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Hello all,
So I am the proud owner of a 76 Cutlass S which I bought about two months ago. Eventually I plan to put a 350 in it, but for now it has the 260. It runs really well but is short on power. Here is what I am wondering:
I'm told the 260 uses the same block as the 350. Are the exhaust manifolds the same or compatible? I am thinking about putting headers and dual exhaust on my car which would give me a little more power and then when I can afford to put in the 350 I would already have the exhaust system I was going to use anyway.
Also, I don't know much about the 260, other than it was the "economy V8" from the gas crisis years of the 70s and everything is kind of necked down for fuel economy. Is there anything about it that makes my idea not worth it?
Thanks in advance for all your help. Everybody on this sight is always really great about helping us amateurs!
They are not the same block, however they are the same dimensionally. All brackets and accessories will bolt up. When you are ready to change to the 350, if you add headers and dual exhaust, you will have no problems.
Yes, I have done it, made a noticeable difference. As said, accessories swap right over. Another thing about a 76 is it is a solid main block. The cylinder walls may be thick, I don't think anyone has ever checked a block. Even if it could go .200" overbore, that would only allow standard 307 pistons. The only difference is, if boost was used, yes it has been done, it actually might survive for more than a day or two. The windowed blocks died quickly. The #10 heads are unique to the 75/76 260, smaller raised intake ports with tiny valves. The only 4bbl intake that fits is the discontinued Edelbrock SP2P idle to 4500 rpm economy intake. Although with some port matching, some have actually made the giveaway 85 and up 307 aluminum A5 swirl port intake work. The ports are similar size but the 307 ports are more in the center of the head.Those who have used the SP2P on a 260 said it brought acceleration from dangerously slow to acceptable to keep up with traffic. I had one, sold it before I got my 260. I used it on Olds powered trucks. Part throttle was super responsive like port EFI and pulled through the low 4000's shift points. Full throttle was good with 500ish GM TBI. The 800 cfm Qjet fell on its face on full throttle, too much air and fuel, part throttle was very good. You want the secondary air door limited quite a bit on opening if using a Qjet. Good luck, it may get out of it's own way with possibly 135 hp and 225 ft/lbs of torque with full length headers and duals, that is closing in on 307 Vin Y power🙃.
Thanks for the help, Edzolz and Olds 307 and 403! I appreciate it. I actually found an article on upgrading the 260 on motortrend.com. Basically, the first paragraph said "don't do it, its not worth the effort." Then the rest of the article told you how to do it if you ignored the first paragraph. Sounds like you guys could have written that article!
I'm planning on doing the headers/dual exhaust when I can and keep saving for the 350. Shouldn't take me too long, and in the meantime that 260 runs pretty good, so I might as well get some use out of it. I mostly drive it to car shows and to work 1-2x a week when the weather allows.
Nice looking car. Color looks great on there. I remember as a kid seeing that body style everywhere. We thought nothing of them. Now as I get older I like them more and more. Love your car. Is a 76 front end one year only? Very Nascar.
Welcome to the group... Nice looking 76 Cutlass... For your future effort, 350 is the way to go, easy swap... With a little work, 455 is also an option from a power standpoint...
I'm planning on doing the headers/dual exhaust when I can and keep saving for the 350..
I don't think you will find headers for the 260 and 350 headers would probably leak around the small exhaust ports of the 260. Save your money, look for engines in your price range, then buy headers to match the engine. Also a 403 is a small block dimensionally so it would be an option.
The exhaust port is the normal shape. The 2A is the same as the 5A with the really recessed center divider, my headers sealed just fine. His number 10 heads should have the normal exhaust ports like all 76 and older heads. Here are pictures from that article mentioned. Not sure why they didn't show the 260 intake ports, which are much smaller. The only intake port they show are the 7A swirl port heads which are more centered.
As an owner of a 79 260 for the last 37 years, I have to say I agree with what everyone's mentioning above. There's really not much you can do with the 260. What I did to my 79 Calais didn't deal with the motor, I got 3:08 posi gears and a 200R4 transmission. That made acceleration go from horrible to bad. It did help for a more pleasant ride around town though, keeping it in 3rd.
Nice deal on yours, especially the nose of that car, really changes the profile for the better.
I remember as a kid seeing that body style everywhere. We thought nothing of them. Now as I get older I like them more and more. Love your car. Is a 76 front end one year only? Very Nascar.
I have vivid memories of being hit by one in 1987 while bike riding. For a moment, I was a hood ornament. That is one vehicle front end that I will never forget.
Yeah, I bought this car specifically for that front end and the fastback roofline. In high school I had a 76 LeMans; my neighbor had a Cutlass with that front end and I just liked it better. That front end is actually nicknamed the "NASCAR front end," I think they won a few races with these cars in the late 70s.
They only made it in 76 and 77. In 76 it was on the Cutlass S and the 442; in 77 only the 442 had it. Even the 4-door Cutlass S had that front end. My greatest fear is this car getting into an accident that damages the front end, because I'm not sure where I would find a replacement, though I have seen a few beaters you could part out.
Now it makes sense!! My mom had a '77 Cutlass S with the "square" front end. I assumed all the '77 Cutli looked like hers and couldn't figure out why I kept seeing posts attributing the NASCAR-looking front to '77 models! Mom's looked like the one below, White on Red - I sure wish I had kept that car. I've got a 455 on a stand that would be Awesome in that car. Hers had the anemic V6
To the OP "Eventually I plan to put a 350 in it, but for now it has the 260." I would consider a 403 out of a Trans Am if ya run across a deal. A lot of those 403 TA's are getting either Poncho swapped or LS swapped and complete running good 403 deals do come up and yes on the headers ! But also of course a aluminum head 455 is better but then I like to put the biggest factory engine that bolts in normally.
I dig these cars a good bit. Growing up my best friend had a pretty light blue metallic 74 350 Cutlass with white top and white buckets ,loved that car. Seen some gorgeous red 76 442's plus recall a big smog "W30" 455 Hurst Olds with swivel buckets in the old yard by Dad's where I saw my first Rallye 350 and could have got that for $200 in the 80s. I recall also they had a 70 Cutlass Supreme hardtop that was a 4 speed car
Last edited by GEARMAN69; November 18th, 2021 at 05:06 AM.
Hello all,
So I am the proud owner of a 76 Cutlass S which I bought about two months ago. Eventually I plan to put a 350 in it, but for now it has the 260. It runs really well but is short on power.
Beautiful car !
Originally Posted by olds 307 and 403
Another thing about a 76 is it is a solid main block.
Fantastic feature, an engine most associated with the malaise era. But actually sharing a trait with muscle era quality.
Originally Posted by olds 307 and 403
it may get out of it's own way with possibly 135 hp and 225 ft/lbs of torque with full length headers and duals, that is closing in on 307 Vin Y power🙃.
Incredibly thorough post altogether Olds 307 and 403 !
Chris as you can see by Olds 307 and 403s internet handle. He is well versed and a proponent of the aftermath of the malaise era. He has painted an incredibly clear picture of what your looking at by messing with a 260.
That engine as reliable as it may be should never have been put in a mid 70s car that weighs 4000 lbs. And it will disappoint you unless you pour way to much money into it...
The fact that you are considering a 350 swap tells me you see the writing on the wall as well.
If you had the time and patience I would love to see what she runs for you bone stock and well tuned. Then with headers and true dual exhaust. And finally with a healthy bone stock 350 etc. ...
Originally Posted by BlueCalais79
As an owner of a 79 260 for the last 37 years, I have to say I agree with what everyone's mentioning above. There's really not much you can do with the 260. What I did to my 79 Calais didn't deal with the motor, I got 3:08 posi gears and a 200R4 transmission. That made acceleration go from horrible to bad. It did help for a more pleasant ride around town though, keeping it in 3rd.
Had a mint burgundy version in the family, good looking car with a comfortable ride, overall a good solid driver, would call it great but the TH200 transmission had issues... You turned it into a great car with the 200R4 swap.
Originally Posted by BlueCalais79
Nice deal on yours, especially the nose of that car, really changes the profile for the better.
Couldn't agree more !
Originally Posted by Chris Scott
Yeah, I bought this car specifically for that front end and the fastback roofline. In high school I had a 76 LeMans; my neighbor had a Cutlass with that front end and I just liked it better.
That front end was what sealed the deal for me. It is now one of the 4 most desirable cars I have ever wanted based on looks. The slant nose 1976-1977 Cutlass coupe is gorgeous.
Originally Posted by Chris Scott
That front end is actually nicknamed the "NASCAR front end," I think they won a few races with these cars in the late 70s.
Yes sir, legendary driver Richard Petty won the 1979 Daytona 500 with one.
Originally Posted by GEARMAN69
I would consider a 403
Chris Scott, this is a great recommendation. A stock healthy 403 is a great option for your ride. Headers with performance mufflers and a tune for maximum performance will double you cars original horsepower rating. The best part being that your 76 should already have a TH350 and 8.5 rear. All that was missing at that point in time was power.
The 403 with true dual exhaust has the same amount of torque as a high compression 1968-1970 350. And you can get it without paying the premium that those 350s incur. Added bonus you will have no gas quality issues.
Chris Scott, this is a great recommendation. A stock healthy 403 is a great option for your ride. Headers with performance mufflers and a tune for maximum performance will double you cars original horsepower rating. The best part being that your 76 should already have a TH350 and 8.5 rear. All that was missing at that point in time was power.
I suspect that the TH200 was used behind the 260 motor.
they are small 1 5/8” primary and very long with a small 2 1/2” collector.
They’ll help out that 260 and will be fine for the 350 in the future
I agree. I used the Sanderson 1 5/8" primary shorties and 2.5" exhaust but the Hooker's will gain more. I used the 1 5/8" primary tube A body Flowtech full length headers on a 307 in a 78 1/2 ton, they performed quite well.
If Joe P is right and I think he is, ditch that Metric 200, it can't handle any kind of extra power. Heck mine blew up putting in 3:08's at the back end!
If Joe P is right and I think he is, ditch that Metric 200, it can't handle any kind of extra power. Heck mine blew up putting in 3:08's at the back end!
1976 was the first year for the TH200. The easy way to tell is to count the pan bolts. The TH250/350 uses 13 bolts on the pan. The TH200 uses 11 bolts. The shapes are similar - square with one corner cut off.
It was an automatic swap at the one shop I worked at. If a car came in with a TH200 and a trans issue, we grabbed a TH250 or TH350 from my boss's yard to replace. One was leaking but shifting fine, we still swapped it rather than replacing seals. Make a TH350 or a TH2004R as part of the 350 or 403 swap
Make a TH350 or a TH2004R as part of the 350 or 403 swap
Many of the 200-4R internal parts are common with those in the TH200, at least for the later models. The 200-4R internal architecture is derived from that of the TH200. The same upgrades work for both. There's a growing following using the TH200 in drag racing (with the right mods) due to the featherweight design. The trans is only 90 lbs, yet the three gears often improve times from a Powerglide.
Yeah, the 2004R failed as well stock, common occurrence around 130,000 km supposedly, told that by two different people. The big advantage is the lock up converter, same TH200 1 through 3 ratios, which I like, a deep .67 OD and fit right where the TH350 goes as long as the particular car has the TH400 crossmember spot and all have the BOPC pattern.
Yeah, the 2004R failed as well stock, common occurrence around 130,000 km supposedly, told that by two different people. The big advantage is the lock up converter, same TH200 1 through 3 ratios, which I like, a deep .67 OD and fit right where the TH350 goes as long as the particular car has the TH400 crossmember spot and all have the BOPC pattern.
I have several 200-4R transmissions with over 125K MILES, not KM on them. Admittedly they are behind VIN Y 307s. As far as strength, which was the whole point of this discussion, they are no different than the TH200 that is likely in the OP's car currently. They still require appropriate upgrades. Replacing a TH200 with a stock 200-4R behind an early 350 doesn't fix the problem. No one is arguing the benefit of OD.
Just what I was told, weird they both mentioned the same number. I have cooked three 2004R's myself, 1/8 mile Racing and slicks. Well my Daughter finished off one. I have also seen the TH350 fail behind stock mid 70's 350's. I have a feeling the TH350 is a better choice for his goals, especially if the stock gears are staying. Another thing to watch out for is a TH250, weaker, look for a stud near the cooler lines or the "C" lock up transmission, unless he is OK with the factory 1600 stall. I got over 400,000 km behind a TH250C with 307 and mild 350. It lasted one day behind a 403.
Sorry for the late reply, folks, I was working odd hours.
I appreciate all the advice and comments, gives me a lot to think about. I think I have a TH350, but now I am going to double check! Thanks for the chart, Joe P! Thanks for all advice on the headers, too. Good thing is, I might have a little extra cash soon (decided to sell a different car) so maybe I can bump up the engine upgrade sooner. I'm still leaning towards the 350, but a 403 or 455 aren't out of the question, I am thinking a 350 wouldn't be much heavier than a 260 so maybe I wouldn't need to upgrade the suspension. Of course, tightening up the suspension and steering aren't bad ideas either.....
The weight will be almost identical from a 260 through 403. The real difference is iron vs aluminum intake manifold. The 455 adds a few extra pounds, especially with an iron intake manifold. You definitely don't want a TH250 behind a 403 or 455. Mine lasted one day behind a mild 403.
The weight will be almost identical from a 260 through 403. The real difference is iron vs aluminum intake manifold. The 455 adds a few extra pounds, especially with an iron intake manifold. You definitely don't want a TH250 behind a 403 or 455. Mine lasted one day behind a mild 403.
The 1977-up V8s are marginally lighter than the 1964-76 motors. They have windowed mains, thinner walls, larger pockets in the heads, etc. The difference isn't significant - probably 20-ish lbs or so. The difference between a pre-76 BBO and SBO is about 50 lbs, assuming both are stock (iron intake, stock exhaust manifolds, etc). And while this isn't a particularly scientific comparison, I personally weighed a bare 403 block (170 lbs) and a bare 455 block (200 lbs) on my highly calibrated Chinesium bathroom scale from WalMart. I'm guessing that an early 350 would be in the 180 lb range.
November 6th, 2021, 07:47 PM
