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Injektor Pump Timing Question 617 Engines:
Just a quick informational post to see how many of you are using advanced injektor pump timing and how it is working out for you in terms of performance, fuel economy and driveability in general.
I haven't found much benefit when delivery starts at anything over 30° BTDC on the 617. I use this setting (along with 4° of camshaft advance) on nearly all of the 617's I tune. Any input on this subject would be greatly appreciated...Bert |
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Ok Doc I'll bite. I've never tried anything past 28 degrees and have always used stock cam timing. What benifits have you found with the an advanced cam and start of injection? I'd be interested in playing around with different cam profiles but there is not much available. I'd think about having one custom ground to go with the increased boost and tuned pump I'm working on.
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Bob D. Parrish, FL 1 SDL, 1 D, 1 TD, 1 Mog |
#3
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I've enjoyed the perception of increased throttle response since bumping up the IP timing to 14 ATDC on my OM603. Same 28-33 mpg as before. No change in 0-60 though.
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I need to check my W116 timing closer.......when it gets warmer.
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Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche |
#5
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Quote:
The advanced camshaft and injektor timing does increase the audible sound of combustion slightly (sounds more harsh) but yields great acceleration off-boost. I think 28° to 30° on the start of delivery is about the point of diminishing returns and 4° (crankshaft) on the cam timing is about the limiting point also. The later '05' camshaft is a nice upgrade in the earlier engines...Bert |
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Quote:
__________________
Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche |
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Hey Doktor,
Its been a while since I degreed in a cam and that was on Pontiac drag engines. How about a step-by-step on degreeing the cam to find out what the cam timing is? I have a degree wheel and dial indicator somewhere......... Thanks, RT
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When all else fails, vote from the rooftops! 84' Mercedes Benz 300D Anthracite/black, 171K 03' Volkswagen Jetta TDI blue/black, 93K 93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K |
#8
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Quote:
Sure thing...Let me work on that...Bert |
#9
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Doktor,
My HS drag car was: 72 Firebird Esprit with swapped in 455, 0.030 over 9.25/1 KB slugs, 4 bolt mains, custom main caps, nitrided crank-stock journals, shotpeened rods w/ARP bolts, Ram Air 400 heads that were ported by Valley Head Service, Milodon timing chain, pan pump and windage tray, Comp cams magnum 280H w/lifters, roller-tip rockers, chromolly pushrods, Carter electric fuel pump, Holley 850DP, Edelbrock performer, Hooker headers, Complete B&M rebuild kit in a TH350 w/transbrake and 2800stall converter, Megashifter, 3.73posi rearend from '77TA, Competition Engineering slapper bars, 6pt cage and "sticky Mickeys" on the back. Ran a 12.51 at Englishtown, NJ in 1987, right off the street, no prep, with wheelspin. For its time it was pretty quick. Whats your 400 in? RT
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When all else fails, vote from the rooftops! 84' Mercedes Benz 300D Anthracite/black, 171K 03' Volkswagen Jetta TDI blue/black, 93K 93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K |
#10
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Quote:
I want to borrow a dial guage and determine what it is now and use an offset key to put it there.
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Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche |
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You might just want to buy one from harbor freight. I think they were like $40. you can use it to set the wheel bearings as per the manual too.
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Bob D. Parrish, FL 1 SDL, 1 D, 1 TD, 1 Mog |
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But is that 4 degree cam advance really 8 degrees at the crank.....or is it really 2 degrees on the cam and 4 degrees at the crank? I assume its the latter......but it concievibly coud be the former.
__________________
Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche |
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I guess only Bert can say what he means since he is advocating this. If he is talking 4 at the cam 8 at the crank I'd begin to wonder about interference valve to piston. especially at high rpms. Those spring are not that stout and valve float may be a possiblity
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Bob D. Parrish, FL 1 SDL, 1 D, 1 TD, 1 Mog |
#14
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Why look for trouble. Set it to factory specs and be done with it. Stuff like this just invites disaster. Or as Marshall would say: "YOU WILL MELT YOUR PISTONS"
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Bill Reimels Now down to one: 1972 300SE 3.5 W109 (Euro delivery) |
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Quote:
Of course the actual offset would be dependent of whatever correction you need to get the cam timing to spec as I understand in production these varied more than a little. So the 4 degrees should be advanced from spec if the motor was dead on with the timing already.
__________________
Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche |
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