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Thornton 350jr manifolds and small block olds headers have a big block 400/455 outlet. That's why a big block downtube is used. This according to the owner Tom Thornton.
Just to clear up any confusion that might be out there concerning any of the Thornton manifolds or headers, all of them take a Big Block Olds downtube (Pypes DOF10S). The 350jr small block manifold has larger inner ports than stock and a 2-1/4" outlet on both sides, just like a BBO. Hence the need for BB downtubes on a 330/350/403. Same goes for their headers. These manifolds / headers / downpipes fit A,F,& G bodies, as well as '71 & up B&C bodies (downpipes still untested on B&C bodies though). Thornton also offers SB Chevy headers, which follow the same design principals as the Olds. Same physical footprint as a SB log manifold, only with a 2.5" outlet. As with the Olds, you use a Big Block (Chevy) downtube. We carry everything you need: http://classicmusclecarexhaust.com/p...-455-pypdof10s http://classicmusclecarexhaust.com/p...aust-manifolds http://classicmusclecarexhaust.com/p...ceramic-coated http://classicmusclecarexhaust.com/p...on-sbc-headers
LARams1, keep in mind shorty headers and the like while relieving you of clearance issues are not much help in the boosting of power department. Yes they are better than factory manifolds but not much... 3-5 HP gain, which is the equivalent of putting a crossover/balance tube between your true dual exhaust with original manifolds. Long tube headers while being a pain in the you know what... Will give you a 20 HP gain when properly tuned.
Originally Posted by LARams1
Had a few people suggest to replace the carb with an Edelbrock 1405 or 1406.
I have heard the exact opposite for decades. The word on the street always was they are for show not go. (great intakes avoid the carbs) Anytime I have heard somebody complaining about a carburetor its always this same make. Yes there are some people that say you just need to know how to set them up correctly, I say if its that much more challenging why bother.
Quadrajet first and foremost, Holley second, Edelbrock dead last, but that's me.
Originally Posted by LARams1
Rebuild will cost about $45 then there's the application issue 472/500 Cadillac vs 350 Olds.
With that kind of savings the application issues may be worth it....
Thanks 69. I read the hotrod article and for the most part I was like"what-what" above my limited knowledge but I'll reread it and see if it sinks in 🤔😒. Ports, vacuums, etc,.. I'm definitely going to finish the rebuild just unsure how I'll tune it but like everything so far learning on the fly. So concerning the headers basically you're saying there are long piped headers out there? I never found them. I even had the restoration shop look for me and they replied they didn't find any mostly found them for LS swaps. Let me know if you know who sells them please.
[QUOTE=69CSHC;1293186]LARams1, keep in mind shorty headers and the like while relieving you of clearance issues are not much help in the boosting of power department. Yes they are better than factory manifolds but not much... 3-5 HP gain, which is the equivalent of putting a crossover/balance tube between your true dual exhaust with original manifolds. Long tube headers while being a pain in the you know what... Will give you a 20 HP gain when properly tuned.
Back in March of 2019, a dyno test on a W31 was performed comparing Thornton 350jr manifolds vs Thornton SBO headers vs long tube headers. The engine was built to pure stock specs with a 12:1 CR, light weigh pistons, etc. Keep in mind this is a fully prepared racing engine. With 350jr manifolds it put out 475hp & 526 lbs-ft. Switching to Thornton headers showed an increase to 500.7hp and 540.9 lbs-ft. A switch to long tube headers showed an additional increase of 11hp over the shorties. Obviously this is a racing engine and a mild street 350 will have milder results, even when compared to stock manifolds.
This test was done by James Kryta of Inline Tube, a well known Olds enthusiast and racer.
Last edited by CMCE; November 14th, 2020 at 01:58 PM.
Fantastic gain and point taken, I should of specified on engines similar to ours.
Yeah I would really love to see a dyno test of a 350 SBO in the low to mid 300hp range. Stock vs 350jr vs shorties vs long tubes. Anybody out there in the Northeast with a 350SBO sitting on a dyno in their garage with nothing to do that's willing to donate some dyno time? There's got to be dozens of people out there that fit that bill!
Removed the V6 out of the F85 Saturday and now have tons of questions of " what would you attack first?". I've been given great advice from the CO community and look forward to the majority rules as I have to date. Please comment on first things first if it were your car. To date all the suspension front and rear, brake system and fuel system (gas tank and lines) are new. I've got a rebuilt Olds 350, custom 200R4 and complete dual exhaust in the garage ready for install. Looks like I'll cleanup and repaint the frame cross member, for lack of the correct term, that supports the motor. Electrical, where does that fall in the course of this process? I know I'll need a new harness but what harness. Also there's an electrical " strip" that runs under the carpet to the rear tail lights should I replace that? Open to any and all suggestions, majority rules. Thanks for any advice.
Left out the '71 Rochester Quadrajet off of a Cadillac and an alternator that came mounted on the rebuilt 350 Olds, not sure if it also needs a rebuild.
When my engine was out i wire brushed and POR15d everything i could easily get too.
the wire harness if in poor shape should be replaced, my car had the front part replaced already, your car might be different as its older. I would guess you need the harness for your car, but may need some modification, because the engine is different. I know one of the big harness suppliers offers an hei or points version, so maybe they can accommodate what you need as well.
the alt n carb can be looked at after the engine is in
This is not a jab but the brake line routing is not very neat, looks haphazard and I question the power steering hoses which look long enough to reach the trunk! Lol. Now to get serious you are moving along pretty quickly with this project, cool. You may want to think about upgrading your fuel line to a larger diameter to feed the V8. Also note the 8 cylinder cars had the fuel line run on the passenger side as that's where the fuel pump sits on the V8. Like the picture upgrades!
Retro would you install a new harness pre-motor/transmission or wait. The first thing I noticed when I removed the engine was the crappy bends on the brake lines cause I'm a designer of hydraulic systems and thought exactly your comment Olds. I know they have hand benders for those small lines.
I would get some degreaser and some simple green and clean as you can. Pressure wash it all down.
Paint the frame sections with chassis black. Paint the fire wall with mat-black. If you can just clean up the wheel houses, see if the factory color still shines, or paint semi-gloss black.
Figure out all your wiring to fit your new engine, tape up and wire covering to be clean set up.
Also somebody on this forum should have the alternator brackets for the passenger side mount. And use 68/72 power steering pump and bracket from anon A/C car. You can order from “Rock auto” the quick ratio power steering box. You should look that up under the 68/72 Cutlass. Direct bolt on.
Get the measurements of the radiator opening and order an universal radiator with the hose connections that fit your new engine. For me, I would get the biggest electric fan to fit. I run mine with key on fan on. Be sure to use the fan relay kit.
Should keep you busy and nice winter project.
Gene thanks for your input. I was going to ask about paint and there's my answer BOOM! Back about 2 weeks or so I took a picture and posted on this thread. The header was BRACKETOLOGY. Are any of those brackets what I'm looking for, if you know or anyone who might know? They may be for other components.
I kinda remember the thread. I don’t think any of the stuff you had pic’s of would work.
Make want ad, for the passenger side alternator brackets. It is a simple two bracket parts. Bolts to the passenger side cylinder head.
a 68/72 power steering pump and bracket from a small block or big block on an engine with out A/C will work. You can order hoses from Rock auto or your local parts store. It just has to be a non A/C set up. The alternator you show in the pic, I guess is good. Just throw away the bracket.
Did you get pulleys with the engine ?
I got a box of parts and it's possible there may be a pulley in there but I believe this is the only one I recall. This I believe attaches under the water pump.
Those are for the bottom, attach to the balancer.
neither are any good. The one with the large and small pulley may be for an add on A/C kit. The other is from an A/C car.
I may have confused with the photography that is a single pulley, unless they're attached, taken in 3 views. Is adding A/C a big undertaking with this old a model vehicle? New interior switches and cutouts in the firewall or is it even more than that minus electrical?
To add factory AC it's a pretty big task made easier with a donor car at hand. Aftermarket AC would work well, look a little different and have a more modern efficient compressor and condenser.
I've recently removed the Buick V6 from my 1964 base F85. While cleaning the cross member I found these suspect welds on the passenger side. I also found less obvious shoddy welding (weld spatter) on the driver's side. Was there ever a problem with these welds where Olds or a qualified shop/dealer needed to reinforce these seams? A bit nervous as I ready the cross member/frame for an Olds 350. Hoping to figure out why this looks as if it were rewelded. Maybe the car took a hit to the passenger side and hairline cracked the original manufacturers welding? The motor I pulled looks as though it was never removed prior to my disassemble and removal. Please post if you have an opinion. Passenger side Drivers side Drivers Passenger Driver Passenger Passenger
Does anyone know of a website or have a picture/s of an Oldsmobile 350 SB V8 with the components and supporting brackets/hardware so I can be sure I have the correct fasteners and such?
November 11th, 2020, 01:50 PM
