Where to start - SBO 350 rebuild??

[WanaBa442]

Been reading till my eyes bleed, learned alot, head still feels empty though.
About to dive into a rebuild on the '69 350 long block I snagged a couple of weeks ago. Here's where we're at:
Block is torn down, will need a dunk, sonic check and a bore. Hoping .030 over will cure what ails it.
Crank has been turned 10/10, still looks real nice and bearings show no wear.
With a bore, I'd need to choose a piston to finish out the job, and possibly a minor cleanup to square the deck if it's off, or to end up close to zero. Rods resized, new bolts and top off with a new slug.
Have a set of #5 heads that need cleanup and checking out. Have had the crossovers plugged, new springs but gathered some corrosion before I got 'em.
May need everything, with luck clean and go after checking chamber CC.
Here's where I'm stuck.
Will need to pick a cam to make it all work together.

Plan is to swap it when done into a '78 Cutlass, mated to a TH350. Gonna replace the 260/TH200 that it currently has.Looking for a solid driver, enough power to have some fun (9 - 9.5 CR) but not break the bank (or the 7.5 rear). Eventually move from the current low 2's up to a 3.08 rear gear.
Should I do the heads first, see where we end up with CC's and then spec the piston/cam combo and do the block?
Do the block prep and see where we end up?
It's a budget build that'll have to be done in stages as funds allow.
I'd follow a valid recipe if you'll share, as long as it doesn't say " Swap in a 455" That ain't gonna happen..

 

[64nailhead]

No replies for days???

First item to check is the block and crank. From there you should come up with a goal, i.e. HP, intended use, and of course budget.

Regarding your heads and rods, if the heads don't have hardened seats installed, then all money spent on them will be better spent on an aftermarket set or a set of Vortecs; you can pick up a set of Scat rods ready to go for the price of reworking a set of stock rods.

Give us some more info on your goals/intentions and the heads. From there much better advice can be provided.

EDIT - are you rebuilding an Olds or Chevy?

 

[Clutch]

Sounds like one of my cars. I'm guessing that you have #5 heads there a good head but they don't have hardened seats I would start there and get a game plan for the rest of the motor. Your keeping the 7.5 so I'm thinking no reason to go ajustable valve train pick a cam and intake combo and buy pistons to match sounds like you have this well in hand

 

[lilbowtie]

Sounds like your looking for a nice street car with a little punch. I would mimic the W-31 for a nice driver and have 325 HP

 

[olds307 and 403]

Get either these Olds School forgcnn-bo7000-008-8/m.summitracing.com/parts/slp-l2321f30#
Or these https://m.summitracing.com/parts/dms-6020x-4080
If your engine can get away with just a hone. https://m.summitracing.com/parts/cnn-bo7000-008-8
Of it depends on your head CC and I would add 2.07/1.625 valves with the bowls opened up, if any work is done to them. Contact Cutlassefi on here. He will have cam choices and I believe a pick a ton that will put you into the low 9's for compression.

 

[olds307 and 403]

I had Cutlassefi do a custom cam grind that would work OK with my current 2.78 gears and have acceptable manners. It is a nice cam for 9 to 1 compression, 214/214 .472/.472 on a 110 lsa. I would run at least a 2000 stall, if not a 2200 to 2500 stall. I just put a stock 1800 stall behind it, ok but not as nice. The 2300 stall was much more fun but the 2004R was ran low on fluid and cooked.

 

[olds307 and 403]

I would upgrade to the Yukon spider gears if they show any sign of wear. Do a gear oil change and see what they look like. Mine exploded and took out the gears and girdle cover.

 

[WanaBa442]

Thanks for the replies.
Motor is a '69 OLDS 350, with #5 heads. Already have the big valves in 'em, but they need a good cleanup and overhaul. I've heard seat upgrade is unnecessary on the earlier heads because of better metallurgy in the casting? Go too deep and you hit water, making decorative door stops out of a decent small chamber set. That'd make me mad. Going to be a driver with a little more kick in the butt than what you got new in '78. Block is going for cleanup, dunk, sonic check and rough bore to see if the cylinder bores will clean up. If it checks out, we move forward.😎

 

[olds307 and 403]

Just make sure the bowls were opened under the valves. Olds heads have almost no issues with seat recession, leave them alone. Cutlassefi will have a few sets of the new Mahle Olds 350 pistons in 4.065", 4.100" and 4.155" over sizes, 10cc dish and a super modern thin ring pack in the very near future. Those will give you ideal compression. Olds 350 blocks will usually take a .100" overbore, if necessary.

 

[MrSony]

I've heard that about buicks with the better metals, not to sure on the olds. A nifty tool I found (works quite well) for calculating compression is from this site: http://cochise.uia.net/pkelley2/DynamicCR.html
Just put in your engine measurements and cam specs (need to hop around a bit between the tabs as specs for one come from another, etc).
Anything with a DCR of 8:1 or lower is considered ok for pump gas. You might as well bore it .030, if you want a good reliable engine. I'd only advise honing for an engine you're gonna sell or just to get something running again. If there are no deep gouges or holes, .030 should clean up just about anything. There are plenty of proven formulas out there. A stock rebuild (with new valve seats, have the machine shop leak test the heads, check the valves, etc), and pick a cam to match your compression. The 1969 350s were either the 4bbl with 10.25:1, or 2bbl 9:1 if i recall. Grab a piece of plexiglass (5x5 inches would be enough, maybe 1/4 inch thick?) drill a small hole in it, grab a syringe with some visible liquid (green rubbing alcohol, water with food coloring) and check the size (CC) of your heads and pistons. If it's the stock bore, the bigger CC pistons will probably denote the 9:1 motor and that will be fine with 91+ octane.