Well to start out I have rebuilt the carb on my 86 f-250, Jason my mechanic said the power valve is out already. I can't get the idle strait ( too high or too low ) I guess the power valve is leaking fuel into the engine and flooding it when I turn it off, not too mention very poor mileage even for a 460. I believe the power valve check valve is not working causing the power valve to blow out prematurely. I found some kits that drill out the old and replace it some how. Has anyone ever used these? and could I get buy replacing these two $10 dollar parts and not the whole carb? Thanks for reading and any feed back is always appreciated.

 

Have you had problems with it spitting back up through the carb because of something else wrong? These kits seem to be a big deal now, and I agree it would be a good safeguard against blowing out the power valve, but the power valves just don't "blow out" for no reason. There are many of these carbs running around without these protectors on them, and they are running fine.

When the power valve is leaking, the exhaust will smell rich, but the idle will usually be steady. I would look down the carb throat with a flashlight while the engine is idling, and see if you spot any liquid fuel dripping down into the engine. If you do, I suspect your float levels are too high in the bowls.

 

Dave is right, as always. The only time I've had a power valve go is when the engine backfired through the carb, and every time it did I lost the power valve. But, otherwise no problemo.

In addition to the high fuel level, might high fuel pressure cause a similar problem? Don't know what fuel delivery system the truck has, but....

 

I had a power valve go out before, and the engine wouldn't even idle. But your 460 might be capable of digesting that extra bit of fuel.

While I was in there the accelerator pump transfer tube o-rings were bad too.

 

I'm not sure about the backfiring out of the carb, but it does backfire out of the tail pipe and it is usually a big fireball. The floats are now set to the proper level but the truck is not here right now so I will check down the carb on monday I guess.
The idle is very low at start so i will adjust it and once it warms up its too high. After it sits for a while and cools back down it's flooded and idles poor and runs very rich. There is a dyno shop called RPM right next to my shop I am going to stop buy and see what they have to say. I see a lot of fords in there shop.
Anyone think I should bite the bullet and buy a new carb? I have wanted to for a while but the local shops want $600 bucks for a re maned one! Could'nt I get a new holley or edlebrock one for that price?

 

The only time I had fireballs come out of the exhaust was when I had a bad Duraspark II module.

If your emmision components are gutted or non functioning then replacing it with a typical Holley/Edelbrock would be a good choice, if you cannot get the current carb to function correctly.

 

I dont think its emission controlled like my 79' , but I 'm almost positive its all factory. But! you never know how good the po was at hiding stuff. It has already passed emissions, but we're smog exempt out here sooo.... ...whatever? My mechanic said it's good to go accept the power valve. When I bring it home I'm going to situate it in the yard and pull the carb and replace the power valve, $25.00 bucks or less. Probably Tuesday, work and softball Monday.

 

You will probably need some gaskets also when you change out the valve, unless you are lucky and don't tear any.

 

yeah good call dave. might buy another rebuild kit for extra parts.

 

I had a powervalve problem. If I accidently ran one tank empty and it backfired running lean .... there went the powervalve! I had a NAPA fuel pump in the front tank for a while that couldn't keep up with the carb ... run lean, backfire, blown powervalve. I think it was during my 2005 rebuild my Carb Guy recommended one of these:

Power Valve Shield - Holley Power Valve Protection - WITHOUT Drilling! - Vehicle Parts and Accessories - For Sale Ads

There's a little check ball in the screw that replaced one of the bowl screws IIRC (it has been a while) and, after more than a few backfires, I haven't had a problem since.

Now here's that bad news; the link I had Holley Power Valve | Bullet Proof Vest | Carburetor Tuning at Powervalveshield.com is dead and has been for more than a few years. I dug up the picture from the link below the picture and really can't give you more than to say mine has worked well for years, it's a good product and somebody, somewhere, somehow knows more than I do.

Good luck with it,

 

Damn! I poked just a little bit more and look what I found!



Eliminate Holley power valve blowout-Without drilling | eBay

Go figure .....

 

My new '69 Super Bee had a Holley. The first one I ever had and I swore I'd never, ever have another. I'm on #3 now, but that's another story. Anyway, I once rebuilt the Holley in the Bee using a non-Holley kit. Had used Holley kits many, many times as the bowl gaskets would leak, causing the bowls to go dry, causing the cork gaskets to shrink, so I had to buy kits all the time. Later I found out that Holley had a problem where the primary metering plate came from the factory warped, causing the leak.

Unfortunately, the non-Holley kit had a gasket that wasn't symmetrical like the Holley gasket, so had to go in the right way or the accelerator pump passage was blocked off. I missed that, and no acc pump. Apparently I had the choke adjusted a bit light as it would fire up when cold, but w/o the acc pump it would sag and then backfire thru the carb - and blow out the power valve. Boy, did I go through power valves until I found the problem!

 

Thanks clydesdale and gary lewis! This is what i would hope someone would confirm that it can be fixed with out replacing the whole carb. If it doesn't it's only time wasted, and I got that. By the way I think a new carb can be had for close to $300!

 

Around here, NE OK, used Edelbrocks go for around $100. Watch Craigslist. But, you need the Ford linkage, which can be added on for something like $35 from Edelbrock. And, were it me, I would want electric choke over manual. Their #1406 is a good one for these engines.

 

Just orderd this Eliminate Holley power valve blowout-Without drilling | eBay . Can't wait to get the truck home tomorrow! Thanks again clysedale!