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Ford 302 rebuild

813 Views 19 Replies 12 Participants Last post by  BogiesAnnex1
Hey, im rebuilding a ford 302 and when i got the engine I noticed that the engine at some point got bored .04 over. When i took the engine apart i saw some odd dark marks on the inside the cylinders, i dont know if its a casting defect or if its rust from the engine sitting or something else. What do yall think it could be? And what should i do?
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Super rustry block that didn’t clean at .040 over. That’s about the limit on these thin wall blocks. Going over that should really not be done without a ultra-sound inspection. Some blocks will go .060 over but that’s fairly rare.

Bogie
 

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Is that hone job as rough as it looks in the first two pictures??
Because damn, looks like it was done with 80 grit !?!

I agree with Bogie, that's either rust deep enough that the bore job to .040 didn't fully clean up...
OR
It was a nice bore job, but then someone let it sit exposed with no rust preventative on it and it got rusty, and was then hand honed by the assembler who tried to clean it up and put it together.


Was the motor down for a rebuild because it was using oil, burning oil??
 

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Hey, im rebuilding a ford 302 and when i got the engine I noticed that the engine at some point got bored .04 over. When i took the engine apart i saw some odd dark marks on the inside the cylinders, i dont know if its a casting defect or if its rust from the engine sitting or something else. What do yall think it could be? And what should i do?
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Take it to a machine shop. Ball hone in a situation like this is a band aid at best. Don't try to re ring it this way. You won't be happy with the outcome.
 

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Discussion Starter · #6 ·
Is that hone job as rough as it looks in the first two pictures?? Because damn, looks like it was done with 80 grit !?! I agree with Bogie, that's either rust deep enough that the bore job to .040 didn't fully clean up... OR It was a nice bore job, but then someone let it sit exposed with no rust preventative on it and it got rusty, and was then hand honed by the assembler who tried to clean it up and put it together. Was the motor down for a rebuild because it was using oil, burning oil??
I have no knowledge of what happened to the engine before i got it. The person i got it from said he took it out running and then it sat for awhile. I also tried to look up the machine shop that did the previous bore but it is now desolved and isnt around anymore so the previous history is unknown besides the obvious. I plan on using all completed new parts. Im trying to avoid boring it and adding sleeves. Which would be cheaper than buying a 302 core from what ive seen.
 

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Discussion Starter · #7 ·
I have no knowledge of what happened to the engine before i got it. The person i got it from said he took it out running and then it sat for awhile. I also tried to look up the machine shop that did the previous bore but it is now desolved and isnt around anymore so the previous history is unknown besides the obvious. I plan on using all completed new parts. Im trying to avoid boring it and adding sleeves. Which would be cheaper than buying a 302 core from what ive seen.
Also i forgot to mention that there is some rust inside the block in the water passages. So its gonna have to get cleaned by a machine shop.
 

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If this is a performance build, anything more than three sleeves needed most (honest) machinists will tell you it's scrap.
You bore away too much parent material.....4 sleeves or more and you've got a block that is weaker than it was stock.
I know a lot will say even one sleeve is not good, being the stock block SBFord is a really thinwall casting.
Sleeve a daily driver or a occasional use vehicle, but not a performance build on a stock block.

If it is a performance build, and you plan to use forged pistons you could look at just having them made custom in .045 or .047" oversize, maybe even .050" oversize and then you could just have the shop hone it to the new oversize to clean it up nice (y) . Get a nice modern narrow ring package, let the company guide you there to what the best fit is.
 

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Hone it with the right grit for the rings you are using and run it. Unless you are "already on the podium" the nano-percent of performance you might loose means nothing.
 

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The person i got it from said he took it out running and then it sat for awhile.
I've seen perfectly good engines ruined by "sitting for a while". One was an SBC with a fairly fresh +.040 bore and pistons. It was inside a small shed that was open on one end. Of course that's where the engine was sitting! It was even covered with a large plastic yard bag, but the wind moved the bag around and the rain got inside a couple bores through cylinder head intake ports. The owner thought he had a fine, low mileage engine until I pulled the heads, Sad.
 

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Hey, im rebuilding a ford 302 and when i got the engine I noticed that the engine at some point got bored .04 over. When i took the engine apart i saw some odd dark marks on the inside the cylinders, i dont know if its a casting defect or if its rust from the engine sitting or something else. What do yall think it could be? And what should i do?
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Build it and run it. While not perfect, like new, it will work VERY well for a long time. After you build it run it a couple of thousand miles do a compression test and a leak down test. I expect you to find very good results. If not then just sell it, I am betting it will be great.
 

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Discussion Starter · #16 ·
So im trying to do this all by myself as a project. How would i go about cleaning the water passage and crap? I noticed theres a lil crystal/rust crap from what i think it came from the engine not being properly drained. What would Yall recommend to do to get it all cleaned. Or just say screw it and get a machine shop to clean it?
 

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I just did a re-ring job on my 5.0. I used a 240 grit ball hone and it did a great job. Do about 40-50 passes per cylinder and do the last 10 passes rather fast. That'll give it a good 45* crosshatch. I used a 1 gallon milk jug with the top cut off and filled it with a couple of quarts of 30wt for lubricant. Just dunked the ball hone into it and went to town. Oh yeah....it'll make a mess!

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Get a machine shop to clean it especially if you can find a shop that still hot tanks.

The cylinders are shot if there are divots in the wall that either allow combustion gasses around the rings and hold pockets of oil. Combustion gasses getting around the rings will give the engine considerable blow by. Where they can hold pockets of oil that will be pumped into the pressure holding rings gumming them up and into the combustion chamber where the oil will burn. None of this leads to an engine that runs clean nor runs a long time. If your thinking of high performance use the very hot combustion gasses escaping around tge rings will erode the piston structure supporting those rings, this will go bad to worse in pretty short order. These walls either need to be bored till smooth if there is enough material remaining to leave a sufficiently strong wall, or they can be bored out and sleeved this is a pretty expensive process but very successful one.

You really need a professional engine machinist to look at this to see if the walls are salvageable by boring. In the end the cylinder walls need to be round and straight top to bottom and centered on the crank throw. Ball honing while looking pretty is unlikely to deliver any of these technical constraints.

Bogie
 
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