Needing a little help here......

[Maclin]

Re: Needing a little help here......

I was assuming you have a ThunderBoltxx system, sorry to mislead if you do not.

 

[mylesm260]

Re: Needing a little help here......

Yup, I agree with them.

Too much initial timing + Ignition curve = too much timing in higher RPMS

Remember, as your RPMS go up, your plugs are firing "earlier" (more advance)

Seeing as how you're mechanic claims your making 85 more HP with just a .020 over bore and maybe a cam, I would wager your compression ratio is higher as well.

Just out of curiosity, what are you running for fuel? (87 or 94 octane)

Higher compression ratio = higher chance of detonation = higher octane needs

Do as everybody else suggested, retard your timing by 8 degrees or so, and take it for another rip. You will loose a little bit of bottom end, but I would wager your top end would come back, because you will no longer be detonating at higher RPMS.

Sounds to me like you need either less timing, or more octane. Another quick and easy way to find out, go to a roofing supply store and buy some Toluene and add it to your tank. Do some research first, but it's a surefire way to get rid of detonation. I used to run this stuff in my turbocharged drag cars. Don't go to concentrated, or you risk damaging your pump, lines, or seals. 20% or so is okay, and would give you a significant octane boost.

Here's a little bit of info from wikipedia

http://en.wikipedia.org/wiki/Toluene

Toluene can be used as an octane booster in gasoline fuels used in internal combustion engines. Toluene at 86% by volume fueled all the turbo Formula 1 teams in the 1980s, first pioneered by the Honda team. The remaining 14% was a "filler" of n-heptane, to reduce the octane to meet Formula 1 fuel restrictions. Toluene at 100% can be used as a fuel for both two-stroke and four-stroke engines; however, due to the density of the fuel and other factors, the fuel does not vaporize easily unless preheated to 70 degrees celsius (Honda accomplished this in their Formula 1 cars by routing the fuel lines through the muffler system to heat the fuel). Toluene also poses similar problems as alcohol fuels, as it eats through standard rubber fuel lines and has no lubricating properties as standard gasoline does, which can break down fuel pumps and cause upper cylinder bore wear.

 

[krisnowicki]

Re: Needing a little help here......

I would set it at 8 deg btdc and I bet it runs very well

 

[Bigdave196]

Re: Needing a little help here......

15 btdc is a little far have to tried moving to 10 or so ....

I will give it a try.

 

[Bigdave196]

Re: Needing a little help here......

Yup, I agree with them.

Too much initial timing + Ignition curve = too much timing in higher RPMS

Remember, as your RPMS go up, your plugs are firing "earlier" (more advance)

Seeing as how you're mechanic claims your making 85 more HP with just a .020 over bore and maybe a cam, I would wager your compression ratio is higher as well.

Just out of curiosity, what are you running for fuel? (87 or 94 octane)

Higher compression ratio = higher chance of detonation = higher octane needs

Do as everybody else suggested, retard your timing by 8 degrees or so, and take it for another rip. You will loose a little bit of bottom end, but I would wager your top end would come back, because you will no longer be detonating at higher RPMS.

Sounds to me like you need either less timing, or more octane. Another quick and easy way to find out, go to a roofing supply store and buy some Toluene and add it to your tank. Do some research first, but it's a surefire way to get rid of detonation. I used to run this stuff in my turbocharged drag cars. Don't go to concentrated, or you risk damaging your pump, lines, or seals. 20% or so is okay, and would give you a significant octane boost.

Here's a little bit of info from wikipedia

http://en.wikipedia.org/wiki/Toluene

Toluene can be used as an octane booster in gasoline fuels used in internal combustion engines. Toluene at 86% by volume fueled all the turbo Formula 1 teams in the 1980s, first pioneered by the Honda team. The remaining 14% was a "filler" of n-heptane, to reduce the octane to meet Formula 1 fuel restrictions. Toluene at 100% can be used as a fuel for both two-stroke and four-stroke engines; however, due to the density of the fuel and other factors, the fuel does not vaporize easily unless preheated to 70 degrees celsius (Honda accomplished this in their Formula 1 cars by routing the fuel lines through the muffler system to heat the fuel). Toluene also poses similar problems as alcohol fuels, as it eats through standard rubber fuel lines and has no lubricating properties as standard gasoline does, which can break down fuel pumps and cause upper cylinder bore wear.

I have always run 91-93 Octane thru the boat. The motor says 87 or higher but we always have ran Premuim grade fuel. It maybe costs $4-$5 more a tank but its cheap insurance in our books. I h ave never heard of Toluene, so my next question is, Is it expensive??

Thank you guys, I will have more results for youy this afternoon.

 

[mylesm260]

Re: Needing a little help here......

It can be pricey, yes, depending on where you're buying it from.

How old is the fuel in your tank?

Also, if detonation is the reason your engine isn't running properly, than you would be best to keep it under 3000 rpms until you figure it out. Prolonged detonation can blow head gaskets, melt pistons, etc.

Modern engine management systems have "knock sensors" that listen for detonation, and if they hear it, they automatically retard the timing.

Figure out the proper procedure to set your timing, and retard it by a couple degrees over stock. Your ignition curve was for your original engine, it's no longer setup for your new engine, to play it safe, I would recommend knocking out a couple degrees over stock.

 

[Bigdave196]

Re: Needing a little help here......

Ok, the plugs are fine. Throttle linkages are adjusted to where at WOT on the carb open all the way to meet the same distance where the carb wont go any further. Timing is at 9 degrees BTC and advances to just about teh 12 O'clock position when the motor is reved up while in netural.
I disconnected the throttle linkages today to see if maybe there was something keeping it from pulling the last 1500-2000rpms and there is not.

The 4 Barrels do open fully and the "upper butterfly's" on the rear of the carb move effortlessly while the "lower butterflies" attached to the carbs linkage open when the throttle reaches a certain point mechanically. You can easily hear the carb sucking in the air at both an idle and under load while moving forward in gear.

The boat still pulls like a bat out of hell from an idle to 3800 rpm and then it just tops out. It would almost be like im trying to turn a 28 pitch prop with a 4cyl motor, LOL!!! No sputters from a lack of fuel going into the float bowls ( i have not tested fuel pressure just yet but I believe it is fine), no backfires thru the carb, no hesitations in performance at any rpms.

The only odd thing I have even noticed is that the left exaust manifold (facing the motor) is noticeably warmer then the right side where it bends 90 degrees from the manifold to go to the exaust pipes (is that the right word?).
Could that have anything to do with it?

 

[Maclin]

Re: Needing a little help here......

The fact that it still runs that hard off the line after pulling 6 degrees out has me now REALLY wanting to know what the total advance is using a dial-back timing gun. I cannot relate the "12 o'clock position" to a degree figure. Seems like pulling 6 degrees out should have made some difference at both ends.

The 4,00rpm ceiling is also a symptom of too much pushrod preload on the lifter. Are you sure the valve lash is set correctly? Did they use Rhoades lifters or similar bleed down lifters? Or non-stock rockers and ratio?

 

[mylesm260]

Re: Needing a little help here......

Yeah,

I'd really start inspecting you're valve-train.....

It sounds like your cam timing may be off as well, if you jump your cam one tooth forward on the chain, you will gain bottom end, and loose top end (hence why everyone uses variable valve timing now)


If you can't find anything wrong with any other system, then you've gota tear down a little and pop off your timing cover, and verify that your cam timing is correct (and verify it's correct as per your new camshaft's manufacturer)

 

[Bigdave196]

Re: Needing a little help here......

Ok I got a little confession here. I dont believe I have correctly set the timing. After doing a little moer research, I have not set the timing correctly and I cant find the purple/white wire. I found a purple one that runs right near the transmission linkage, but no purple/white one anywhere. I set the timing by way of just using a timing light and normal adjusting. I am so sorry if this has caused anyone here that kind of confusion, because it has frusterated me to all hell.
So how do i tell if i have a Thunderbolt IV or V ignition? Is there a picture anywhere to help with this?

 

[Bigdave196]

Re: Needing a little help here......

Ok, I have a Thunderbolt 4 Ignition. So there isn't a Purple/White wire. Nor Do I have a "Knock" sensor. Im sorry if I caused any confusion, I was misled. I am still open to ideas or suggestions. A friend of mine said something about a Rev Limiter. Any ideas on what way I could go without chasing a ghost or tearing the valve covers and cheching valve lash?

 

[mylesm260]

Re: Needing a little help here......

don't be sorry, that's what these forums are for.

Again, download the manual, and set the timing for your specific model.

If it still doesn't run right, I bet it's your valve train or cam setup.

 

[Bigdave196]

Re: Needing a little help here......

Ok went out again today and when I was in the water behind the boat I noticed that it is running way rich. You could see the darker exaust come bubbling up thru the water against the hull all around the outdrive. Pulling power to get someone out of the water is almost what you would expect a 4 cyl to do, and not a 5.7.

I did how ever ground the distrubuterthru the bold that goes thru the cap to an unused ground but that made no difference.

I am looking at the wiring diagram for the carb'd 5.7 with the thunderbolt iv ignition and it shows a ground wire going to the back of the distributer, but when I l ooked and felt all around I saw no such location to attach or screw a ground to it.
Any Ideas?

 

[dan t.]

Re: Needing a little help here......

T-bolt 4 times just like mechanical advance, set the idle at 600 ar less and set to 8 initial, advance rate and amount is controled by the module, post the numbers off the module

 

[Bigdave196]

Re: Needing a little help here......

Just pulled the plugs and took a nother look around the carb as I was coming back into the harbor and here is what i found.

The carb has fuel in odd places. In the first pic of the carb the fuel was in the little square area at the 3 & 9 o clock sides of the carb. and in the areas just outside the throats of the 4bbls on the back of the carb. The screwdriver points to the areas where fuel was. I used a can of compressed air and as i sprayed it into these areas the motor bogged and fuel splashed around.

Here are the plugs, all 8 are black as hell and darker on one side.
pics are in the next posting. Mind you these plugs have 8-20 hours on them and mostly idleing in netural and not under load.

 

[dan t.]

Re: Needing a little help here......

looks like the fuel level is too high, float level? needle valve not seating? leaking float? check it out and let us know

 

[Bigdave196]

Re: Needing a little help here......

looks like the fuel level is too high, float level? needle valve not seating? leaking float? check it out and let us know

Where the heck is the float level screw?

 

[dan t.]

Re: Needing a little help here......

looks like an edelbrock or an AFB, no external float adjustment,that is holleys only. you have to remove the top, invert it and measure from the gasket to the float,sorry dont have the specs handy

 

[mylesm260]

Re: Needing a little help here......

Hey dave, maybe you should start a new thread, now that you've narrowed down your problem.

Put something like: *name of your carb here* running rich

then in your post, explain your top end problem as well as the fact that you've pulled the plugs and they show a rich condition. That way it will get the attention of the carb experts who can reply with their suggestions.

 

[Bigdave196]

Re: Needing a little help here......

Well the problem is solved. My 14 year old carb was the new overall culpret. My floats were set to 1/16" from the top allowing fuel to literally treat my carb like Niagra Falls and with all the lower placed possibilities for fuel to flow out and into the motor I was running extremely rich.

My air valves, and needle jets were also not allowing the proper elements to pass thru them and everything just felt "sticky" when you manually operated the carb off the motor.



An overnight bath in Chem-dip and a rebuild kit from Edelbrock made all the difference. I couldnt believe the crap that was in the bottom of the float bowls either. Its time to add a secondary fuel filter as well.



Thank you all for your help and hopefully I can run into a few of you sometime and thank you in person.