Engine and Transmission Tech

I have a 215" block with '64 Buick 300 heads. I used the Felpro 8172 head gasket as recommended in the 1985 Hot Rod article. My #7 cylinder is full of coolant and it appears that the gasket has leaked between the water jacket and the cylinder. Both the head and block surfaces had been planed. Since this gasket is for an engine with a 3.75 bore but my engines bore is just 3.56 it provides a narrower mating surface than a gasket for the smaller engine. Is there an alternative gasket?
As I unbolted the head I noticed that several of the lower head bolts seemed to unscrew very easily as soon as they broke loose. I am doubtful of the strength of the threads in the 52 year old aluminum block. Since this head is on the driver side it is very close to the steering shaft and I had to disconnect that motor mount to get access to those lower bolts. Should I try to install helicoils or a comparable product? Would I have to pull the engine? Would ARP studs be necessary? What do you do if, when tightening a stud the block threads let go?

A very serious problem, and more common than folks will admit.
Having tried the standard solutions I would suggest you first try the studs. The extra thread engagement may provide the strength you need to avoid thread pull-out. If that doesn't work you have little choice but to try helicoils or threaded inserts. Helicoils can be done in the car, possibly inserts as well. There is room to stack two helicoils. You need to make a guide to be sure the tap goes in straight, this can be done using a bar that bolts or clamps to the block. But even with this I'd recommend the studs. I've heard that the later Rover blocks have stronger threads.

The ultimate solution? The iron Buick 300 block.

Jim

Several head gasket options listed on the D&D site - suggest giving Mark a call for a recommendation.
GUG-702538 Head Gasket – .016 embossed for 3.5” bore Buick or Rover.
ETC-7819 Head Gasket – .018 embossed for 3.7” bore Rover.
ERR-7217 Head Gasket – .050 composition for 3.7” bore Rover.
8172-PT Head Gasket – .040 composition for 300” Buick.
1174-BS Head Gasket – .040 composition for 3.5 bore Buick or Rover.
7984-PT Head Gasket – .040 composition for 3.5 bore Buick or Rover.
7995-PT Head Gasket – .040 composition for 3.5 bore Olds.

Jerry, If I recall correctly, that Felpro is smooth steel, on one side ? Theses aren't too forgiving, on this kind of problem. IMHO, a Rover composition gasket should seal better.You might also use a sealer around the leak areas. 14 bolt Buick block ? Buick 300 heads don't use the bottom row,(near exhaust ports). Do you mean bottom row of (10) bolt pattern ? If so, very important to have suitable threads,(at least 50%). I always use "Time Serts", as they are solid, thin and strong. If converting to studs, 5lbs. MAXIMUM torque into block. Ok to use a steel ball, in bottomof hole to keep stud threads, from bottoming on deck surface. Because studs are fine thread on top, I would reduce the final torque #. Don't give up on aluminum blocks, just because Jim B. did. Good Luck, roverman.

I am delighted and impressed by all 4 helpful replies within 8 hours!
No chance of using a 300" Buick block. In a Healey there is not enough room on the left side of the engine. In truth a 289-302 Ford would be a better fit but I wanted to stick with the quasi-British engine.
Yes the Felpro gasket is smooth on one side. I will phone D and D for advise on which of the gaskets cited by ex-tyke would most improve my odds.
I am inclined to try the "Time Serts" cited by roverman. I may resort to studs but balk at the nearly $200 cost given that, so far, one head seems to be sealing.
I certainly hope to get this resolved without pulling the engine. If it comes to that I have a fresh rebuilt 215 with rover 4.0 heads and an aluminum crankcase that I will install. By the way the engine in the car has a girdle which I made from a plate of T6 aluminum when I first put the engine together over 30 years ago. I had to mill the tops down on the main caps to make it work. (I had been spooked by a guy who blew the bottom out of a 215 he had in a dragster.)
Many Thanks Guys,
Jerry

You might check around to see if you can get a mls (multi-layer steel) head gasket. If you can find them those are quite good. Also, those bottom (3rd row) head bolts are decorations.

Jim