For those who know oldsmobile engines, what simple mods do olds 350's respond to using a small chamber 68-70 head? Compression? Cam? Headers? Thanks, Kevin
Go to the Pure Stock section of this website and ask Casey or Dave H. The former has a hot W-31 that gives Buick 455 fits, and Dave has been around Oldses for about 40 years.
Kevin--what exactly do you want out of the motor????--ie how much performance-wise. For a good performing street motor these motors respond, like all the others, to the usual mods. The more you do the more you get (and spend more $$$). One mod you should definitely consider while the heads are off, is having the larger 2.00" W31 intake valves put in the heads. Don't worry about the exhaust side as far as valves go. The nice thing about the small block Olds is its big bore----so there's plenty of room for these larger intake valves without any problems of intake valve shrouding from a small cylinder bore. Other typical mods---Edelbrock Performer or more likely use the Edelbrock Performer RPM intake. --Carb--a well built Rochester carb will work fine on this motor. --Headers--keep your eyes open for a new "shorty" header that Hedman Hedders is supposed to be coming out with for this motor--should be pretty cool if they make them. --Ignition--talk to "Ignition Man" -Dave on this board about his small body HEI conversions. --Cam---Depends on your brake situation--power brakes=less cam Give me more details of what you want from the motor AND what your budget is! There is one particular Olds engine performance parts vendor that has been associated with Olds for a long time----AVOID THEM! Give us some more details. Patton
Thanks a lot for the reply! You answered all my questions on what parts to use. First, I got a running driving 70 cutlass for free. People have told me to turn it into a sleeper, so I would like to build something for it, out of the 350-2bbl it already has. Price wise, I want to build an engine that has 350 flywheel horsepower, and around 400 ft.lb. for $2K. The car has a 12-bolt olds under it, and I have a 3.42 posi carrier for it. Tranny wise, I think the TH-350 will do fine. Whats your take on this plan? Thanks, Kevin
Yeah--Batten no longer exists at least for Olds cylinder head production. Avoid the other guy. You are talking about a pretty healthy set up (350 hp) so you better forget power brakes for that combo...the 70 W31 motors were factory rated at 320 hp or so and there was no way you could get power brakes on any W31 Cutlass. If you are talking about a complete rebuild w/forged pistons then you'll have a hard time keeping the price at $2K--- how long do you want the motor to last? If for a while then count on everything being replaced and with QUALITY parts----roller timing chain, oil pump, new valves and valvetrain (likely some type of roller rocker or roller tip rocker)---then you'll need to find someone that does decent machine work and will set the Olds up properly ---clearance-wise. Count on it costing twice that and you may be pleasantly suprised. Some port work on the heads would also be nice---nothing major but it adds to the cost. I am really serious, also, about installing the larger W31 2.00 intake---these are large bore motors and you are wasting time (and losing easy hp) if you don't install these. Go to RealOldsPower.com and get on the "Engine" section for more info and advice. Patton
I thought it out for a day and came up with this theory. An engine of this sort relies completely on cylinder head flow to make horsepower. Since the heads on this motor are the "6" castings, they will flow very well for a street engine. I would run a 10:1 flat top piston and with head milling 10.5:1. With a lumpy hydraulic cam, I could compensate for the head flow, and the higher compression ratio. The big cam would give a nice torque curve at a reasonable RPM, so with a 3000 stall converter and 3.42 gears, the car would have an excellent holeshot. :TU: :TU: I think this is reasonable.........Do you? Thanks, Kevin
it would give you a nice holeshot, but you also need to think about driveability if it's not a pure strip car (which, by your description, it isn't). If you get too big a cam, you'll lose vacuum pressure to run power brakes and if you're stall is too high, it can get annoying.
Like Matt said----with a true 10.5:1 compression ratio and iron heads you are probably looking at some detonation (pinging) problems in this motor on regularly available pump gas. Your cam selection is going to be critical, of course, for hp---but you better remember you are going to have to drive the car on the street. Answer some questions here----I already asked----power brakes? The more detail you provide the better the info that we can provide. As I said b4---if you are looking at new pistons then you'll be most likely going through the whole motor (ie complete rebuild)---so check your budget again. Sit down, make a list of what you'll need (or want) parts-wise and price the stuff. Then, hopefully, you can find a decent machine shop and get some basic pricing. Also-on the heads I mentioned larger intakes.....well, I believe W31 motors also had larger exhaust valves than what is in your non-W31 #6 heads right now---so once again--take advantage of this and go with both larger intakes and larger exhausts. All motors perform, in part, relative to the cylinder head flow---not just this motor so I don't quite get your point about that. Did you check the board or ask questions on RealOldsPower.com yet?---- Engine Tech section. Patton
One thing about Olds 350's is that they love NOS. I used so much NOS that I bought my own refilling equipment and refilled my own bottles. I always had two or three in the freezer. I spit a few head gaskets but switched to diesel gaskets and never had a problem again. I ran a Performer RPM(when they were first released). I ground the name off and blasted it and nobody knew what it was.:Brow: I also cut a 1" deep by 1.5" long slot in the divider (dual plane). It helped it breath on top with a 1" spacer plate. It pulled hard to 6500. For what it's worth, I also spent a lot of money with the other guy mentioned and due the business practices of that person, I gave up on Olds and went for the motor I always wanted.....Buick 455. Gotta say that it was the best move I've ever made. The folks are a lot nicer and the comraderie makes me appreciate my car more. My Olds was in a Regal anyway!
I live in a high altitude environment, (no air) so you need as much compression as you can possibly get. If I run 91 octane, it should work. If it does ping I can take some timing out of it for the street, for the strip I would mix in 100 octane and advance it. Regarding the lose converter, my dads Stage 1 has a 3500 switch pitch in it with 3.55 gears. With the hoosiers on, that car has a wicked launch. I can't imagine having a car with no holeshot. Thanks for the input guys, you're giving me some good ideas!! -Kevin
