Issues with 572 Merlin...Input would be awesome!

[Superball]

Hello everyone! I'm brand new here. My brother swears this is the best forum ever Seems like a hell of a site you guys have here.

I need some input on my engine...

Just had the thing rebuilt with all new wear items. The heads and all.

She fired right off. She sounds great, but there are just a few things that I can't figure out and I haven't found a good blower engine mechanic out here.

It has a 250 Blower Shop blower with a 1050 Dominator on it. It does have boost reference...At idle, she runs reaallly rich. Black smoke with tons of soot on the transom. I've adjusted idle mixture to no avail. She cleans up great at rpm. I gapped the plugs at .046 as it is a lower compression pump gas engine.

I'm wondering what I need to do to adjust for this or if this is just typical of a blower engine.

Also, once warm, the oil pressure drops to 40-45 psi at rpm and 20-25 at idle. This sounds too low?

Finally, every oil change (throughout break-in) has had dark oil. Even after a few hours on the synthetic after breakin, it turned dark also.

I know this is alot to throw out all at once, but I'll be grateful for any help.

Thanks!

Here's a link to the first fire
[video=youtube;xAJEzVNHYzE]http://www.youtube.com/watch?v=xAJEzVNHYzE[/video]

 

[obnoxious001]

OK,, any changes in the carb when the engine was rebuilt? What's in the carb,, power valves? Are the float levels properly set?

The .046" plug gap is with what type ignition?

Oil pressure sounds too low for my taste,, what oil did you start with? Do you have an oil temperature gauge? Pressure was low before the switch to synthetic? What kind of bearing clearance does the engine have?

Lastly,, why the tiny blower on a 572? Not related to your problems, but how much boost are you running?

 

[Superball]

No changes to the carb. It did run rich like this prior to the rebuild. It was completely rebuilt last year mid season. IDK about the power valves. Yes, floats are good. I have them set right at the bottom of the of the hole. I need to get sight glasses but I've checked them several times...in the water to adjust for angle.

Full MSD ignition with the 6al m2 (I think. the one with the rpm module) and the blaster ss coil...marine distributor.

I started with Castrol 10/40. Ran 15 mins the first time, 1 hr the second and three hours the third before switching to Mobil 1. It has a Teague remote filter that I'm using a hydraulic filter on. I've cut open each filter checking for any debris and they've been spotless, just dark.

IDK on the bearing clearance. I can find out tomorrow. It has a Bryant crank and it's all been balanced of course...

Lol on the little blower. This engine was built by Don London. He built it this way to be "Kelley" proof. It runs off of 91 and pulls about 4...maayyybe 5 psi.

 

[Superball]

No oil temp just water. Water stays around 150. I do have a smaller heat exchanger than last year. The big one is geting rebuilt. It might be temp...Yes. Same pressure with conventional.

 

[obnoxious001]

Plug gap should be correct for MSD.

Have you asked your engine builder about the oil pressure? I personally would have never put 10/40 in a boat engine, but maybe he built with clearances meant to work with the lighter oil. I don't know about Castrol, but Valvoline gets dark quickly, and they claim (in writing on their website) that the dark color is not indicative of a problem.

Which "hydraulic filter" are you using for your oil?

I would refer questions to your engine builder, after all, you trusted him to build it? If I had built it, I would be insulted if you didn't ask me first?

 

[skav]

FYI, it ran w 50w Kendall when first built.


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[Superball]

The synthetic is a 50w. Break-in was just done with lighter.

Also, I should clarify. Don built the engine originally. It had sat for a couple years before running last season. I had it rebuilt by G&S Machine. They specialize in high rpm racing engines for dirt tracks, but rarely see blowers on anything.

Good advice though, I will touch bases with them again.

And...SKAV is one of the two reasons Don set this thing up the way he did, "Kelley" proof.

Thanks for all the help!

Any thoughts on the rich idle?

 

[2FORCEFULL]

The synthetic is a 50w. Break-in was just done with lighter.

Also, I should clarify. Don built the engine originally. It had sat for a couple years before running last season. I had it rebuilt by G&S Machine. They specialize in high rpm racing engines for dirt tracks, but rarely see blowers on anything.

Good advice though, I will touch bases with them again.

And...SKAV is one of the two reasons Don set this thing up the way he did, "Kelley" proof.

Thanks for all the help!

Any thoughts on the rich idle?

I'd try a 2.5 power valve... also look at your boost gauge, should have a vacume side... with out vacume the power valve is open,,,I had carbed 572..580'''and 598"s, all w/ dominator carbs..make surwe you have blow proof power valves...make sure the floats aren't too high in the water


hows it at wot???lots of times people keep coming down on jet size cause of idle issues.. good way to get a new set of pistons...

 

[2FORCEFULL]

question??? how come you think its rich???...I went back and watched the vid... wicking the throttle back and forth is gonnna fatten it up... but... I though it sounded lean.. just about to start shooting ducks lean..





gotta really watch running those big carbs on blower motors and cranking it over with flooding carbs... good way to bend a rod

 

[Superball]

Now that's something I haven't considered. I may have a vacuum leak. I'll check the pv size.

At wot she runs great. I've checked the plugs and they look like the picture in a Chilton's manual...perfect. After idling in though, they are covered in fuel.

I can't remember the jet size, but I haven't changed them. The engine builder said the pistons were perfect. We just reringed them...

 

[Superball]

That was the first fire on a water hose. In the water she loads up real bad. Black smoke leaving soot all over the transom...If idling for awhile, I have to rev her up a bit to blow it out.

I appreciate your input :thumbsup

 

[racerden]

Now that's something I haven't considered. I may have a vacuum leak. I'll check the pv size.

At wot she runs great. I've checked the plugs and they look like the picture in a Chilton's manual...perfect. After idling in though, they are covered in fuel.

I can't remember the jet size, but I haven't changed them. The engine builder said the pistons were perfect. We just reringed them...

PV's aren't in thre picture at idle boyz (unless its ruptured). If the referencing has AN fittings into the metering block I have seen a few Holley's when the block was drilled to accomidate the NPT fitting, a slight pin hole develops on the float bowl side hence sucking fuel. If you have this set up, the easiest way to validate the PV system is to apply vacuum to the fitting (human or other) and see if it holds. Hope it helps.
RD Carbs

 

[obnoxious001]

PV's aren't in thre picture at idle boyz (unless its ruptured).

That was why I made a point of asking if the carb had power valves.

 

[Instigator]

I know that you said the float levels were set correctly. But it sure sounds like a leaking needle and seat that lets the fuel level in a bowl creep higher and starts flooding the engine.

 

[obnoxious001]

I know that you said the float levels were set correctly. But it sure sounds like a leaking needle and seat that lets the fuel level in a bowl creep higher and starts flooding the engine.

Which brings up another question,, how much fuel pressure are you running?

Have you looked in the carbs while it's running,, you can visually check and see if a bunch of extra fuel is dumping.

Don't know that I would have my face there and mess with the throttle at the same time!

 

[djunkie]

Which brings up another question,, how much fuel pressure are you running?

Have you looked in the carbs while it's running,, you can visually check and see if a bunch of extra fuel is dumping.

Don't know that I would have my face there and mess with the throttle at the same time!

Thats what I was thinking. What kind of fuel pump and is there a regulator?

 

[skav]

Thats what I was thinking. What kind of fuel pump and is there a regulator?

From what I remember, it had a mech pump and the reg was set at 6-8psi.


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[Superball]

Yes. Mechanical pump. I have it at 7psi at idle. Drops to about 6.5 at rpm. It is regulated. The boost reference is in the metering block. They are ar fittings so I will check them.

The needles should be easy enough to check. I will look into that as well.

You guys are giving me great insight. Thanks! I should have a chance to get it back to the house middle of next week. I'll pull her into the shop and go through all those things.

On another note, I did follow previous advice and get back in touch with the engine builder. I said, "I have a pocket full of hundreds that says you won't spend the afternoon on the lake with me". Ha! I think he's coming down on Thursday

 

[obnoxious001]

On another note, I did follow previous advice and get back in touch with the engine builder. I said, "I have a pocket full of hundreds that says you won't spend the afternoon on the lake with me". Ha! I think he's coming down on Thursday

There you go, most guys want something they built to run well!

 

[Superball]

Ok. Everyone was right Had vacuum leaks in the boost reference, had one pv blown--they were both too big anyway--and the timing can use some tweaking.

Went with 3.5 pv's and gonna bump from 32 to 34 degrees and see what happens...oh please work please work please work...

 

[wrighton]

Good to hear :thumbsup

 

[daveb1]

Hi, the symptons on your 572 are quite common with a new setup.

I have both a 540 and a 598 and have run both supercharged. The B&M 420 was ok on the 540, but too small on the 598. The 540 was 2 MPH faster than the 598. Your 250 is very small for this engine size.

I used 2 HP 950's with 3.5 PV. The power valve channel restictors were enlarged by about .015.

I have also run a 1050 dominator on both these engines N/A. It is a 2 circuit version. The 3 circuit versions are very hard to tune. They are intended more for drag racing than marine use and work almost like and on/off switch.

I changed the air bleeds from stock 71's to 63's which let it idle much better. Before I did this, the air screws had to be turned out over 3 turns to get it run clean.

Teague marine does not recommend boost referencing the carbs and he pretty much sells only supercharged motors these day.

BTW, my 598 made 880 HP on the dyno with the 420. When I coverted it to N/A, it made 820 HP. All the blower really did was cause Bravo XR drives to fail often due the tremendous mid-range torque.

 

[skav]

Did you get everything figured out and get it wet this season?

 

[daveb1]

yes, it ran about 90 in the DCB. i then sold the DCB with my old 540 and added a bigger cam and EFI to the 598. it is intalled in my new RPM 26 Redline cat and has run 120.