hey so I got my 260 fixed now and about to put it back in my car and work on the 350 which turned out to be a 79 hurst engine so ill keep it now. I had to bring back the 260 because I work part time make minimum wage and go to school and the gas millage on the 350 was just killing my account but itll be back hopefully better mpg. ok back on the 260 is there any after market heads for it so I can use a 4bbl intake, carb or should I just use a 2bbl to 4bbl adapter. also is it true if one uses electric fans mounted on the radiator instead of the fan on the engine increases mpg, hp because theres less strain on engine. im trying to make the 260 perform alittle better by increasing air flow in and out. do I really need the catalytic converter or can I go away with it since ive seen some cars without them.
260 is back
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I don't know what year they switched from the pellet type to the honeycomb type catalysts - the former were really bad, the latter, not so much of a problem. I don't think there's much to be gained from that, probably more from the exhaust overall (going to duals)
(most of the following is from the 442.com faq)
The heads on the 260 are the smallest combustion chambers of any small block Olds, at 57cc. Despite this, the 260 is only 7.5:1 compression. Switching to any other heads will drop compression even more. Not worth it at all. The closest would be the #3 and #4 heads at 60cc (1966 and 1967 330 V8), but keep in mind the valve sizes - the 260 only has a 3.5 inch bore, and the #3/#4 heads have 1.875 intake and 1.562 exhaust valves - that might be cutting it way too close, and still loses a small amount of compression.
The intake runners and intake ports for the 260 are also tiny. I am told that the roller-307 engine's 4-bbl setup might work, as the roller-307 had very small intake passages and intake ports.
I don't know what the valve sizes are on a 307, but this link suggests using the 5A heads and Edelbrock intake, though I imagine the use of the 5A heads with the A5 intake of the roller engines might be good on the 260.
Still, I think that the first thing would really be dual exhaust. That'll give you a little bit more power and a slight improvement on fuel economy - that's probably true for any V8, though.
(most of the following is from the 442.com faq)
The heads on the 260 are the smallest combustion chambers of any small block Olds, at 57cc. Despite this, the 260 is only 7.5:1 compression. Switching to any other heads will drop compression even more. Not worth it at all. The closest would be the #3 and #4 heads at 60cc (1966 and 1967 330 V8), but keep in mind the valve sizes - the 260 only has a 3.5 inch bore, and the #3/#4 heads have 1.875 intake and 1.562 exhaust valves - that might be cutting it way too close, and still loses a small amount of compression.
The intake runners and intake ports for the 260 are also tiny. I am told that the roller-307 engine's 4-bbl setup might work, as the roller-307 had very small intake passages and intake ports.
I don't know what the valve sizes are on a 307, but this link suggests using the 5A heads and Edelbrock intake, though I imagine the use of the 5A heads with the A5 intake of the roller engines might be good on the 260.
Still, I think that the first thing would really be dual exhaust. That'll give you a little bit more power and a slight improvement on fuel economy - that's probably true for any V8, though.
The intake runners and intake ports for the 260 are also tiny. I am told that the roller-307 engine's 4-bbl setup might work, as the roller-307 had very small intake passages and intake ports.
I don't know what the valve sizes are on a 307, but this link suggests using the 5A heads and Edelbrock intake, though I imagine the use of the 5A heads with the A5 intake of the roller engines might be good on the 260.
Still, I think that the first thing would really be dual exhaust. That'll give you a little bit more power and a slight improvement on fuel economy - that's probably true for any V8, though.[/quote]
thanx so you think some roller 307 5a heads and intake will help or should I try porting them. I have a dual exhaust from the cat to the back and was thinking on doing a true dual exhaust from the headers back and using an xpipe and maybe glasspacks instead of a muffler since I have the car bagged except air hoses so the bags were filled up to keep on driving but I had flowmaster mufflers on it and I laid frame for the first time when bags were installed and crushed the mufflers up into the floorpan.
I don't know what the valve sizes are on a 307, but this link suggests using the 5A heads and Edelbrock intake, though I imagine the use of the 5A heads with the A5 intake of the roller engines might be good on the 260.
Still, I think that the first thing would really be dual exhaust. That'll give you a little bit more power and a slight improvement on fuel economy - that's probably true for any V8, though.[/quote]
thanx so you think some roller 307 5a heads and intake will help or should I try porting them. I have a dual exhaust from the cat to the back and was thinking on doing a true dual exhaust from the headers back and using an xpipe and maybe glasspacks instead of a muffler since I have the car bagged except air hoses so the bags were filled up to keep on driving but I had flowmaster mufflers on it and I laid frame for the first time when bags were installed and crushed the mufflers up into the floorpan.
My opinion; you will waste way more time and money doing a headswap with little to no gain anywhere. The 260 has such a small bore that other olds head will not work well ( if at all ) and no aftermarket heads for your application either ( and if there were they would cost you more than what you could afford anyway ). 5A heads are from a NON roller 307. 7A heads are from a roller 307, but they ain't going to help you. Just go with a true dual exhaust setup and tune your carb right. Running the stock air cleaner setup will help a little bit in MPG too ( though not so much for HP ). I don't know if the ports will match up well or not, but if they do you can run an A5 intake from a roller 307 then run a PROPERLY jetted/tuned Qjet. Make sure your engin is timed properly too. Bumping up a couple degrees may help a little.
Electric fans are going to cost you way more than any gas you might save, so that doesn't seem like a viable option to me.
If you have money and want to spend it somewhere, get a 2004r transmission and some better gears. That will increase performance and milage.
Electric fans are going to cost you way more than any gas you might save, so that doesn't seem like a viable option to me.
If you have money and want to spend it somewhere, get a 2004r transmission and some better gears. That will increase performance and milage.
I am doing things to my 260 for some of the same reasons you are, I got an older small runner Edelbrock intake from a user on here. I originally planned on cutting the 2bbl flange off the original aluminum intake and welding a Wilson Intakes carb flange on, it is fairly easy to do but I couldn't pass up the deal I got so to save time I bought the intake. I had a hydraulic roller cam cut by Comp Cams to match the little motor, cut the intake and exhaust seats out to install larger valves, milled the heads to bring the comp. ratio up to 9.75-1. I also cut the rocker stands off to use a adjustable roller rocker set up, my car has ver low miles on it and the bore was still in great shape so I just re-ring the bottom end. I was looking to increase the reliability of the car, not so much the power. I used a Holley 390 cfm vacuum sec. carb, welded the center exhaust ports, installed headers, and I'm down to figuring out what exhaust I want. I eliminated the AIR pump, EGR, cat, mechanical fan, and went to a four pin HEI to eliminate the temp controlled timing, set it up 13 degrees base and 39 total mechanical, with a easy pull vacuum canister to finish it out. I havent driven the car completely done only in stages so I can't tell you mileage wise how much better it is, I was averaging 16-18 mpg driving it everyday with a split between in town and 75 mph highway, my car still has 2.29. But the motor does run much smoother, starts better, but I had a junk 2bbl, and four cam lobes wore down. No obviously if you can't do this stuff yourself it would be a little pricey, but just some thoughts for you
I got an adapter that works both ways from a 2bbl- 4bbl, 4bbl- 2bbl except don't know what kind of carb to use either the one on my 65 since its still not running. I know comp cams has a cam for this engine but don't know if itll fit because it says 260-403 olds engines. the 260 is all up to date with tune ups and everything in spec an clean i just want to improve it for longer trips and what ever. ive run into the problem of the 260 does not like the vaccum advance which when I fist bought it it had a screw in it. the car is not all stock trans has a shift kit with locking converter, rear end gears are alittle higher I have no exhaust on it right now because im getting a new exhaust built a true dual one, I like how it sounds with out exhaust its really loud sound like a drag car which is bad when its only running 16s "Honda civic territory"
All Olds cams will fit in all the blocks but Comp nor anybody else makes a cam for the 260 the lift, duration, and seperation is all wrong for these motors. They have to regrind a off the shelf cam to work well. Every motor will " like" vacuum advance it just has to be done correctly, do a search on here I have gotten into this before, if you understand motors and how to tune them you can always make a car run better and more efficiently with vacuum advance, or just put a mechanical advance only dist. in it, it will run ok, and anyone can get a car to run on one of them
Fox80, how did you calculate your CR of 9.75 because that seems way high for just shaving the heads. Still cannot believe you went through all that effort and expense on a 260, but I'm not here to start that up again with you so don't worry about that.... :wink: . I will say this though, you better get that thing down the track soon because you're the only person ever who has put that kind of money/time into a 260, so we all need to know what that thing can do.
I would love to make a couple passes in it, but the nearest track is quite a drive. I should have done it when it was still bone stock. The comp ratio was supposed to say 8.75-1, my mistake I didn't even notice it until you mentioned it, to achieve that was the milling of the heads, dropping the valves and seats into the chambers and having a .020 head gasket made. I calculated the motor stock the RT side averaged 7.8 the LT side averaged 7.75, so because of the uneven deck I cut the two heads differently to make both sides even. It kept both head gaskets the same but actually ended up with a right and left head. I had to adjust the rocker stands accordingly so the pushrods could be all the same. In all reality it would have been easier to pull the motor and deck the block, but I did all the work on my time. You are right if someone had to pay for all this machine work it would have been more than one of these cars are worth let alone the motor. Parts wise the roller lifters were the most expensive part. And I am not the first one to work on a 260 if you do digging you can find info on guys who have built these up, most did a bottom end because you would have to turn these motors to get any real power out of it. I'm not interested in that just the drivability and decent fuel economy
OK that CR seems reasonable then. My friend had/has a bonestock 79 Cutlass with 2.29 gears and a 260 just like you and he ran it at the track recently. It ran somewhere in the 19-20 range which is pretty bad. He then added 3.42 gears. With those he never ran it at the track but it still couldn't even spin the tires I think. We then installed a low milage bone stock 403 ( still with crappy stock converter and single exhaust ). With drag radials it went very high 14's and he won the street class at this years Olds Nationals his year with it.
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