Noob: How do I tell if an engine needs a rebuild?

dubbsix

Member
Oct 18, 2006
347
2
19
Katy,TX
How do you figure out if your engine needs a rebuild without having hear it run? Bought an 88GT with a bad fuel pump. I ended up yanking the motor to replace all gaskets and upgrade cam.. but now im stuck trying to figure out if i should just have it totally rebuilt.

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If you already have it apart, You might as well strip it down to a bare block & take it to a machine shop so they can check the crank, rods, & cylinders. this way when you put it together you know every thing is in good shape. Depending on your power goals, it would be a good time to install upgrade parts or at least the shop will let you know if you need stock or over sized bearings & rings. you could get away with just bearings & a re-ring kit. plus they will clean the block & let you know if its worth building or if its cracked or whatever. better to do it right the first time than to be sorry later. you could put it together as is only to find out you have a rod knocking or no compression or things like that & have to do it all again. just my opinion.
 
I was thinking the same thing. I guess i'll just have it rebuilt. The only problem I have his my rebuilder says that the replacement pistons are cast.. but the pistons in there now are forged. That doesnt seem right!
 
No. I got a rebuild kit from Summit & I got forged pistons with mine. They actually upgraded my kit to Keith Black pistons because the Summit ones where still on back order 2 months after I received the rest of the kit. I did my own engine rebuild. I got a stand on craigslist for $20. Then I bought a cheap ring compressor from autozone & some assembly lube. I also bought a "How to rebuild the small block ford" manual there too. It's about $20 too. The rebuild kit came with the plastic gauge to measure the bearing clearances & every thing else was just fallow the step by step instructions & torquing everything to spec. Its not that hard & you will have a huge since of pride when you are done to be able to say "I build that". My rods had all been stamped with the cylinder they came out of. not sure if that is a factory thing or not. the pistons had a little arrow pointing to the font. also make sure you keep the rods & caps together.
 
If the bores are in good shape you do not need to replace the pistons, clean what you have, upgrade rod bolts, new rings, bearings, oil pump and timing chain...
 
No. I got a rebuild kit from Summit & I got forged pistons with mine. They actually upgraded my kit to Keith Black pistons because the Summit ones where still on back order 2 months after I received the rest of the kit. I did my own engine rebuild. I got a stand on craigslist for $20. Then I bought a cheap ring compressor from autozone & some assembly lube. I also bought a "How to rebuild the small block ford" manual there too. It's about $20 too. The rebuild kit came with the plastic gauge to measure the bearing clearances & every thing else was just fallow the step by step instructions & torquing everything to spec. Its not that hard & you will have a huge since of pride when you are done to be able to say "I build that". My rods had all been stamped with the cylinder they came out of. not sure if that is a factory thing or not. the pistons had a little arrow pointing to the font. also make sure you keep the rods & caps together.

thanks for the tips and I would take the same pride in saying I built it too. I will have to make sure my guy at the shop knows that the stock replacements should be forged.
 
"Well, you've gone this far......"

Too bad you didn't do a leak-down and compression check before tearing it down. It does look like you have some ridge on the tops of the cylinders, but the cross thatch pattern on the cylinders still looks good.

I know of many people who have done whats called a Refresh where they put in new bearings and rings while they were in there. It works but usually it doesn't last that long. Kind of makes the engine run like new, but the worn parts don't extend the life of the engine much. Refreshing is generally for a newer, less worn motor to keep it at 100%. Many racers I know refresh their engine every year, however these are already rebuilt engines. Not engines with 100K+ miles.

Some go a bit further and ridge ream and re-hone the cylinder bores while doing a refresh, but generally if your cylinder bores need this, it's time for a re-bore and new pistons as well. Often what happens is the re-bore makes the clearances way out, so the piston tends to rock around in the cylinder bore and it doesn't last very long, never gets that good of compression, and well, might as well gone the extra distance and actually rebuilt it.

Many say (this is many machinist and pro-engine builders) if you are going to do it, do it right and do a full rebuild. For these Ford engines, it is way too cheap not to.

I guess it's all about budget and what you intend to do with this car. If you are planning to build any real power or racing it, you might as well start with a good foundation.
 
"Well, you've gone this far......"

Too bad you didn't do a leak-down and compression check before tearing it down. It does look like you have some ridge on the tops of the cylinders, but the cross thatch pattern on the cylinders still looks good.

I know of many people who have done whats called a Refresh where they put in new bearings and rings while they were in there. It works but usually it doesn't last that long. Kind of makes the engine run like new, but the worn parts don't extend the life of the engine much. Refreshing is generally for a newer, less worn motor to keep it at 100%. Many racers I know refresh their engine every year, however these are already rebuilt engines. Not engines with 100K+ miles.

Some go a bit further and ridge ream and re-hone the cylinder bores while doing a refresh, but generally if your cylinder bores need this, it's time for a re-bore and new pistons as well. Often what happens is the re-bore makes the clearances way out, so the piston tends to rock around in the cylinder bore and it doesn't last very long, never gets that good of compression, and well, might as well gone the extra distance and actually rebuilt it.

Many say (this is many machinist and pro-engine builders) if you are going to do it, do it right and do a full rebuild. For these Ford engines, it is way too cheap not to.

I guess it's all about budget and what you intend to do with this car. If you are planning to build any real power or racing it, you might as well start with a good foundation.


does the cross hatch mean the cylinder walls are still in good shape? I didnt have any compression issues out of the motor. the only reason i broke it down was to know for myself that it was a sound engine to play around with.
 
Are your immediate plans to put it back together with performance parts?

Yes I wanted to see if it was healthy on the bottom end and just bolt heads and a new cam into it and see what it would do. Now, I've resolve to rebuilding the engine myself at my own pace.. to save money and to experience actually rebuilding my own engine.