a certain setting on the injectors. With N75's you should have the advanced timing for sure. This entails removing the tranny and rear housing. You have to change the gear meshing to the "A" setting. Bill |
Geoff (Geoff) (66.238.120.101)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 26, 2004 - 9:30 pm: | |
There are two generic timing settings for the engine-- the first one is the gear train timing, which can be set at std. or advanced. The Detroit specifications call for standard timing on a naturally aspirated engine with injectors up to size 60, or with a turboed engine. If you have a non-turbo engine you are supposed to have advanced timing to use injectors bigger than size 60.
The second timing setting is the injector height on the injector arm-- it can be 1.484 or 1.460. Usually the 1.460 is used on std. timing, and the 1.484 is for advanced timing.
In Steve's case, he is drowning the engine with fuel! I know people get away with going one size over, but Steve, you are three sizes over! You might have more power, but you are washing the clyinder walls down with excess fuel and could very easily seize a liner jug climbing a grade. Changing your injector height is not going to do much of anything for you.
Good Luck!
--Geoff
'82 RTS CA |
Jim-Bob (12.46.52.74)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 27, 2004 - 11:34 am: | |
I recently changed from N60 to N65s in my straight 6-71. Both the old ones and the new ones were set at 1.440" with standard cam timing & 2 valve head on the advice of a guy who used to run a fleet of 4104s in competition with bigger, newer buses.
What I found is that once the bus is warmed up, there's no smoke, except for a small grey puff starting from a dead stop (stick shift). The bus runs noticeably better with the N65s.
Now the 4104 engine was equipped with a "Fuel Modulating Governor" that overrrides your foot and forces the rack closed as you approach full RPMs. This has no effect on takeoff smoke.
The book for the 4104 lists 70 or 80 injectors as standard but maybe the modulating governor tempers that amount of fuel at higher rpms?
I am just getting ready to install a 4 valve head & I was planning to go to N75s figuring that the engine could absorb the extra fuel with the extra air.
I've also heard that the inline engines can use slightly bigger injectors because they breath better.
What HAS changed with the injector timing advancement is that now I get a big cloud of fuel smoke on start up which stops in a minute or so.
What do y'all think about all this? |
John Rigby (24.174.238.253)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 27, 2004 - 8:22 pm: | |
I have the old type N70,s in my 04/671 / advanced timing and high compression pistons/ two valve head.Not a trace of smoke after she backs off from full fuel on initial start up.Lots of power.
Leaving the bus bash at Louiville last year I ran with a greyhound/MC12/Series50. he took me slowly on each hill but I passed him back up on the flats ( he was governed at 73mph)we ran for an hour and a half like that.
John |
Jim-Bob (12.46.52.74)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 28, 2004 - 9:35 am: | |
John, how fast will your '04 go on the flat? I've got the optional 3.55 rear axle w/12R22.5s & I top out right around 73 at 2100RPMs.
Do you still have the fuel mod governor? (Has a cap over the high speed spring with a safety/tamper wire. Truck gov has high speed cover with two bolts fastening it.)
BTW, I have the high comp. N kits w/ 2 valves too. |
John Rigby (65.112.227.94)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 28, 2004 - 12:21 pm: | |
Jim.
My 04 has 11/22.5 @ 2150rpm at the driver gauge under load/hyway, I top out at 76mph.No smoke period no mater what I do,on start up when the rack pushes to full fuel, I get grey smoke for 30 seconds to 1 minute.
I have over found in the past that it was easy to over heat. including blowing a cyclinder head gasket in L.A. But now I have changed my old 4 passage radiator core, to a new 7 passage radiator core,$695,I am a lot more confident that I can control the temp better in the mountains.
Were are you located? We are trying to do an informal GM ( anyone is invited ) get together in Southern Arkansa, June or July.
John |