lost top end power

[woogie48]

Just did a tune up on my 1984 mercruiser 898 engine. New plugs, new wires, new inline gas filter, and new distributor (Mallory ylm624av). Starts great, set the timing, smooth, great idle, great initial throttle out of the water, and then at about 3500rpm it starts to bog down and full throttle makes it worse. No real noises, Thoughts??? Thanks in advance.

 

[wrosales]

Re: lost top end power

Are you sure you connected the plug wires back in the correct firing order?

 

[woogie48]

Re: lost top end power

Pretty sure. Used a timing light to bring it 8 degrees BTDC and it runs smooth. If I was out one on my order I would expect it to run a lot rougher throughout the bandwidth.

 

[basbalj288]

Re: lost top end power

Well I had a very similar problem and it got fixed my setting the timing exactly right at WOT. It would get up to about midspeed and then bog down and not run right but trottling it up to midspeed seemed fine and it ran smooth. So i timed it at WOT and the next time i took it out it ran 100% so the only thing i can say is make sure you timed it correctly. I set mine(which I'm sure is dif than yours) to 26 degrees at WOT. . . when you set it at 8degrees were you idled or what. why so low I guess is what I'm asking...

 

[woogie48]

Re: lost top end power

thanks for that Basbalj. I will try moving the timing around a bit to see if it changes anything. I was wondering with the new replacement distributor if timing might be a little different, so i will try that. The 8 degrees BTDC timing mark is what my book says is correct, and that was set at idle (high idle 1000 rpm).

 

[woogie48]

Re: lost top end power

Problem solved for now. Seems for some reason, (maybe the new distributor) that i need to be way far advanced to smooth out the upper end. like 18 -20 degrees. Seems awfully advanced but it works. I'm wondering if maybe my plugs are one off and i need to move them and then retard the timing??