72 Thunderbird Formula w/twin 165hp Mercs

[archbuilder]

That sucks. I remember when I first got Miss Morgan in the water, I had to fight with the Mercury. Every time I thought I had the issue figured out anther one popped up! Finally after charging, ignition, and fuel pump parts I got everything fixed. I can only imagine what you are going thru with two engines! I'm with alldodge wondering what the compression and plugs look like.

 

[hogbare35]

Mark make sure throttle is operating fully , check for vaccum leaks not much problem at WOT , air adjustment on carb . My 2 pennies . good luck

 

[Mark72233]

Well I checked compression on the port engine and they are all good running 140-155psi. Checked the plugs and they look good, checked the timing again and adjusted the carb screws and still best I could get was 3300rpms. Also checked throttle linkage and that's good.

 

[alldodge]

Great at least the engine is in good shape. So its either fuel, spark or distributor advance. Don't see it being the advance but also don't want to rule anything out.

 

[Mark72233]

AllDodge thanks for jumping in here. I checked the timing with a timing gun and took it out twice the same thing about 3100-3300 rpms and on both days I even did what my dad used to do which is push the throttles to the wall and while someone else was driving I loosened the distributor and twisted it looking for max rpms and again best I could get was 3100-3300. I cant see fuel being the issue. If it wasn't getting enough fuel once the bowl started running dry it would start stalling and than quit, right?

 

[hogbare35]

Mark are you sure that outdrive is the same gear ratio as the other one . Prop in good shape . You might try swapping coils between the 2 engines . I got my brain buzzing , if I come up with something will let you know .

 

[72fj40]

Hi Mark, I've been watching you're build from a far. Great job, awesome boat.

I have some questions, ideas and checks that maybe helpful. Some maybe redundant, as I don't recall all that has been done. 1st would be questions on you're equipment. Are you getting you're tach readings from the boat tach? Is it set on 6cyldr? I know the tach in our boat is not accurate. Is you're timing light a basic strobe light only? Better lights contain a tach and advance/retard buttons and are generally a little more helpful with the issues like you are having. Now for the motor. Look at the easy checks 1st. If it has points, is they dwell set within spec? When you rev the motor with the timing light hooked up, do you see the timing advance. If not, this could be you're issue. If it does then i'd check total advance while on smooth water. You would have to do research on what rpm total advance is achived and what that number is, for you're 6cydlr. This is where the better timing light is handy. Fortunately you have another engine which seems to run correctly, and creates a base line, so you can double check you're findings with it. It also allows you to switch carbs and distributors to narrow down if it's fuel or ignition. Also make sure you're exhaust and spark arrestor are not causing any restrictions.

If the dist. Is advancing, I'd make sure both engines are set alike. I know nothing about mercruiser dists. On our mallory distributor the timing advance can be adjusted. We have to remove the top plate that the points mount to, to get down to where the adjustments are made. Hope this helps and good luck. Ken

 

[Mark72233]

hogbare, yep both outdrives are 165s. I had both engines running good and at 4100rpms synced up perfect before the right engine had to be pulled and rebuilt. That's the weird part I haven't done anything to the left engine other than pulled the mechanical fuel pump and installed electric. Prop seems good, I can push throttles to the wall from dead stop and both engines jump up there and she pulls a great hole shot and steady right on up to 3300 rpms which is where the left engine levels at and the right engine will keep climbing up to 3900rpms at which time both engines run smooth and steady just the rpm difference. Doesn't seem to have any prop slip and if it did I should get high rpms not low. Both coils are brand new also but I guess I can try swapping them out that's easy enough. For the heck of it today I am putting the mechanical back on the left engine and disconnecting the electric. I will try that after I get off this afternoon.

 

[Mark72233]

72fj40, yes on the tachs they are the boat tachs and have been set for the 6 cylinders and again I ran the boat on several trips and put about 20 hours on the engines before the right one had the issues and had to be pulled and rebuilt. Also going by speed of boat. Boat would run at 41mph Wide open throttles with engines running at 4100 rpms so it is easy to remember because for the most part from about 2600rpm and up the speed of the boat would almost perfectly match the rpms of the engines. If both engines were running at 3800rpms boat would be doing about 38mph and so on. Now the boat will only max at 35 mph with the left engine at 3300rpms and the right at 3900rpms.

Yes the timing light is the old style strobe light but it does have a knob on the back for advancing and retarding I have never messed with that before. Simple and quick to try that first.

Replaced the points with a Pertronix ignitor and coil which so far has worked out well. I will check to see if its advancing. The distributors I have are the simple old school styles with the advancing weights and everything was cleaned and lubricated when I built the engines but salt and rust could have gotten in there so I will check on that today also. Thanks Ken

 

[hogbare35]

Mark I talked to my master mechanic , he think you are suffering from lack of fuel . When running ,hit it with a shot of starting fluid ti see it will open on up . might try swapping the carbs between the engines . He is real good at this stuff and thinks its fuel problem . Good luck .

 

[72fj40]

Mark, find out what total advance for the 6clydr is. Run the boat up to that rpm with the light connected, then adjust the dial on the light to bring timing the mark on the crank down to zero on the timing cover scale. Now, read the number on the timing light dial, that wold be your total advance.

Another question, upon assembly did your crank timing gear have multiple keyways on it? If so, was it oriented on the correct one. Also, again I'm not familiar with chev straight 6's, but on chev V8's when timing gear marks are line up together, tcam gear dot down and crank gear mark up, places the engine at top dead center on the exhaust stroke. A lot folks stab the dist in, thinking it's at TDC on comp stroke, but in fact it's installed 180 out.

 

[alldodge]

I cant see fuel being the issue. If it wasn't getting enough fuel once the bowl started running dry it would start stalling and than quit, right?

It might still be fuel, part of me says no but the other side says maybe. Since this is a two engine boat the one more doesn't have enough power and slows the other down. If it was a single engine their would be a chance for the motor to lean out enough for a backfire. I like the idea of try more fuel but would suggest staying away from starting fluid.


Put some in a squirt bottle or oil can and at max rpm give it a bit more

Don't leave the gas in plastic long

 

[Mark72233]

Well its been almost a month since I have posted which I think during the last 2 years is a record .

Need to try and remember where I left off and what's happened since my last post. I messed with the timing and carb adjustments and never could get both engines to run up to full RPMs it just happened that one day both engines ran up to 4000 rpms and I haven't had an issues with the rpms since.

Anyway since that time I have taken the boat out several times fishing and family trips with out issue until last Saturday which was July 23rd at the end of a day of pulling "Big Bubba" pictured below I noticed the right engine running at 200 plus degrees and after slowing down and taking the load off of it the engine still wouldn't cool off so I shut it down and limped back to the boat ramp. When I got home I ran it on the hose and it ran fine at 180-190 running anywhere from idle to 3000rpms. I took it to the closest ramp and put it in and sure enough in the water with or without a load it would run up to 200*. I checked all the hoses and even though I know it was a brand new impeller and housing I figured that was where my issue was so I dropped the foot and sure enough the impeller was missing one blade and two blades half the blades was gone and the rest was pretty beat up which makes me wonder if it was a new impeller after all or some old dry rotted thing. The housing and everything else looked perfect. I had an extra impeller so switched it out and put it back together and sure enough cranked up engine which ran at 180*, awesome so I let it run on the hose for about 15 minutes varying the speeds for idle to 3000 rpms and still ran at no more than 180* so I dropped the speed down to 1500rpms and began getting the Yukon ready to pull the boat down to the closest ramp for a quick test run before it got dark. Well Murphy was with me and as I left the engine running on the hose I moved my Yukon unknowingly the hose was laid over the trailer hitch and was stuck on it by the ball so as I drove the Yukon onto the yard around my wife's car which had me blocked in I also pulled the hose off the engine that was running at again about 1500rpms. in all this moving cars around I didn't notice the hose was pulled and than as I was backing the Yukon back into the driveway on the other side of my wife's car which is now behind me and to the right side of the Yukon in my blind spot because I am looking out the drivers side window at the boat and trailer I really didn't notice how close I was to her car and yes I backed into the passenger side front door luckily only dented it in a small spot without scratching or creasing the paint and by the next day the heat of the day popped out the dent. Anyway now I am flustered and walk right past the boat running at 1500 rpms DRY and go into the house to inform the wife I have dented her car which she cares less about and states who cares its a lease and we paid extra in case of damages. :grumpy::facepalm: That's when I finally start tuning into the strange noise the engine is now making and realize the hose is stretched out into the yard and all becomes clear but before I could jump up on the boat and kill the engine the damage was done. Thankfully the engine itself never got super heated but I knew the impeller had to be melted after running at least 5 minutes at 1500rpms with no water. So dropped the foot and sure enough impeller showed significant damage to the ends of the blades and the housing was a mess. Lucky for me I had an extra housing and West Marine was open and only charged $15 for a new impeller so put it all back together and put the foot back on only to run the engine again but now its running at 200* oh the joys. More to follow. Below is a picture of "Big Bubba" in action.

 

[Mark72233]

Ok so boat is now running at 200* on the hose and I am at a loss for why so after a day or 2 of rest I pulled the foot back off and start looking with a flashlight at everything at which time I noticed when I installed the foot the last time I must have hooked the lower shaft oil seal that sits at the bottom of the upper housing, man I love working on boats. Luckily I had an extra seal so I replaced that seal and returned to my search for why was the engine running hot. Since I had the lower section off I hooked up a female hose end in side the boat on the main water hose right before it goes into the thermostat housing and ran water the opposite direction or back flushed the outdrive at which time a melted plastic material came out which was debris from the melted impeller that must have gotten hung up in the upper housing somewhere. Anyway rebuilt everything and put it back together and engine is running like it should and have taken it out twice since at it never runs over 190 even when pulling "Big Bubba".

 

[alldodge]

You have sure had a time, all that time and only an impeller and housing. Sure hope we hear no more troubles and all good times

 

[nurseman]

Holy cow Mark! Do you ever feel like you are the star of some twisted comedy show? I would have laughed at the absurdity of that whole event if I hadn't been cringing while reading! Hope you have everything ironed out and can get on with enjoying your boat.

 

[sphelps]

Someone should really do something about that Murphy guy !!

 

[thomas15]

Hopefully Mark you have nothing but smooth sailing from here on in. After reading your account of the last month I no longer feel sorry for myself. First week of April I decided to replace the impeller in my outboard. One thing after another but lets just say that up until last weekend I had the boat on the water for a total of 2 hours this whole summer. Lots of time and money fixing stupid stuff due to mistakes I made saving money. Ran fairly well last weekend. Tonight it ran great on the muffs. I have learned more about 2 stroke outboards in the last 4 months let me tell you.

I hope you are able to get in some good quality stress-free time on the water now. You deserve it my brother.

 

[kcassells]

Holy WOW OH Wow Mark....So many things have flipped you upside down, Beat you like an old rug, rolled you up and the Best of it all..
You are My Hero again as expected! You really keep at it and churn thru the issues. You are a great inspiration to all of us!
On a lighter note I still see now why Pop was flippin the Bird!
Thank you!
KC

 

[archbuilder]

Wow Mark, you need to run Murphy off! But look at it this way, you are pretty handy fixing everything on the boat now