[Senor Frogs]

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.

 

[Senor Frogs]

Anyone? ........

 

[Senor Frogs]

Im finding it hard to believe that this has been up for 3 hours in a forum with 1200 viewers and not have a single answer... This should be a SIMPLE question for anyone who has ever put an engine together with full floating pins... Someone, please help as my build is halted because im uneasy about moving forward not knowing this myself.

 

[[email protected]]

Just got in the house from a long day in the toy shop.

Yes the pin will be OK once the engine is fired.

What did you use for assembly lube? Some of the high viscosity lubes will cause the same conditions with a snug bearing fit. Also will disappear with the first start.:thumbup:

 

[64nailhead]

What are your bearing clearances? Did you check them with plastigage or an internal bore micronometer? If the answer is 'I didn't check them', I'd recommend pulling the crank, to clean off all of the assembly lube from the bearings and crank, and check them all with plastigage if the appropriate mic is not available - ESPECIALLY if the crank was cut - trust no one. If the answer was yes, I'd put the double and triple check on making sure the caps are in the correct locations and the bearings are installed properly (via bearing tang).

I'm sure someone will tell, or has told you to not use plastigage. I'll tell you that it works and has worked for years, and it is a quick final check to confirm that all is going according to Hoyle.

Regarding the wrist pins - I defer to Bob.

Good luck - Jim

p.s. - starting to get dark on the right coast here, hence, no computer time when it's 75 and sunny during a day off (especially after the winter and spring we just had:thumbup - been playing/messing with this and that all day.

 

[Senor Frogs]

What are your bearing clearances? Did you check them with plastigage or an internal bore micronometer? If the answer is 'I didn't check them', I'd recommend pulling the crank, to clean off all of the assembly lube from the bearings and crank, and check them all with plastigage if the appropriate mic is not available - ESPECIALLY if the crank was cut - trust no one. If the answer was yes, I'd put the double and triple check on making sure the caps are in the correct locations and the bearings are installed properly (via bearing tang).

I'm sure someone will tell, or has told you to not use plastigage. I'll tell you that it works and has worked for years, and it is a quick final check to confirm that all is going according to Hoyle.

Regarding the wrist pins - I defer to Bob.

Good luck - Jim

p.s. - starting to get dark on the right coast here, hence, no computer time when it's 75 and sunny during a day off (especially after the winter and spring we just had:thumbup - been playing/messing with this and that all day.

Youre right I didnt plastigauge... I hear plastigauge isnt very accurate, but I dont think its meant to be "accurate" more of a quick check like you say. Do I have to pull the crank? I have all my pistons/rods installed! Could I just pull the caps and clean the cap bearing and the half of the journal where I will plastigauge?

Thanks

 

[Senor Frogs]

Just got in the house from a long day in the toy shop.

Yes the pin will be OK once the engine is fired.

What did you use for assembly lube? Some of the high viscosity lubes will cause the same conditions with a snug bearing fit. Also will disappear with the first start.:thumbup:

Im using Sta Lube E.P Anti Seize Engine Assembly lube Im not sure of the viscosity. im wondering why only a few were tight. I know wrist pin clearances are really tight, so maybe I got a cat hair or something in there? hah

 

[johnsongrass1]

It's likely the assy lube your using is causing the pin rotation thing. The pistons and rods do have a spec and I've been told the scats are a little tight out of the factory. As long as you can turn the pins once installed I'd run it.

As far as bearing clearances go this is something that needs attention to detail and can't go unchecked. The possibility of them needing attention and the level of destruction makes them a necessary chore.
Plastiguage isn't as accurate as a .0001 ball mics and DTI gauges but you don't need that kind of accuracy anyway. Plastigauge will get you within .0005 and it will also show you journal taper at the same time. You don't need to pull the crank for this. Just the main and rod caps. Your shooting for .002 to .003 on the rods and .003 to .0035 on the rear main cap. Too loose is better than to tight.

 

[Senor Frogs]

It's likely the assy lube your using is causing the pin rotation thing. The pistons and rods do have a spec and I've been told the scats are a little tight out of the factory. As long as you can turn the pins once installed I'd run it.

As far as bearing clearances go this is something that needs attention to detail and can't go unchecked. The possibility of them needing attention and the level of destruction makes them a necessary chore.
Plastiguage isn't as accurate as a .0001 ball mics and DTI gauges but you don't need that kind of accuracy anyway. Plastigauge will get you within .0005 and it will also show you journal taper at the same time. You don't need to pull the crank for this. Just the main and rod caps. Your shooting for .002 to .003 on the rods and .003 to .0035 on the rear main cap. Too loose is better than to tight.

I think there was only one that wasnt turning in the rod. I installed it anyway and forgot what one it was! I might have to pull them out one by one till I find it!

Thanks for the reply. Im going to get some plastigauge tomorrow and get to work.. I want this engine put together! haha. I have ARP main bolts. How many times can you use them? Ive torqued them down now two separate times..

 

[johnsongrass1]

100's of times

ARP used to tell you to "burnish" the threads by tightening and loosening 5 times before final torque. That was before they come with the ARP Moly Lube. I suspect it's the same thing as whats in Sta-Lube with Moly Graphite.

I know you want it together! Trust the guys who can tell ya from experience(me) that you would rather it stay together then go together quickly. I'm embarrassed about the time I forgot to check a few things and killed a $22.000 Super Late Model engine cause I didn't want to hang out in the Home Depot Parking lot all night. I killed another one on the Hell Tour cause I got lazy and didn't check the lash that week. There's more but Ill shut up now.

 

[Senor Frogs]

100's of times

ARP used to tell you to "burnish" the threads by tightening and loosening 5 times before final torque. That was before they come with the ARP Moly Lube. I suspect it's the same thing as whats in Sta-Lube with Moly Graphite.

I know you want it together! Trust the guys who can tell ya from experience(me) that you would rather it stay together then go together quickly. I'm embarrassed about the time I forgot to check a few things and killed a $22.000 Super Late Model engine cause I didn't want to hang out in the Home Depot Parking lot all night. I killed another one on the Hell Tour cause I got lazy and didn't check the lash that week. There's more but Ill shut up now.

Alright. Im a little less stressed than I was 5 hours ago haha. Thanks again. I get you, Ive already spent more than I have to build this engine, I would die if I through it all away because I didnt take the time to check clearances.

 

[vinniekq2]

not all answers come quickly

 

[tresi]

I've used sta lube a lot and I never had it make a bearing feel tight like some of the sticky assembly lubes. If one got tight after you torqued it you need to find out why. Hopefully it's just a case of mixed up main caps or something simple.

 

[Senor Frogs]

I've used sta lube a lot and I never had it make a bearing feel tight like some of the sticky assembly lubes. If one got tight after you torqued it you need to find out why. Hopefully it's just a case of mixed up main caps or something simple.

The crank isnt tight. Its the wrist pins that are tight. What the crank was doing is it feels like its frozen up. I cant spin it. But with a little effort it i can get it to break free and it spins normally. and feels normal. but if it sits for a little bit, it freezes up again, like the oil is settling and once it gets moving again its fine..

 

[Senor Frogs]

not all answers come quickly

HAha I got you. I think sometimes when I get that way I need to step back and take a break. Its not like I have a deadline on this engine.

 

[4 Jaw Chuck]

Two piece or one piece main seal?

 

[Senor Frogs]

Two piece or one piece main seal?

Two piece from a felpro kit

 

[dogwater]

I had the same problem with my Scat rods an Speed Pro pistons, a few were tight, like yours they would spin on the piston bores but not in the rod bores. I took those apart an cleaned off the assembly lube then used some 600 grit wet sand an lightly buffed the inside of the rod bore, using my finger. It worked. Are you using an after market crank shaft? If so watch out for where the fillet side of the rod goes. If its an OEM crank don't worry about that. I did have to sand the thrust bearing together the right crank end play.

 

[Senor Frogs]

I had the same problem with my Scat rods an Speed Pro pistons, a few were tight, like yours they would spin on the piston bores but not in the rod bores. I took those apart an cleaned off the assembly lube then used some 600 grit wet sand an lightly buffed the inside of the rod bore, using my finger. It worked. Are you using an after market crank shaft? If so watch out for where the fillet side of the rod goes. If its an OEM crank don't worry about that. I did have to sand the thrust bearing together the right crank end play.

How much do you sand? like one pass? I know the rod to pin clearances are really tight, something like .00015" - .0002" and i dont want to take too much away.

 

[johnsongrass1]

They will grow that much just holding them in your hand too long. A couple strokes with a small wheel cylinder hone and K1/10w-30 is a down and dirty way of getting there. Clean them well after word.