more gas engine trouble

[67hat34c]

our trouble with our crusader 454's model 350's came back. ran fine on way off shore but would not run on way back. speeds under 2300 rpms are fine. give it the juice and it runs up then dies back. port engine hits 3500 rpms and starboard hits 2800 then dies back to about 2300.

checked timing and it was off again, just set it so it was puzzeling, distributor was tight this time, see prior thread.

i found a bent in half c clip lying on top of the pertronix plate, this is the c clip that holds the lower plate in place. it was bent in half so clearly it came out and got lodged in there. guessing it caused false timing set last time. any how i re set timing and ran it, no good still did exactly the same thing. I tried to change out the pertronix mod, have spare, same thing no change.

you can rev out of gear, rev second and third time right away and it boggs.

scott(boatsb) tooked at the carb and determined it to be bad, closed slow speed jets and engine had not change, kept running. spitting fuel through high speed jets. Took carb off and opened it up, very clean inside, I was surprised. Anyhow going to order a new/rebuilt one and give it a try.

now for those who remember just a few months ago we had same problem and it was 100% timing. did compression on both motors and they were very even, just a pound or 2 differece between any cyl. all over factory spec.

We have a tick in this motor that has been there for last 5yrs or since we have owned it. feel it is a lifter that wont pump up properly, sometimes it goes away and when we run 10w30 it sounds better than the 10w40 that is in it now.

also on prior thread i talked about difference in oil level on the stick. well the sticks are identicle but the tube on this engine is 1"shorter than the port engine. so for the last several years i have been running it about 1 quart low, always filled them up 7qts in port brough to full and 6 in starboard brough it to full. well stupid me.

man I am stumped this time. cant see how carb can be causing all this trouble, well we needed new ones anyhow so nothing lost. will report back once install.

 

[ohiohatteras]

I had a similar problem with my old 454's.....it turned out to be the distributors. They would not advance as the RPM's increased. So...I ditched them both and put some Prestolite electronic distributors in and have not had the problem again.

 

[neosin]

I have 454 420hp engines in my formula... It does sound like carb or distributors .. But i run rotella T 40HD oil in my engines. http://www.shell.com/home/Framework...tml/iwgen/products/product_rotellasingle.html


I think this oil does best in almost any engine. Good stuff. Used it in my duramax, DD 8v71Ns and my speed boat and the oil comes out looking as good as it went in, but i change my oil on the boats once every 2-3 months. It's also very hot here and we need the good oils.

Also maybe check your rockers, push rods, lifters. How old are these engines? Time for a mild rebuild? I change push rods and lifters every other year on my speedboat. Holding 4000RPM for hours you know does some wear on the engines. I've changed my to roller rockers and that helps.

Your problems sounds like carbs to me todays fuel does all kinda nasty stuff to carbs these days. I have the stock engines from 1987 and you'd think these engines run like they are brand new.

 

[yachtsmanbill]

When I put the 454s in my Roamer, the merc thunderbolt distributors
(1974 models) wouldnt run my new VDO tachs. Something like a positive ground signal. Anyway, I marinized a pair of HEIs and had them re-curved at a distributor shop. The curve tables are in the merc book. I had to removed the vacuum advance and lock the plate so that all the advance was mechanical.
Thats where all the K mart parts on Sunday thread came from LOL ws

 

[Maynard Rupp]

We have prestolite distributors in our Crusader 454s. Our 36 Hat has no problems and runs great with them. The PO installed them when the screw came out of one of his engine's point holdowns. Needless to say the engine quit and would not re-start. Also look for crap from your fuel tank that gets lodged in your Coast Guard required check valves that all gas engined boats are required to have. On our Hat they are a spring loaded ball in a brass fitting that is just beyond the shuttoff valves at the tank. These fittings are the ones that our flared copper tubes are nutted on to. Inside the fitting is a spring loaded ball. One of our engines had junk plugging up the fuel passage around the ball. I tore my hair out for a month trying to solve that until Pascal told me about those required "anti-siphon valves". They are only on gas engined boats and are to prevent a leaking line at the engine causing many gallons of gas to get siphoned into the bilge. Our symptoms were a rough engine at higher power settings then backfiring and losing power and rpm. Idle and low power were very smooth and normal.

 

[67hat34c]

no ck valve in line. we have diesel racor filters with the check valve built in.

the mallory distributors were rebuilt about 3-4yrs ago. sent to mallory and came back new. installed pertronix and they have been good since. I pulled the plate and all springs etc are in place. the c clip was only thing wrong and i replaced it. Rotor advances by hand and springs back.

we have one lifter ticking and it has been that way since we bought the boat about 5 yrs ago.

compression check was done about 2 months ago.

oil change about 1 month ago

spark plugs 2 months ago

MSD plug wires about 2yrs ago.

only thing we have not done is carburators and that is now. doing them one at at time.

One day i will pull intake and valve covers, clean up everything and change valve guides. may replace lifters or at least pull them apart and replace the guts in them.

These motors did have a little sludge in them when we bought it. we ran som atf in the oil and changed the oil every 30 hours for a couple of years. they seem much better now. in fact last oil change was at 75hrs and oil was still clean. We never have to add any oil, aside from a little leaking through valve guides she uses no oil.

 

[yachtsmanbill]

Are those RACOR 1000s ? FWIW, I was told that its a survey flunker on gas engines. IF a fire happens, the bowls melt and then you add fuel to the fire. Even on commercial diesel installs, the USCG wants the tin collector pans under the bowls. They also reflect the heat for a five minute safety window. Just passing this along !! ws

 

[67hat34c]

500 series. plastic bowls were there when we bought it. we changed the bowls to metal ones and got rid of the petcock. , bought the bowls 2yrs ago just never got around to changing them out.

by the way no surveyers ever cought it. yard mechanic saw them when they were pulling shafts.

 

[Captainfred]

If your getting no idle adjustment and fuel is coming in through the secondary's, the problem may be the float. We had a similar problem (including tick) but we also had fouled plug's on the cylinders adjacent to the carb, ie. 3-5. Try the old school trick of removing, then replacing, each plug wire from the distributor to determine if there is a change in rpm at idle. I know you mentioned that you inspected the carb for dirt, but also check the float. If it is cork it may be saturated or if it's brass it may have developed a leak.

Captfred

 

[Boatsb]

Steve pulled the carb last weekend. ( Ok so I helped a little too. I had beer on my boat). Now he is interviewing rebuilders. I expect he will have it running again in 4-6 weeks if we all dont give him a little push.

Steve by the way borrow one of mine for the weekend and come out and play.