Technical Experienced engine builders of SBC’s - need your advice!

This engine was built in 2000/2001 and sat until 2023. My God Father spent this time building the car so the engine was never turned over and I was told it may have been slightly locked up and I am not sure what the hot rod shop he worked at did to refresh it and or on budge it free. Also not sure if they performed any type of break in procedure. No serious metal in the oil that was drained.

I am trying to address the mechanicals now that there is 600 miles on the motor/car and one of the big things was the rear main seal was leaking badly.

What are your thoughts on the look of this bearing? I did not feel any major grooves with my fingernail.


ALSO - should I loosen all the other main caps and tighten them back down to 75 ft lbs since it has been sitting so long?


Following the David Vizard small block chevy book. For this rear main seal and the other main caps I still intend to do, I plan to tighten each bolt on each side of the bearing to 25 foot pound the to 50 foot pound, finally to 75 foot pound increments.

350 SBC - 73’ Camaro 2 bolt
Back casting # 3970014
Front casting # 135553235 -
T0322 CKJ


I want this engine to last so any tips are appreciated. Not sure if I need to mess with valve lash as the car seems to run quite good.


I plan to pull and look at the plugs and also replace them with some standard AC Delco ones, also replacing with a melling M55 standard volume oil pump, upgraded metal driveshaft, and new oil pick up since the old one is welded and would sit about .65 inches or more above the bottom of the oil pan and since the old one was welded on.


Much appreciated for your guys time, i’ve seen a ton of conflicting information between general Internet searching and YouTube (I won’t get started about facebook and the endless experts there). Also planning to call around to local engine builders/ machine shops to pick their brain if they are willing to spare some time.

cleaned up



Before clean up

 

The bearing looks perfectly fine for 600 miles.

The seal was most likely deformed from sitting for 20+ years with the crank in one position (it would no longer be centered in the main bore as the weight of the crank would cause it to settle down onto the bearings). When you fired it up, the deformed lip could no longer seal as the crank was lifted off the bearings by the oil pressure. Replace the seal and move on.

I would loosen and retorque the mains, starting with #3 and moving out to the ends of the engine. Probably not necessary, but it will make you feel better.

Always a good idea to check valve lash on an engine that has been sitting for a while. If it is running good now, you can wait until your first oil change.

 

The parting line of the seal should not be lined up with the parting line of the block / bearing cap.

I always clean the new seal mating surface(s) with brake parts cleaner to remove any possible mold release agents remaining from manufacturing before applying a dab of RTV.

 

My personal opinion, from 60 years building SBC, is I would disassemble the engine and at a minimum have the crank polished and possibly ground. I don't like the looks of the crankshaft and the engine may need a complete rebuild. Could become costly but you'd know what you have.

 

Yeah the bearing is fine, but shows the crank was ground but not polished. Good time to go through it and check everything.

 

70 or 75 ft lbs? Vizard book states 75 but jegs and summit, other sources say 70 ft lbs

Also, any good ways to check lash without removing the intake or is the finger tight then 3/4 turn method the best?

Good info thanks!

I’d love to and also prefer this route, however, if I take this path the car would end up sitting for several years due to lack of time, and funds. Short driving season here and I’m hoping to rebuild another 350 on the side with my little ones in a few years. I’d like this motor to hold up for 5-10k miles before I pull it. I appreciate the input!

Full tear down or what items would you check, from the bottom view it didn’t look like any of the cam lobes were being harmed and cylinder walls with limited visibility looked good. Need to. Hand crank it for further investigation.

 

It looks pretty good in there and since it already has 600 miles its probably fine. Install a new rear main seal in the correct direction with dab of sealant on the ends and a light coating of oil or lube on the crank where the seal rides. Make sure everything is torqued to factory specs (refer to a service manual as needed), new oil and filter, and then run it. Is there is a build sheet on it somewhere?

If it had not been run yet and I did not know who did the machine work, I would've torn it down and determined bearing clearances, piston to wall clearances, what the ring gaps are, and a whole host of other small details including having the crank polished. Then a thorough cleaning before re-assembly.

Securing the pick up to the oil pump by Welding or Brazing is a common thing to do. No need to remove the intake for valve lash. Some folks have different idea's on setting valve lash so I won't start a debate on that. I'll assume it's a hydraulic flat tappet cam. Just make sure you know what you're working with. Setting valve lash on a solid cam is an entirely different procedure.

 

Polish the crank where the seal rides to make sure it cleans up . A strip or 2 of crocus cloth will do . Loosen all the main caps to make it easier to install the seal . Before you disassemble any more , get a good look at the cam lobes .

 

I have installed the seal, added permatex ultra grey to the ends of the seal and lightly to the mating surfaces to the main cap per recommendation of the David Vizard Sbc rebuild book. I also added permatex ultra-slick engine assembly lube to the cap since wad not sure how long it will take me to get everything back together.

I wish I had a service manual!! I will have to look on eBay but if someone here was looking to hand it off to the next generation I’d buy it off them.

-Any further details/description on this crocus cloth (grits/brands?) and techniques (wet/dry/etc)? I’ll do some searching on here but I’d like to make sure I get the right material and also use it properly.

- Is it ok if I rotate the crank with only that bearing off to clean it all the way up?

-Does it matter that I already reinstalled the rear main cap with silicone on part of the bearing end end of the main seal or well, I have to scrape everything off and get a new seal?

Luckily I didn’t need to loosen the caps to install the new seal.

Much appreciated guys!

 

I personally wouldn't attempt to push a seal in place with the crankshaft in place too. Even loosening the torque wont make it easy really, and you don't want the rear main seal to leak again. I'd remove all the main bearing blocks, and raise the crank up a little with plastic shims at to other bearings and then install a new rear main seal. Be sure to not leave the ends flush with the surface, and instead raise one side 1/8" or so to offset seals from the cap and block surfaces. Then put a dab of black RTV on each end to ensure a good seal.
Remove the shims and re-torque all the main caps and it's ready to go back together.

 

I do not like the crank shaft sealing area .

If it were mine and it was leaking after few hundred miles Id pull the crank and have it polished .
I know you said time was a factor but if you got busy your only looking at less than a days work to do this and as far as cost your looking at top end gasket kit and having the shop polish the crank . the engine is already out and you have it apart already .


I cant confirm 100 percent on a SBC but I know for a fact the crank can be removed on a BBC with out pulling the heads I have done it and have the engine still minus crank with heads still on to prove it.

Id torque the main bolts if there a two bolt main to 70 foot pounds with oil on the threads and head of the bolt . 4 bolt man is less on the outer bolts as I recall.
rods should be 45 pounds on a 3/8" bolt .

If there ARP or some other after market stuff then you need to follow there recommendations .

Lot of rust and crap on the crank flange was it rebuilt or just freshend up ?
are the bearings under sized ?

 

Lots of rust as the motor was rebuilt 2000/2001 and never ran until 2023. The engine is still in the car, was not planning on pulling it and not sure on the bearings. I do not have an engine stand, cherry picker, or the proper gauges/equipment to check things (like the bearings) or put the engine back together if I remove the crank to have it polished. I’ve been looking on marketplace for used tools/gauges to rebuild a spare motor I have with my little ones but that is a few years down the road realistically.

If anyone knows someone, or they themselves are looking to get rid of engine building gauges/specialized tools in PA or eastern Ohio I would be interested!

 

If I understand correctly. You got the car, started the car, and have 600 miles on it. The only noticeable problem was a leaking rear main, which you’ve repaired properly. No big pieces in the oil when you drained it.

I guess you could do another 500 and an oil sample. But it’s running good. Keep driving. No way to pull it, no tools for machine work or measuring, and no problems. I’d just drive it.

 

You really won't need guages if it's right now.
Polishing the crank won't remove much and if just the sealing area it won't remove any thing as far as the bearings.

The area the seal runs on looks rough .
I'd fix it.

It's possable the crank had wear or rust on the seal area and was reworked and can't be fixed even with more polishing. Hard to tell from the pictures.
The sealing journal is not turned undersize like a bearing journal.

Are the bearings under size ?

 

How can I identify if the bearings are undersized?

Also, I’m having a heck of a time finding 800-1000 grit crocus cloth to polish the seal portion of the shaft. I found some on McMaster Carr but the description is vague at 1500-2000 grit. There is some on eBay but again lack of grit ratings.

I found 1000 grit on this website but I need to make an account before even knowing the price..


On a side note while waiting, working on wiring and a part I’m super excited for to keep hot rodding going for the next generation:



Modified Ford fusion child seat anchors from a upullit when I was in Houston for work. On top of the seat belts so it can easily be removed for an adult. Working on greasing all the joints next.

 

I've used 400 to 600 grit wet or dry successfully in the past . Unless you're going to remove the seal ( if you haven't rotated the crank) you'll not be able to polish the crank . For lube , a little light oil ( WD 40) will work for polishing . Getting the silicone off the ends of the seal is the problem trying to reuse it . I'm surprised you were able to roll the seal in without loosening the crank .

 

@McMac 31
There was Times I have polished crank
With Flat wide shoe string & sandpaper
with W -D ,
Reading Bearings ,
For standard STD
Most /Typical then will say
10
20
30 ,

there are some will say .01, .02,.03 &
so on for a more precise build-
Witch are .001 of inch over sized bearings


I had a SBC one time with 25-30 cold oil pressure , Hot 5 ish pounds , drove it for several years
Not trying to take it North of
5,000 rpms
Rule of thumb 10 PSI Per 1,000 RPMs
So @ 1,000 =10 Psi
@ 5,000 = 50 psi

 

Pop the bearing out of the rear main cap and look on the back side. If it is undersized you will see .010, etc. near the part number. Not guaranteed, but usually.

 

You look a the back of the bearing and see if has .010 or .020 or even ,030 stamped in it . ' if your this inexperienced I suggest you find some one to help you a bit.
Taking the bearing out and putting it back requires a bit of care and proper technique but its a 3 second check . of the bearing has no under size mark then it is likely standard and the crank has never been turned under sized . checking the bearing under size would have been the first hting id have doen after pulling a cap to see if teh crank is original or has been turned . I suspect this rebuild might not be all you think and the crank might be an original that was only polished . the wear area on the seal loo like it was worn and prior and maybe already polished or cleaned up .Agai tha tis not a area that can be turned under size like a bearing journal . I don't know of any under size rear main seals .

You go trying to polish the seal journal in place your likely to end up with grit and crap in every thing . You need to be carful and if your asking these basic question it shows you have not had much experience yet ., Not a insult but a observation. This is a good time to learn . Were you 100% certain the seal was actually leaking and not the pan end seal ?

I did not know ere to tell you to go for 1000 grit or even 800 crocus cluth so i did a 5 second search and found about 100 places .
https://www.amazon.com/MiJunHD-Sand...3fa308085fc9217e77bbd11&qid=1748795532&sr=8-3

 

The clue to whether it is a rear main leak or oil pan leak is to look at the back of the flywheel/flexplate. If it is a rear main leak, the back of the flywheel/flexplate will be wet and have a radial pattern from the centrifugal force of the spinning flywheel. With an oil pan leak the back of the flywheel/flexplate will be dry.
In no particular order, other leaks that can appear as if from that area: freeze plug at the back of the cam, oil pressure switch or line to the gauge, rear gasket for the intake, distributer gasket, valve cover gasket.

 

I definitely am inexperienced regarding engine building, which is why I’m reaching out for your guys’s help. I don’t mind admitting that I’m inexperienced but I do have a pretty strong mechanical aptitude so I’m not scared, but Internet searches and books cannot provide the same info that the advice of people that have decades of experience can.

Also I thought I was not supposed to use Emery cloth like the link you provided? I think the difference based on my research is crocus cloth is made with iron oxide (rust) and Emory cloth is made with aluminum oxide or other stuff? The majority of my Internet searches, kept providing Emery cloth minus a few.

Good info! go figure the flywheel and flex plate were relatively dry, I assumed the rear main was going to need replaced since sitting idle for 20 years, even if it didn’t start leaking immediately I assumed it would only be a matter of time of course I could be wrong I am inexperienced in this area and the longevity of these types of seals.

I needed to at least change the oil pump and pick up since I am switching over to a steel pan and getting rid of the aluminum one which could leave me stranded if I hit something (Pennsylvania roads, lots of construction and have personally scattered an aluminum oil pan on an unmarked man hole cover in a construction zone). I figured since I’m all the way there I might as well do the old rear main seal for preventative maintenance.

 

For some reason I thought this engine was out of the car. I went back and blew up the picture of that seal surface and I'm with 1biggun here, the more I look at it the more I don't like it. Starting to think that crank was not ground at all, but is all pitted from rust. There's some trash lines in the main journal as well.

@McMac 31 Don't try to polish that crank while it is in the block and in the car. You only have two choices, either put it back together and run it the way it is, or take it out of the car, tear it down and take the parts to a reputable engine machine shop for evaluation. This could be a great opportunity to gain some more experience and have some fun! Of course it will cost some money.

 

It's really not going to matter what you polish it with if you clean it well after . The only thing your going to polish is the seal area.

It's hard to tell from the pictures but if it's pitted / rough your not going to polish it out with 1000 grit easly or at all.

If it had a Cal CUstom cast aluminum pan you very likely had a leak at the pan rubber end gaskets. Those things can be a PITA to seal .

Not sure why your replacing the oil pump if it was new when installed and not rusty now. Just reposition the oil pick up weld it back if you must.
About 80 million SBC'S factory built with no welded pickup that never failed . Can't hurt but not 100% needed if properly installed .

 

Also I never used 1000 grit to polish a crank journal on a normal build .
Most crank polishing belts are 400 as I recall .
Really no need to micro polish a normal crank shaft .

I use 600 grit to clean anything like a nick or scratch on a journal..

 

Interesting read .

https://www.enginebuildermag.com/2005/01/crank-and-cam-polishing-are-you-smooth-enough/

 

Hi guys thanks for the feedback, I do think it is a Taiwan made Cal custom aluminum oil pan and it wasn’t sealing well. Regardless I’m glad I took it off because even with a smaller depth pan I’m about 0.65” from the pick up before adding the thick one piece felpro gasket, it was probably way higher than the recommended 0.25-0.50” in the aluminum pan too.

I’m replacing the oil pump because the original is REALLY welded on, and I was nervous cutting it off would contaminate the oil pump with all sorts of metal shavings if I accidentally cut through the pick up tube while trying to remove the tack, weld.

I bought a standard volume M55 melling and new oil pick up, I don’t have a welder so I bought this pioneer oil pump screen fastener and plan to use high temp red loctite on the bolts.

Sounds like the consensus is to run it or tear down and I’d rather not have the car sit for the next 5 years as the car should really get out of primer too.

I may need to remove the main cap again, I followed the Vizard book and it may be too much silicone.

So DONT polish the crank where the seal rides, loosen and retighten main caps middle outward to 70ft not 75, install oil pump and set for .25” pan height before gasket, and install steel oil pan.

I appreciate all the advice, and I do wish I had the in house capability to tear down and reassemble, just not there yet tool/gauges/knowledge wise. Someday!

What is the consensus with where to apply the silicone on the rear main seal and/or cap?

here is what the David Vizard sbc rebuild book shows:


zoomed:





Is either of the below correct, or both even? I haven’t seen great illustrations around the web based on general application and location, do’s/don’ts it has been mixed.

 

I personally wouldn't put it back together with a new pan gasket using that same oil pan. Odds of that pan leaking again, no matter how well you seal it are not good. I'd find a decent steel pan to put back on it instead. Might cost you $50 or less, and well worth having a better sealing stock pan.

 

China anything when it comes to timing covers , pans is a crap shoot...Get USA original tin...Had a timing cover that was removed twice till we realized it wasn't even dimensionally correct...

 

Why are you not polishing the crank ?

 

He already said the engine is still in the car, and he has no tools or cherry picker to remove the engine.