I have a 327 I have just tore down. Took a reading on the bores any where from 4.003 to 4.005 I would like to hone and put new rings in. This is a 68 L79 motor dome pistons all original. Will be porting the heads new manifold, cam, lifters. Crank is perfect was hoping to use the original pistons and rods. Can I get a away without boring the block? If I have to bore the block and get new pistons can I still use the same rods there is nothing wrong with them.
Stan

anybody?

What are you measuring the bores with? If you have .005 wear, then I would bore it. You may still be able to get .020 pistons. No sense in going .030 if not neccessary. How do you know the rods are perfect? I would bet they are out of round. The small journal rods are not the strongest with the small 11/32" bolts. They do work well if prepped correctly. Have them checked and resized if neccessary.

Chances are if those walls have .005 taper in them you will find the ring lands will show some wear as well.

I would bore it and if you want a good jobe have it plate honed for good round cylinders with the heads torqued on.

Those rods use 11/32 bolt have them resized and checked for bend and twist and they should be fine.

Good luck with your build.

Thanks for all the good info. Also the rods are the large ones 3/8 bolts.

Thanks for all the good info. Also the rods are the large ones 3/8 bolts.


Must be a late 68 vintage

Large journal 327? pretty uncommon, I've never seen one dressed as L-79.

What the other guys said, if you want a good engine that lasts, doesn't burn oil, etc bore and hone with torque plates. L-79 has too much compression to run pump gas and run right. You'll end up retarding the timing and whatnot to keep the pinging under control. Get a set of flattop pistons if you're going to use the factory iron heads and something resembling the stock cam.

I have a 327 I have just tore down. Took a reading on the bores any where from 4.003 to 4.005 I would like to hone and put new rings in. This is a 68 L79 motor dome pistons all original. Will be porting the heads new manifold, cam, lifters. Crank is perfect was hoping to use the original pistons and rods. Can I get a away without boring the block? If I have to bore the block and get new pistons can I still use the same rods there is nothing wrong with them.
Stan

Stan,
There are some "ifs" and "maybes" here.
First, where did you measure the bores, top or bottom?
If the bores are a MAX of 4.005 at the bottom, you MAY be able to hone the cylinders and re-ring it. But if the max bore is 4.005 at the top of the cylinders, then it is likely the cylinders are tapered and you will see 4.006-4.008 at the bottom. Makes a big difference where you took the measurement.
Now, on a couple of 283s, years ago, with negligable wear, I had the machine shop lightly hone the cylinders (took off .001-.002), and they were .005-.007 oversize. I installed new rings and bearings and rebuilt it from there. It ran GREAT, no smoke, virtually no oil consumption for several years until the owner wrecked it.
Sooooooooo, in my opinion you CAN fudge and get by (ya, ya, ya, ya, all you engine experts, I know you're gritting your teeth) with .004-.007 cylinder oversize, AFTER HONING, with new rings. You may also want to consider having the pistons knurled. If this was going to be a long term, daily driver that would accumulate LOTS of miles, I would be against doing this. But if it is to be an ocassional driver, I would not hesitate doing it in a heartbeat. If you do just hone it and rebuild it with the std pistons, BE SURE the ridge at the top of the cylinders is removed (if the ridge is left, the new rings could damage the top ring land of the pistons).
One last comment. IF, just IF, you hone the cylinders, re-ring it and go back with std pistons, there is a chance, not very big, but a chance you will notice a little piston slap when the engine is cold. The L79 pistons were forged, not cast, thus engines with forged pistons are built with slightly larger piston-to-cylinder clearance, and after start up, until the engine is warmed up, it is possible a little piston slap may be noticed. The 350 in my 51 Chevy which I built 33yrs ago sometimes has some piston slap when its real cold. And 33yrs later, its still my daily driver with 200K+miles on it. :D

Rods,
Yes, you certainly can re-use the stock rods. The rods used in L79 engines were good rods. They are the large journal version (2.1in rod journals). ALLLLLLLLLLLLLLLL 68-later small blocks have the large journal rods, no exception. Even the SB400s used the same size rod journals (but a shorter rod).
If the engine is currently in good shape (just lots of miles), and the crank is in good shape, I would not even have the rods re-sized-------------------UNLESS, you install new rod bolts. And, depending on the overall condition of the engine, I'd probably re-use the original rod bolts (if it were a small journal rod, I'd definitely install new ARP Waveloc bolts and have them re-sized). The ONLY thing that I'd have done to the rods is have them shot peened.
That's what Tom Parsons would do if this is only going to be a pampered, ocassional driver, and the desire was to keep it moderately stock.
I WOULD put in a new L79 profile cam/lifters, or, if your original L79 cam still has good looking lobes, you may want to consider having it reground and installing new lifters.
Also, I WOULD spend extra money on the heads and I'd be VERY careful about how much material is removed. Personally, I'd only have the intake ports/intake manifold port matched and just "clean up" the intake runners and lightly "clean up" the bowls. The important areas would be the valve guides and new seals. I WOULD NOT have hard exhaust seats installed, because there now seems to be enough experience with older heads and unleaded gas which supports that INSIGNIFICANT wear has occured in MOST vehicles that are not continually subjected to severe duty over extended periods. The stories of valve wear/seat recession (particularly ex valves/seats) now seems to have been somewhat of a scare tactic. My reasoning behind this is because your heads are 40+yrs old, and old, 2.02 heads could very possibly be borderline prone to developing cracks (depending on past usage, abuse and heating). The 2.02 heads are quite thin between the intake and ex seats, and to cut them for installing hard seats is less than ideal. And one last thing I'd do to the heads is install a set of good stainless valves.
Now, you are going to get lots of input on what I've said. There really isn't any right or wrong way to rebuild your engine. I'm just providing input based on how you've described your engine and your desire to (if possible) stay with stock size pistons.

Large journal 327? pretty uncommon, I've never seen one dressed as L-79.

What the other guys said, if you want a good engine that lasts, doesn't burn oil, etc bore and hone with torque plates. L-79 has too much compression to run pump gas and run right. You'll end up retarding the timing and whatnot to keep the pinging under control. Get a set of flattop pistons if you're going to use the factory iron heads and something resembling the stock cam.
sounds like a good E85 motor starting point to me... keep some domed pistons in it and run the smallest chamber heads you can find to clear the domes...

I have a 327 I have just tore down. Took a reading on the bores any where from 4.003 to 4.005 I would like to hone and put new rings in. This is a 68 L79 motor dome pistons all original. Will be porting the heads new manifold, cam, lifters. Crank is perfect was hoping to use the original pistons and rods. Can I get a away without boring the block? If I have to bore the block and get new pistons can I still use the same rods there is nothing wrong with them.
Stan

What do the pistons measure ?

See what the piston to wall clearance is and dont just go by bore,, I have seen GM do strange things plus it could have been rebuilt by a rebuilder

The bores may measure 4.005" but the piston may measure 4.002" for example

He, He!!

Dingle-berry hone her and then knurl BOTH the piston skirts and valve guides and GO!!

pdq67

Thanks again for the help. 12 to 1 motor up here is not that big of a thing. We are at 5000 foot run 93 fuel and it does not ping. At sea level I could see where that would be problems. Motor only had 3000 miles on rebuild. It never burned a drop of oil. Tore it down for a father son project.
Stan

5000 feet, that's point or 2 of CR. Where are you in Mt? I lived in Ronan one time, near starved/froze to death.

Large journal 327? pretty uncommon, I've never seen one dressed as L-79.

What the other guys said, if you want a good engine that lasts, doesn't burn oil, etc bore and hone with torque plates. L-79 has too much compression to run pump gas and run right. You'll end up retarding the timing and whatnot to keep the pinging under control. Get a set of flattop pistons if you're going to use the factory iron heads and something resembling the stock cam.

Tom,
There were TWO 68 L79s at CB07. One was HD 3sp (floor shift), the other was 4sp.
Were they genuine? If not, they were the best darn clones I've ever seen!!! :thumbsup:

By the way, there were 9,440 L79s in the 68 Vettes.

Tom, we live in Livingston, 30 miles from Bozeman, 50 from north entrance to Yellowstone Park. The park is a fun place to criuse in the spring and fall to many people in the summer. 100 cars stop to look at a damm rabbit.
Stan