Twin Chrysler inboards will not go over 3300RPM

1978 Marinette has twin 440&#3

1978 Marinette has twin 440's. Engines were probably 1976+. They have 2000 hours but were rebuilt at 1200 hours. I have not been able to get over 3300 RPM and no more than 24 MPH. When the boat was new it would get 4200 RPM and run at 31-33 MPH. Original props are on the boat (19x23's). Using RJ14YC withh 8mm wires. Fuel pumps are original and gas filters have been changed. Hsd the carbs reguilt 2 years ago. Primaries and secondaries all seem to be working fine. I have been fighting this issue for 4 years now and getting very frustrated.

why size boat were you pushing

why size boat were you pushing at 4200rpm?

37' Marinette. All alumin

37' Marinette. All aluminum.

"Do those dists have the advan

"Do those dists have the advance springs in them if so maybe they need lubed and worked loose to work proper again....Wow 33mph youd blow by me@only 15knots...Id hate to fuel those babys.."

"It sounds like an overly-simp

"It sounds like an overly-simplified possibility but.....do you get your fuel from the same marina and, if so, do you know when/if they introduced ethanol?

While it's doubtful that "bad" gas alone that would cause poor enough combustion to starve you of 1,000 rpms, the amount of time you've been fighting this (4-years) coincides with the time when ethanol started being heavily introduced. It's only been within the past couple of years that we've started to get a grip on the havoc that ethanol is wreaking on engines (especially those of us who also play in the 2-stroke powersports world).

Not sure if you have a metal gas tank and/or old copper lines on that boat but, these are things that will be completely demolished by ethanol.....especially if the ethanol was, at some point, mixed with non-ethanol gas without advanced treatment/prep. Ethanol is also proving to go bad much quicker once in the tank.

Again, I'm not suggesting that you're simply running on crappy gas....but where you're still on your original pumps, there may be other orig fuel system components that are worth examining. Since both motors are behaving the exact same way, I'd actually be optimistic about it being a "global" problem (vs. the coincidence that they're both suffering from identical mechanical issues).

Also, if you're still running points, you may want to consider doing a Pertronix electronic conversion. It's cheap and incredibly easy. If you go that route, it can't hurt to check/re-time the motors with the new ignition."

"Don,

I would check and mak

"Don,

I would check and make sure that both motors are set-up to fire correctly.This manual isn't for 440 but rotations an firing orders are same on big block Chrysler twin V8's.

http://www.correctcraftfan.com/Downloads/Chrysler%20Marine%20Engine%20Manual.pdf

make sure that you scroll down and check all rotations including props, i know that sounds stupid, but i've seen it.

Make sure the plug wires match the diagram one-by-one. Then move to your timing.

Those Chrysler ( 440 TNT ) aren't called "TNT" for nothing, they should kick serious ass on the water even in a tugboat they should pull like mad, they've got serious torque when tuned properly.

Your motors should be electronic ignition, if someone, or for some reason you have a points type ignition it's most likely the culprit. A good tuned and worked 440 will chew up ignition points in as little as a week.

If boat has points, find an electronic distributor bolt in like a petronix conversion.

http://www.pertronix.com/

Hope this helps!

Ps: mopars like fresh wires and Champion plugs on a regular basis. the Champion RJ14YC should work well so long as there fresh an gapped right. if all else checks out you may want to get an exra ECU brain box to test things out. ( swap side to side )

http://www.mopar.com/performance/muscle/index.html

C. Orange Electronic Control Unit
For general high-performance use up through 6,000 rpm.
1 P4120505 ECU, Orange Box, Hemi/ Big Block/ Small Block"

"Sorry everyone the boat was t

"Sorry everyone the boat was titled in '82 and put in the water in '83. I was thinking of the 32' Marinette we had. Both are great boats. Economical and fast. The 37' used to run at about 1 mile per gallon. We took a 1000 mile trip up to the north channel 5 years ago and used about 1,000 gallons of gas. This is approx. when we started having the problems and had the engines rebuilt that winter. The boat has not run right since then. We do have electronic ignition but did not consider the Ethanol issue. Thanks fro the great input. As I said the disributors were rebuilt last year and the carbs 2 years ago with no change in performance. WE are running RJ14YC with 8mm wires. I also heard that we may want to go to a better wire. 9mm or 10mm. We also heard to try a smaller prop. This would be expensive and I would assume that you might get more Rpm but at the expense of speed. Next would be fuel filters and after hearing the Ethanol issue we might want to change all fuel system components. Thanks for the great input. Please keep it comming."

"Don - can you rev the engines

"Don - can you rev the engines into the 4's in neutral? Are you having other issues relating to the lack of full-revs (bogging, backfiring, etc.)?

If not, and it's running smoothly up to the 3,300 max, if you haven’t already, I'd really suggest having the timing checked against, and/or reset to, specs that you KNOW are accurate for those motors. It's possible that they haven't been properly timed since the rebuild and what you’re experiencing is advance-related. I'm not sure if a mechanic did the work for you but, these days, mechanics and marinas who’re familiar with the old “automotive” type marine engines are fewer and further between. With the high probability that they don’t have manuals/specs for 30-40 year-old engines, it’s often easier for them to track down the specs for automotive applications……..for example, referencing timing specs from a 440 powered Mopar vehicle from a similar year.

Like my ethanol suggestion, I’m being a bit presumptuous about all of the details. However, these are things that, if you haven’t done yet, should be easy enough to check without continuing to replace/rebuild parts as a process of elimination. Someone like Fast Jeff can probably give you the timing spec for those engines off the top of his head."

"Hi Don,

from what i've

"Hi Don,

from what i've been able to find on Marinette, the only boats that ran 440's came pitched with a 19" x 21", 4 blade prop and a top speed rating of 30 Mph.

That covers years 1954 to 1991 built boats. The engines should be Twin 330HP Chrysler (440CID)

Sounds to me like your boat has steeper props than what the factory recommends.

Too much prop can hurt as much as 2 little.
According to the factory none had (19x23's)



http://www.marinette.com/tech_props.asp

that would expain an rpm drop on the water as well as a drop in top speed.

Hope this gets you closer!"

"Let me answer Bogdenz first.

"Let me answer Bogdenz first. The engines will rev in neutral. We were having issues with one engine backfiring at 3000 RPM but I checked all the wires and plugs and retimed both engines. Everything was fine on the starboard engine. Timing was at 5 degrees which is what the spec in the owners manual call for and all the plugs were tannish in color. On the port engine the number 6 plug was black and the timing was at 2 1/2. I replaced that plug and reset the timing to 5 degrees. Today the boat ran fine at 3000 RPM and 24 MPH. We could not try to go any faster due to the water conditions. As soon as we can we will push it to see what it can do. We do have all the spec sheets for the boat and it calls for 5 degrees before TDC. Good ideas. As for the black plug we will keep an eye on it. Someone suggested pulling the valve cover to make sure one of the springs is not broken. The next step will be to replace the plugs and wires.

Brian, The book from the Marinette manufacturer calls out a 19x23 prop. These are the props from day one. Like I said, we were able to get 4200 RPM and 33 MPH with them up until 4 or 5 years ago. You are not the first person who has said the props are too big but we are going by what the Marinette dealer in _______ Shores Michigan. Maybe I will give them a call and double check their specs and see what they think. Like I said you are not the first so there might be something to this also. The props have been redone a couple of times and maybe something was done incorrectly. YOu are also correct on the engines. They are twin 330s, 440 c.i.

The other thing that looks very interesting is the ethanol issue. Maybe its time to replace the fuel pumps, filters and gas lines. The tanks are metal, I believe stainless steel.

Thanks loads for all the input. Don"

"Don,

I think you might fin

"Don,

I think you might find that those fresh plugs & wires will do the trick.

At Our Marina We run a 45ft military steelcraft with tug props for towing boats, it's got 2 chrysler 413 CID wedge big block motors and it will rev like mad.

That's why i think you're gonna find it's an ignition related issue. The big block chryslers run well,but frequently need ignition system attention.

Keep cracking at it !"

Today we ran 3300RPM and 25MPH

Today we ran 3300RPM and 25MPH and everything was running smooth. Still could not open it up due to water conditions. Next weekend we will put in new wires and plugs and see what happens. Thanks everyone for all your input. I'll keep in touch.
Don

"Are there special spark plug

"Are there special spark plug wire sets for marine engines? Any recommendation on size? 8mm, 9mm or 10mm for the chryslers?"

"Don,

I would not worry so

"Don,

I would not worry so much about size of the wires as i would the type, - IE Marine wires. The ones i got at Napa auto parts were marine specific for my twin LM-318's and came with a solid copper core ( most auto wires are resistor type carbon core )

I would suggest you go to Napa and make sure that they gave you marine wires,not car wires.

Mercruisers come with carbon though, sooo.. i would make sure you get whatever Napa's marine Catalog calls for."

I have seen several reverse ro

I have seen several reverse rotation 440s that had the timing at 5 after rather than before TDC? Clean the timing marks and make sure the scale isn't for a normal rotation engine. Use an adjustable timing light on both engines and make sure you are getting full advance (about 25-30 degrees) at 3000 rpm.

Dan

"Dan,

Excellent point ! tim

"Dan,

Excellent point ! timing maybe was set on the wrong side of tdc, worth a look."

"Not sure of the 440s, but the

"Not sure of the 440s, but the small blocks (318/ 360) use an arrow timing mark at the flywheel end that's rather clever. The point of the arrow is at TDC. One side of the arrow is 5 degrees for the regular rotation motors, where the other side of the arrow is for the reverse rotation motors.

Jeff (32 Marinette)

PS: Every once and a while I check how the motors are running by this little trick: Set the boat at a comfortable cruising speed, then open one throttle all the way. Note the rpm achieved, then return to the cruising rpm. Next, open the other throttle and see what rpm IT achieves. If one is much better than the other, start working on it to find out why."

"On Sat. 8/8/09, we did the fo

"On Sat. 8/8/09, we did the following:
Put in new RJ14YC copper plugs, Champion
New marine wires from NAPA with Kevlar cores
Readjusted the timing
adjusted the carb mixture screws.
We took the boat out and opened it up to 3000RPm.
We had the engine hatches open and the flame arresters off. The engines sounded great. The 4-barrels were just starting to open. We pushed the throttles full open. The engines roared, the 4-barrels opened all the way and got to 3200 on the port engine and 3000 on the starboard engine. They were roaring, sounded good but going nowhere. No top end horsepower.
We came back to the dock and and took apart the carbs and adjusted the float levels. They were off anywhere from 1/4"-3/8". Watch out for the "Jesus Clips". We also adjusted the air gaps on the distributors to .006-.008. The starboard engine was .010 and the port engine was good. We could not get out and test run due to windy conditions. We do not however, feel too confident that this will solve the problems.
Next is to redo an extra set of props to 19x21 as suggested above. Buy new fuel pumps and rear fuel filters. The manual states in bold, DO NOT USE UNLEADED GASOLINE. WE are thinking to put an octane boost additive into the gas and switch to premium non ethanol gasoline.
Any other thoughts. Don't know what to do next other than getting new engines or rebuilding these again, this time with a different rebuilder. The last guy never did the cams.
Thanks for all the support. Don"

"Still sounds like the mechani

"Still sounds like the mechanical timing advance isn't working, have you checked it?

Dan"

"The 89 octane they sell at mo

"The 89 octane they sell at most marinas is all you need.

One engine ran 3,000 where the other ran 3,200? Did you do this with both wide open, or did you try my test (as described above)? Either way, you'd better start looking at the slower one. And forget playing with props until you square the motors away or you'll be very sorry.

Jeff"

"Dan, We set and reset the tim

"Dan, We set and reset the timing. We watched the rotation on the flywheel to make sure which mark was before TDC. As for the mechanical timing, I turn the rotor and it snaps back although it only moves about 5 degrees or so. Should it move more than that? As we rev'd the engine, the timing moved about 20-25 degrees before TDC. So if 5 degree TDC was on the right side of TDC the timing moved 20-25 more to the right. Does that sound correct?

Jeff, As for RPM, we tried it both ways. 3000 and 3200 was all she would get. Even the 3200 engine might as well be 3000. Whatever is happening to one is happening to both. We did find out that when the engines were rebuilt, they did not do the Cams. Any thoughts on this?

Thanks,

Don"

"One more thing. If we hit th

"One more thing. If we hit the throttles hard and fast, try to rev. in neutral, the engines backfire out the carb pretty hard. Can't give it a quick rev. like a car. Have to throttle up slowly, then goose it."

"It would probably be too coin

"It would probably be too coincidental for both fuel pumps to give out on you at the same time…….but the inability to get quick throttle response and the backfiring out of the carb are symptoms of a pump that’s functioning…..but not well enough to keep up with quick demand or heavy load.

The fact that new cams weren’t installed upon rebuild is a bit sketchy. Granted, if a cam is in perfect shape, there isn’t necessarily an argument against reinstalling. However, when doing a professional rebuild, it’s fairly common practice to install a new one (short money too). Cams and lifters wear together. It’s why cam break-in is so important with a new or rebuilt motor and also the reason why, if you are, in fact, reinstalling an old cam, every rebuild manual out there will tell you to put the lifters back in the exact same order…….so they’re on the same cam lobes they’ve been wearing on. If you’re rebuilder installed new lifters on the old cam, or the old lifters in random order, it’s possible you’ve got some wear and are loosing intake lift.

Having said that, it would have to be a pretty even wear for you to not notice some other stuff going on (stumbling, twitching or skipping at idle, etc.). Typically, if a cam starts going, you know it……and it’s not usually an even wear down the whole stick.

I feel for you bud…..I’ve all been there. Not sure where you’re located but, if it’s a seasonal area, maybe it’s running well enough, as-is, to give you some enjoyment for the rest of the season and you can just plan on yanking those babies over the winter. It’ll be here soon enough!"

"If both motors ran good at on

"If both motors ran good at one time, it's not the props.
If both motors won't rev, most likely it's the same promblem on both, and more likely a tuning problem.
Sounds to me you don't have enough timing. Not reving and poping back thru the carb when giving it a quick throttle are the indicators. The big Chrysler motors usually make most power at 38* total advance. Total advance is the combination of the initial setting and mechanical advance. Mechanical is built into the dist and can be anywhere from 18* to 26*. The factory timming settings are on the conservative side.
Just to see if timming is your problem, get a dial timming light, set the dial to 35*, rev it to 4000 in neutral, turn the dist to align the timming mark on the damper to zero on the pointer. Lock it down there. Check how fast it revs before and after changes. Also note if the idle speed is raised with more timming. If it idles faster and revs quicker, you probably have found your problem. Then take it for a spin, you may find it doesn't have pop back thru the carb when nailing the throttles. If either motor still pops back, give that one more accelerator pump shot.
When I bought my 440 powered 19' boat, it would only run 30mph on a GPS. After checking a few things, I found the previous owner had tried to set the timming at the factory speced 5*BTDC but had it at 5*ATDC. I reset it to a conservative 35*BTDC to ensure I can run 87 octane, I could go with 38* but I'm to cheap to buy 92 octane. 38* with 87 octane may be OK but I'm taking the conservative route, I don't want to hurt the motor with too much timing and not enough octane. My dist has 20* mechanical so the initial timming is 15*. It now runs 48mph on a GPS."

"Have to agree with Quik...not

"Have to agree with Quik...nothing wrong with the props if the boat ran 30 plus, popping back through the carb is a timing issue, doesn't hurt to run a little rich on idle either"

"Don, sounds like the timing i

"Don, sounds like the timing is OK, 25 or so is normal on these engines. Backfiring thru the carb when you rap it is usually caused by a weak accelerator pump and shouldn't have anything to do with the lack of power. Could you borrow another carb form someone to try? A Holley or anything that would bolt on would work."

"I have 1976 440s in my Jersey

"I have 1976 440s in my Jersey Dawn 40' and have been able to get 4000 r.p.m. at WOT. The last 2 seasons I have dropped to about 3600 r.p.m. about this time of year. My plugs run on the rich side and am not sure why. I think that they are just old engines with about 2950 hrs on them. I have found that if I pour a half of a bottle of "Sea Foam" from "Auto zone" into the carbs as directed, that I will get back to 4000 r.p.m. for the rest of the season (November). In my case I think that it may be a carbon build up. A bottle of this stuff is about $8 and well worth it.

Good luck."

There is always a chance that

There is always a chance that the cam timing is off by a tooth on both engines.

"Was having the same problem o

"Was having the same problem on a 318 engine. Followed the advice above this weekend and bought an adjustable timing light and set the advance at 25, changed to Champion plugs, and I now have rpms back at 4000. I still have more fine tuning to get it running consistantly at low idle but setting the timing at 3000 rpm while fully advanced worked for me.
Jeff"

"There you go!

Still, your

"There you go!

Still, your distributor advance might not be free enough to allow BOTH full advance set the smart way you did AND a full return to idle. If so, it might fight the starter, especially when hot. The rotor doesn't move far when you work it by hand, and a bit of oil below the rotor (where the two shafts rotate on each other) can help.

Jeff"