351w 2v. Mostly stock but had some work done at some point since gaskets aren’t factory, but I can’t find hard parts that were replaced.
Quick summary, the cylinders are polished from wear, but very close to a stock 4.0 in with only a slight ridge that I think is mostly some carbon build up. I asked for a clean and hone to see if it is capable of using stock diameter pistons since the original 9.5 compression pistons look good and measure round. The press in pins look good as do the rods/caps, so am I foolish to clean them up and reuse them? I am keeping the stock cam and the only notable upgrade is a 4v performer intake and a Summit 600 CFM carb, so there shouldn’t be any significant increase in stress on components.
I’m also considering putting in flat tops and trying to recreate the 10.7 static compression ratio of the M code motor. Is there an aftermarket piston that is close and works with my 69 block deck height, and if so, am I risking detonation on 90ish octane ethanol free gas?
It may be helpful to explain why the engine was taken apart. Was is using too much oil? Fixing what was broken plus some mild upgrade? Having it gone through for peace of mind? Possible future plans? These answers should help getting to your goals.
It started with a rear main oil leak and loose timing set. Everything was textbook until I tried to get the factory rope seal out of the block. The cap portion and pin were silly easy and then I used every trick I could research to get the rope seal out of the block above the crank to no avail. I didn’t want to drop the crank out of the block so I pulled the engine and solved the problem on an engine stand. Once I was that far in and not knowing the history of the motor, I ended up where I am.
This is a weekender and local show car, so I’m not looking for a high rpm racer.
If the block cleans up and the bores aren’t excessively tapered or out of round, you can put a proper hone on it and re-ring it with the existing pistons. I’ve done this plenty of times with engines that were good runners but leaked/consumed oil/ or smoked badly. They lasted many tens of thousands of miles for minimal investment.
I would definitely have a valve job (and guides if needed) done on the heads. Have the crank checked out and ground if required.
It started with a timing set replacement and as long as I had the oil pan dropped, it made an opportunity to replace the leaky original rope rear main. It was so rotted it wouldn’t pull or press out, so the crank had to come out, so I pulled the engine to do that…and well…kept finding until I had a bare block! I already had a new Melling pump and pickup based on info from others who had seen clogged mesh from the nylon bits of the cam gear, so those are definitely going in. The “how did I get here” story is a long one!
After years of being jerked up and down the journals are not round anymore. The machinist takes a couple thousandth off the rod cap then grinds the journal round again to spec.
I use a set of flat tops to get over 10.5 in my W, more or less like the factory. You’ll just need to know how far in the hole your pistons are, which the machine shop should be able to help with after they measure deck height after cleanup. You can adjust a bit with head gasket thickness and calculate compression theoretically fairly easily.
FWIW, mine runs fine with no pinging. But I also use Alu heads and a pretty dialed in ignition, which make a difference in what it will tolerate.
Good info and since I will be using the factory iron heads and stock distributor, I will likely stick with a lower static ratio since it is a cruiser and not a strip car.
I am always amazed at how well the completely stock but fresh 289 and 302 cars run. Not fast but just great drivers. Just adding a larger front sway bar is about the only thing that is lacking. And in a lot of grid iron country with hardly any curves you can live without that.