Originally Posted by cutlassefi

Good choice on the pistons, I can probably help on those if you're interested.
I'd opt for Molnar rods instead of the stockers
Ditch the 2711, use a 7111.
Small roller on a 111-112-113 lsa if you want smooth. I have those too.
Don't waste your time on restrictors or polishing the valley.
And you wasted your money on the Thornton manifolds. They won't get you much more than the stock ones, and are miles away from long tube headers.
Ask lots of questions from your machinist. If he can't answer them then he should offer to find out, not just guess.

Hope this helps.
Mark

Originally Posted by Fun71

The Pontiac distributor will not drop into the Olds block. Post a Wanted ad for an Olds HEI; someone on the site should have one for sale.

I would recommend the TransGo shift kit. I have used one in every TH350 since the early 1980s and have not been disappointed. The only modification I make is to retain the factory spring on the Control Valve Assembly. Using the spring from the kit allows a 2-1 downshift at any speed, which can cause issues. Retaining the factory spring keeps the 2-1 manual downshift high-speed lockout feature so you don't grenade the transmission.

Originally Posted by ZSmith74

Compression & Block Work

Olds decks don’t leave much material compared to other GM engines, so I’m cautious about zero decking unless measurements make it worthwhile. Going off stock numbers, the engine still sits at the low factory compression, but once the machinist measures true deck height and chamber volume, I’ll finalize the plan. Target compression: 9.5–10.0:1.

Questions:
• For a street 350, is zero decking worth it, or safer to stick to a light cleanup cut?
• Ideal quench distance for pump gas?
• Is ~10:1 comfortable at higher elevation?



Machining & Clearances

Factory clearances were written for old oil standards. Modern builds seem to prefer slightly looser bearing clearances for better oiling. I’ll be using good oil and ZDDP. Block, rods, and crank will be at the shop for measurement and inspection. I’ll have them install new cam bearings and fit pistons after bore size is confirmed. I know 4032 forged pistons need specific piston-to-wall and ring gaps.

Questions:
• Any clearances you deliberately set different from factory specs?
• Chamfer or radius crank oil holes?
• Lightly chamfer lifter bores for roller lifters?



Pistons & Overbore

I know Olds blocks tend to live longer with minimal overbore. My cylinders look close to standard, but the machinist will confirm. Leaning toward Mahle 4032 forged pistons for stability and street manners. I’ve seen Olds Performance Products pistons but don’t know how they compare.

If honing cleans it up: Mahle 197815365 (4.065")
If not: Mahle 197815300 (4.100")
Not sure I want to jump straight to .040”, but options seem limited.

Torque-plate honing is recommended, but not all shops have Olds plates. I’m open to providing one.

Questions:
• Do you prefer the smallest overbore possible on a 350?
• Any real-world experience with Olds Performance Products pistons?
• Should I buy/supply a torque plate for the machinist?
• If stock rods check out, are they fine to reuse with ARP bolts?



Cylinder Heads (#7)

Bowl blending seems to be one of the most effective upgrades on these. Planning a bowl blend, hardened seats, a proper 3-angle valve job, and a cleanup mill. Open to 2.00/1.625 valves if the bowls are reshaped. Winters here get cold, so I’m inclined to keep the exhaust crossover functional.

Questions:
• On a bowl-blended street 350, do larger valves help noticeably?
• Keep heat crossovers functional in a cold climate?
• Any throat-size or seat-angle instructions I should relay to the shop?
• Safe spring pressures for stock rods + street roller?
• Typical pushrod changes after stud conversion + roller rockers?



Valvetrain & Stud Conversion

Olds valvetrain geometry differs from Chevy/Ford, so I don’t want to assume anything. I see many builders convert to screw-in studs, guideplates, and full roller rockers—especially with rollers—but I’m not sure whether that’s essential for a mild street cam.

Questions:
• Are screw-in studs + guideplates necessary for a mild hydraulic roller?
• Are pedestal roller-tip rockers reliable long-term?
• Any geometry quirks with #7 heads?



Camshaft Selection

Looking for a mild–moderate hydraulic roller with strong low/mid torque and good vacuum for A/C. Don’t want a cam that wrecks idle or drivability. Still learning what lift/pressure #7 heads tolerate.

Questions:
• Duration/lift range best suited for this combo?
• Preferred LSA for vacuum and drivability?
• Any lift or guide clearance limits on #7 heads?
• Spring pressures appropriate for a street roller on stock rods?



Fuel & Ignition

Running an Edelbrock 2711 intake. I have a JET Stage 2 800 cfm Q-jet and a Holley 4160 (600 cfm). I understand the Q-jet won’t “overfeed” the 350. Also have a DUI HEI and a GM HEI from a ’79 Pontiac. From what I’ve read, a proper GM HEI distributor can be more solid than other aftermarket optioins.

Questions:
• For this combo, use the Holley or the Q-jet?
• Any downside to an 800 cfm Q-jet on a 350?
• Will a ’79 Pontiac HEI drop into an Olds 350?



Exhaust

The only seized bolt I found was on the stock manifolds, and the boss snapped—so dual exhaust became mandatory. Picked up Thornton cast-iron manifolds and an Inline Tube dual exhaust kit. Everything I’ve read says the Thorntons perform great on the street, but I’m curious how they compare to long tubes.

Questions:
• Thorntons vs long tubes—what differences should I expect?
• Any heat or clearance concerns with Thorntons?



Transmission (TH350)

TH350 shifted well before teardown, so I’ll clean/inspect/refresh it rather than rebuild it unnecessarily. I know the converter stall should follow the cam choice. Guessing 1,800–2,200 rpm. Heard TransGo kits are still the way to go.

Questions:
• Ideal stall for a mild roller with 3.08/3.23 gears?
• Are TransGo shift kits still preferred?
• Add an external cooler for long highway runs?



Rear Gears

Factory 2.56 gears are great for economy but not much else. Debating 3.08 vs. 3.23 for a good street/highway balance. Planning to add a posi.

Questions:
• For my use, would you choose 3.08 or 3.23?
• Preferred posi carriers for a street Cutlass?



Oiling System Considerations

Olds engines have well-known oiling and drainback quirks. I’ve read about opening drainback areas, chamfering returns, smoothing casting flash in the valley, and other small improvements. Also aware of the debates over standard vs. high-volume pumps, HD driveshafts, windage trays, and PCV baffle mods.

Questions:
• Should the shop clean/open the drainback paths in the heads/block?
• Smooth lifter valley casting flash for better drainback?
• Any reason to run a high-volume pump, or stick with standard?
• Windage tray or crank scraper on a street engine?

If I’ve missed any Olds-specific quirks (oiling traps, machining pitfalls, geometry issues, or anything else) I’m all ears. Appreciate the guidance and picking your brains. Thanks for your time, gentlemen.

Originally Posted by ZSmith74

• For my use, would you choose 3.08 or 3.23?

Originally Posted by OLDSter Ralph

This has the appearance of a ChatGTP answer. It dredged up several "Olds myths" from yesteryear. Be aware that not all machine shops are equally good. Find the good machine shop.

Originally Posted by olds 307 and 403

Yes, not all machine shops are equal. Don't waste your money on hardened exhaust seats. Not necessary on Olds iron heads. As far as zero deck, my block was cut .016" and the pistons are .002" to .003" below deck. You will need your heads milled to around 64cc and pistons at zero deck for 9.6 to 1 with the 10.2cc dish Mahle pistons. I will be at 9.3 to 1 with new 68cc Edelbrock heads, pistons .003" below deck and a .040" Mr Gasket MLS head gasket.

Originally Posted by olds 307 and 403

Your 350 has very thick cylinders. Cutlassefi has a 3cc piston in a 4.125" bore as well. I have the 4.100 bore Mahle pistons, my block would not clean up at 4.065", Molnar rods and a 330 crank, 2100 stall 4L80E and 3.08 gears. Only the one bolt needs the small head on 7111 intake. Right now #6 iron heads with 2.07/1.56 valves, 3711 intake and the Edelbrock 204/214 cam, it does Ok. I will be installing the SEFI bunged 7111 with HolleyTerminator X Max, the new 68cc Edelbrock aluminum heads and a mild 218/218 hydraulic roller cam over Winter. It should be around 400 HP/450 TQ. Consider full length headers, I had to heat and dent one tube on the drivers side of my $200 Chinese stainless headers and use a very compact mini starter. The passenger side fit perfect. Later style mounts would have cleared. Good luck.

Originally Posted by 70sgeek

I have the Thornton manifolds on my 350 - they aren't as much of a 'performance' choice as they are a 'replacement' option for damaged or otherwise heavily worn OEM manifolds. I didn't want full headers as my car is a street-highway cruiser, thus I didn't want to encounter clearance and/or excessive drone noise issues. Mine were on sale at the time of purchase, so that made it even easier for me to decide on them.

I like them for what they are and happy with the choice on those.

And Mark is right on the rods - go with his suggestion on that and any other advice he offers - he built my 350 roller motor and it rocks!

Originally Posted by joe_padavano

The difference in RPM between the two is less than 5%. Assuming 26.6" tall tires (245/60-15s as an example), that's roughly 2800 RPM vs 3000 RPM at 70 MPH (assuming some converter slippage). Get the 3.23s and don't look back.

Originally Posted by 67OAI

Replace the oil pan with one from a big block Olds or a custom pan. The stock 350 oil pan does not have a baffle to help contain oil in the sump especially on hard braking. Some people will steer you away from the Toronado pan, mostly due to the way it will trap oil in the forward portion of the pan and the fact it has no baffle. I have used a Toronado pan with welded in baffle in my street vehicle for years with no issues. I also use a standard volume oil pump with high pressure relief spring, granted my motor is not a 350 but an "E" block 400. Your 350 will not require any mods to the oiling system for a long living street motor.

Originally Posted by 67OAI

Pedestal rockers from Harland Sharp or Scorpion should be fine with a mild roller cam that does not require ridiculous high valve spring pressures. By the time you include the cost of machine work and other items required to support stud rockers it may be close to the same. Either way you choose, establishing the correct pushrod length will be critical to longevity. As others have mentioned, the pre 1977 blocks have plenty adequate cylinder wall and deck thickness. Keep in mind that you most probably will not find any .017" thick steel shim head gaskets like the factory used. Today's replacements are about .040" thick composition type. Even milling your heads .030" will not return you to the static compression ratio that your engine had from the factory but will help with intake manifold fitment. One last thought, with changing your valve train to fully rollerized, there is no reason to use specialty oil and/or ZZDP additive.

Originally Posted by ZSmith74

Yeah, you're not wrong. I'm ashamed, but kept my questions somewhat organized instead of asking you folks to pick through my word-vomit novels to see what I'm asking.
I've been poking and prodding my local shop to keep an idea of whether they'll do me good or not. I've heard mixed things but you know how people are, I've had good experience before, but I only had them tank and clean up some nasty heads and an intake manifold. Next shop is 120 miles away, but if I have to that'll be where I spend my weekends. Ha

@olds 307 and 403 Thanks for that. Another one of those things I had seen, probably more when I was looking up some stuff about a pair of BBO "G" heads I've got and they came factory with hardened exhaust seats.
In regards to cylinder walls, I've always kept a comment in the back of my head I heard back in the Navy. Talking to a friend on the smoke deck about my first car, '82 Buick LeSabre that had an Olds 350 Rocket in it, and him mentioning the folks he knew in his experience cracking those blocks from over-boring too much. Keeps me on the cautious side while I'm looking at a 54 year old block, but thick cylinder walls is refreshing to hear, thank you for that.

I've got a set of Molnar rods on the way as of this morning.
Is having larger valves installed still a viable thing to do on #7 heads?
ChatGTP introduces long debunked myths that still float around the internet, thus making them hard to discern truth from fact. Since there were several in your post, I didn't waste my time trying to point them out.

Poking and prodding your local machine shop is fine, but unfortunately, you need to be knowledgeable enough about Olds to recognize when they don't know what they are talking about. If the machine shop uses ChatGTP to give you answers, they are just not a shop you want to use. There are machine shops that think they know, and there are shops that DO KNOW. There are several stories on here about shops building Olds engines that were a "mess". Cutlassefi will have one such example he corrected on the dyno shortly.

Oh man, wheels and tires will be another can of worms I open eventually. It had some 15" American Racing wheels on when I got it. I keep looking at Mickey Thompson wheels and tires to match my valve covers, but also have to keep telling myself that wheels don't do much good for a car without a motor in it....
Segue aside, thank you for making my mind up on that. With that small a spread, makes sense with how I actually drive.
My theory on tire size is to get as much "meat" (tread width) on the ground as possible, while keeping an eye on tire diameter and rear differential ratio. Keep one thing in mind.....Thornton exhaust manifolds and "smokin the tires" doesn't win races. "Drone" comes from muffler choice, not "long tube" headers.

Appreciate all of ya, helping me out and answering questions that I'm sure have been asked more often than a motel mop bucket begs for mercy. Cheers.