another timing question on a 3.0

[jmarines]

okay guys.. Hoping you all can help me out. I started a thread in the props section but it turned out it wasn't a prop issue. I wanted to start a new thread in the proper section so here I am. I am having a rpms issue. I couldn't get over 4000rpms @29 mps with a 19* prop. I checked my compression today to rule that out. compression was great 150 155 160 160 so My next step was timing. I put it in base timing mode which as soon as I jumped the wires from the switch the motor died. I did it a few times to me if maybe it was a user error but it still did the same thing. After a bit of research I came across a thread where someone was having a similar issue because his time was so far off. So what I di was start and have the engine idle and adjusted timing to 12* BTDC. I was able to get it to 10*BTDC because the wiring harness coming out of the distributor was hitting the hose that went to the power steering pump. As soon as I set it I put it in base timing mode which now the engine stayed on which was great. The timing was set at 2*ATDC . I then read to throttle up to 2800rpms and check to see if the timing went up to 28*BTDC but when I reved up it went to 12* BTDC. Am I doing something wronge? How do you even read 28* BTDC if the tab only goes up to 12? Am I supposed top be adjusting it on the ATDC at idle to 12* then when I throttle up it goes to 12* BTDC which would add up to 24* increase? As you can tell Im a bit confused... well to be honest.. a lot.

 

[fishrdan]

You're not going into base timing mode correctly if it's killing the engine.

1- start and warm engine
2- jumper the 2 white leads on the distributor with a home made jumper wire
3- disconnect and jumper the shift interrupt switch wires going back to the distributor, harness side (the engine will bog as it drops into base timing mode)
4- time the engine to spec (2* BTDC, 1* BTDC or 1* ATDC, whichever) and re-tighten distributor lock bolt
5- remove jumpers (switch then dist) and check that timing goes to 10-12*BTDC

To check that the timing goes to 24-28* at 2800 RPM you need an "advance timing light", Harbor Freight has a cheapie for $30 or so on sale. A timing tape would work also, but I don't know where you would get one correct for a 3.0L, or if you're good with math, you could figure out how far 24* is around the harmonic balancer (and 28*) and use those marks with a normal timing light,,, somewhere around 1.5" would be my guess.

 

[jmarines]

You're not going into base timing mode correctly if it's killing the engine.

1- start and warm engine
2- jumper the 2 white leads on the distributor with a home made jumper wire
3- disconnect and jumper the shift interrupt switch wires going back to the distributor, harness side (the engine will bog as it drops into base timing mode)
4- time the engine to spec (2* BTDC, 1* BTDC or 1* ATDC, whichever) and re-tighten distributor lock bolt
5- remove jumpers (switch then dist) and check that timing goes to 10-12*BTDC

To check that the timing goes to 24-28* at 2800 RPM you need an "advance timing light", Harbor Freight has a cheapie for $30 or so on sale. A timing tape would work also, but I don't know where you would get one correct for a 3.0L, or if you're good with math, you could figure out how far 24* is around the harmonic balancer (and 28*) and use those marks with a normal timing light,,, somewhere around 1.5" would be my guess.

I'll go ahead and give it another try this afternoon. I'm pretty confident that I was getting into base mode but not 100 % positive. When I originally tried the motor would die out . As soon as I timed it to 10 * btdc and repeated the steps to put it into base timing mode it went right in without any issues. I'll go ahead and repeat the steps and set the base timing then throttle up to 2800 rpms and verify that the timing did advanced. One question though. .. well actually 2 questions.. shouldn't it go into a gear and then throttle up .. I always thought if you just free reved it that the timing wouldn't go up because there isn't a load on the motor. Also what would cause the motor to not advance timing while throttling up ( if base timing is spot on) the timing light you mentioned is the exact one I have. I didn't know what the advanced knob was for but looks like I do now...lol
Thanks for all the help !

 

[Bondo]

well actually 2 questions.. shouldn't it go into a gear and then throttle up .. I always thought if you just free reved it that the timing wouldn't go up because there isn't a load on the motor. Also what would cause the motor to not advance timing while throttling up ( if base timing is spot on) the timing light you mentioned is the exact one I have.

Ayuh,... The timin' follows the rpms, load or not,....

No advance in yer case would be a failed or failin' electronic component,....

In an older points distributor, it'd be rusted fly-weights,....

 

[jmarines]

One question I forgot to ask.. does rpms matter when your setting base timing? The reason why I'm asking is because my rpms sit around 1k. When I adjust the idle screw it doesn't go any lower but if I press on the linkage it does lower. I didn't think much of it since there is only a 300 rpm difference from where it should be . I'm thinking maybe the throttle cable may be too tight but I'm was so involved in setting the timing I really didn't worry about it

 

[Bondo]

One question I forgot to ask.. does rpms matter when your setting base timing? The reason why I'm asking is because my rpms sit around 1k. When I adjust the idle screw it doesn't go any lower but if I press on the linkage it does lower. I didn't think much of it since there is only a 300 rpm difference from where it should be . I'm thinking maybe the throttle cable may be too tight but I'm was so involved in setting the timing I really didn't worry about it

Ayuh,... Remove the cable from the carb, length it a turn or 2, 'n try it,...

The cable should be pushin' against the idle screw, slightly,....

Idle should be 650/ 750 rpms, in gear, in the water,....

'n, Yes, raisin' the idle, advances the timin',....

 

[jmarines]

Just wanted to say thanks for everyone's advice. I guess i needed a fresh outlook on it because now it's timed perfect. It was off pretty bad from what I could tell but I'll definitely know for sure when I take it out. .. hopefully that will be tomorrow afternoon weather permitting. I also went ahead and ordered a 4 blade 18 *pitch prop. Wanted to have it by memorial day for the just in case we head to the lake for the weekend. I was going to go ahead a order a 3 blade prop for cruising /top speed but I wanted to do a little more research on which one would be best for my setup. Again. . Thanks

 

[fishrdan]

I also went ahead and ordered a 4 blade 18 *pitch prop.

Watch the WOT RPM's with that 18P prop. I mentioned it worked well for my (heavy fishing) boat, but it may be too little pitch for your faster hull. If prop puts the RPMs in the 4600-4800 RPM range all is good, but you don't want to overshoot into the 5,000 RPM range. If you do, just be sure to keep the RPM's under 4800.

 

[jmarines]

Watch the WOT RPM's with that 18P prop. I mentioned it worked well for my (heavy fishing) boat, but it may be too little pitch for your faster hull. If prop puts the RPMs in the 4600-4800 RPM range all is good, but you don't want to overshoot into the 5,000 RPM range. If you do, just be sure to keep the RPM's under 4800.

I'll definitely keep a eye on the rpms. I spoke to the iboats.com sales department for quite a bit... explaining what I wanted and how many passengers in would be carrying . This was there recommendation for prop size. As soon as I test this new one out (and happy with it) I'll go ahead and order one for cruising and top end speed. And if for some reason I'm not happy then I'll caulk it up to inexperience and have a spare one if I ever need one. They recommended going to a 20* 3 blade prop for top speed but currently I'm unsure.

 

[jmarines]

Just wanted to update this just in case anyone else had a similar issue like mine. The cause of the rpm issue was the fuel filter. Would be something simple. I replaced it a few weeks ago but just now had the time to take it out due to all the rain. Boy what a difference! I had to remove the 4 blade prop due to damage from the boat ramp.. son didn't put it up enough while trolling to the boat launch to load up... anyways I reinstalled the 3 blade 19*prop and boy was it fun. Took it to 4600 rpms and a top speed of 36mph with about 1500 pounds of gear and passagers. Now I need to purchase a prop for top speed...