Advice on buying a rebuilt 392

scout-n-josh

scout-n-josh

New member
Tomorrow I am going to go and look at a 392 that was out of a 67 dump truck and I was told it was rebuilt a few years ago. It hasn't been started yet after the rebuild and has been sitting for about three years now. The guy claims it has been proffessionally rebuilt, but who knows? He's selling it for $500 bucks which if it is what he says it is I think that would be an okay deal. The things that make me nervous about buying this engine is, who really knows if it's been rebuilt, unless he has the proper documents which he did say he has them at his other shop, but again who knows unless he can present them. Also it's been sitting for a few years, so what are the residual effects of that? What would I have to do to it before I started it? Does anyone know or recommend a good link to proper break-in on a rebuilt 392. Any advice on buying an engine that you haven't seen or hear run. What would you expeirenced guys do in a situation like this? Any advice and help would be much appreciated!!!!
 
As for bringing an engine to life that ahs been sitting non-rotated for years, review nearly all threads in this "gas engine tech" sub-forum!!! You will then have some background information on what to do...it's all there including an extensive procedure I've developed which you can download/print.

Without documentation for an engine build...then it's just a dam unknown/used motor, that is the point I always work from! I deal with this all the time regarding engines, carburetors, distributors, etc.! To most folks, blowing degreaser onna carb and changing the fuel filter is a "rebuild"! Replacing spark plugs is a "tune up". Pouring two cans of "renew" inna engine replaces all the metal that has worn away over time and is referred to as an "overhaul.

Not trying to be a smartazz...but do your homework and ask the right questions that can be documented with paper!

Here's a file for ya that outlines the "unknown motor condition" scenario and how to check it out.
 

Attachments

  • Old Iron Pt 1 v1.2.pdf
    75.5 KB · Views: 532
Last edited:
Check with Jesse b on this board. I found a similar deal on a 392 out of a wrecker. Owner claimed it had been rebuilt but never put back in, and had been sitting in the corner of the shop for the last 6 or 7 years. Jesse came with me to see it, Jesse decided for the $200 the guy was asking he would take it. Well thousands of dollars later, the motor is being rebuilt correctly. I would be careful, $500 seems like a lot for not knowing much about the rebuild. Good luck
 
Unless the guy provides proof of the rebuild, an itemized list of what was done to the block, and a phone number of the builder, $500 is too much. Also make sure that the block was adequately sealed up. No holes that critters can crawl into, including insects that make homes/hives. Without documented proof, consider the block to be a core, that's it.

As Matt wrote above, I paid $200 for mine, with no written proof. We did pull the valve covers and the plugs before I bought it and you could tell from the condition of the cast iron that the heads had been hot tanked, the rockers cleaned up, and you could see the new aluminum pistons through the spark plug holes. The crank rotated fine. This is about all we were able to do in the in the guys garage. I figured for $200, I'll roll the dice.

I got it home and started to tear it down because there was just no way I was going to try to start it without at least checking it over. The engine was rebuilt, as it had a variety of new parts in it, but the engine assembly was just plain awful. The engine was stored without a distributor in it so some mice crawled in through the hole and made a nice home in the lifter gallery. (boy were they surprised!) the cylinder walls were lightly rusted due to condensation getting in through the valves, the pistons were new, but poorly fitted, the block did not appear to have been properly hot tanked (all the plugs were not removed), the rings were not gapped correctly, etc. The only thing done correctly was the machining on the crank. Everything dialed in there perfect. So I had to redo nearly everything. So I figured it to be a core, and I was right. I got lucky in one way, I had to bore it out .060, so I have the nice set of new .040 pistons and rings that came out of it for another build.

Frankly, I wouldn't trust a rebuild done by anyone else farther than I could throw it. Read the other post about mr. Potter for some insight there. Most engine rebuilds are done quite poorly be people whose only interest is getting your money and hoping the engine lasts long enough out of warranty (if it even comes with one.)
 
Great advice guys...your help was very usefull....really appreciate it!! Saturday I went and took a look at it, turns out it was in fact rebuilt, everything under the valve cover looked nice and fresh, pulled the oil pan last night and it too looks good. All the entry/access holes where indeed covered. So right now I'm crossing my fingers that after I go through it some more that everything was rebuilt the right way and not just slapped together. It is just a temporary motor untill I get my 392rebuilt and I was able to get it for $400, so as long as it gets me through the next year or so it should be allright.

Thanks again...and I will definitely be reading a majority of these posts!! Very helpful for a guy like myself!
 
Last night a buddy of mine calls me up and had said the flywheel from my engine might not fit the flywheel on the new engine. To go into more detail the engine that I have is an improved cooling 392 with a torqueflite 727 auto tranny, the engine that I just got is a 1967 non-improved cooling with a manual tranny and the combo was out of a dump truck. My question is: is my flywheel off of my old 392 going to work on the new engine so I can use my tf 727? If not, what kind of options do I have? Would the flywheel on the new engine work? Any help would be much appreciated!
 
Jesse b. said:
the two flywheels will interchange. You should not have a problem.
Click to expand...



Whew! I gotta admit I was started to freak out a little bit, even was tossing and turning last because of it and I couldn't wait to get to work this morning just to write in on ihon because I knew I would get the answers!!!!

Thanks much!!
 
Yeah it should be fine. Just fyi and for proper reference, the ring gear for use with a 727 is called a flexplate instead of a flywheel. Make sure you also retain and install the spacer that goes on between your starter and the bell housing.
 
I think I have read here that you need to use "thread sealer" on the bolts that go into the crankshaft (for the flex plate / flywheel) to stop possible oil leaks.

My mechanic used permatex #2, I think, ( the green / non-hardening stuff ) for this, but I think michael mayben has used / recommended a different brand in posts on this site.
 
robertc said:
I think I have read here that you need to use "thread sealer" on the bolts that go into the crankshaft (for the flex plate / flywheel) to stop possible oil leaks.

My mechanic used permatex #2, I think, ( the green / non-hardening stuff ) for this, but I think michael mayben has used / recommended a different brand in posts on this site.
Click to expand...

A flex plate for a tf 727 app must have the crankshaft spacer installed for it also if the engine originally was equipped with a flywheel...this is not the "spacer" for the starter that "some" set ups (but not all) use. This spacer is a large chunk of steel a nominal 2.0" thick and includes a special sheetmetal washer "plate".

Any kinda gasketgoop/sealer (except rtv!!!) will work just fine on the flywheel/flex plate retention bolts. P-tex #2 has been the standard since the 1920's...along with indian head. I use hylomar which is a much more "advanced" product comparatively speaking. A teflon-base "pipe dope" works just fine also.

When swapping around flywheels or flex plates amongst I-4 or sv engines that they were not originally installed on, expect some increase or "change" in engine vibration. These motors were balanced as a unit in an automated fashion during the production cycle with all rotating items in place as spec'd for "which" powertrain they were going in front of. They were not just "built" for random selection from inventory.

In some cases, this increased vibration will result in an unusable combination it's so pronounced. And yes...flex plates and torque converters were included in the overall "balance" scenario. For instance...ya cannot mount an sv flywheel to an I-4 or visaversa, the resulting vibration is uncontrollable! However, they flywheels (or flex plates will interchange as far as bolt-on).

Here's a link to a thread that I need to get back to for updating regarding the "flywheel" subject:

http://www.forums.IHPartsAmerica.co...-light-duty-engine-flywheel-I-d.html#post6142
 
michael mayben said:
a flex plate for a tf 727 app must have the crankshaft spacer installed for it also if the engine originally was equipped with a flywheel...this is not the "spacer" for the starter that "some" set ups (but not all) use. This spacer is a large chunk of steel a nominal 2.0" thick and includes a special sheetmetal washer "plate".
Click to expand...

So once I remove the "flexplate" from the old 392, the spacer & sheetmetal washer should allready be there since it was hooked to a tf 727 and then I should just be able to transfer the spacer, washer and flexplate to the new engine making sure I use thread sealer(not rtv) on the bolts. Is that correct?
 
Scout-n-josh said:
so once I remove the "flexplate" from the old 392, the spacer & sheetmetal washer should allready be there since it was hooked to a tf 727 and then I should just be able to transfer the spacer, washer and flexplate to the new engine making sure I use thread sealer(not rtv) on the bolts. Is that correct?
Click to expand...

Exactly!
 
You must log in or register to reply here.
Back
Top