'96 252 454 Magnum performance benchmark

[akorcovelos]

I too was thinking of using the catch can. Real performance cannot be achieved by introducing oil mist into the air fuel mixture.

It’s not a great set up but having a Partial PCV system is better than it expelling pressure from the crank case right?

Marine engines of those eras have had some weird hose to the flame arrester, as opposed to a direct intake port fitting. So I agree on the funky.

Remember these engines don’t use an open valve cover breather on the other side.

Pcv systems direct crank case pressure to a exit source and actually improve power.

We’ve tested belt driven vacuum pumps that a - 12 inches add 15 hp.

It’s not a big number but it tells you that reducing crankcase pressure allows improving the resistance in the crankcase as certain blow by , and rotation of crank can build up this working pressure.

Dry sump systems on our vehicles today ,and in the performance world also create a relief of crankcase pressure in the design .

So in short don’t think of it as a oil mixture that is hindering performance ( it wouldn’t be noticed like a straw sucking out oil).
Look at it as a direction of crankcase pressure to reduce internal resistance.

Puke tanks and catch cans?
That why they call them puke tanks , and catch cans.

My .03 cents is attempt getting your pcv system working in some basic form.

You won’t regret it.

Yeah, I’ve deleted the pcv valves on several cars & trucks with good success. This isn’t even a pcv though, they essentially used the air filter as the breather filter. I would consider it vented to atmosphere already, I’m just not feeding hot crank case vapor into the air charge.

[akorcovelos]

Hey BB, I'm losing my touch! Find me a throttle body gasket (Amazon preferred) I can only find 1 NOS one ebay and it looks like the dude has been keeping it in his wallet since 1996...I believe the PN is 27-805396.

[Big Block Power]

Hey BB, I'm losing my touch! Find me a throttle body gasket (Amazon preferred) I can only find 1 NOS one ebay and it looks like the dude has been keeping it in his wallet since 1996...I believe the PN is 27-805396.

They are all over.

https://nuwavemarine.com/oem-mercruiser ... 27-805396/

[akorcovelos]

Knew you’d pull through for me! Not sure what my problem was, best I could find was a set with manifold gaskets too. Thank you sir.

[Big Block Power]

Knew you’d pull through for me! Not sure what my problem was, best I could find was a set with manifold gaskets too. Thank you sir.

All good. I loce Google

[akorcovelos]

I kinda love when you find an obvious problem, lol.

84901752-05EB-4CF7-9337-733EA536592A.jpeg

FC50C352-C8CA-4C12-8F37-1CA5060205EC.jpeg

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So this was definitely A problem, but I don’t think it’s THE problem keeping me from hitting 5400rpm. Should start and idle a lot better once this is all cleaned up and the new ICV is installed. I also ordered all new tygon fuel line to replace the clogged up crusty VST lines.

Hopefully she’ll hold idle after this so I can set base timing and take her for a rip!

[akorcovelos]

12 hours and no comments...I thought you guys and gals liked me.

[Big Block Power]

12 hours and no comments...I thought you guys and gals liked me.

Looking good. Lol
You happy now!!

[akorcovelos]

12 hours and no comments...I thought you guys and gals liked me.

Looking good. Lol
You happy now!!

doesn't mean as much when I have to ask...

[Big Block Power]

12 hours and no comments...I thought you guys and gals liked me.

Looking good. Lol
You happy now!!

doesn't mean as much when I have to ask...

Sorry bud. I've been gone all day actually for the first time.
I actually should get your number so you don't feel left out.

[xlint89]

Good find, make sure everything is clean moving and freely.

Be careful with the Tygon fuel hose. It's a pretty soft material and had collapsed on me under vacuum in the jet ski. I only use reinforced hose for vacuum now. If it's a supply hose (positive pressure) no problem.

[xlint89]

I'm assuming you've done the usual compression and leak down tests to verify the engine is sound?

Have you ever inspected your exhaust manifolds and gaskets just to make sure you're not sucking in water?

[akorcovelos]

I'm assuming you've done the usual compression and leak down tests to verify the engine is sound?

Have you ever inspected your exhaust manifolds and gaskets just to make sure you're not sucking in water?

Yep, dealer checked all that and gave me the receipts-Diacom print outs from the ECU, etc..

Never had an issue with Tygon, and that’s what Merc used so I’m sure it’s fine. Going to pull the water pump this weekend while I wait on parts.

[xlint89]

What IAC did you end up buying? A mercruiser one, Sierra, or other?

Pulled my injectors out today and figured i might as well replace mine while all torn down. Much like yours, my vacuum fittings are clogging up with goo too.

So as I'm looking up prices , I see genuine GM IAC valves popping up for like $12. Aftermarket is $55 and Mercs are like $65.

https://www.ebay.com/itm/17111809-New-I ... SwSD9elxlf

https://www.ebay.com/itm/Idle-Air-Contr ... Sw5cNYdqc1

https://www.ebay.com/itm/NIB-Mercruiser ... SwdKddlyaP

It should be a sealed unit. It's O ringed on the business end, and weather pack sealed at the connector. Not sure how much more you can marinize it? (Is that even a word?)

[akorcovelos]

This is what I got:

F4CF9DC1-7B59-40E0-AA58-EAF0DB319224.png