Thread: 400 SBC problem - Newbe

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We have a 1965 Austin-Healey replica that is loads of fun. We had it painted this past winter and the new color makes it look great. There are always 2-3 people standing around and looking at it when at car shows.

The engine uses about 1 quart of oil it when we drive about 120 miles 55 mph and above. Oil pressure is about 80 lbs when cold and goes to about 60 lbs when warm. When coming to a stop oil pressure drops to about 10 lbs when warm.

I noticed the other day after driving home (about 35 miles) and engine was warm, I stopped to pick up a few groceries. When starting up the car it shot blue smoke out of both pipes. I had the cylinder pressure checked a couple years ago and they were about 125 PSI. Does this indicate valve seals, valve seats or rings need replacing?

What would a rough estimate be for re-bore, pistons, rings and heads be?
Thank you for your feedback.

Duane

The cost could run the course from a few hundred to a few thousand, depending on who does what. To do it properly, I'd set aside about $1000 just for machine work. Begin with getting the main bearing bores round and parallel with each other, then register the block on the mains and cut the decks to square based on the stack of parts you will use. Then bore the block to the pistons you want to use. If you get the block squared up, the heads will sit level on the block, the manifold will sit level on the heads and everything should seal up properly. It may be close as to spending the money to refurbish the cylinder heads you have currently or choosing a new set of first-class aluminum heads. Pro-Filer 195's can be had complete for under $1100. That's the head I would choose for you if it were my job to do so.
SBC 23 Degree Cylinder Heads
Make sure whatever heads you use are drilled for steam holes.

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Welcome to CHR, Duane! Hope you find what you’re looking for and that you have a nice long stay here. Love those old Healeys. Had a coach in high school that drove a 3000 – black with tan leather and a real wood dash. Sweet little rides.

Blue smoke is never real good. There are typically two causes – one fairly easy to remedy and the other is, as you’ve alluded to, rather costly. I’d start with the breather system. Make sure you have a clean PCV valve and a clean breather on the engine. Typically there is a breather in the valve cover on one side and the PCV valve on the other. Soak them in a non-flammable solvent overnight and see if that helps with your problem.

The oil pressure numbers you mentioned are not atypical for a SBC – especially one with a few miles on it. Do you know what the mileage is in this engine? Have you pulled the plugs and looked at them? 125 is well within specs for a SBC (100-160PSI) so I wouldn’t jump to rings right away. Valve seals could be the culprit and they can be replaced with the engine in the car. It’s an “all-day-sucker” and you need to have a few specialized tools to pressurize each cylinder and compress the springs. It can be a little tricky and it’s easy to destroy the new seal if you’re not real careful. Watch this little video to determine if it’s something you can tackle of if you want to have it done.

https://www.youtube.com/watch?v=OsGqmOQus6Y

The guides could be worn and to properly fix requires pulling the heads and have them knurled or replaced.

A quart every now and then might not be such a bad thing at this point.

Let us know what you decide. Again, welcome to CHR!
Glenn

A puff of blue on starting is usually valve seals or guides. I have had several 400's and they all did it, the local guru said it was a result of the large diameter, short skirt pistons. Pick a story you like, I guess.

Thank you very much for your expertise and advice. I will have these things checked out to see if a rebuild will be the best route to take.

Thank you for your great reply and advise. I will be taking the car into the shop the end of September to be checked out. From the sounds of things it might be the valve seals. Thanks again.