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123pugsy 04-27-2011 04:18 PM

Blowby Crispies
I took off the passenger rocker cover from my 350 small block and found black sand like particles along the edge of the gasket and also starting to form inside the cylinder head. I knew I had some blowby as it was coming out the breather which I had installed on top of about a 10'' high tube to try to keep oil off the engine.

PCV valve may not be as effective as it should as this is a TPI engine with the wrong cam and vacuum drops off immediately upon acceleration.

I take it this blowby comes from the rings and is making its way to the cover with the breather as its the easiest place to flow to.

The block was rebuilt about 30 K miles ago and taken out of my last truck and left in the garage for a couple of years.
I then took it to a guy that does alot of high performance stuff and he recommended honing and new rings, bearings, cam, lifters. This was from a visual inspection.

I had asked originally to bore it out .060 but he persuaded me not to.

Is it rebuild time or time to change the cam and hopefully get better vacuum for the PCV system?

Can Specs: Comp CS 260H-10
Operating Range: 1200-5200 RPM
Duration Advertised: 260 Intake / 260 Exhaust
Duration @ .050'' Lift: 212 Intake / 212 Exhaust
Valve Lift w/1.5 Rockers: .440'' Intake / .440'' Exhaust
Lobe Separation Angle: 110

mud bros 04-27-2011 04:36 PM

that cam should work well its not overly large

problem is the egr crossover in the manifold bakes the oil and turns it to crusty crap the tbi system also runs on the lean side raising the operating temp of the engine.

also sounds like your using cheep oil as better oil can handle higher temps before turning to coke.

123pugsy 04-27-2011 04:44 PM


Oil is Shell Rotela.

The stock cam is actually 114.5 LSA.

Its a TPI setup.

The EGR crossover cooking the oil is a good thought although the blowby seems quite severe.

mud bros 04-27-2011 05:21 PM

you wont need to use rottela as it tends to loosen all the junk accumulated over the years due to high detergent levels.
it is good oil tho

mobil 1 syn would be easyer on loosening crud
and still have great protection(something i dont think will help now)

i think the egr is external on the tpi so that kills that idea too.

i guess its just plain wore out

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