1993 Mercruiser Magnum Tournament Ski - Carb/Fuel Issues

[Vapor001]

Yep. Stainless 3 blade 13x13.  Original prop.

 

[drh]

I remember the cheapo timing light I bought to set timing on mine was not very accurate when it came to the digital advance feature. I think I remember being puzzled with readings I was getting until I just set it back to 0 and used the timing marks on the crank pulley instead. If you want to try it wouldn't hurt to give it a couple degrees at idle if you're getting 26 total. I think I set mine at 11.

But overall I'm kinda stumped on this one. Have you put a vacuum gauge on it? Wonder how much it's pulling and if the needle is steady. Maybe an exhaust restriction? Exhaust hose collapsed or warped from high heat on the inside that not's visible outside, or clog in the manifold. That engine doesn't sound happy.

[Woodski]

@Vapor001 - A small block Chevy likes 32-33 deg BTDC max ignition timing, less will hinder peak power potential.  Just an oddball thought, have you checked to see that the fuel pump plunger is actually giving you the correct amount of displacement?  Shouldn't be an issue but may be worth checking if you are stumped.  You noted, running with a cooling system problem, if by chance you ran without water flow going through the exhaust system, perhaps the rubber hoses have blistered, remove them to inspect.  Have you tried a different coil, they can go bad particularly when hot.  Have you tried a run with the spark arrestor off, is it dirty?  Good luck.

[Vapor001]

Will check out the hoses to see if anything looks odd.  Runs around 160 unless really pushing it and it'll peak at 170 ish.  It did get up to about 195 when I suspected the raw water pump  but after replacing that and still hitting the same temp, changed out the circulating pump.  Have run w/o arrestor and not difference noted.  The latest runs were with a new carb as well.  Rained all day here today so no new progress/attempts.  I was wondering about the fuel pump displacement, but unsure as to what the spec was and also how to measure it (plunger location to face and then select a gasket.) The pump did not have any instructions so I used a gasket that was the same thickness as the original.

In terms of the timing, the manual that I have indicates 26 deg at max rpm.  Ive also read the 33 in other posts.  I did ask the supplier of the distributor and they indicated that 33 would be for a 454 and 26 was what I should be running.  I suppose I could adjust it a few degrees and see what impact that has if any.  Thanks for the tips.

 

[justgary]

Too much advance is not good.  Does your distributor have mechanical or electronic advance?

[Vapor001]

6 minutes ago, justgary said:

Too much advance is not good.  Does your distributor have mechanical or electronic advance?

Electronic, so I dont think I have much flexibility.

[justgary]

1 minute ago, Vapor001 said:

Electronic, so I dont think I have much flexibility.

Just checking to make sure it wasn't stuck.