SBC 383. Blow by

[73c34me]

Aluminum heads. I ran 93/94 octane with a boost, 180-190 coolant temps and did not lug the engine. Perhaps that compression ratio can’t be done. Track time would have had race gas.

I will start with a camera inspection and see if I can borrow a decent leakdown tester.

[F-BIRD'88]

A compression ratio of 10.5:1 will be a lot more reliable on your 93/94 pump fuel. There is no free lunch.

[73c34me]

Update. I drove the car approximately 100 miles the other day. No changes from before, which facilitated my original post. I drained the catch can after the drive. I got about a teaspoon of oil. I could not see tail pipe smoke, but am sure there would be some. My original post- i drained nearly a cup of oil from the catch can after a 125 mile drive, so a big reduction. I have ordered an oil analysis kit and will use a bore scope soon. But currently- the car runs really strong and good...

[C.A.R.E.]

While you inspecting things with the Bore scope check the pushrod relief in the heads. When the last head work was done it may have been ported to thin and be cracked from the port to the pushrod relief. It'll pull oil thru the crack. Especially high vacuum ( idle & coasting with the throttle closed. ASK Me how I know !

[73c34me]

Good advice! I have wondered if i am pulling oil from a crack. A couple areas were getting a little thin during the porting phase... the porter was stubborn! I am the guilty party.

[73c34me]

Update. Flipped the breather and PCV around; pcv on driver side. Replaced the hose to catch can w/ clear reinforced hose. I can see an oil trail flowing up the hose to the catch can.
Also, layed painters paper (thin)over valve cover (pcv) hole. When running it does not suck into the cover. It pushes away slightly.
Also. Sprayed some carb cleaner in the same hole on engine idle. It did not pickup rpm. Duplicated this test using acetylene- again no change in rpm.
Blackstone oil analysis kit arrived in mail. Will sample and send off in a day or two.
Will get a borescope on my next session.

[Schurkey]

Update. Flipped the breather and PCV around; pcv on driver side. Replaced the hose to catch can w/ clear reinforced hose. I can see an oil trail flowing up the hose to the catch can.

Excessive blow-by, or insufficient baffling. Maybe both.

layed painters paper (thin)over valve cover (pcv) hole. When running it does not suck into the cover. It pushes away slightly.

Confirmation of excessive blowby; assuming all is well with the PCV valve and intake vacuum.

Also. Sprayed some carb cleaner in the same hole on engine idle. It did not pickup rpm. Duplicated this test using acetylene- again no change in rpm.

Not surprising, since the excess blow-by would push the carb cleaner or acetylene right back out the hole.

[73c34me]

Removed the carb today, looked down the intake runners. I can see where the bottom edge of the fel-pro 1205 gasket has raised up to where the printo-seal is visable. Also, oil is present on the floor of the intake. I have dimpled the floor with the tip of a 3/16th drill bit. Most of those divots have oil in them. Pretty sure i am going to need a corrective cut on the intake manifold face; block cut .020” & heads milled .025”. Whrn i pull the manifold i will inspect with a borescope.

[Schurkey]

Removed the carb today, looked down the intake runners. I can see where the bottom edge of the fel-pro 1205 gasket has raised up to where the printo-seal is visable.

I had a 1205 issue that was similar. My fault, not the gasket maker's--I just used a gasket set that had too-large port openings. Over time, the gasket extruded and deformed until #1 and #3 were dead at idle due to vacuum leaks; and the center dividers on each cylinder pairs were distorted. Replaced with a Fel-Pro 1256 intake gasket set, end of problem.

K1500_2020_Intake_Gasket_01.jpg

K1500_2020_Intake_Gasket_04.jpg

[Bob Hollinshead]

a leaking intake gasket will burn some oil but will it create blowby past the rings?

[turbo camino]

After the oil from the leaky gaskets gets mixed into the charge and causes detonation and breaks stuff, yes it will.

[MadBill]

... Pretty sure i am going to need a corrective cut on the intake manifold face; block cut .020” & heads milled .025”. When i pull the manifold i will inspect with a borescope.

It would be useful to also check for angular misalignment, perhaps via the "Plasigage on steroids" approach: Cut 1/4" lengths of (preferably resin core) solder and using dabs of grease or silicone, locate one at the top and bottom at each end of the intake gasket surfaces of the heads and at the four corners of the China walls, then carefully lower the manifold into place and torque the fasteners enough to slightly compress the solder. Measure and compare the thickness of each. A lot of guys like to see the bottom clearances a little tighter and the China wall gaps larger.

[73c34me]

Thank you for the steroid plastiguage tip; will do.

[73c34me]

Pulled the intake today. A couple ports look like pulling oil from the valley. However- all the closed intake valves had a puddle of oil in the bowl and valve head. I am thinking the guides may be bad. Gonna pull the heads. Pics

030D2603-755F-41EA-8829-41A85F26FECA.jpeg

26B104D5-E3AE-4F73-A8AC-D9312A218571.jpeg

DCA47482-B1A6-46F6-ABE2-36542BC608A5.jpeg

[73c34me]

Removed passenger side head. Cylinder walls looks ugly. #8 looks similar

attachment=0]045745DD-5C5A-4758-8DEA-62FEA198DC60.jpeg[/attachment]

5B0C2996-9734-4B75-A649-8F6D7886B190.jpeg

41DC4152-B873-417A-8465-32FA1C8DFA97.jpeg

E912FE3D-1374-4396-AE8C-92433AD0453D.jpeg