What next? STILL not running right?

Question Steve.    What size fuel line between tank and pump?

3/8" = nevermind.
1/4" = replace with 3/8"


AT

DrCC wrote: Question Steve.    What size fuel line between tank and pump? 3/8" = nevermind. 1/4" = replace with 3/8" AT

Al, I have a 3/8" rubber hose from the tank to a shutoff valve that is located about 2 feet before the mechanical feul pump. I have 5/16" steel line from valve to the pump and from the pump to the carb. It had 5/16" steel line all the way to the tank until this summer.

Tony,

The boat will start with a bump of the key after its been warmed up. You can rev and hold it at 3+Gs in Neutral. When crack the throttle the vacuum drops quickly to 3 or 4" then back up. when you let off the throttle at 3Gs, the vacuum loads to about 25", then back to the 17 or 18".


After 3 carbs and changes of metering rods, jets, and float levels, coupled with using a 5 gal gas can and an electric fuel pump hooked right into the carb, I dont think fuel is the issue anymore.

What do you think of the cold compression ratio ?
btw, where you at in WI?

I would sure think it would run with that compression,does show you could use rings if the compression change that much with "a few squirts of oil" I live in Tomah Wi. and have a place in Eagle River also,where are you?

I took the plugs out yesterday to start looking at cam timing and run a compression test. Check out the wierd colors of them... they are white on one side and brown/tan on the other. Something to do with valve orientation?



Notice #3 is black on the one side... I turned it in this pic...




What gives?

Steve - Have you tried using the old intake manifold elbow? Maybe it's possible your new elbow is causing the fuel to drop out of suspension. I have heard of this problem with highly polished intake ports - some turbulence is needed to keep the fuel/air mixture 'stirred up'.
Just a WAG.

Good luck figuring this out.

79nautique wrote: looks like a ring or two is leaky and oil fouled a plug or two.

Chris,
I saw the plugs first hand at GL. The picture quality isn't the best and a couple may look oil fouled but that's not the case. They are all quite clean on one side and the other side are brown. A couple are a darker brown but still only on one side. Strange!!!

Pete I don't think we have ever met, at least I don't recall meeting. Do you get to Eagle River often or stay in Three Lakes?

92ccc wrote: Pete I don't think we have ever met, at least I don't recall meeting. Do you get to Eagle River often or stay in Three Lakes?

Tony,
Usually the only thing that gets me up there is if I need to go to Nelsons when Three Lakes Hardware doesn't have something or Napa!

I have no doubt it is over propped. Last year the boat was running like cr@p most of the season. The boat has never ran over 3300 or so since Ive had it. It was propped with the 12x12 when I got it.... never thought that much about it.

We ran the 12x13 for almost two years with no big problems. It just wouldnt spin over 3Gs or so. That was never really an issue, as we only cruised at 2800 or so. Even then if I forced the throttle it just would not respond... but didnt actually fall down.

I do have a 12x10 on the shelf I am going to try, as well as a fresh set of Autolite 45 sparkers, before the next outing.

Question.... why would a rebuilt/good head, now w/aprox 8.5:1 comp, not be able to respond at least as well as the old junk head with 7:1 comp?

again, if over propped wouldnt the engine just not have enough ponies to pull the upper R's" ... Why would that make it fall on its face if pushing the throttle much past half way?

Munday wrote: Steve, read this whole post last night and feel yur pain.The only thing I could come up with,is throttle linkage opening past wot?If the cam was retarded it would run and idle fine but lack any high rpm power. Looking forward to the real answer hope you find one! Bob

thanks for the consolation .. what really bugs me is this should be "Basic Engine 101" and here is this dang ford 6 banger ...kicking my butt!

...and yep, the throttle does open all the way. hoping to check cam timing some night this week..
.

Just throwing this out there, since it hasn't been mentioned at all yet:

Is there anything on your boat at all that might cause excessive exhaust back pressure?

I've seen cars with plugged up catalytic converters exhibit symptoms very similar to what your boat seems to be showing. It will start fine, rev with no load fine, but just not accelerate.

Doc, ever heard of the scientific method?

Steve changed 2 things at one time (prop and engine top end). Result = bad performance. The first thing I would do would be to go back to the old wheel and be sure that the problem is engine related. If that 12x13 prop is an unknown (ie, its performance never characterized), then how do we know it hasnt been repitched to 15" or something crazy? I sure as hell wouldnt be dinking with the cam timing until the easiest and most obvious stuff was checked first.

My apologies for introducing a bit of logic to the discussion. Perhaps if your troubleshooting were better, he wouldnt be here asking the rest of us for advice?

Regardless of troubleshooting, Bruce's datapoint indicates that both the 12x13 and 12x12 props are way too large for a 170ci 100hp motor. Makes perfect sense to me.

Billy and Tim, I DO appreciate ALL of your input into this PITA problem... Great thing about this site... most everyone has "been there" in some type of situation.

Tim, The prop I changed last year was from one 12x13 to another 12x13(damn river logs), And the second prop did have different characteristics. The engine started "acting up" earlier in the season last year with the 13 I had been running for the whole prior season. Like i said The 12x10 will be on for the next test.

wonder if two cylinders wires are crossed and not matched to the cam's order?

Jacking with a prop at the moment seems like a waiste of time to me. better head worse performance using the same prop tells me that it's not the prop that is the only issue.