Don Terrill’s Speed-Talk

70MC wrote: ↑Sun May 17, 2020 11:51 am What part number intake gasket are you using? From the pics it looks like a stock replacement gasket, I do believe they recommend performance gasket with aluminum intakes.

That was my initial thought as well. Unless everything is absolutely perfect, I haven’t had the best luck getting those type gaskets to seal well with an aluminum intake. I’ve had better results with the softer Edelbrock/mr. gasket performance type intake gaskets.

What rings? Who did the cylinder hone and to what spec? Today's rings should seat instantly.

PackardV8 wrote: ↑Sun May 17, 2020 2:54 pm What rings? Who did the cylinder hone and to what spec? Today's rings should seat instantly.

Mahle moly top ring. I sub the block work out to a reputable shop. Honed with torque plates 45* 400grit with plateau final.

70MC wrote: ↑Sun May 17, 2020 11:51 am What part number intake gasket are you using? From the pics it looks like a stock replacement gasket, I do believe they recommend performance gasket with aluminum intakes.

Good point. I’ll throw those on when I reseal it.

I suggest checking the angles of the intake face of the manifold vs the angle on the face of the heads. You can do the this by using lead pellets. Drill a 1/8" hole in your used intake gaskets. Drill the holes between the paired intake ports, even with the floor and roof of the ports. Do this on all four locations (eight pellets). Glue the gaskets to the heads and put a dab of grease in each hole, drop a lead pellet (shotgun shell pellets) in each hole. Install the manifold and torque up. Remove the manifold and measure and record the lead pellet thickness' and locations. Ideally the lead pellets at the floor of the ports should be compressed about .003" more the the pellets at the roof of the ports. You want to have the manifold slightly "pinch" the gasket towards the valley. Chevrolet blueprints show the angle on the intake manifold face and the angle on the intake faces on the heads are not the same. They are designed/machined to provide this interference fit. A 1205S-3 Fel-Pro gasket works well on these applications. They have a steel core for durability but use printed silicone beads on the composite face for conformability. Use silicone not end seals on the China walls.

Greg West wrote: ↑Sun May 17, 2020 3:19 pm I suggest checking the angles of the intake face of the manifold vs the angle on the face of the heads. You can do the this by using lead pellets. Drill a 1/8" hole in your used intake gaskets. Drill the holes between the paired intake ports, even with the floor and roof of the ports. Do this on all four locations (eight pellets). Glue the gaskets to the heads and put a dab of grease in each hole, drop a lead pellet (shotgun shell pellets) in each hole. Install the manifold and torque up. Remove the manifold and measure and record the lead pellet thickness' and locations. Ideally the lead pellets at the floor of the ports should be compressed about .003" more the the pellets at the roof of the ports. You want to have the manifold slightly "pinch" the gasket towards the valley. Chevrolet blueprints show the angle on the intake manifold face and the angle on the intake faces on the heads are not the same. They are designed/machined to provide this interference fit. A 1205S-3 Fel-Pro gasket works well on these applications. They have a steel core for durability but use printed silicone beads on the composite face for conformability. Use silicone not end seals on the China walls.

Great info. Thank you. I’m going to write this one down.

Ive seen intake & cylinder head intake runner casting flaws cause this

If it was smoking before the build, then there may be a build-up of oil residue in the exhaust system that needs to be burned out. Drive the truck for several miles at a sustained speed after the rings are seated, and make sure the exhaust/mufflers are not contaminated. Seen this lots of time before the advent of converters. Joe-71

If you're fresh out of 12 gauge cartridges, short lengths of solder will do.

Does the oil smell like gas? Carb float stick? Might be something simple.

Raybo wrote: ↑Sun May 17, 2020 9:12 am Brand new 383 I just built for a truck. AFR heads flat top engine. Runs great, once its up to operating temps it has some smoke coming from exhaust on both banks. I changed intakes, gaskets looked oily and there was oil in runners. Same thing happened. Checked studs to make sure they had sealer. Comp check looks good. I am pulling the intake again first thing in the morning to reseal. If that doesn't fix it I am tearing it down.

Your gaskets should be dry. It sounds like the manifold is not sitting down properly. Don't use the end gaskets as they may hold the manifold up. Use a quality bead of silicone instead.

Try mocking up the manifold with only the side gaskets in place & check how much clearance there is between the bottom of the manifold ends and the block. If there is not enough clearance adjust by removing material from ends of manifold.

If this is ok then make sure your bolts are not bottoming out.

I hope this helps.

Allan.

econo racer wrote: ↑Sun May 17, 2020 11:37 pm Does the oil smell like gas? Carb float stick? Might be something simple.

Clear sight plugs. I can see float level. Looks good.

I feel your pain bro. Have been fighting something similar for a long time. I finally bought a smoke kit to put smoke in the engine which helped me locate some leaks (among which an intake issue) that I since found. I also had one of those regular Felpro intake gaskets fail between 2 intake channels and meanwhile replaced it with an iron reinforced unit that helped great (ITB'd engine which creates a ton of vacuum on decel). Fit is good as I cannot see any smoke in the intake with the smoking machine (dirty stuff and smells awful but it does a great job BTW).

I also use the Wagner PCV which is great. Vacuum line to the engine is completely dry with it. I use it in combination with a Moroso Catch can which is also worth the $.

Compression test was great (very even across all cyls and only a couple of inches below what I had after new)

However, I still have a remaining smoking issue. Not always. Mostly on decal, sometimes at random (sometimes while taking a corner). I also replaced my valve seals which didn't do much. I'm now leaning towards the valve guides having too much clearance. This was also a new head when I assembled it onto the engine BTW. Seems like these assembled heads out of the box come with too much valve guide clearance a lot of times.

UPDATE
Swapped to the 1205 gasket with gasgacinch under the gasket. SO far so good. Got it up to operating temp and little smoke. I think it was residual. Shut it down and let it get a good heat soak and restarted with no smoke. Thanks for all the help. I appreciate each persons input.

Im glad to hear it.