VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Replace pistons and block rebore?

I've torn down a 1954 235 and started inspecting parts. I miked the bores and they basically are within the book's tolerances for out-of-round and taper and they look ok. I was surprised that the motor hasn't ever been rebored. As long as I have everything apart, should I still go ahead and get +.020 pistons and have the block rebored or save the money and put the old pistons back in with new rings?
I'm wondering what others would do because I only want to pull and drop an engine once.

Frankly as long as you have it apart a bore job would be the best way to go. I don't know how you plan to use the engine but it is a USED engine and replacing the rings my not accompish what you want. Did you check the crank, is it round and with in tolerance.

Back in "their day" it was common to just replace the rings if the walls showed little or no wear.Often these cars would come in with 60,000 or so miles, were using oil., but other wise ran OK.We would replace the rings, rod bearings, and wrist pins, adjust the main bearings and grind the valves and they would go another 60,000 miles.The factory rings were of very low tension and easy on the cylinder walls.Also the replacement pistons that you get today are of less quality than the original steel struts that the factory used.
If it were mine I would "overhaul" it.
AND replace the timing gears.

The cost of that "overhaul" job Gene is referring to was $85.00 at a shop that I worked at in the late 50's. Times have changed.

DD

In our shop it was $79.95....plus extra parts such as exhaust valves.etc.

Just take any ridge line at the cylinder off with a ridge reamer, break the glaze on the cylinder walls, check the mains put in a correct set of inserts and new piston rings, check the cam, cam bearings, cam and lifters as shown in the shop manual and have the head redone (grind the valves) replace the guides and seals if needed and get the car back on the road. You can always bore the engine and turn the crank but why? unless it is worn? Machine shops make a lot of money doing jobs that would better have been left alone. As Gene said replace the fibre timing gear and check the timing gear oil supply nozzle and make sure all the oil passages are clean of sludge. It would be a good time to replace the water pump and the oil pump, I check the oil pump and I have overhauled an oil pump but the clearance on the bottom and the gears is critical.
You are lucky to find such a engine, the last two I tore down were worn so bad, the pistons were frozen in the cylinders and the valve stems were about rusted into, The blocks made good trotline weights.

IT sure would be nice if the old timers can rebuild our engine for $85.00. I found a block been turned down already to 040 but the crank is bad at the Thrust so im going to day to look for one. Mr Mack you must eat your wheaty's if you use a Block for trotline, are the crabs that big this year

No crabs in this lake, just big old catfish!

Mr Mack:
I've already decided to replace the cam and lifters, but the crank mikes ok. Surprising to me. Even the endplay was within spec. You don't think I should have it ground though? Should I replace wrist pins?
So far it looks like the pistons are good. I don't know how to check the piston rods for straightness. Should I just assume that since the cylinder walls were in good shape that I have no problems there either.
Scott

Yes, have new wrist pins fitted.....If the cylinder walls are smooth nad bores measure with in .002" leave well enough alone.Does it have standard size pistons or was engine previously rebuilt?

They are standard size pistons. I don't think anything other than rings and a new head. The block is a 1954 235 but the casting number on the head appears to be a 1956 235.???

The 1956 head ending with 48 in the casting number is preferred by many inline 6 gurus, it gives a slightly higher compression ratio.

Interesting -- I wasn't aware that you could swap any of the later 235 heads onto a '54. Does using this head on a '54 235 require any change in the push rods or rockers? What about the cam profile with the higher compression?

If you bought a new head for a 1953-54 235 in 1960 you would get a 1960 head with an adapter for the temp. gauge.The latter heads fit the '53-54.Rocker arms and push rods don't need to be changed.
The 1959-62 rocker arms are different only because the oil grove in the later arms is off set to one side and not as deep.This is due to the fact that the 1959 and up had higher oil pressure to the rocker arms (block oiling change)....If you use a 1959 arm on a 1957 a little less oil will come out of the oil hole on top of the rocker arm.
The 1959-62 blocks fed oil to the lifter gallery from the front and rear cam bearing (earlier from rear only).The oil passed around each lifter (solid or Hyd)-met in the center of the bolck and went up to the rocker arms.Also the connector between the shafts was closed off so there was no spill over.This was done to help eleminate the clogging of the passage from block to head.
Various engine applications used a higher lift cam - head made no difference but stronger valve springs were required.The 1954 PG was the first to use the higher lift cam so from 1954 and up all had stronger push rods and taller, stronger rocker arms.The higher lift cam will not fit in a pre-1954 engine because it had larger cam lobes.The journals were made larger so the lobes would pass thru when installing the cam.
From 1959-62 they went back to a low lift cam for better low end torque and fuel milage.(except 261 engine).The larger displacement engine require a higher lift came for good performance (or larger valves).