The Oldsmobile Connection

78supreme · Joined: 13 May 2007 Posts: 7

i was wondering if any of you happen to know if a intake manifold from a 307 olds would fit on the 260 v8s.... thus enabling you to use a 4 barrel carb rather than that aweful 2 barrel.

andrewk · Joined: 18 May 2005 Posts: 1245 Location: Ames, IA

It might fit, but it wouldn't work very well, IMO.

88 Coupe

andrewk wrote: It might fit, but it wouldn't work very well, IMO.
Vacuum signal to the carb would be less than desirable.

78supreme wrote: ........ if a intake manifold from a 307 olds would fit on the 260 v8 ........
Don't know about specifics, but if you use early 307 heads, the matching manifold will bolt up.

For best results, you'd need to address compression and cam timing issues accordingly.

Norm

78supreme · Joined: 13 May 2007 Posts: 7

early 307 heads... like 81??
also can you elaborate on " it may or may not fit / work well"

also right now my vacuum signal on carb is zero :) literally .... alot of times it will die at idle if the idle isnt set high..... or if the car isnt warmed up... i think it may be something with gasket seals..... when i put my hands or a cloth over the carb directly while its running it actully increases throttle which would lead me to believe its pulling in air from a leak around gasket maby? also spraying ether / starting fluid around the bottom of the carb in some areas it will also increase the throtte ... and i know for a fact it isnt getting sprayed directly in the carb at all.

88 Coupe

78supreme wrote: early 307 heads... like 81? ........
Yes, '84 and earlier. '85 will work if they came off a flat tappet engine.

Quote: ........ can you elaborate on " it may or may not fit / work well" ........
That was andrewk's answer to your original question.

Quote: ........ also right now my vacuum signal on carb is zero literally ........
The engine cannot run at all, without a vacuum signal.

Quote: ........ when i put my hands or a cloth over the carb directly while its running, it actually increases ........
It has a vacuum leak.

Quote: ........ its pulling in air from a leak around gasket maybe? ........
A broken gasket is a possibility.

Quote: ........ spraying ether / starting fluid around the bottom of the carb in some areas it will also increase the throttle ........
That spot, is the source of your vacuum leak.

Is this why you are interested in changing the carb?

Norm

78supreme · Joined: 13 May 2007 Posts: 7

yeah i actually found a recipt from buying a remanufactured carb last february... which is frustrating.... and another reason i want to try the manifold from 307 is because the 2 barrel carb on a 260 performance is a little.....well... below my par, so to speak. but i may as well just suck it up and save the money to get a completely different bigger engine and trans.

88 Coupe

78supreme wrote: ........ because the 2 barrel carb on a 260 performance is ........
The 2 barrel is not the problem. There are a few 260s using that carb, that are running 12s in NHRA Stock competition. Their power is made in the machine shop, not with bolt ons.

Quote: ........ and save the money to get a completely different bigger engine and trans.
Since you brought up the subject of engine changes:

Externally, the 260, 307, 330, 350, and 403, including accessory brackets, are the same, and the heads are interchangeable. The only changes in the "short blocks" are related to the cylinder bore diameters.

Both 400s, and the 425 and 455, will have minor differences in brackets due to their increased deck height and, in some cases, a larger radiator will be needed.

If you are interested, I can also discuss the pros/cons (lack of respect from the Olds community, is a given) of bastardizing it.

Norm

78supreme · Joined: 13 May 2007 Posts: 7

besides changeing the bore, heads, and cam.... what all else would increase the performance?

88 Coupe

Quote: ........ what all else would increase the performance?
Simple answer: Anything else that will raise cylinder pressures and reduce friction, while staying consistent with the application. The actual specs used depends on many factors. The two most important, are the intended application and the size of the budget.

To start: Define your goal. How much power, and what will you do with it?

Next: What fuel will be used, and how much loss in mileage is tolerable? Do you like how comfortably it drives/rides now? How much of that comfort are you willing to give up, to achieve your goal?

The next round of questions will be based on your answers.

Unless one can be specific about his/her goals, there are only two rules: "There is no substitute for cubic inches" and "Speed costs money, how fast do you want to go".

Norm