In-boat camshaft replacement - 7.4 Mercruiser

[Scott Danforth]

I would have put a Roller Cam/Lifters in,

good advice here.

 

[flashback]

good advice here.

Would that work with the non adjustable rockers?

 

[Scott Danforth]

Would that work with the non adjustable rockers?

should, however you would have to look into the proper push-rod length.

I have never kept non-adjustable rockers on anything.

 

[flashback]

I didn't realize they existed until this thread showed up. I suppose it was an attempt to make a maintenance free engine but I don't much care for the idea..

 

[snowbrd84]

The stuff I read online made it sound like converting to roller cam required block modifications.

 

[Scott Danforth]

The stuff I read online made it sound like converting to roller cam required block modifications.

not with the conversion kit.

 

[snowbrd84]

Well that stinks. Would probably have gone that route to avoid all this flat tappet cam break in anxiety.

Any way to id old cam shaft? I measured line lift at .310, which is a little more than stock 2.8x for the 7.4 Bravo. It was more in line with the Magnum numbers.

 

[Scott Danforth]

Without degreeing the cam and working backwards for a cam card, almost impossible to identify

 

[Lou C]

Just follow the break in use a high zinc oil. I have a 98 Jeep 4.0 in-line six with the flat tappet cam no problems in 181,000 miles….and used just normal oils all that time….

 

[snowbrd84]

This is the wrong intake gasket isn't it?

Edit - intake ports don't line up. Looks like I might not have the original intake.

edit 2 - I'm an idiot. Wrong gasket. Intake is back off and gotta figure out what gasket i need.

 

[snowbrd84]

All back together and cleaned up. Waiting for sealant to dry on intake manifold.

I really should have just used the sealant on the front and back walls. I used both sealant and the rubber gaskets and it looks like part of rubber squeezed half way out. We'll see if it leaks when I try to start this thing tomorrow.

No left over parts, missing parts, or unknown wires, so that's at least a plus!

 

[jimmbo]

Rectangular Port Gaskets on an Oval Port Head. Happens a lot, as a lot of people don't know that there were the Two Types. For use below 5000 the Smaller Ports are Better. This reinforces my Idea that Mercury planned on those engines likely being entered in Racing Events that required Stock Carburation. The Heads could be changed to the Rectangular Port Heads, along with the Intake, but the Carb had to be the Stock Carb.

 

[tpenfield]

That blue/purple lighting looks really cool. I assume that you will be running with the engine hatch open just for visual effect.

Not sure if it was covered during this thread, but I assume the engine is a gen 5 454 The gen 6 had the roller lifters and may have avoided the issue.

My main concern about the in-boat repair is/was the ability to get any/all metal shavings from the cam shaft/lifter out of the engine. Hopefully you've got that covered.

 

[snowbrd84]

That blue/purple lighting looks really cool. I assume that you will be running with the engine hatch open just for visual effect.

Not sure if it was covered during this thread, but I assume the engine is a gen 5 454 The gen 6 had the roller lifters and may have avoided the issue.

My main concern about the in-boat repair is/was the ability to get any/all metal shavings from the cam shaft/lifter out of the engine. Hopefully you've got that covered.

Haha yeah a bit of mood lighting with mixed deck and engine room llighs.

Correct on Gen V, but the intake manifold might not be original as iwas told engine was rebuilt 2 years ago by PO. I wish I could have thoroughly cleaned the whole engine on a stand, but just wasn't an option right now. I will note that the cam lobe did not just wipe recently. The guy I bought it from two months ago said it has been lacking power and never went over 30 since he bought it after it was rebuilt. So who knows, maybe lobe wiped during rebuild break in and 4 or 5 oil changes since have cleaned a lot of the junk out. I got a great deal price wise knowing something was off, just not what exactly.

 

[snowbrd84]

It's alive. Primed oil pump, I stalled distributor, and it fired up after maybe 15 seconds cranking.

Immediately to 2500 rpm for 10 min, 2800 for 10 and 2000 for 10. Slowly throttled back and turned it off.
No oil anywhere, no strange sounds. Held 40 psi the whole time and 135 deg on the dot.

Next is confirm timing at 8 deg, idle at 650 and take it for a test drive.

 

[flashback]

May have missed it but I guess you changed all the lifters.

 

[snowbrd84]

May have missed it but I guess you changed all the lifters.

Yes, lifters came with new camshaft. Coated them in Driven Assembly lube.