A few simple rebuild questions...

[kronus]

I'm heading back home for a week to revive my monster. I'm considering the turbo block to be toast, so I'm proceeding with my n/t block.

I obviously know that the n/t block is lacking oil squirters, and I know that the compression ratio is 9:1. That being said, tons of guys run pistons with that compression and have no problems. The real problem is the incredibly aggressive timing of the 1g. This will be handled by my Ostrich/TunerPro combo.

Now to the questions:

Bottom end:

On the last motor, I ported the relief valve in the OFH and had a healthy oil pressure of 85 psi at WOT. This was also with a balance shaft elimination. Will the lack of oil squirters warrant porting the relief valve more, or should it be fine?

I do actually have a set of OEM 1g turbo pistons (7.8:1) on 1g big rods that I"ll be bringing home with me, just in case I decide to swap those in after all. I obviously will need to hone the cylinders, and I've read up on the process a bit, but I'm leary that I could seriously mess up the bores of the block (hence why I am leaning to just running the n/t pistons.) Is honing a block more simple that what I've seen? (for an amateur?)

If I take the rods off of a crank, but do nothing else to either the rods (crank end) or the crank, do I need to polish the crank or replace the rod bearings? (I'm assuming not, but I'd rather be safe than sorry.)

Is it much work for a machine shop to press out the wrist pins and press them back in after swapping pistons?

How can I tell whether or not the crank end of the rods are good? (I'm looking for signs of a spun bearing.)

Can I reuse the rod bearings from the n/t rod/piston combo in my turbo rod/piston combo to eliminate having to get the turbo pistons pressed onto the rods in the n/t motor? (This would also eliminate the need for new rod bearings as well as some machine shop work.)

As you can see these last few questions are regarding this: whether to swap turbo pistons onto the n/t rods, or just put the turbo rod/piston combo onto the n/t crank using the old bearings from the n/t rods. (hope that made sense.)


Head:

The head on my n/t motor has 8 bent valves. I'm wanting to just take the valves from my turbo head and swap them into the n/t head. Is this difficult? Can I reuse my good valve guides from my turbo head? Should I leave it to a machine shop to do this while its there to have the head checked for flatness?

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Another question. Do I really need to replace the rod bearings if the rods going back onto the crank are the same ones that came off of it? I mean, if the crank doesn't need work, then why would I need to replace the rod bearings? Does just breaking the 'seal' on the bearings in contact with the crank cause enough of a worry to just replace them?

And another: If I'm honing the cylinders, couldn't I reuse the rings that are on the turbo pistons I have? They have maybe 20k on them. Technically speaking, you hone a cylinder to make it rough enough to 'seat' the ring. Couldn't I just rough up the edges of the rings. Or even just use the rings that are on the n/t pistons, since they're coming out of those bores. (I know I'd need to keep them perfectly aligned.) Again this is not for the longest lasting motor, nor the most powerful. Just a motor that will last me another year or so and make some decent power doing it.

I know these are pretty basic questions, but bear with me. I just want to get this car up and running w/ some boost. If I have to I'll just run the motor in n/t form.

 

[300dollarGSX]

Most people using the N/T block for their build are using forged pistons. You could actually drill and tap the block for the oil squirters if you wanted to use them. Yes, some people run the 9:1 compression ratio, but again, I'm pretty sure most are using forged pistons. Of course, you do have a method of tuning, so you very well may do okay using the N/T pistons. I would just recommend staying conservative with your boost and tune if you did use them.

Honing can be very simple. The bottle brush type hone is the easiest to use and most forgiving. Pretty much anyone with some oil/cutting fluid and a drill can use one. The stone type hone usually gives a more uniform hone, but are somewhat harder to use. If your cylinder is out of round, the stone type hone will show it pretty quickly.

Honestly, I would recommend replacing the rod bearings anyway. They can be had for under $25 for the set at your local parts store. You can even get some Clevite 77's if you wanted. Check the crank journal for any scarring, or grooves. If anything could catch your fingernail, the crank needs to be polished or turned. If you had the crank out anyway, light polishing makes for some piece of mind.

It's not too much work for the machine shop to press pins. They'll usually cut you a pretty good deal if you're having other work done as well.

If you suspect a spun rod bearing, the crank will likely show damage as well, but check the rod for grooves. Usually there will be some obvious heat discoloration or grooves cut into the crank end of the rod. You can have your rods resized at the machine shop if you wish. Basically, they shave off a slight amount from the bottom of the rod cap, then reassemble the rod and bore the end back out to the stock diameter.

You can use the valves from your other head, but if you need new guides, I wouldn't recommend using them from the other head. They need to be pressed out and usually are junk after removal, anyway. Why don't you just use the turbo head? Is there something wrong with it?

You can technically use your old rings if you wish... as long as you don't bend or break them while removing them to clean. You don't need to "rough them up."

Hope this helps!

 

[kronus]

Lots of good info, thanks! As far as drilling and tapping for the squirters, should I just leave that to a machine shop, or would it be something I could do?

Honing doesn't sound too bad now, I think I'll be good. Are you sure I'd be safe running the rings that came with the turbo pistons? I mean, they look great, have less than 20k on them, and the fresh hone ought to take care of the sealing with those rings anyway, right?

I think I'll do the rod bearings anyway, like you said, cheap insurance. However, I think I'll use the rods from the n/t bottom end, since they most likely haven't seen the amount of abuse that the rods on the turbo bottom end have. Assuming the crank and rods are good, do I just slap in the new bearings and bolt them back up using plenty of assembly lube?

The turbo head was on a motor that ate the #3 piston. Parts of it bounced around and kinda beat up the head. I know that if pistons have any sharp edges, it can cause hot spots, so I'd imagine it's the same deal with a head.

 

[kronus]

Hmmm. Found some interesting information from a 'seasoned' engine builder. What do you think?

How many miles on your original rings...??? Chances are that they are fine and will work fine in the different block. The rings mate to the piston ring lands...specifically the sides of the ring lands in the pistons so you don't want to swap them around on the different pistons. Just take the entire piston assembly from the old block and install it in the new block. They will be fine. Unless you are building a max effort race engine you will never notice the difference with the rings.

Just make sure everything is squeeky clean when you begin to reassemble. Getting all traces of the honing and cleaning grit and gunk out of the bores and the block is far more important.


If you look at the second ring face you can see the polish on it where it is "working" against the cylinder wall. Usually you will see the untouched edge of the ring with only about 25% of the width of it polished. That would make the ring about 25% worn, roughly. As long as there is some of the working face of the ring that is dull or unpolished then the ring is perfectly serviceable and I wouldn't hesitate to reuse it. Once the ring face shows polish over the entire width of the ring face then it is starting to be on the "worn" side and would be considered for replacement. That is usually about the 250K mile point.

Consider that the factory machines and hones all the bores and installs rings into them completely randomly. Taking a ring out of one bore and putting it into another really is fine as long as the ring has adequate tension and is showing partial face contact. The ring never really touches the actual bore surface due to the fact that it is riding on a layer of oil so it really doesn't "mate" to the cylinder wall rather it mates to the sides of the piston ring land. The ring constantly turns on the piston anyway so it couldn't "mate" to any specific point on the cylinder wall since it turns in the groove all the time.

I've removed and replaced dozens of aircraft cylinders for inspections and valve touchup and seen hundreds more done by others with never a problem from reusing the rings. It was standard practice in my shop. Rust in a cylinder is no big deal. It's not a problem until the pits get big and deep enough to bridge the rings. It looks alarming but never seems to develope into an issue.

It is good practice to misalign all the ring gaps during a build but the rings will move around anyway. Chances are that the gaps will never all line up if the rings are moving and even if the gaps did line up the rings would move away from this situation....and it would statistically be unlikely and would only happen on one piston at a time as the odds of ALL the rings lining up on ALL the pistons is astronomically small. If there is a scratch or severe discontinuity in a bore it is quite common for the ring end to "catch" on it and not migrate away...so eventually all the rings end up rotating and catching on the same discontinuity. Even a severely out of round bore can cause this....as the rings will rotate and find the point of discontinuity and stay there. At continuous high speed the rings rotate almost continually. I have seen studies where the rings were doped with a radiometric tracer and a "geiger counter" outside the block could actually measure the RPM of the rings moving around the piston as the engine ran at high RPM. Unless the rings are pinned (like a two stroke) they will definitely move so the idea of not lining up the gap, while a good idea for the initial build, is really not technically necessary.

Koz is exactly right. As long as the corrosion leaves only pits (low spots) and the pits do not bridge the ring (they are not wider than the ring width) they really will not cause a problem. There will be a slight increase in oil consumption due to the oil being trapped in the low spots and then partially being consumed but the effect is pretty minor unless the pitting is very severe. The main thing is to not have any high spots in the cylinder. Clean it with 600, touch it with the dingle berry hone and run it. For a passenger car engine anything more is really wasted effort and time and money....especially for a higher mileage rebuild. If you were trying to win Indy it would be a different deal but the passenger car engines are pretty forgiving in this respect.

Just make sure all the rings move freely in the grooves when the pistons are out. Any sticking in the ring grooves due to carbon build up will cause smoking and oil consumption.

 

[Bohrn]

I suggest you use big rods. Not sure if the N/T rods are big, but if they are go for it.

Turbo pistons are much more robust, and have stronger ring lands to take more abuse. I would really strongly suggest using turbo pistons. 1g or 2g, but turbo ones. You CAN use N/T pistons and they have made decent power, but turbo pistons make great reliable power, proven over and over again.

I also second(or third etc) the use of new rod bearings. Please. No use putting in used ones for the price. Get Sealed Power, Clevite 77 or something good like that. Cheap and for real.

Do the oil squirters if you can swing it. they lower the temps of the piston crown and this is good for both reliability and tuning as it controls chamber temps. It will give you more margin in your tune, if you frig up.

Get which ever rods you use(do the big ones) checked at a competant machine shop. Make sure the crank pins(where the rods fit) are standard sized so they can size them correctly and you can get the correct sized rod bearings.

Honing is NOT hard, but just make sure you do it correctly and take your time. You can frig it up, but you will be ok if you take your time and respect the work you are doing.

Turn your drill to slow speed and keep the speed down. Quick up and down movements with the drill and slow rotational speed are key. Spin it too fast and its not the correct pattern and it can over heat the stones.

Use a 3 leg flat stone "glaze breaker" hone. It gives the most consistant finish.

Don't go too much, you are not trying to make the cylinder bigger, just deglaze the metal to seat in the new rings.

for honing fluid, 1 part mineral spirits and 1 part ATF. I put it in a windex bottle and sprayed it in with one hand while using the drill in the other. Keep it wet but not really sloppy.

TAPE OFF THE OIL JOURNAL HOLES IN THE CRANK!!! This way you can clean your bores etc really well with no fear of grit getting in your oiling system. if you get ANY grit in the oil journals it WILL kill your engine within just a few blocks, really. Have seen it done. If its taped off, its no problem, hone away, clean away. Smile the smile of the no stressed engine builder.

One other tip I will give you(and this comes right from a very good local machine shop/engine builder)

go and buy a toilet brush. Probably the biggest one you can. It needs to be a fairly tight fit in the bores. Its a bit over 3.25"(the one I used)

Cut the handle off so that it will chuck up in your drill.

Then when you are done honing and cleaning up, get a bowl of dish soapy water. Fairly strong soap mix, but lots of water, warm is good.

Dip the chucked up toilet brush in the soapy water and "hone" the cylinder walls with this. This is a simple way of doing what is called "platea honing". it takes the wire edges off the peaks of the scratches you just put in the cylinder walls. If this is not done, these pieces fall off and get lodged in the valleys causing a ring seating issue, and oil smoke etc.

It also cleans the cylinder walls very well, so there will be NO grit left over from honing.

No real technique is needed on this part, just givver!!

best of luck and have a good time on your first build!!!!

 

[kronus]

I know this is a little old, but just wanted to give an update. Thanks again for the help and advice.

I did the rod bearings as well as the hone. Turned out REALLY well. I was a little worried at first with all of the blue smoke, but after the rings sealed up, I have NO smoke on accel or decel at all. It's a wonderful feeling. Just a quick question about the hone for future reference. I didn't take off a lot. Just enough so I could feel the new cross hatch. However there was a bit of 'golden' color still left on the cylinder walls. Does that mean I could've taken a bit more off? My cousin said I should have, but I don't have any problems so I think I'm good. Any more opinions for you guys?

 

[Bohrn]

I have heard both ways actually, but I took it down till it was all a uniform colour.

How long did yours smoke for? I am getting close to starting mine up(life gets in the way).

 

[Clutch GSX]

If it was golden after you cleaned it then it was probably due to the rusting that takes place on unprotected iron. You can't let the cylinders dry or else that will happen.