This is driving my nuts. My brand new heads have maybe 10k miles on them, my rebuilt motor has around 1500 miles. Yet I still blow smoke on startup. What in the world can be causing this? It drives me insane!

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Mark Lock
- 86 IROC-Z - SuperRammed 383/T56
- -= IROC Online =- - The site dedicated to the IROC-Z

 

That would be heads.

Put some positive valve guide seals on it. Use the Teflon variety. Crane has them in a variety of sizes to fit most of the typical guide diameters.

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"So many Mustangs, so little time..."
ICON Motorsports

 

What do you mean by positive? Right now it has what I call umbrella seals that slide down the vavle and rest on the top of the valve guide. When I had the heads off, I checked several of them and they all looked good.

 

Your rings are probably not seated yet, especially if you used moly rings. Moly rings usually will not seat for a few thousand miles.

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Hybrid 89-92 Black 5.7L 5 Speed
'95 Competition Yellow Corvette Coupe ZF6

 

I did go with moly rings. Ive got about 1500 miles on the motor now. I didnt expect them to take this long to seat since I had the bore done with a tourque plate. So I should give it a litle more time before panicing?

 

The umbrella type seals just kind of ride on the valve stem. They only keep oil from running down the valve stem to the top of the guide, which often still allows some oil to run down the stem into the intake ports. The positive type have metal clamps around them that hold them to the guide, and the valve stem slides up and down through them. They prevent oil from getting to the guides, period.

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"So many Mustangs, so little time..."
ICON Motorsports

 

Hmm good description. Thats the kind I have on there now and they appeared to be in good shape.

 

umbrella seals are total junk.
they are not even good when they are new.

I nor anyone I know would put them on their heads.

 

One other possibility, a litle more remote...

The bottom of the intake ports is the crankcase. A bad intake gasket at that point will leak oil into the intake, and vacuum into the crankcase.

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"So many Mustangs, so little time..."
ICON Motorsports

 

I'm with this vote. the old style umbrella ones just don't cut it. Add the new Teflon ones that Jeg's or Summit has. You may have to take the heads back off to machine them down to .500 or .531. But that will stop it.




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350 4 bolt main, Speed-O-Motive 383 stroker kit, re-sized rods ground for clearance,TRW Forged pistons,10.7:1 compression,HPC Coated RPM intake, Speed Demon 750 cfm carb,World Products Sportsman II heads,2.02/1.60 valves, Comp Cam 1.6 roller rockers, Comp Xtreme 284 cam,240/246@.050 with .540 lift,Crane pushrods,ATI damper,Proform HEI and MSD6A box,HPC coated 1 5/8 headers, 2.5" exhaust with 40 series mufflers,TH350 with B&M 3000 stall, Powertrax NoSlip Locker, 4.11 gears.

 

I've built my fair share of motos with moly rings and never had a problem with them seating quickly. Of course, they take longer than plain cast-iron, but I've never seen them take even as much as 1000 miles to come up to full compression. If the bores are properly prepared (correct grit of hone stone!!!) they should be fine. If you had your block prepped by someone who knew what a torque plate was, let alone actually used it, and they knew what kind of rings you were going to use, then that's not the problem. Which is a good thig for you, one less thing to worry about.

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"So many Mustangs, so little time..."
ICON Motorsports