power tuning 140 hp mercruiser

[djvan]

Has anybody ever heard of power tuning? An older circle track mechanic has offered to help me with my missing distributor advance springs, and says to power tune it to run the best it can. Here is the method (to the best my memory can offer). <br /><br />1. Install new advance springs (NLA so will have to play with some different ones).<br /><br />2. Once total advance is achieved with the correct tension spring, mark the total advance required on the balancer. Then raise rpm's up to the point that total advance is achieved. <br /><br />3. Turn distributor so that the mark lines up.<br /><br />4. Set idle and call it a day.<br /><br />Does this sound reasonable? This guy has been around the block once or twice and is a very reputable mechanic. Just thought I would run it by you guys before trying this method, as there are a lot of very Knowledgable people out there that may have experince/advice in this matter.<br /><br /> Thanks,<br /><br />DouV>

 

[Silvertip]

Re: power tuning 140 hp mercruiser

If you got those directions from a circle track guy he was running in the wrong direction. Messing with the springs and weights affects the advance curve -- in other words, how much timing increases incrementally as engine speed increases. Yes there is an optimum combination for any engine. Turning the distributor has nothing to do with the curve. It merely sets static timing. It's the part about advancing the distributor to the maximum advance mark that doesn't make sense. You'd never get the engine started. Static + Mechanical = total advance. Unless you have a distributor machine, you cannot possibly make these changes using the seat of your pants as a gauge. Too much advance and that you will be looking for a dust pan and broom to sweep up parts.

 

[Bondo]

Re: power tuning 140 hp mercruiser

I Agree with Upinsmoke,.........<br /><br />Your Bud's procudure will No Doubt Work,......After the Dist. has been "Set Up" on a Dist. Machine......<br /><br />There's Nothing Wrong with the Procudure,......Except that Step #1,...Can Not be done "Seat Of The Pants" style.......<br />And,..... By the time you Find a Shop with a Distributor Machine,+ You have Them set up the Dist.,............................. <br /> <br />I would think that finding a Replacement Dist. would be Much Easier,...... Simpler,...... And, Safer,.... <br />For the Rest of the motor anyways.....<br /><br />I've seen them go on ebay for Next to Nothing.........<br /><br />Now,...... Might be the Perfect Time to Upgrade to a Electronic Dist............ <br />I Believe that a Later Model T-Bolt IV Dist. will Drop Right In........

 

[djvan]

Re: power tuning 140 hp mercruiser

I live in a rural area and have asked around about a distributor machine. None available. I'd rather steer clear of e bay since buying used I could be getting a distributor with the wrong springs in it or somebody elses junk. I already can do that myself. I do have the timing curve for this engine with this distributor. I realize it's a seat of my pants approach, but I think I don't have a whole lot more options. I just can't believe that somebody doesn't have a cross reference number out there for the correct springs. There must be millions of this set up out there and still being used.<br /><br />If I raise the rpms until total advance is achieved then align the marks earlier talked about, back the idle down, I don't see how the engine wouldn't turn over. I am not setting the total advance at an idle, therefore the advance should lessen when the rpms come down. <br /><br />Thanks for the input.<br /><br />By the way the circle track friend does very well locally so I tend to think he's not running in the "wrong direction".<br /><br />Thanks<br /><br />DougV>

 

[tommays]

Re: power tuning 140 hp mercruiser

The 4 cylinders are real fussy about self-destructing from timeing issues which will really be no fun<br /><br /><br />tommays

 

[Tail_Gunner]

Re: power tuning 140 hp mercruiser

I believe he is refering to the old days of point's and vacum lines, back in the day one could find a sweet spot by advancing the timing on the engine under a heavy load (powerbraking aka max tourq @ max rpm). But with elelctronic ignition its impossible.<br /><br />Now there's a defintion of power tuning dont know if this what you are refering to.

 

[djvan]

Re: power tuning 140 hp mercruiser

Could be, it's what my friend called that procedure. No electronic ignition in my boat.<br /><br />DougV>

 

[fireship1]

Re: power tuning 140 hp mercruiser

If you overadvance the timing and run it for a while like that you will do damage. I have brought many marine parts on e bay with no problems. Just look at the sellers feedback. Lots of good feedback and no negs and you are good to go. If you just don't want to go that route look at some of the marine parts websites. Mercstuff, ebasic power, Doug Russell. Maybe you will find what you need. It was a common as 'ell distributor. Just don't take chances doing it in the blind. Your boating season isn't worth it.

 

[paulrfrancisco]

Re: power tuning 140 hp mercruiser

I'd go with a replacment distributor, unless you know you have the exact spring.... The over all time you put into doing all this is surly greater than replacing the distributor.

 

[djvan]

Re: power tuning 140 hp mercruiser

In my case time is not money, especially since it is winter and I do enjoy the satisfaction of doing things for myself.<br /><br />Am I wrong in thinking that I would not be over advancing the overall timing because that is limited with the weights inside the distributor.<br /><br />Currently I have no springs and it runs OK. But I am sure with springs I could advance the timing more. The problem right now is:<br /> to achieve total advance and time it correctly, the starter will not turn it over. <br /><br />I want to do something and I have a little time to get this right before the weather breaks.<br /><br />Thanks,<br /><br />Keep the replys coming!<br /><br />DougV>

 

[Tail_Gunner]

Re: power tuning 140 hp mercruiser

There is not danger in the above method i have described. However you cannot do this with electronic ignition, donot even try. If you truly have vacum advance and points in you motor the only thing you will do by following the above descriotion is find the true sweet spot in the motor.<br /><br /> When advancing the timing under a heavy load in that type of engine you will find it will run stronger and there will not be knocks present, if indeed it does knock stop immediatley, you are doing the exact opposite of the desired function. Taking into consideration you must be under a heavy engine load you are also probably gonna be at wot, and that could be dangerous and i doubt youd gain much rpm, tourqe yes but the returns would be minimal. All you are realy doing is finding is timing the firing advance a few degree's just balancing any slop in a old motor wich sometimes can be signicant.<br /><br /> Even after finding the "sweet spot" it will not idle right and you have to probaly up the idle and trim the low speed jet.( trim = adjust)

 

[djvan]

Re: power tuning 140 hp mercruiser

That's right no electronic. Points, condensor, not even vacuum advance. I don't necessarily want to achieve near danger advance, just more than I have now. I don't think I will "push the envelope" with the advance if and when I get some suitable springs. Still looking for a distributor shop that can spin one for me.<br /><br />DougV>

 

[Silvertip]

Re: power tuning 140 hp mercruiser

It doesn't have to be a distributor shop. Any automotive "speed shop" can do that for you. But you'll need to tell them what you are after. Have them do a base-line spin with the current setup. Then play with parts. Otherwise its a crap-shoot. The combination of springs, weights, and bushings determines what the curve looks like, total advance and at what rpm max advance occurs. They can probably give you suggestions. You might even have them spin two or three combinations. Mark those parts and then try them in the engine. Use the one that seat of the pants tells you works best.

 

[Bt Doctur]

Re: power tuning 140 hp mercruiser

If you want a "Go Fast" motor ,you need cubic inches and compression.Using a weighted dist. to tune an advance curve needs the dist. machine,base line ,and optimum advance for the particular engine application.changing springs or drilling the counterweights or the stops is whats done.Guess work leads to detonation and internal damage.

 

[Bondo]

Re: power tuning 140 hp mercruiser

Doug,....<br /><br />Post an email addy,.............<br /><br />I'd rather just Send you a used Dist. for your motor,.................<br />Than sit here,+ Watch you Smoke your motor,.... Playing with it...........<br />

Currently I have no springs and it runs OK. But I am sure with springs I could advance the timing more. The problem right now is:<br />to achieve total advance and time it correctly, the starter will not turn it over. <br />

It Can't be Running That Good,...... It's Advanced ALL the Time,......<br />That's WHY it Won't turn over properly........<br /><br />And,... Running like this,.........<br />It's Detonating From Idle to about 3500rpms......<br />1 trip to the pond,+ There'll be Big Holes in the Tops of your Pistons...........<br /><br />Like I said,......... Give me a way to contact you,+ I'll go have a "Look" out in my Old Wellhouse.................

 

[djvan]

Re: power tuning 140 hp mercruiser

Bondo,<br /><br />Has been running like this for 4 years. Didn't know the springs were missing until last summer. I am running the timing retarted so it will start. That's why I'd like to get this straightened out so I will see more power.<br /><br /> If you or anyone has some springs I am willing to buy them, I just can't seem to find them anywhere. It has a prestolite distributor, I can get the numbers off it if need be.<br /><br />BT doctor,<br /><br /> I am not looking for a huge boost in performance, I am perfectly happy with my 4 banger. It does what I want and gets decent gas mileage.<br /><br />DougV>

 

[Bondo]

Re: power tuning 140 hp mercruiser

So give me an email addy,............<br /><br />'ell,....... I send ya a Complete Mercruiser 140hp 3.0l 181cid distributor............<br />I'm 99% Certain that there's 1 out in the wellhouse......There Might even be an Electronic Dist. out there,.......<br />I'll go Have a Look......<br /><br />In turn,....After you Get It,....<br />Send a small contribution to the Shop Beer Fund(to cover the Shipping),.......<br /><br />AND,.........<br />Promise to Pass On this Favor to Somebody Else....................

 

[djvan]

Re: power tuning 140 hp mercruiser

Bondo,<br /><br />XXXXXXXXXXXXXXXXXXX<br /><br />Please respond when you get the address, so I can edit the post and take it off.<br /><br />DougV>

 

[Bondo]

Re: power tuning 140 hp mercruiser

Ayuh,........

 

[djvan]

Re: power tuning 140 hp mercruiser

Thanks<br /><br />DougV>