[BogiesAnnex1]

I have new speedpro pistons and scat 5700 bushed rods. Some of the wrist pins slide in pretty easy and the wrist pin spins in the piston and rod. a few other pins spin freely in the piston but it doesnt spin in the rod. I use assembly lube on anything the rotates/spins/moves I was able to push them in by hand, but they dont spin in the rod like its a pressed fit. Is this normal? Will it loosen up after first start up and it warms up? or is something wrong here?

Another question. After I installed new main bearings torqued them down to spec (I didnt forget to seat the thrust bearing) It seemed like the crank was frozen.It took some effort to break it free, but once it is moving, it spins very freely. But after it sits for a minute it freezes up again. I feel this is normal but im unsure.

The rod to pin if tight but slides together is fine. The primary motion is in the piston pin bores. The floating fit in the rod is a back up for a list of just incases when it comes to articulation while allowing simple assessembly and dissassenbly that does not risk damage to the pin, rod or piston pin bores.

You second problem is called stiction, again not a concern once the engine is fired and run awhile that will go away.

Bogie

 

[dogwater]

Just 5 or 6 turns. Don't go side to side, rotate. Spray WD40 or penetrating oil on the sand paper & rod bore the work it. Be sure to wash the bore out befor test fitting. Here's some tips on crank shaft installing.
1. Without any rods on the crank but the crank shaft torqued to specs you might have to get the crank shaft spinning with a wrench but you should be able to keep it spinning with just your fingers.
2.With the rods, pistons,rings installed on the crank it should not take any more than 40 ft. lbs to turn the crank. Mine was less than 35 ft. lbs. I set my torque wrench first to 40, no click, then to 35, no click. I stopped there because all was good.

 

[Senor Frogs]

So I Plastigauged the crank bearings and they are all within .001"-.0015" and from what I understand, that is pretty tight. But I put my beam torque wrench on the crank with pistons rods and main caps torqued to spec and im getting 30ftlbs of rotational torque. And thats pretty good right?

 

[vinniekq2]

crank polishing time

 

[4 Jaw Chuck]

Two piece from a felpro kit

Two piece seals are always snug because of the design, sounds like your mains are too tight as well.

Take it out and polished it or have it done, 0.0025"-0.003" clearance is more typical.

 

[Senor Frogs]

Update: I called my machine shop guy and told him the plastigauge readings. He said plastigauge usually reads a little tighter then what it really is and he said to run it. The rod bearings are reading the same .001"-.0015"

As for the wrist pins, I Went to home depot and bought 2000 grit sand paper and sanded the pin bore on the rod and everything seems to fit perfect and spin with some resistance now not too loose.

Thanks for the help/advice guys.

 

[vinniekq2]

why not use a micrometer and get exact readings? Your oil pressure is related to clearance. Are you planning on using 0-10 synthetic? or are you using a mineral oil? This is important that you have enough room for the film,,,

 

[Senor Frogs]

why not use a micrometer and get exact readings? Your oil pressure is related to clearance. Are you planning on using 0-10 synthetic? or are you using a mineral oil? This is important that you have enough room for the film,,,

I know what you are saying... But ive already spent too much money on this build and I dont have the money for a good micrometer. If the machine shop guy says run it after I told him the plastigauge readings. I guess I can trust him.. He builds performance engines every day. thats his business, so he should know whats up right? Ill be running Redline 10w30 Synthetic after I break in the rings.

I read this and trust it too Bearing Clearance Info - Tech Article - Chevy High Performance Magazine I dont know... It wouldnt hurt to get a good polish again. Machine shop guy just did it. And he just told me to run it. Im not sure what to do lol.

 

[johnsongrass1]

Run it.....This board is a great board but with this number of members your going to have to choose which advice to listen too. .0015 is a litte tight but it's not too tight and it mostly affects idle pressure but as long as you have at least 10 pounds it's gonna be ok.

That wax string has been around a long long time and proven lots and lots it's ok to use. Not like a set of mics but its works.

 

[64nailhead]

You started this thread looking for answers in a hurry. What you've found is an issue that's going to cost you some time to correct. Accept it and take the time to fix it right. You've found varying opinions from guys here mostly indicating the bearings are just a bit too tight. Do you want to conduct a test to find out who's right? If yes, then run it. If not, then get it checked and corrected if needed.

IMHO, any reputable machine shop would be more than willing to recheck your crank and bearing clearances and if the crank needs a polishing to bring it into spec and they will take care of that as well. I'd run the block, piston & rod assemblies and crank back to the machine shop and get them rechecked. If you machine shop won't do it for you, then sounds like it's time for a lesson in crank polishing or time to find another machine shop.

Keep in mind that everything might be fine, but peace of mind would be worth it to me. Where are you located? Maybe someone here can recommend someone near you.

 

[BogiesAnnex1]

I wouldn't have sandpapered the inside of rod bushings, this is an area where a little too tight isn't as bad as too loose. Plus you need to be more than matiulous in cleaning sanding residue any left imbedded in the bushing will continue to sand the part.

Frankly I haven't found Plastigauge to be all that off as many others report. It's just part of my routine to get several checks on bearing clearances so I use it along with mics to get a handle on these critical clearances. Since your numbers are almost exactly .001 tight I'd first look to the bearings to see if they are a plus .001 set before I go and grind or polish on the crankshaft. Bearing packages can usually be had in standard or .001 over and .001 under for a proper fit without regrinding the crank. There are also oversizes for .010, .020. .030 or more undersized jounals so don't get these things confused. .001 over are often sold from parts stores for worn cranks.

It sounds like you need to put some money into at least an inexpensive set of micrometes from Harbor Freight. That way you can take some measures without guessing.

A set of telescopes Telescoping Gauge Set 6 Pc

A set of outside thimbles from 1 to 3 inch in 1 inch increments is a minimum 3 Piece Micrometer Set

A dial indicator magnetic base Multipositional Magnetic Base with Fine Adjustment

A dial indicator 1" Travel Machinist's Dial Indicator

Or you can go to Granger and or MSC and shop around for similar items. These imports won't hold up in a production shop but they are plenty sufficient for the occasional engine builder. They read with marks to the .001 you can estimate the .0011 to .0019 range.

Bogie

 

[Senor Frogs]

You started this thread looking for answers in a hurry. What you've found is an issue that's going to cost you some time to correct. Accept it and take the time to fix it right. You've found varying opinions from guys here mostly indicating the bearings are just a bit too tight. Do you want to conduct a test to find out who's right? If yes, then run it. If not, then get it checked and corrected if needed.

IMHO, any reputable machine shop would be more than willing to recheck your crank and bearing clearances and if the crank needs a polishing to bring it into spec and they will take care of that as well. I'd run the block, piston & rod assemblies and crank back to the machine shop and get them rechecked. If you machine shop won't do it for you, then sounds like it's time for a lesson in crank polishing or time to find another machine shop.

Keep in mind that everything might be fine, but peace of mind would be worth it to me. Where are you located? Maybe someone here can recommend someone near you.

Thats the thing, I Had him only do machine work. The stuff I dont have the machines for. He bore/hone, hot tank/magnaflux, decking, mic and polish crank, engine balance. So when I got my engine from him, all the bearings were still in the plastic wrapping never touched. Id probably have to pay him to re polish my crank.. and I really dont have the money... I have enough to buy the break in oil and synthetic oil.. Using every penny of my budget and then some.

I live in Sacramento California.

 

[CNC BLOCKS NE]

Most if not all rods I have seen need to HONED to fit the pins.0009 to .0011 on small block has always worked and is what recommended.

Trying to polish clearance into a crank does not work either all you end up with are journals that are no flat.

If thats an old GM block it might be a good idea to measure the housing bores and make sure they are to spec and in most cases its a misalignment issue that block has been that through many heat cycles.

When buying a rotating assembly everything needs to be checked including the block specs.

A wrist pin will slide through at .0002 clearance which is far from .0009 clearance.

 

[Senor Frogs]

Most if not all rods I have seen need to HONED to fit the pins.0009 to .0011 on small block has always worked and is what recommended.

Trying to polish clearance into a crank does not work either all you end up with are journals that are no flat.

If thats an old GM block it might be a good idea to measure the housing bores and make sure they are to spec and in most cases its a misalignment issue that block has been that through many heat cycles.

When buying a rotating assembly everything needs to be checked including the block specs.

A wrist pin will slide through at .0002 clearance which is far from .0009 clearance.

Im not to worried about the pins anymore. I got them to feel right. Im gonna roll with it. My bearing clearances is whats got me nervous...

I didnt buy a full rotating assembly. The crank is still stock.

 

[dogwater]

Back in the 70's when I was in high school, before cable TV, internet an a lot of other distractions I would hang around my neighbors house cause he had the tools to rebuild engines. Every couple of weeks there would be another Chevy or Ford without an engine in it. I saw a lot of half *** engine rebuilds but they all ran, an a few were for the drag strip only. Things didn't get measured very well, all those engines had heads for this & that, crankshafts that were just looked at an used but everything worked & ran fine. Now that were older being anal is the norm. I wouldn't build an engine like that anymore. Don't worry so much, it'll be OK.

 

[Senor Frogs]

Back in the 70's when I was in high school, before cable TV, internet an a lot of other distractions I would hang around my neighbors house cause he had the tools to rebuild engines. Every couple of weeks there would be another Chevy or Ford without an engine in it. I saw a lot of half *** engine rebuilds but they all ran, an a few were for the drag strip only. Things didn't get measured very well, all those engines had heads for this & that, crankshafts that were just looked at an used but everything worked & ran fine. Now that were older being anal is the norm. I wouldn't build an engine like that anymore. Don't worry so much, it'll be OK.

You know, When the original 350 in my chevelle blew up, my buddy did a straight trade with me for his 307sbc. It had about a thousand miles on it before he took it out for a bigger engine. It sat on a stand dry for 20 years. It had surface rust on everything. in the bores. On the cam lobes... The ONLY thing I did to it before I put it in my car was clean the head gasket surface and prime the engine with oil. It fired right up! Ive now put about 15000 hard daily miles on it (Have to drive it hard to have any fun with it) and its still running like a champ. 16 flat in the 1/4. Sure it smokes a bit on start up... lifters tick... and leaks oil like a mother**** because I half assed the gasket installation.

I think im just so concerned about every little thing because Its going to be my daily driver. And I want it to last longer then 15000 miles. I plan on a few road trips too. I know tighter clearances makes for higher bearing temperatures. Im worried that could be a problem on a 2 day 1500 mile trip. I think I have to stop with the worrying though and trust my machine shop guy...

 

[64nailhead]

Bogie's advise about the .001" oversized and undersized bearings is GREAT advice. If you could correct this with a different set of bearings, then that would be your quickest and cheapest route out of Self Torment and Concernville.

In hindsight from rereading this thread, I'd take his route.

My two cents and best of luck to you - Jim

 

[ericnova72]

When you did the plastigauging, was both halves of the bearing dry, or did you leave 1/2 oiled and only cleaned and dried the side you put the plastiguage on??

That can make a difference right their, as the oil on the other side of the bearing journal will take up some space.

 

[Senor Frogs]

When you did the plastigauging, was both halves of the bearing dry, or did you leave 1/2 oiled and only cleaned and dried the side you put the plastiguage on??

That can make a difference right their, as the oil on the other side of the bearing journal will take up some space.

I plasti gauged them twice, Once with oil on the bearing in the block and dry on the cap, and once with oil on both block and cap bearings... I see what youre saying though. Should I re plastigauge completely dry? The reason I wasnt thinking about the oil was because Plastigauge says on there website to use oil to keep the string in place. So I didnt think it mattered

 

[dogwater]

Just spray some WD40 on your finger an wipe it onto the crank an place the plastigauge on the wet spot. Otherwise than that no other oil on crank.