Hi, I have a vortec 350 from a 99 Tahoe. It has low mileage (180,000km) and as far as I know doesn’t burn any oil, runs perfectly quiet. I’ll be switching the heads most likely to pre 87 heads to fit my intake but I’m not looking for a lot of performance. Keeping stock cam etc. I can’t decide if I should just clean the engine, gasket it and put it in or if I should do rings and bearings as well. At that point, do I change pistons? Like I said this thing runs perfect and had low mileage but I’ll be daily driving the truck and I’m looking for other’s opinions on it. Thanks!
To rebuild or not
- Thread starter Matt98
- Start date
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All or nothing. Once you’re in there looking around and messing with everything cleaning up , I think it will just hit you that you should just do the job .
Restrorob
Newbie
Hello,
Being a retired auto tech, 180,000 isn't what I would call "low mileage", if your going to daily drive it and you have the funds I would suggest tearing down the bottom end. Have the crank checked, if okey install new bearings. Have the cylinders checked and re-cross hatched then install new rings, if the pistons look good I wouldn't worry about replacing them.
Nearly every higher mileage engine I performed a valve job on or swapped heads on started smoking and using oil shortly after, better seating valves raised the compression and the worn rings couldn't handle it.
Good Luck !
Being a retired auto tech, 180,000 isn't what I would call "low mileage", if your going to daily drive it and you have the funds I would suggest tearing down the bottom end. Have the crank checked, if okey install new bearings. Have the cylinders checked and re-cross hatched then install new rings, if the pistons look good I wouldn't worry about replacing them.
Nearly every higher mileage engine I performed a valve job on or swapped heads on started smoking and using oil shortly after, better seating valves raised the compression and the worn rings couldn't handle it.
Good Luck !
Thank you, the pistons were moreso my concern. The original plan was to either just send the block out or drill hone it and put new rings in it, though I think I’d rather send it out but I noticed the kit can come with bearings rings gaskets and with or without pistons and I figure if I was just keeping it stock and there’s nothing wrong with the engine as it is why change them.
I do believe in just doing it. Haven’t decided if I want to try to source new aluminum heads with the old style intake or get the vortec heads gone through. The biggest factor is I have an Edelbrock efi intake that is for the pre 87 heads and I don’t think you can buy just the intake without the whole efi kit which is over 3 grand.
I am also a tech but usually would order a scrap yard engine and put it in. Most of the old chevys I see have double that mileage on them now so I figured 100k ish miles is nothing for one of these
Sean Buick 76
I'm Awesome
I would toss it in and run it. H would also not remove the heads I would use a carb intake and made a plate to mount the TBI but that’s just me.
No existing problems, head-swap "just because"? I think you need to reconsider removing Vortec heads to install older junk castings. You're throwing away ~30 horsepower.
I would look at the ridge at the top of the cylinders. That would be my "deciding factor" unless something else grabbed my attention during teardown.
If you can catch your fingernail on the ridge...you're goin' in deep.
Ridge is minuscule--under .001? Leave the short-block alone. Well, clean the lifters ONE AT A TIME, and verify the timing chain/sprockets. MAYBE a different oil pump. Gaskets/seals as needed.
"Service limit" for bore wear is .001. That means the ridge is .0005. And that's lovely, but maybe just a bit too conservative depending on application. The block I rebuilt had .0015 wear, (ridge = .0007-ish.) I ran the dingle_berry brush through 'em, new rings, and all these years later it's still doing fine.
I would look at the ridge at the top of the cylinders. That would be my "deciding factor" unless something else grabbed my attention during teardown.
If you can catch your fingernail on the ridge...you're goin' in deep.
Ridge is minuscule--under .001? Leave the short-block alone. Well, clean the lifters ONE AT A TIME, and verify the timing chain/sprockets. MAYBE a different oil pump. Gaskets/seals as needed.
"Service limit" for bore wear is .001. That means the ridge is .0005. And that's lovely, but maybe just a bit too conservative depending on application. The block I rebuilt had .0015 wear, (ridge = .0007-ish.) I ran the dingle_berry brush through 'em, new rings, and all these years later it's still doing fine.
You say it runs well. Did you do a dynamic compression check. Then a differential compression check ? That would be a consideration in overall engine health. Making choices based on " just cause it's open " that cost money that adds up quickly, without justification. Replacing and reverting to previous design TBI is a huge step backwards.
From what you described a perfectly suitable running engine, your tearing into to change, for what gains, what advantages?
From what you described a perfectly suitable running engine, your tearing into to change, for what gains, what advantages?
Well the main reason is I don’t want any leaks to form so I’m changing all the gaskets.
The reason to get rid of the vortec heads is that I have an Edelbrock MPFI (pro flo 4) and I don’t think you can buy just the intake to switch it to vortec, you need the entire kit again. It looks like a carb but has 2 fuel rails on the intake as well and works really well and I don’t want to change that out
Sean Buick 76
I'm Awesome
In that case I would use some Chinese alum heads. If possible buy then bare and have a good shop do the finishing work. Buying then ready ti bolt in is convenient but thier quality control is terrible.
Sean Buick 76
I'm Awesome
Or AFR makes bolt on head.
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