Injektor Pump Timing Question 617 Engines: - PeachParts Mercedes-Benz Forum

Doktor Bert · #1 02-21-2005, 11:57 AM

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

h2odiesel · #2 02-21-2005, 09:10 PM

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.

H2O2 · #3 02-21-2005, 09:25 PM

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.

boneheaddoctor · #4 02-22-2005, 08:15 AM

I need to check my W116 timing closer.......when it gets warmer.

Doktor Bert · #5 02-22-2005, 04:07 PM

Quote:

Originally Posted by h2odiesel

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.

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

boneheaddoctor · #6 02-22-2005, 04:09 PM

Quote:

Originally Posted by Doktor Bert

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

What years/models started to get the '05 cams?

rwthomas1 · #7 02-22-2005, 05:27 PM

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

Doktor Bert · #8 02-24-2005, 02:07 PM

Quote:

Originally Posted by rwthomas1

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

Pontiac!!!!! You would love my .060" oversize 4-Bolt Main 1970 400 Block with a 1962 421 crank!!!

Sure thing...Let me work on that...Bert

rwthomas1 · #9 02-24-2005, 08:45 PM

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

boneheaddoctor · #10 03-08-2005, 09:53 AM

Quote:

Originally Posted by Doktor Bert

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

Is this 4 degrees of camshaft advance 4 degrees at the cam....or 4 degrees at the crank?

I want to borrow a dial guage and determine what it is now and use an offset key to put it there.

h2odiesel · #11 03-08-2005, 01:05 PM

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.

boneheaddoctor · #12 03-08-2005, 01:44 PM

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.

h2odiesel · #13 03-08-2005, 03:41 PM

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

billrei · #14 03-08-2005, 03:54 PM

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"

boneheaddoctor · #15 03-08-2005, 03:55 PM

Quote:

Originally Posted by h2odiesel

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

Well to make sure Bert sees this I will bump it ....I am assuming he means 4 degrees at the crank......but if I am going to the bother I want to do it right.

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.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
The Big Timing Chain Question	braverichard	Diesel Discussion	96	09-29-2012 08:41 PM
Camshaft & Injektor Pump Timing:	Doktor Bert	Diesel Discussion	17	11-09-2008 09:00 PM
Timing chain question	oilslick	Diesel Discussion	2	10-27-2004 09:02 PM
M103 camshaft timing question	Gerard	Tech Help	7	04-29-2004 02:00 PM
Gas Octane question w/retarded timing	bobboyer5	Vintage Mercedes Forum	13	01-27-2004 06:54 PM