Engine Build Questions

[pitaSHO]

I am planning a complete rebuild of a 3.2 for my 93 MTX. Here are my plans.

3.2 block, cleaned and honed
New freeze plugs
New main bearings and rod bearings
Stock pistons with new rings
Cleaned and refreshed heads
* Valve stem seals
* New valve springs
* Tri-flow cams
* Maybe some porting and gasket matching
UDP
Rebuild steering pump and rack from shosource
All new sensors
All new steering components
All new hoses
I want it to look like new when it's finished.

Here are my questions:

Should I get the block and rotating assembly balanced by an engine builder? I am going to use a crank from another motor (the 3.2 originally had a spun bearing) and one connecting rod and piston from another motor to replace the ruined one.

Is there any advantage to the gap-less piston rings sold by RCM?

This is going to be an ongoing project through the year as I have money. I'm in construction and money is hard to come by, but I REALLY want to build a motor.

yamahasho, toolman, shospazz, nik97, shopartsnw, Lance Cheney, any feedback would be appreciated.

Thanks.

Chris K.

 

[rubydist]

Chris,

My input is that having the rotating asm balanced is a very good idea, since you have substituted a rod from another engine which is very likely a different weight than the original.

I would use the original piston if its not toast, since they are select fit to the bores at initial assembly. I would only re-hone the cylinders if the original honing marks are not visible or if there are score marks on the cylinder walls.

I would be very tempted to re-use the original rings, if they look good after everything is cleaned up and if the bores still look good like they typically do. I might be 'old-school' but I don't like the gapless rings.

 

[Phoenix]

Just so you know The gapless rings are made-to order , I just ordered mine before xmas and Im still waiting on the confirmation of that.

 

[Lorenr]

Rebuilding the 3.2

I would do what you are doing and would:

1. Hopefully not re-hone the block and anyway you should not need to. Clean the bores with ATF.
2. I would use new rings. They don't cost much and would be worth 5 to 10 horsepower at a minimum. Long story why, but it is true.
3. I would reuse all the pistons after cleaning them, just with new rings.
4. Use new seals, but buy a lapping tool and just hand lap each valve to its seat. You should not need to do more and this is easy and cheap. Probably is within a few horsepower of a three angle valve job.
5. Use all new bearings.
6. Scrub everything with detergent and water. wipe everything down with ATF or engine oil.
7. Get a gram scale and weigh the new rod against the other seven. If they all seem similar I would probably go with the factory balance. The factory machining is probably pretty consistent since I bet they machine all cranks and reciprocating parts to be the same.

Ever since I first listened to one of these motors run the first thing that came to mind was "these motors are really well balanced".

 

[Racer X]

- If you're using new rings, a light (and I mean light) hone isn't a bad idea.
- Keep the pistons.
- No need for new valve springs unless one is broken or damaged.
- I'd just replace the rod bearings. The main bearings are not known to wear (the 210k mains I pulled from my old 3.0L were spotless), and the thrust bearings are unobtanium.

Everything else seems spot on.

 

[pitaSHO]

Thanks for the feedback. I just wanted to clarify a few things;
- I am using the original stock pistons, including the piston off the bad rod. I thought about going low compression in case I decided to add boost later, but this is my dd, so I decided to build it stock.
- I have to use new main bearings. You would not believe how bad the original ones were. I showed them to Mike Stimson and he could hardly believe it either. They were pitted and gnarly. Bad maintenance and very long between oil changes. All the rod bearings and most of the main bearings looked bad. Any of them could have spun.
- This is more of a budget build. It's not going to be the uber engine build with all the extra stuff like polishing the crank or shot peening everything. I'm just going to rebuild it from the ground up with stock parts, COMPLETELY CLEANED AND LOOKING LIKE NEW, and replacing gaskets and bearings, adding all the bolt-on goodies like Tri-flows and UDP's. It will eventually get chipped and tuned when it gets assembled and installed.
- I was under the impression that it is best to hone the block when using new piston rings because it gives a fresh surface for the ring to mate to, similar to seasoning rotors and bedding pads for the brakes.

Phoenix, why did you go with the gapless ones? How are they installed? Thanks for letting me know about the order time. I'll keep that in mind if I go that route.

Thanks again for the feedback.

Chris K.

 

[AREA 91]

I am planning a complete rebuild of a 3.2 for my 93 MTX. Here are my plans.

3.2 block, cleaned and honed
New freeze plugs
New main bearings and rod bearings
Stock pistons with new rings
Cleaned and refreshed heads
* Valve stem seals
* New valve springs
* Tri-flow cams
* Maybe some porting and gasket matching
UDP
Rebuild steering pump and rack from shosource
All new sensors
All new steering components
All new hoses
I want it to look like new when it's finished.

Here are my questions:

Should I get the block and rotating assembly balanced by an engine builder? I am going to use a crank from another motor (the 3.2 originally had a spun bearing) and one connecting rod and piston from another motor to replace the ruined one.

Is there any advantage to the gap-less piston rings sold by RCM?

This is going to be an ongoing project through the year as I have money. I'm in construction and money is hard to come by, but I REALLY want to build a motor.

yamahasho, toolman, shospazz, nik97, shopartsnw, Lance Cheney, any feedback would be appreciated.

Thanks.

Chris K.

Since you are using a rod from a different engine, get it balanced.

DO NOT HONE THE BLOCK FOR THE NEW RINGS!!!

There is no need for new valve springs. Stock are just fine.

Gapless rings do seal slightly better than conventional ones.
I have used both. It's your call if you want to spend the extra money.

 

[Devin]

Great thread on honing:
http://www.shoforum.com/showthread.php?t=45176

 

[Phoenix]

Thanks for the feedback. I just wanted to clarify a few things;
- I am using the original stock pistons, including the piston off the bad rod. I thought about going low compression in case I decided to add boost later, but this is my dd, so I decided to build it stock.
- I have to use new main bearings. You would not believe how bad the original ones were. I showed them to Mike Stimson and he could hardly believe it either. They were pitted and gnarly. Bad maintenance and very long between oil changes. All the rod bearings and most of the main bearings looked bad. Any of them could have spun.
- This is more of a budget build. It's not going to be the uber engine build with all the extra stuff like polishing the crank or shot peening everything. I'm just going to rebuild it from the ground up with stock parts, COMPLETELY CLEANED AND LOOKING LIKE NEW, and replacing gaskets and bearings, adding all the bolt-on goodies like Tri-flows and UDP's. It will eventually get chipped and tuned when it gets assembled and installed.
- I was under the impression that it is best to hone the block when using new piston rings because it gives a fresh surface for the ring to mate to, similar to seasoning rotors and bedding pads for the brakes.

Phoenix, why did you go with the gapless ones? How are they installed? Thanks for letting me know about the order time. I'll keep that in mind if I go that route.

Thanks again for the feedback.

Chris K.

I wanted to go with hi-compression pistons , but with the possibility that it may require high octane gas (higher then pump gas) I dicided to go with rings that "seals" better and may offer a better compression.

 

[Lorenr]

Balancing an engine

How important is balancing an engine?

First of all the only part that we cannot do easily is crank shaft balance. The rest of the parts can be balanced using a borrowed gram scale. The way out of the crank shaft issue is to think about it.

Manufacturers cannot stop the assembly line process to balance parts, but they can make parts that fit a standard. The new milling machines are very fast and very accurate. I have no doubt that they can cut a crank to about 1 gram. That is way better than we need.

1. Weigh each bare piston and mark the weight of each.
2. Weigh each matching piston pin and pin retainer. Remember to NOT mix each original piston and pin. Get new pin retainers. You may weigh each pin and piston together as a unit if you wish.
3. Way each ring package (top ring, second ring and 3 piece oil ring). They should be the same weight but if not add each set to the weight of the piston/pin/retainer. Try to obtain a common matching weight. 3-4 gram differences are pretty good.
4. Now weigh each rod and rod bearing. If they are all the same, stop. If not move the rod bearings around to average out the weights. I know that a balance beam scale is normally used to weigh the rods large and small ends, but for our needs, just weighing the rod will work well. Besides, grinding on the small or large ends of the rods in this case could cause more issues than it fixes. If weight removal is required, remove it from the balance pad on the small end of the rod or if a pad is available on the large end, do it there.
5. Now average the weights of the piston/pin/retainer/rings package to the rod/rod bearing package.
6. We are now balanced and spending more money at the machine shop probably won't give a better result. Be sure to clean everything. I sneak into the kitchen in the middle of the night and use the dishwasher with automatic dishwasher compound as the cleanser.

When we were drag racing we routinely spun the motors to 9500+ RPM. We were sure that the motors needed to be balanced to 1 gram. Chrysler's engineering department told us that so much was going on in the motor including globs of oil sticking to all the parts that balancing was not an especially big deal. They said that on their test motors they just pulled parts off of the shelf and simply tried to match the weights.

However, I'll bet NASCAR engines are balanced to 1 gram.

 

[yamahaSHO]

If it were me, assuming you still have a (MTX) 3L block...

- Bore 3L block to fit 3.2L pistons
- Resize rods
- Micropolish crankshaft
- Balance entire rotating assembly
- New main and rod bearings, reuse thrust if good or source another good used one

Heads:

- If you know they're good to go, clean them up

If you are honestly thinking you'll boost at any point in time:

- Use stock cams
- Don't spend money on most bolt on parts aside from exhaust/intake


With that said... You could slap it all back together with new bearings and no balance. We've swapped a rod and crank on an SC SHO about 4 or 5 years ago and it's still running fine. We didn't bother to do anything in the balancing department since we only took out that rod an piston.

As far as rings, I would do a very light hone, but as others have mentioned, you could try the above. I stayed away from gapless as I thought I read that someone in the SHO world had issues with them. It's been quite some time since I put my motor together and did the research. In the end, for whatever reason, I decided against them.

 

[Lorenr]

Micro polishing your crank

I'm posting this stuff so that I can hopefully help some of the readers who might not want to spend a lot of money.

Lets micro polish our crank. We may want to do this if the bearings we are replacing look like they have been abused. Before we begin run your finger nail across each bearing journal. If your nail hangs, stop and send it to a machine shop the following won't help.

Lets do it:

1. Mount the crank in any home made fixture that gives us access to each rod and main bearing surface.
2. Get some 600 grit wet or dry emery/sanding paper and cut it into widths equal to the width of each bearing surface. The paper must be long enough to circle each bearing surface twice. Soak these in solvent.
3. Get a boot length leather shoe lace.
4. Wrap the wet paper round the bearing surface. Wrap the leather lace twice around the mounted paper so that an equal length is left to pull from each side. Pull the lace for and aft in a rapid polishing motion.
5. Check your work frequently and viola you will have a micro polished crank.

Fear not you are not removing material when you do this and you will not cut through any factory nitriding like you would if you cut the journals for oversize bearings.

 

[firebat45]

7. Get a gram scale and weigh the new rod against the other seven. If they all seem similar I would probably go with the factory balance. The factory machining is probably pretty consistent since I bet they machine all cranks and reciprocating parts to be the same.

Wishful thinking?

 

[yamahaSHO]

I'm posting this stuff so that I can hopefully help some of the readers who might not want to spend a lot of money.

Lets micro polish our crank. We may want to do this if the bearings we are replacing look like they have been abused. Before we begin run your finger nail across each bearing journal. If your nail hangs, stop and send it to a machine shop the following won't help.

Lets do it:

1. Mount the crank in any home made fixture that gives us access to each rod and main bearing surface.
2. Get some 600 grit wet or dry emery/sanding paper and cut it into widths equal to the width of each bearing surface. The paper must be long enough to circle each bearing surface twice. Soak these in solvent.
3. Get a boot length leather shoe lace.
4. Wrap the wet paper round the bearing surface. Wrap the leather lace twice around the mounted paper so that an equal length is left to pull from each side. Pull the lace for and aft in a rapid polishing motion.
5. Check your work frequently and viola you will have a micro polished crank.

Fear not you are not removing material when you do this and you will not cut through any factory nitriding like you would if you cut the journals for oversize bearings.

This sounds like good advice, however, I have to tag onto that and mention I paid $150 after tax for a micropolish and balance.

Just trying to give a better idea of cost.

 

[pitaSHO]

If it were me, assuming you still have a (MTX) 3L block...

- Bore 3L block to fit 3.2L pistons
- Resize rods
- Micropolish crankshaft
- Balance entire rotating assembly
- New main and rod bearings, reuse thrust if good or source another good used one

Heads:

- If you know they're good to go, clean them up

If you are honestly thinking you'll boost at any point in time:

- Use stock cams
- Don't spend money on most bolt on parts aside from exhaust/intake


With that said... You could slap it all back together with new bearings and no balance. We've swapped a rod out on an SC SHO about 4 or 5 years ago and it's still running fine. We didn't bother to do anything in the balancing department since we only took out that rod an piston.

As far as rings, I would do a very light hone, but as others have mentioned, you could try the above. I stayed away from gapless as I thought I read that someone in the SHO world had issues with them. It's been quite some time since I put my motor together and did the research. In the end, for whatever reason, I decided against them.

I DO still have the 3L from my wrecked 95 sitting on the subframe in the garage. It's been fully 60k'd and is a known good engine that has only ever seen premium oils; very clean. I was going to try to sell that motor to pay for the cams. I know I could also use it as the donor motor for all the MTX stuff... Might just do that...

If I was going to go boost I would leave the stock cams in for sure. I was thinking Tri-flows and all the bolt-ons because it's going to stay N/A. I've gone the route of adding all the available bolt-ons except the cams to my 95 and decided that if I was to ever do it over again I would skip most of the those and just boost it. At least for my non-DD car.

What do you mean by re-size the rods?

What would the advantage be of boring out the 3L block vs using the 3.2 I have?

Sorry for all the questions; I'm just trying to get my head into available information so I can decide based on the best known facts from those that have done this before.

Thanks again.

Chris K.

 

[yamahaSHO]

If I was going to go boost I would leave the stock cams in for sure. I was thinking Tri-flows and all the bolt-ons because it's going to stay N/A. I've gone the route of adding all the available bolt-ons except the cams to my 95 and decided that if I was to ever do it over again I would skip most of the those and just boost it. At least for my non-DD car.

To be honest.... And just my opinion... With the amount of money you would spend on cams and the bolt-ons, you'd be really close to having a very sizeable difference in power with even a low boost turbo setup. Again, IMHO.

What do you mean by re-size the rods?

http://www.hensonracingengines.com/Rod_Resizing.html

One thing I should highlight:

Inspect rod bolts for stretching and thread damage. If in doubt, replace the rod bolts. This should be done before the connecting rod is resized because some bolts are pressed into the rod and will cause distortion that will be corrected during the resizing process.

The SHO's connecting rod bolts are pressed in.

What would the advantage be of boring out the 3L block vs using the 3.2 I have?

Boring the 3L block will allow for a completely fresh and straight bore without worrying about any previous scores, pits, etc. If you can find a torque plate to simulate the stress that bolted down heads provide, you'd be able to do that even better.

Is it required? No. Is it something I would do? Yes.

 

[pitaSHO]

One thing I probably should have mentioned before is that I already own the following bolt-ons from my 95 that would just get switched over to the new motor:

EHIR's
BBB's
UDP
9lb Fidanza
SPEC Stage II
Quaife
TwEECer
Silicon couplers and vac lines

Jason, thanks for all the info.

Chris K.

 

[Schumacher609]

Hey if you decide to sell that 3.0 let me know I may be in the market for one. If I can swap a new 3.0 into my 92 project/learning experiance then I can drive it AND learn more about the engine at the same time.

Thanks alot for all of the information in this thread and linked treads.

-Mike

 

[victorymike18]

...
Lets micro polish our crank.
...
2. Get some 600 grit wet or dry emery/sanding paper and cut it into widths equal to the width of each bearing surface.

Just wondering (and I'm probably not thinking correctly) but isn't 600 grit fairly rough?

I've seen wet-sanding paper for body shops, and something like a 2000 Grit is very fine. But I though the lower # grit gets rougher, no?

 

[rubydist]

Yeah, I thought the same thing - if I was going to do that, I'd use 1500 or 2000 grit emery. The point of that exercise is to take the peaks off the tiny ridges in the crank, and you need 'very' fine grit to do that without creating new scratches.