opos

Looking for some thoughts about getting a bit more power from my 73 Cutlass and if it's even worth bothering with.

I have a super nice '73 Cutlass Supreme with 71K original one owner miles..it runs great...no oil burning, etc...the car is rust free and frankly as nice a stock one as i've seen (or owned..have had 2 in the past)...being a '73 it's got the "anemic" motor...I'm not looking for a hot rod...I'm an old guy and just want a car that has more performance than the 180 hp I'm getting now...I'd considered (and still am) having a buddy swap out the 350 for a 455...I've located a 68 455 in decent shape for a rebuild..

If I could gain much without sacrificing reliability by building up the existing 350 that might be the best way to go...please give me some thoughts of what can be done with that particular engine or if it's just got a basic design that is not so good for adding h/p. It is an Olds engine (not a generic GM) and again is really solid...

Any thoughts really appreciated..I know the 73 is not the most popular body style but frankly I really like this car and plan to keep it and drive it a lot...
Thanks

opos

svnt442

If it were me I'd do the 455. The torque is where it's at and bang for the buck it's the best way to go.

Fun71

The 73-76 engines have 8.5:1 compression ratio that is achieved by using #8 heads with large combustion chambers (79cc ?) and ~14cc dish pistons. If you replace those heads with earlier heads that have smaller ~68cc combustion chambers, you get a nice bump in compression. Add a better cam, free flowing exhaust, better rear gears and you're set.

RetroRanger

Opo you find olds 350 engines pretty easily and inexpensively. A local shop could build you a reliable higher hp engine then you could drop it in replacing your lower hp engine. First thing to watch for is might as wells, once you pull the motor you might as well clean up the engine bay and while its apart you might as well add dual exhaust, and etcetcetc.

For only a little more money you find and build a 455. The 455 is only 1" taller and slightly wider than the 350. It weighs only ~100 lbs more than the 350 too. A stock rebuild on a 455 will double your current 350 hp and add torque, gas mileage will not be as good, but your 350 probably doesn't get great mileage either. I recently replaced my 350 w a 455 and my last fill showed 12 mpg...that's w plenty of 100 mph excursions and WOT "testing"

Is it worth it? IMHO yes you have a very nice looking car in good shape, if more hp will let you enjoy it more I say do it, but plan your build and ask assistance if needed don't just throw the summit catalog at it.

Just saw ken's reply he is 100% correct if your engines in good shape for less money that method will net you some gains as well.

jaunty75

Nice car. I'd hate to see its originality destroyed, even if it isn't one of the most desirable collector cars out there. It's still pretty desirable.

opos

Thanks folks...the car is such a nice one I really don't want to alter it much...it's got a set of dual chamber flow masters on it and it sounds like there is something "happening" under the hood...I don't raise the hood when we park...keep them guessing....I might just keep the car as it is..it's got great factory A/C..perfect interior..I added a new vinyl top and when they pullled the old one there was not one spec of rust..I was amazed but it came from St. George Utah which is about no percent humidity all year round.

Maybe just keep this for an "ice cream getter" and if I wan't to play..get something that is already done and ready...probably cheaper in the long run...lots of cars here

Thanks again

opos

80 Rocket

I just did a 350 build for someone with a 76 Cutlass. Same situation, wanted an upgrade in performance that didn't break the bank. All you need is a good top end as well as a cam for that.

I used the stock 73-76 bottom end and got rid of the #8 heads. I did a mild port job on 7a heads complete with bigger valves and milled for a 9:1 compression. A performer intake topped it off. I also converted to the Comp Cams roller tip rockers. The cam was a Lunati hydraulic flat tappet with 221/230 duration @ .050. The engine made 343hp and 377lb/ft of torque.

If you are interested, I can do a set of heads for you. I can also match the intake so it bolts right on with a good fit. PM me is interested.

olds 307 and 403

Either early heads with 2"/1.625" valves, bowl work, mildly milled or flat top pistons and the same head work to your factory #8 heads and a mild cam would do wonders. If you pull the motor, a mild stall would help and maybe a 3.08 gear instead of the factory 2 something gearing.

lemoldsnut

If you change the rear gears to like 3:23 or similar you will see a huge difference in how it drives. Without doing anything to the engine. Would still be stock and reliable but still not a hot rod.

All of the other items mentioned would help. Being in California I am sure you have issues with passing inspection or similar stuff. A gear change will not effect emissions at all and gives a huge seat of the pants dyno feel for the dollar.

Just my input

Larry

olds 307 and 403

How does that 221/230 cam idle in a 350? I know a few guys like the milder 217/221 Lunati cam.

80 Rocket

If he is just trying to wake up the engine on a budget, why pull the engine out to:

- press of old pistons
- install new pistons (need to be pin fit as well)
- bore/hone block
- wash block after machining
- new bearings/rings
- balance crank because new pistons are used
- r&r cam bearings

^^^^doing all of the above just to use #8 heads seems silly to me (which are going to require $$$ as well), and will most likely yield less power unless the heads are done right. He has a low mileage short block that can yield decent compression, why suggest a full-on rebuild when it is completely unnecessary?

The 221/230 cam idles fine in a 350. It's not radical by any means.

76olds

opos, I had the same questions at one time here, If you can hold off for a few months ther may be some decent aluminium 350 heads produced in stock form for a very reasonable price. The heads #6 will allow for a stock fuel pump to be used, no clearing of the head or going to electric fuel pumps.
All good suggestions here from these guys.

Eric

442fanatic

I have done both, rebuilt the olds 350 and spiced it up and then gone and spiced up a 455.

Hard to build a motor for cheap. If you do your 350, you know it, it runs. Do the heads older not #8s. Have them scanned for cracks. I would put the larger valves, hardened seats, new guides, some mild porting. Scrap the smog intake, you can find a non smog cast four barrel intake cheap. Or buy an aftermarket better flowing intake and a new carb. Go with a different carb, update the timing chain and gears from the crap plastic stock setup.
Personally I would replace the main and rod bearings... Back in the 70s lower end overhauls (mains and rod bearings) were what an every 40k event?

You mentioned it is dueled out. Did you go with headers? Or just cap off the cross over hole on the passenger manifold?

Change the gear ratio to a 3:23 or the most you would want to go to would be 3:42. Put in a posi either way.

Firewalker

How about just changing gearing to start??

A 700R transmission and mid to low 3 something gears in back alone would wake it way up, and give it better mileage.

2.48 first gear X 2.70 rear say=6.696 gearing taking off leaving the converter multiplication out of it. 100 foot pounds X 6.696 it 669 ft lbs for leaving the light.

Now a 700R is 3.09 in first X a 3.42 say= 10.5678. Now that same 100 foot pounds becomes 1056 ft lbs of tire ripping throw you back in the seat power. And the motor is still like it was. On the highway you now have even less rpms in overdrive and with the converter locked up reducing them even more. Making it even quieter, with increased mileage for an even better grocery getter than before.

A whole lot less work and money spent, and less chance for bad results.

Fun71

I don't remember ANYONE doing rod/mains every 40K. My 70 Supreme had that done for the first time in 1980 with 99,000 miles on it, and then only because I ran cheap gas with a lot of advance, detonated a piston and had to do a rebuild.

olds 307 and 403

There are still a good number of mid 70's 350's in good running shape. The Olds variety, not that sbc junk. I agrees, the early heads make the most sense, unless the motor needs an overhaul anyways, then the #8 heads make just as much sense. At 71k, that should be like new inside, I should have paid attention to that. How would that 221/230 cam run with a what, a 1800 stall and 2 something gears? If you go for an OD trans, run a 2004R and at least 3.73 gears. Move the cross member back and you are good. The 700R4 needs an adapter plate and the drive shaft cut.

76olds

I took Fun71's ( Kenneths) advice several years back and,
I put 3:42 gears with a posi unit in my 76 350 and it was a totally different car off the line.
This 350 being a stock refreshed engine with thicker head gaskets.
Headers and duals certainly helped as well.
Very nice 73!!

Eric

redoldsman

Your 73 looks like a very nice car but it is never going to be highly collectable. I would do whatever is in your budget to improve performance. Gears are pretty good bang for the buck. If you 350 is in good shape, you could change the heads and maybe put a mild cam in. If it doesn't have a 4 barrel put one on and a decent set of dual exhaust and you will probably have all you want. The 455 is going to be way more expensive but it will be fast. It might be more than you want. You could run the turbo 350 but you really need a 400. Let us know what you do and good luck with it.

steverw

I love the 73's, yours looks really nice. I want one myself. I say build a 455 and enjoy it. It will cost approx the same as doing a performance build on the 350, only it will put a bigger smile on your face. It dosent alter the car, you can always keep your original motor, and put it back if you ever want to. You say you found a 68 455? That should be a pretty stout motor just the way it came, or if it needs rebuilding a good 3 or 5 angle valve job, balancing, and perhaps a slightly hotter cam, your 73 will smoke the tires off. Put a 3 series gear in the rearend, i say around a 3.08 to a 3.23 would be great and still usable on the highway.
Good luck

macrover

Very nice '73! Considering how nice and close to original it is, I say try the gear change before modifying the original numbers matching engine/transmission. That way, you're not taking away or deviating much further from it's originality and value. If you decide to go with the 455, look into getting a transmission as well.

Although it may not be considered a "desired collectable" in some cases, there are plenty of Us out here who desire and appreciate these cars for what they are, especially in their stock and factory form.

Plenty of good advice has been given so far but ultimately, it's you car and your decision. Good luck with your plans, it'll still be a very nice '73.

Firewalker

A 5 to 1 in back will make a 350 very fast, and with a 700R4 it will still have a 3.50 gear in overdrive. With a 200r4 you would have still a 3.35 gear in overdrive. Its all about torque and gears are the cheapest and easiest of all. First gear with a 5 to1 and a 3.06 first 700 is a staggering 15.30 launch multiplication of torque. A 200r4 is 13.7 overall in first with a 5 to 1.

Fun71

That should make a nice tire smoke machine out of it!

Firewalker

That's what slicks are for The mild mannered quiet low compression stock engine, that runs away and hides from the souped up/modified costly Olds clan at will. On his way to get ice cream with the AC on. A legend in the making

BlackGold

Are you seriously recommending 5.00:1 rear gears for someone who says he doesn't want a hot rod and doesn't want to sacrifice reliability?! That's just silly. Assuming the present gears are a 2-something, going to 3.08 or 3.23 along with a TH-200 4R will wake it up plenty.

But my favorite performance improvement is to not bolt on anything. Simply spend some time learning how to tune your ignition and carb and make sure everything's working the way Oldsmobile intended. These cars were not dogs when new.

Firewalker

5 to 1 is too much power?? How does it sacrifice reliability?? Btw I ran those gears on the street in the early 70s, with a low compression 350 stocker and TH400, with a 3000 stall. It was very reliable and streetable, though the 700r or 200R4 with standard stall lock up would made it even more so. The 5 to 1 was also a factory option.

While I agree a tuneup and faster timing might help the first thing I would do would be replace that time bomb plastic timing chain Olds used. Next would be a can of Motor Flush (at idle for 5 minutes), and then change oil and filter.

If I was going to a "lighter" rear gear 3.42s sounds good, with the 4 speed autos. But thats more of a highway car gearing, and less so for to the store and back routine. Either gear should make him happy. The foot then controls the rest.

olds 307 and 403

3.42 is the minimum in my books with 2004R. Even with a 25.6" tire I ran at 1850 at 60 mph. I am sorry 5 to 1 is insane.

Firewalker

Have you tried 5 to 1?? No, but I did many decades ago when it wasn't unusual for Chevy's to be running around with 4.56 and 4.88 gears and most with short tires like F70s or G60s, and then there were all the 14inch wheels then. Now, there is the glorious over drives dropping the rpms down to what use to be normal highway rpms, even with a 5 to 1 in back.

BBC normally had 3.55s to 3.73 gears standard, plus short tires, and were just fine at 80-90 on the highway. I recommended less than those in over drive, and I'm insane??

svnt442

5:1 was not a factory option, it was a dealer installed option and not recommended for street use. I also don't know it it was available after 1970 when they dropped compression.

Firewalker

Most gears choices were dealer installed options. Considering the long warranties back then they were not thrilled, with the added mileage/wear these would cause. They were also having to meet government emission standards, which are lowest with 2 something gears.Having the dealers install them might have gotten them around all this, and there were quite a list of them, and not just 5 to 1.

I ran 5 to 1s on the street back then and it was no problem with about a 27-28 inch tire, but I would not recommend them for highway driving very far or often without over drive. But then again those were 3 speeds with 1 to 1 gears, and even the 4 speed, with no overdrives.

In town, how often do you see 48 mph. That is only 3000 rpm, with 27s and no overdrive. The highest speed in my town is only 45, and mostly 25-35 mph, except 15-20 for school zones.

Fun71

Every day all the way to work and back. Main roads are posted 45 MPH and average speeds are 50 MPH. Stoplights are at intersections every 1 mile so I'm doing 50 MPH on surface streets all the way.

If I get on the highway the speed limit is 65 MPH in the city limits and average speeds are 70-75 MPH; outside the city speed limit is 75 and average speeds are 80-85 MPH.

Firewalker

Big cities are a little different than the smaller towns most live in. But even in big cities its not going to be that big a deal, with over drive, and it sure wouldn't in the smaller towns and it would still be a highway car, if desired.

olds 307 and 403

I thought a little but with a 255/60R15 tire and a 2004R with lock up is only 2500 rpm at 60 mph. I am sorry but running at 4000 grand with a non lock up 3 SPD at 60 mph would be nerve racking and meant for very few. I meant the gears should be numerically higher than 3.42 otherwise you are running at 1700 rpm at 60 mph with the same tire. Fine for a stock engine, I plan on running 2.78 gears with the little 260 and a 2004R for this next year, 1500 rpm at 60 mph. I will probably drive 70 mph everywhere and it should get ridiculous mileage. I am stepping up to a 3.90 posi, adding a GN governor behind my 9.5 to 1 custom cam, ported head 350. Other than a common circle track rear end, 5 to 1 gears are hard to find.

Firewalker

Sounds like you are thinking mileage rather than pep, that he wanted around town. I consider all ratios behind my BBO with a 200R4, that fit in my 9.375 housing, and then look at all the other variables and pluses and minuses.

Depending on how old you are, and how much and long you have to drive, at higher rpms can change how nerve racking higher RPMs are. A couple of times a year for short distances, or for just a few minutes at a time 100 times a year changes that perception.

Things that may sound crazy to many may be very practical depending on the normal situation and that varies. Super deep gears without over drive, with open headers on a blown big block may sound crazy and nerve wracking for the highway, but when just going 7 miles to the dragstrip once a month it is not so crazy.

2 something gears can also be poopy, and get worse mileage because the engine is not working in its most efficient range. Something to consider.

olds 307 and 403

I agree on the above. I am only mileage for now, the 350 with my short tires, 2004R with 3.90's will run around 2000 rpm at 60 mph. That will be perfect with a 217/223 cam and an upgrade from 2300 flash to a 2800 stall that is tight for around town and cruising. The 2.78 gears are awful for anything but a stock motor.

coppercutlass

The 3.90's with the th350 are not too bad at all. I regularly drive 70-80 mph with my olds. The rpms are not even a issue. Just the noise from my loud @$$ exhaust.

Firewalker

Get down to about 63 and you will see about the engine speed you would have, with over drive and that 3.90, at 90. My L78 Camaro from the factory was short F70 tires and 3.73, and topped out over 150, before I did a thing to it. 3rd gear on the M22 was about 120. It was loafing at 90

coppercutlass

Not worried about overdrive. not worth the cost. The engine runs very happy at those rpms keeps its cool. No worries

Fun71

Uhhh, if you had F70-14 tires the engine would be turning 4300 RPM at 90 MPH in 4th gear (1:1 ratio). That's hardly "loafing" by any means. Also, 150 MPH would equate to an engine speed of 7200 RPM in 4th gear. That is unbelievable performance from a factory engine.

Firewalker

11 to 1 forged piston. Aluminum intake. 780 holley, and solid lifters, large square intakes ports and large valves. Forged Rods with 7/16 rod bolts, forged crankshaft, 4 bolt mains. Smokey slapped a set headers on one and hit something like 186, at the Salt Flats. Then there was Grump..

The Grump selected the SS396 model with the RPO L78 option. Announced in January 1967, several months after the Camaro’s launch, it featured a 396ci big-block V-8 rated at 375 hp and was offered only with the Muncie four-speed transmission and 12-bolt rearend. With a four-bolt block, rectangular-port aluminum heads, an 11.0:1 compression ratio, and a solid lifter cam, the L78 was essentially a smaller-displacement version of the 427ci, 425hp L72 package sold in Corvettes and fullsize Chevrolets. It was rated well below its potential, and by Indy that year, Jenkins had the combination thoroughly dialed in.
The ’67 U.S. Nationals featured one of the deepest fields of factory-backed Super Stock teams ever assembled. The Ford camp included Hubert Platt, Dick Brannan, Ed Terry, Dyno Don Nicholson, and Fast Eddie Schartman. The Chrysler contingent was led by three Plymouths from Sox and Martin and two Dodges from Dick Landy. The Fords were knocked out in the early rounds, leaving Grumpy surrounded by an army of Mopars as he marched up through the ladder. Jenkins had to eliminate two Sox and Martin cars himself in successive rounds before facing Bob Brown’s SS/A ’65 Plymouth A990 race Hemi in the final. Jenkins rocked the clocks with an 11.55 at nearly 116 mph, winning the first Indy Super Stock Eliminator crown.

coppercutlass

Is this rambling legit lmfao. My head hurts after reading this lol. The only people running chevy's around here are the lame people and fords are a sin. so how does any of this make sense.