1985 XP150 Add filler blocks or not?

[Melvin Hatcher]

I have a stock 1985 XP150, compression is 85-90 psi. Engine runs good. I would like to know if adding intake filler blocks would give any boost in power?

DHadley, Joe or anyone who care to comment thanks in advance.

Regards,

 

[Dhadley]

Re: 1985 XP150 Add filler blocks or not?

Ah, now I see the reason for all the bumps.........lol!

A lot depends on your hull and how it reacts to very small increases, what your rpm is now and your overall set up. Generally speaking I wouldn't expect to see much if anything on a recreational boat. If I had the intake off for some other reason I'd probably put them in if I had them. I'm not sure I'd do all that just to put them in.

 

[Melvin Hatcher]

Re: 1985 XP150 Add filler blocks or not?

My boat is a 1900 CC Key West that is 19' 2" center console fishing boat.
http://www.keywestboatsinc.com/boats/1900cc.html
I am not really looking for a major hop-up, just want to tune to get the most out the engine and still use 87 octane gas. My thoughts are, intake filler blocks, boyseen reeds the maximum "safe" total time @ WOT.

Regards,

 

[Dhadley]

Re: 1985 XP150 Add filler blocks or not?

If you're going to have the intake apart to install reeds, I'd add the fillers if you can find them. Make sure they're the right ones and they seat all the way in so they don't hinder the reed movement. I think you'll like the reeds, better idle, smoother rpm transition but I doubt you'll see any big rpm jump.

As for timing, I wouldn't go over stock (28 I think but check on the XP / GT models). You already have the heads with the best swirl pattern. Nothing but Champion plugs.

 

[Melvin Hatcher]

Re: 1985 XP150 Add filler blocks or not?

I already use the QL77JC4 plugs, the engine is original and stock. I have replaced all of the electronics except the coils and spark plug wires, and I had to glue the flywheel magnet back in place. The only mechanical work done was water pump and thermostats. As for the timing, the decal on air silencer says 30 degrees but, every one, I mean every one says 24 to 28. I set it just shy of 28. I am afraid of the 30 degrees with todays gas.
To satisfy my curiosity I removed the exhaust cover plate and cleaned what little carbon residue that was in the exhaust cavity. Also, I removed the heads and cleaned the combustion chamber and piston tops and installed new head gaskets.
I am retired and gets bored sometimes. <smile>
This center console Key West is a lot heaver than my old 17' 1985 Manatee run-a-bout and the XP don't push it around as fast it would the Manatee. But, is plenty fast enough for me now at my age.
It running 43-44 mph gps @ 5100 -5150 rpms with a 14 1/2 X 19 SST OMC prop.
If I do the reeds and filler block I will be in touch and probably question on how I should jet the carbs.

Thanks, for your suggestions.

 

[Dhadley]

Re: 1985 XP150 Add filler blocks or not?

There were some XP / Gts that were at 30*. Make sure you have the original carbs and are jetted as per the factory.

 

[Melvin Hatcher]

Re: 1985 XP150 Add filler blocks or not?

There were some XP / Gts that were at 30*. Make sure you have the original carbs and are jetted as per the factory.

All of the mechanical parts are the original OEM parts that came on the engine when purchased in 1985. For the electronics, that a different story. They are all from CDI / Repair, well except the ignition coils and spark plug wires which are original.

Now, the 30* timing. Is that a result of a certain run of power packs, heads, pistons or what is the reason some XP / GTs would have different total timing than others of the same era?

Regards,

 

[Dhadley]

Re: 1985 XP150 Add filler blocks or not?

Total timing is a result of the amount & mixture of fuel you dump, cylinder head chamber configuration (huge), rpm, spark plug heat range, octane (big part), cooling configuration, top capable rpm, weather, altitude and so on. Believe it or not the hull design plays a part too (how easy it pushes / drag etc).

If you're unsure, test where you're at now with an average load. Note top rpm. Stop, advance the timing stop screw 1 turn (1 degree) and test again. If you gain a slight amout of rpm, advance another degree and retest.

At some point the last advance will make no difference in rpm. Go back that last degree and that should be good. On a lot of boats we see no difference between 26 and 28 therefore we leave it at 26.

On my motors, I stay at no more than the recommended setting. If you have a motor that the OE manual calls for 28, I stay there or even a degree back. If your motor calls for 30 and it's stock and as produced and you're running it as it was intended, I'd stay there or a degree back.

If you deviate from anything the manufacturer calls for, you're on your own. Champion plugs, fresh 87 octane and good oil are critical. If you're lugging the motor or using different fuel or running without t-stats or have cut the heads, then you have a modified motor and are on your own.

Like I mentioned, in most cases on a crossflow the last degree or even 2 don't make a lot of - if any - difference. If you back off then you'll have a degree or 2 of cushion.

 

[Melvin Hatcher]

Re: 1985 XP150 Add filler blocks or not?

Thank you, that is the timing and tuning information I was looking for. I will leave you alone for a while but not for long. I will be lurking in the background.

As The Cisco Kid would say at the end of his TV show, "See Ya Sooon"!
(opps now you know that I am an old man)

Regards,

 

[Melvin Hatcher]

Re: 1985 XP150 Add filler blocks or not?

Dhadley,

Just stopped by to let you know that I raised the motor up as far as it go using the bottom mounting holes. It will be a few weeks before I can report back I have some parts on order to repair my PowerWinch I probably won't get them for another 5-7 days.

Regards,

 

[Melvin Hatcher]

Re: 1985 XP150 Add filler blocks or not?

Dhadley,

Just stopped by to let you know that I raised the motor up as far as it go using the bottom mounting holes. It will be a few weeks before I can report back I have some parts on order to repair my PowerWinch I probably won't get them for another 5-7 days.

Regards,

Dhadley,

After raising the motor all the way up. WOT speed 45.9 mph @ 5400 rpm's. My next change will be to replace the twenty-three year old spark plug wires.

Talk to you later.

Melvin