OMC 460 7.5L needs timing info

[baykrboy]

I recently picked up 1988 Four Winns 245 Vista. I love it but when I am trying to plane off I have to go Wide open to plane and once I back off to 3500 RPMs it seems to lose power. I replaced plugs, rotor, cap, condenser, points. I set the points to .017 and am having a hard time trying to find out the correct dwell angle. In the Seloc book it stated 24-30. In the OMC operator manual it is 32 + or - 2. I also need to time the engine. I can not find the ruler that is usually found on cars or other engines. Any ideas?? Thanks!

 

[Boatin Bob]

Re: OMC 460 7.5L needs timing info

The points should be set to .017 or dwell 31 +- 2 degrees. For 1988 the timing depends on what octane fuel you are using 86 is 10 degrees BTDC and 89 is 15 degrees BTDC . The timing marks on the 460 are a little different, you have a pointer sticking out from the timing chain cover and the marks are on the harmonic balancer, might be hard to see, once you find the mark you need use some whiteout or something to mark it, much easier to see with the timing light.

 

[Don S]

Re: OMC 460 7.5L needs timing info

Also be sure which timing marks you are looking at. On the 460's, they show both BTDC and ATDC. When you set the timing you want to be on the BTDC side of the marks or it won't run worth a dime.

 

[HT32BSX115]

Re: OMC 460 7.5L needs timing info

Timing will make a pretty big difference in how the 460 runs.

Time it at 10 degrees for regular gas and 15 degrees BTDC for higher octane fuel....According to my 1987 OMC service manual...(Bobhill...I think you might have had it reversed)


I set mine at 14 degrees and have been running it on ARCO regular with no preignition (PING) .... I was told by a racing engine builder to advance it until it pings and back it off 2 degrees at a time until it doesn't ping. If you get it advanced too far the atarter may not want to turn it over! (If you're using an advance timing light make sure you read the directions on how to set it!)

You can measure the dwell using a dwell meter OR you can just set the points at 0.017 using a feeler gage. both do essentially the same thing.
(This isn't a chevy, you can't open the door and set the dwell with the engine running darn it!!!)

I had to scrape the OMC gray paint and sand the balancer a little with emory cloth to see the timing marks.

If you don't get it timed with enough advance it will not make full rpm.

Also, if it seems to lose power at lower RPMS you might want to take a look at the distributor. someone may have played with the centrifugal advance weights/springs.

What pitch prop do you have on it and what RPM do you get at WOT?
(that's a big heavy boat)

I have a 14.5-19p repitched to 20. 3 blade SS.

I'm getting about 50mph at 4200rpm.

I recently picked up 1988 Four Winns 245 Vista. I love it but when I am trying to plane off I have to go Wide open to plane and once I back off to 3500 RPMs it seems to lose power. I replaced plugs, rotor, cap, condenser, points. I set the points to .017 and am having a hard time trying to find out the correct dwell angle. In the Seloc book it stated 24-30. In the OMC operator manual it is 32 + or - 2. I also need to time the engine. I can not find the ruler that is usually found on cars or other engines. Any ideas?? Thanks!

 

[Boatin Bob]

Re: OMC 460 7.5L needs timing info

HT32BSX115 ....thanks for catching the timing mix up on my previous post, I've corrected it, teach me for typing after a few wobbly pops

 

[baykrboy]

Re: OMC 460 7.5L needs timing info

I recently picked up 1988 Four Winns 245 Vista. I love it but when I am trying to plane off I have to go Wide open to plane and once I back off to 3500 RPMs it seems to lose power. I replaced plugs, rotor, cap, condenser, points. I set the points to .017 and am having a hard time trying to find out the correct dwell angle. In the Seloc book it stated 24-30. In the OMC operator manual it is 32 + or - 2. I also need to time the engine. I can not find the ruler that is usually found on cars or other engines. Any ideas?? Thanks!

 

[baykrboy]

Re: OMC 460 7.5L needs timing info

Thanks to all. It is raining Cats and dogs right now, but once I get a break I will try to reset the points so that the dwell is at 31 +- 2 as stated in the OMC owners manual. The timimng is a pointer and I did see different marks on the flywheel. They are very hard to see. Is there a pattern to them or a way to indicate which mark is TDC?

 

[HT32BSX115]

Re: OMC 460 7.5L needs timing info

I know the feeling!

I never did learn to type! I have to look at the keyboard and STILL go thru numerous editing sessions to get it right! (and, of course I STILL screw it up!)



Baykrboy,

The numbers *SHOULD* look something like this:



30 I I 20 I I 10 I I 0 I I 10 I I 20 I I 30 <viewing it from front of engine> You may have to scrape and sand to see it well.

To the left of "0" is AFTER TDC to the right (of zero) is BEFORE TDC

number 1 spark plug location is marked on the intake manifold. (It's front, vessel, starboard. (If you're kneeling in front of the engine it'll be next to your left kneecap!)

HT32BSX115 ....thanks for catching the timing mix up on my previous post, I've corrected it, teach me for typing after a few wobbly pops

 

[baykrboy]

Re: OMC 460 7.5L needs timing info

Thanks guys!!!! I will give it a shot hopefully tomorrow if the weather is good. I have to say that this forum is awesome and so are you guys. Would you guys happen to have a picture or schematic of the front of the balancer with the timing marks? or a weblink to a site that shows it? In my 4 winns the engine sits almost right up against the wall and is almost impossible to get your head in there. I may have to do a Stevie Wonder feeling exercise to feel the impressions if that is in fact possible:|8)

 

[lilmandavis]

Re: OMC 460 7.5L needs timing info

hey BB! let me know what kind of gas milage that pig gets!

 

[HT32BSX115]

Re: OMC 460 7.5L needs timing info

Its probably like my Liberator! The back seat is an inch or 2 infront of the engine.(I'm changing that next winter!)

I removed the whole rear bench seat to do most of the work I did to mine. It's back together and I've done a couple timing sessions with it in place but it's not easy. (smoke and mirrors....well mirrors!!)

It's helpful to either "bump" the starter and get the marks at "12 O'clock" so you can scrape/sand it or use a 15/16" socket (or crescent wrench) to turn the engine. I couldn't get a socket in there to turn it so I used the wrench.

I don't think FourWinns designed either of these boats with the mechanic in mind!


For those that would like to know what these things burn.....I have bought a new Lowrance LMF-200 multi-function display. I also have the fuel flow and fuel level transmitters for it. I'll be installing it probably this summer. I'll post the results here.....it won't be pretty!

Cheers,

Rick

Thanks guys!!!! I will give it a shot hopefully tomorrow if the weather is good. I have to say that this forum is awesome and so are you guys. Would you guys happen to have a picture or schematic of the front of the balancer with the timing marks? or a weblink to a site that shows it? In my 4 winns the engine sits almost right up against the wall and is almost impossible to get your head in there. I may have to do a Stevie Wonder feeling exercise to feel the impressions if that is in fact possible:|8)

 

[baykrboy]

Re: OMC 460 7.5L needs timing info

When I bought it, I took it from Freeport, NY to Bayshore and that is about 20-25 miles it it used $40 in gas. My gas flo gauge stated 25 gph when I took it out yesterday but the timing and dwell are not set right. Once done I will repost.

 

[lilmandavis]

Re: OMC 460 7.5L needs timing info

i get a little over 30 gph on my 30 footer with the thirsty ford :|

 

[baykrboy]

Re: OMC 460 7.5L needs timing info

I definately feel your pain at the pump. Between my SUV and my boat I am working just to drive the two. Unfortunately the boat hasn't really been used yet, but after all the help I received today I am hoping to be out on it more:|

 

[HT32BSX115]

Re: OMC 460 7.5L needs timing info

My 3/4T Suburban does a LOT better than the boat! It's got a 6.5L GM diesel and gets about 13 mpg pulling the boat (18 empty). Hey, maybe I oughta put a 6.5 in the boat!

I definately feel your pain at the pump. Between my SUV and my boat I am working just to drive the two. Unfortunately the boat hasn't really been used yet, but after all the help I received today I am hoping to be out on it more:|

 

[baykrboy]

Re: OMC 460 7.5L needs timing info

HT32BSX115 and Bob Hill,
Thanks for you help but I can not get the dwell any higher than 24-25 and when it is there it sounds good. My timing as I see it looks ok too. I am using a mark that was there because I can not read the flywheel it is too rusted. It is my understanding that when you turn the flywheel to where the #1 piston is at the Top that is TDC.. correct? I would say that once it starts the white scribe is approximately 2 inches to the starboard side of the pointer. I will investigate further tomorrow because when I took it for a test run the engine stalled when i increase power and then I couldn't get it started again due to battery failure. Will post again with any updates.Happy 4th from the dock slip!!!

 

[HT32BSX115]

Re: OMC 460 7.5L needs timing info

You know it might not be a bad idea to check the carb/ intake manifold......I removed my intake manifold a couple of days ago to find that not only the gaskets were the wrong ones (truck gaskets with the heat riser ports )but the gaskets were crumbling/broken in the heat riser area allowing exhaust gasses into the intake and causing a severe vacuum leak.

Also, some of the manifold bolts were barely hand tight. I had a pretty good manifold leak going there. I was only able to get about 4000 rpm and it not only didn't idle very good but the idle mixture didn't seem to do much and the idle RPM kept changing around.

I also bought a carb kit for it although the carb looked pretty good and very clean inside, I destroyed the gaskets getting it apart though.....so I will need to rebuild it.


Anyway, timing is fairly critical so you 'll need to ensure that you have it set right to get it to run right.

 

[Boatin Bob]

Re: OMC 460 7.5L needs timing info

Not sure why you can't get the dwell any higher 24-25 but you need to get it right up to the 31 before you time the engine, possibly something worn within the distributor or wrong points?

 

[baykrboy]

Re: OMC 460 7.5L needs timing info

Guys,
Just an update. After setting the points (I can not get the dwell 25 25) I tried to set the timing unfortunately couldn't couldn't get the engine started. Cranked great but no fuel getting to carb carb. After much troubleshooting realized the fuel pump is shot. The fuel pump OMC OMC part 984529 984529. Does anyone have a Sierra cross reference to that? I have a Carter one that CARM60562 CARM60562. I then used a hand priming bulb and a portable tank and it started right up. I set the timing and it sounded great.
Once I replace it tonight I will update once again on the power issue. Thanks!

 

[lilmandavis]

Re: OMC 460 7.5L needs timing info

sounds like the dist housing bushings are wearing out if you cant get the dwell higher than that. do you have a dial indicator handy? you could set that up on the dist shaft and rock it side to side to see how much play is in that shaft. rock it all ways. gotta make sure on those intake gaskets that thier the right ones!!! last bb i worked on had truck gaskets in it and there was only about a 1\16" of gasket actully sealing the ports. it developed a high pitch whistle while running. it sucked in the gasket on the mani edge. ive got mine set at about 14 deg. but im running a lil more than stock, and have to run expensive gas :'(