used motor (REBUILD TIPS)

[vmax735]

Hello All,

My name is Phil Cummings and i'm a founding member of the SHO club in Colorado... We have been around for about 5 years and have maintained a pretty steady membership of about 25 Sho owners. We meet once a month and usually get about 10 guys together... it's been fun.

I'm driving a 92' SHO with 222Kmiles on the clock and counting. I have the opportunity to buy a used 92 motor for 100 bucks. I'm thinking that this is an excellent opportunity for me to get a motor rebuild it and have it ready when i'm done with this motor.

So let's get technical. I'm thinking i will need to do a major rebuild on the "new" motor. Rings, Headwork and whatever else may fall into a "major rebuild". What other items should i be leary of as i would like to keep my cost down but i don't want to half *** this project once i start into it .

Also does anyone know what a major rebuild is going to cost ?

Thanks in advance for any and all replies... i'm a newbie to the motor so hit me with anything you can think of cuz i probably dont' know about it.

Take care Phil

 

[rangerj]

Here are some thoughts, assuming you are building a "street" engine and not a racing engine. Check with a high quality local machine shop for prices. Disassemble and lable all parts, eg #1 piston and rod, including nuts and bolts.

Heads:
3 angle valve job, valve seals, guides, and seats. Check all springs for height and tension and inspect all valve "keepers".
Check the heads for cracks, warpage, and or any other damage. Check the cams for wear and the cam journal/bearing surfaces for wear and or "out-of- round". Check the chains for wear and the sprockets for wear, damage, or cracks. Check the chain tensioners and chains for wear/servicability. Mike the cam lobes for wear and the cams for straightness and bearing surface wear.

The heads can be planed if slightly warped. Replace all exaust studs and any other fasteners with corroded threads or damaged threads. Chase all threads in the heads and repair damaged threads (heli-coil). There are specific thread repair heli-coils for spark plug thread repair. Porting and polishing is an expensive option because it is labor intensive.

If the heads are servicable they should be cleaned before and after all work.

Block:
Have the block magna-fluxed before putting any money into it, other than the cost of having it cleaned.

Mike the cylinders to determine if they are "round" (not oval shaped or tapered) and straight up and down.

The crank bore should be straight. If it is not it should be "line bored". The rods should be straight and the wrist pin bore and the crank journal bore should be within specification. The rods and crank should also be magna-fluxed for cracks. As needed replace the rings, wrist pin and pistons.
Then all gaskets and seals, including the freeze plugs, should be replaced. All rubber products should be replaced, ie hoses and belts. I would replace the block drain with one made of brass. I would also use brass freeze plugs.

Again, chase all threads. I would replace all fasteners, including the head bolts, rod bolts (nuts), and crank bolts.

If you have to have the block bored go with the absolute minimum necessary to get straight cylinders.

Again clean the block before and after ALL work. Clean every nook and crannny. When you think it is clean enough, clean it again!

The OEM block was painted Ford Engine Gray, but use the color of your choice. The overall cost will depend upon what parts you buy, where you buy them, and the cost of the machine work necessary. A set of OEM gaskets could cost as much as $600, whereas a Fel-Pro gasket set could be 1/2 that amount. DO NOT try to save money by getting "cheap" machine work done. Find the best engine machine shop in your area to do the machine work. The long life of the engine will compensate for the cost of the machine work. rangerj

 

[rangerj]

Additional thoughts:

Check the deck of the block with a machinests straight edge. If the block is not level, within tolerance, have it "decked".

If the block has to be "decked", that is cut to make it level, and the heads have to be machined to correct for warpage, then thicker head gaskets will be needed. The cumbustion chambers can be milled to decrease the increase in compression if the decking of the block and heads are necessary, and the thicker gaskets will not do that for you.

You will also need a shorter timing belt if the heads are cut, and/or the block is decked.

If done right a rebuilt motor is better than a new motor because the block has been conditioned by the may times it has been heated up, and cooled down. Let us know how the project goes. rangerj

 

[vmax735]

Thanks for the detail ! More than I expected . You didn't mention stuff like replacing the crankshaft position sensor and isn't there a cam something that should get replaced ? What do you think this would set me back ? Doing this to the letter, with all the machining and such ? I'm teetering on getting this or not .

My other thought is to just do the heads on my sho and be happy with whatever i get out of that.

thanks Phil

 

[AutoSHO]

Phil,

Since you know the motor you are getting was running well, chances are you can assume it won't need major machine work - probably just a hone in the cylinders, and some headwork. Its so easy to swap motors that I would go ahead and spend the money on sieger's motor and do all the work on it out of the car. Working on an engine stand is very nice in comparison.

The complete upper gasket set (head gaskets and up) is only ~$150 from napa. Rod + Main bearings and the lower gaskets will only set you back another ~$200 and the rings for a 3.0L can be had for ~$60. Chances are that is all you'd need aside from the machine work on the block (which will most likely be minimal).

Swapping the motor in a SHO is getting easier every time I do it... Not a very hard swap at all, and a great time to fix any minor issues the car has that are otherwise hard to get to (power steering leaks are on the top of this list).

 

[rangerj]

Phil,

You asked about a major rebuild and I responded to that. If the motor you are buying is known to be in good condition why rebuild it? Do a compression test and see if it has good compression. If it does it may not need rings, or any major motor work. If it has 100K or more on it I would do the rod and crank bearings because those are easy to do when the motor is out of the car. The bearings are relatively cheap.

It would also be a good time to replace the rear main crank seal, as well as the front crank seal and the camshaft seals. If you decide to pull the heads for valve work, then replace any other seals or gaskets you remove.

Whether you replace the CPS and/or any other sensor is a matter of choice. It would be a good idea to replace the CPS and CID sensors because they are relatively inexpensive and a PIA to get at once the engine is installed.

If the water pump is original, or old, I would consider replacing that as well.

How much of the above you do would depend on the age (milage) on the engine and its components. If the engine and its components are in good shape then run with it and fix things as necessary. rangerj

 

[vmax735]

Ranger,

I did and i very much appreciate your input. I'm actually debating whether or not i want to yank a 222k mile motor that runs great but is down on power and drinks oil like i drink coffee with a similiar motor fully rebuilt. To fully analyze this, I need to know How much it's going to cost and i think that if it runs much over 1000 dollars (including motor) that it's not going to be worth it.

I should do the compression test and a leakdown but it's too frigging cold. I think i will just get the motor and wait on it til late spring. Work on it here and there. You just made me nervous when i you started talking about decking this and machining that, I'm not the most literate when it comes to this type of stuff and sure don't know how much that stuff costs. I want to build a decent motor but need to keep it reasonably within my budget.

So are there any opportunities while i have this motor apart to pump up the HP ?

thanks Phil

 

[750sho]

if i were you, i'd buy the motor, put new rod bearings in it, and a full 60k, and call it good.
Leave the heads on, and try to keep everything simple.
That's what i would do, unless this motor is going to be part of a project car, and not your daily driver.
But, i'd say if you do that, you'll have a motor that will be capable of lasting another 100k or so. ANd it's exactly what i did with my old SHO. My girl drives it now, has about 195k on the car, and 88k on the engine. Oil looks brand new during changes, never leaks, never burns it, and she's proven to be capable of 28 mpg. She maybe a little rusty on the outside, but that engine is healthy as ever.

 

[rangerj]

Phil,

Before you spend any money you have to decide what it is you want to do and/or accomplish. There is no inexpensive way to "pump up the horse power". So, if you want to keep down the cost you need to rethink your objective. If you have access to a good used motor and want to restore it to a low milage condition you can do that on a budget.

If the engine has good compression leave the heads on. Replace the rod and crank bearings, the timing belt, check the valve clearance, change the CPS and crank seal (front and rear), water pump (if necessary), etc. Aim for a good dependable motor that is not tired and worn out and leaking. And before you put it in the car make it look good, ie nice, neat, clean, and painted.

Think about what you want to accomplish and how much you want to spend, and then adjust one or the other (IMHO). All of the work I mentioned in my first thread was just to rebuild a motor back to factory specification, and not add any HP. Additional HP will substatially increase the cost because of the amount of additional precission work and expensive special parts. In my opinion, don't go there! rangerj

 

[Off Road SHO]

Phil,


Additional HP will substatially increase the cost because of the amount of additional precision work and expensive special parts. In my opinion, don't go there! rangerj

Without a doubt, that should be the first commandment of SHO ownership. I think I will have that printed on a plaque and hang it in my office.


Tom

 

[Stracey R]

How does one do the compression test? Any write up on this?

Thanks

 

[rangerj]

There are numerous write-ups on compression testing. You will need to buy or borrow a compression testing tool (gauge). It threads into the spark plug holes (ALL plugs removed). Crank the engine over untill you hear at least 3 (but no more than 5) "thuds" of compression in the cylinder. Test all of the cylinders the same exact way. Read the gauge.

Do all six cylinders (one at a time) and compare the results to the specified compression for the engine. You should be getting about 90%, or more, of the "new engine" compression, and all of the cylinders should be at least within 10% to 15% of each other. The closer the cylinders are to being equal the better.

There are some differences of opinion as to what tolerances are acceptable. The tolerances I have stated are generally accepted, but I prefer better results.

Keep in mind that poor compression can be caused by a head gasket problem, a valve, valve guide, and/or valve seat problem, and/or worn or broken rings, as well as a hole in the piston or a cracked head. If rings are suspected you can squirt a little motor oil in the cylinders and retest compression. If compression comes up, then the rings are worn.

Do yourself a favor and read through the past threads on the subject and read what is on the SHO Times web site about the subject. You may also want to go to your local library and read about the use of the compression test as a diagnostic procedure. Owning a car, and specifically a
SHO, is a never ending learning process. rangerj

Tom,
I recently finished a Chevy 454. The block was bluprinted, line bored, decked, and balanced with high performance rods(shot peened), pistons, rings, valves, valve guides, springs, roller rockers, cam, Malory ignition, ****** Headers, etc. The cylinders are "O" ringed.

The heads were Factory competition heads from a 69 427 Vette which were ported, polished, and CC'ed then put together with the aforementioned performance parts. With a duel pump Holly 750 she dynoed 530HP at the rear wheels. The head bolts alone were over a $100. You do not want to know what the machine work and the parts cost! The engine is in a 1967 SS Chevell. It is a thing of beauty, but it cost as much as the whole car is worth. But, it is the owners "other woman". (It is not mine)