The Olds 260 head is the worst flowing factory head?

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Oct 14, 2008
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Check out the flow numbers at the end and much bigger than the factory 3.5" stock 260 bore size those numbers were achieved at! From the Mod Everything site on YouTube.
 
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64nailhead

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Dec 1, 2014
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I wonder what the true, not government rated, HP was of these. I see wikipedia indicates 110hp. My first G had one, and I recall it was a turd off the line, but performed much better than 110hp on the highway (78 Cutlass Cruiser).

At the rate that these things are still being discarded, it would be neat to have 8-10 of them and add boost to them to see what their breaking point is.
 
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Oct 14, 2008
8,806
7,746
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Melville,Saskatchewan
I wonder what the true, not government rated, HP was of these. I see wikipedia indicates 110hp. My first G had one, and I recall it was a turd off the line, but performed much better than 110hp on the highway (78 Cutlass Cruiser).

At the rate that these things are still being discarded, it would be neat to have 8-10 of them and add boost to them to see what their breaking point is.
The mod everything guy is adding twin turbos to a TRANSPLANT Olds 260 in a heavy 76 Cutlass! He also added a Turbo 3400, I believe in 90s 2wd full size truck. He has gone through 5 used 4L60E transmissions!
 

64nailhead

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Dec 1, 2014
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The mod everything guy is adding twin turbos to a TRANSPLANT Olds 260 in a heavy 76 Cutlass! He also added a Turbo 3400, I believe in 90s 2wd full size truck. He has gone through 5 used 4L60E transmissions!
As mentioned, having 8-10 of these things to see how far the ports can be opened before hitting water or oil would be good info. And then finding a machine shop guy that's into having some fun with opening up valve size by another .2-.3 and throwing 15 psi on it.

It could be fun and then a found use for something that is unwanted. I know a guy that does the same with 305's and small blowers.
 
Oct 14, 2008
8,806
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113
Melville,Saskatchewan
I wonder if the intake valve would fit the exhaust side, it should. Then the 307's 1.75" intake valve should make a big difference with a bowl hog cutter. The lousy 7A swirl port heads flow 135/110 bone stock, the only numbers have ever seen for them.
 

Metzger82

Greasemonkey
Dec 15, 2021
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I agree with 64nailhead, my 1982 Cutlass Supreme still has its original 260 and going from a stop is like playing chicken with traffic but once going it moves pretty good.
 

Clutch

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Apr 7, 2017
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The 260 was always a dog I looked up the one that was in my 78 cutlass and I think it listed at 100hp mine felt lucky to make 50 I only saved it in the trunk of my parts car because the parts car has a running 79 350 that knocks and I figured I'd use the crank from the 260 in it.
 
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rogue_ryder

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Oct 27, 2017
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I wonder what the true, not government rated, HP was of these. I see wikipedia indicates 110hp. My first G had one, and I recall it was a turd off the line, but performed much better than 110hp on the highway (78 Cutlass Cruiser).

At the rate that these things are still being discarded, it would be neat to have 8-10 of them and add boost to them to see what their breaking point is.

I'm sure the 110hp was close to being accurate. What's never published is the Torque curve, I bet that what you were feeling was that engine was in its sweet spot of the torque curve on the highway. I've never driven a 260 but that was exactly how old 1980s non-turbo Diesel Mercedes and VWs behaved on the highway; the cars were slugs leaving a stop light but felt like a freight train on the highway and had far less than 110hp (59 & 89 HP).
 
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Oct 14, 2008
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With less than 8 to 1 compression and an even smaller cam and exhaust crossover, it just didn't have a chance. Add on these awesome 2A, heads, the real flow masters🤮. No power house, I found mine adequate with dual exhaust.
 

Metzger82

Greasemonkey
Dec 15, 2021
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NW Ohio
Just for sh*ts and giggles I've wanted to hop up my stock 260 to see what it could do but the more I read I see why it was replaced with the Olds 307. Too bad Chevrolet had to snuff out Oldsmobile and their high performance aspect besides all the emissions crap. Could you imagine a factory W31 Olds 350 or W30 Olds 455 Gbody Cutlass......
 
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