275,000+ mileage bottom end

[zraffz]

I recently picked up a 305 S10 and want to do a small budget $2,000-2,500 all said and done build. I have a 1997 Suburban laying around my house that has well over 275,000 miles and hasn't moved in 2 years... it became a parts truck for my other project.

I had the bright idea to use the motor for my S10, planned on freshening it up, having the heads machined and cleaned, and throwing a cam in it. Well, I know the pictures aren't the greatest but I think picture number 3 speaks for itself. The grit on the pistons isn't anything more than gunk that fell in when I pulled the heads off.





I am very surprised. The pictures seriously don't do the cylinder walls any justice. The lifters look brand new, the cam wore very evenly and the heads have minimal carbon build up. I am not even going to pull apart the bottom end. I had the pan off and everything looked pretty good. Got a few measurements to take and the heads are off to the machine shop on Monday.


Best part is this motor usually went an extra 2,000 miles before oil changes

[chrisfrom nj]

the motor doesnt look bad at all my motor had 297,000 miles when the oil pump blew

[zraffz]

I popped one of the heads off and saw a big **** eating grin on my buddy's face and before I could get a look he was saying "no ******* way!"
I will be getting an oil pump but that's it for the short block. Throwing in a 276HR from Comp Cams, 1.5 rollers, timing chain and the heads will be getting cleaned/valve job/valve seats ground/new valve guides and whatever springs/retainers I need.
Entire build should be right around 2 grand. Behind a 2,000ish stall torque converter it should be a tire roasting rocket in a little 3,000lb truck.
It's already got a 305, 2004R and some other goodies in it. Got a spray plate laying around that might go on for a few giggles.

[chrisfrom nj]

you got 2 projects going a once your going to forget about your camaro build your investing too much money between 2 projects is there anything good left on that parts suburban

[1320B4U]

Its a testament for regular oil changes and servicing..no surprise here. Going a few thousand miles over isn't such a big deal, i put in my log book -500 less for the next scheduled change so when i know its time i can go a bit longer. Also a testament to the sbc and its design.

[BonzoHansen]

very nice. also a testament to EFI. precise fuel measuring and no more washing down the cylinders on cold starts.

[JL8Jeff]

Looks pretty clean. One thing to watch out for when doing the heads, it will tighten up the top end, but that may put some added pressure on the bottom end which could lead to some sort of failure, especially on a high mileage bottom end.

[greenformula92]

I would to quick rebuild on it. IE bearings and rings just to be safe. Its already out apart

[69RSZ]

my tahoe just turned 200,000 miles,same motor 350 iron block and heads,great motor.I bought it new and ran mobile 1 oil since new.

[WildBillyT]

Skip it and buy my 454

Looks good man. GL with the build.

[zraffz]

Originally Posted by WildBillyT

Skip it and buy my 454

Looks good man. GL with the build.

Would love to but it's not practical to stuff into an S10. Already got a set of headers for the SBC/S10 anyway


And I know I really should do bearings and rings but I'm just going to run it and see... not like it's my only toy and if I was able to get away without doing anything to the bottom end I'd feel way more victorious

[greenformula92]

Originally Posted by zraffz

if I was able to get away without doing anything to the bottom end I'd feel way more victorious

[zraffz]

Well I took the day off work today and paid a visit to the machine shop. My heads were in the tank when I got there but he was very impressed with the lack of carbon build up on the valves. He said the exhaust seats showed every bit of 275,000 miles but other than that they were perfect. We got to talking and he stressed that I should freshen up the bottom end. Springs/retainers/locks/rocker studs should be in tomorrow.

Good thing I listened and took the main caps/connecting rods apart. All 8 rod bearings showed significant wearing where the bearings seat in the connecting rod caps. Looks like all 8 were getting ready to spin!
Main bearings wore very good for the amount of miles on them, crank has a few hairline scratches so it's going to the machine shop to get turned .010/.010.

[greenformula92]

good thing you pulled it apart.

[zraffz]

Yeah now I just hope to god that my connecting rods aren't destroyed. Caps have some slight wearing from the bearings moving; won't know if they are good or bad til next week when I drop them off.

[greenformula92]

Originally Posted by zraffz

Yeah now I just hope to god that my connecting rods aren't destroyed. Caps have some slight wearing from the bearings moving; won't know if they are good or bad til next week when I drop them off.

Depending on what your power goals are you can get away with a cheaper OEM style rod. If you have big power goals you may want to upgrade, but only you can decide that

[zraffz]

I understand but at what point do I just buy a new rotating assembly? I mean if the rods are beat I am looking at having the old wrist pins pressed out, new rods, turning the crank .010/.010, rings, repressing wrist pins and rebalancing - approximately $700. As opposed to an entire new bottom end for a little bit more?

[WildBillyT]

Originally Posted by zraffz

I understand but at what point do I just buy a new rotating assembly? I mean if the rods are beat I am looking at having the old wrist pins pressed out, new rods, turning the crank .010/.010, rings, repressing wrist pins and rebalancing - approximately $700. As opposed to an entire new bottom end for a little bit more?

A bottom end that's a little bit more than $700 is not a very good quality new bottom end.

[zraffz]

Originally Posted by WildBillyT

A bottom end that's a little bit more than $700 is not a very good quality new bottom end.

You misunderstood. I said to turn my crank, new rings, new rods, re-use my pistons and have the wrist pins taken out and reinstalled.


Either way, I took another look at the rods and they should be fine to reuse. Will have it double checked by the shop but their is no grooves in the rod caps but they do show some discoloring from the bearings being on their last stand.

[greenformula92]

for a decent quaility rotating assembly you will have to spend at least 1200 depending on the brand

[WildBillyT]

Originally Posted by zraffz

I mean if the rods are beat I am looking at having the old wrist pins pressed out, new rods, turning the crank .010/.010, rings, repressing wrist pins and rebalancing - approximately $700. As opposed to an entire new bottom end for a little bit more?

I did? Looks like you were weighing the $700 cost to refurb vs paying "a little bit more" for an all new one.

[zraffz]

Originally Posted by WildBillyT

I did? Looks like you were weighing the $700 cost to refurb vs paying "a little bit more" for an all new one.

SCAT has a rotating assembly using a cast crank, 4340 rods, and keith black pistons (along with bearings) for $1,100. Comes balanced, machine shop even says every crank he's measured from that kit was spot on.

Sorry for the misunderstanding.

[zraffz]

My buddy brought me by his shop to clean up the valve covers, oil pan, rods/pistons in the parts cleaner tank. Afterwards everything but the pistons/rods were further cleaned with a pneumatic whiz wheel.

Before and after picture of the tanking. It sucked, that stuff melted through about 15 pairs of gloves before I gave up on gloves. Caught my hand with some Gum Gutter later in the night and had my hand turn bright red and go numb for a few hours...


The rings were beat. Some came off in one piece while others moved about 1/4" inch out of the ring grooves and snapped.


Still waiting on my heads to get finished, apparently it was a bad week for the shop
(Kinda anxious to see if the springs are seating at the right height without needing machine work).


... in the mean time I ordered a nitrous kit, gauge and blow down tube to melt the current 305 with a 150 shot lol.