Hello again.

The air pump in my 86 f150 4x4 300cid with np435 seized up. I've been doing a couple hours of searching but cant find diagrams for belt re route for the 300.

I eventually plan to convert back to a regular carb but I've got to get this thing running by Monday so I'll have to bypass the air pump.

Right now I've got two belts running from the crank to air pump and alternator and one from air pump to power steering.

Should I get two smaller belts to run from just the crank to alternator and then another smaller belt to run from the crank to power steering or just run one big belt or get a bypass pulley?

I'm assuming my ac is toast since it isn't hooked up so it'll be non ac belts.

What's the best/easiest option and are there any diagrams or write ups?

Can I just leave the pump in their for now or do I have to remove and plug holes regardless?

Thanks guys. I know this has been covered but I can't find much info concerning pre 87 setups that aren't 351 or 302.

My carb has been running great and i hate to remove a quasi essential component but have little choice.

No emissions testing in Ohio btw.

Thanks a million to anyone who helps.

 

This is what you need if you have A/C.

This is just in case any of you 4.9L owners out there decide to delete your AIR PUMP, the drive belt you will need is part # 25-060806 - Napa belt.. this is if you have AC.. but delete the air pump..

May save you a couple trips to the parts store..

 

Thanks.

My ac is present but does NOT work and isn't routed. I'll need belts that also bypass ac.

Thanks again. Pics on the way.

 

Sorry guys I can't get these pictures uploaded.

I don't think a bypass pulley is available for the 4.9l. Also, the one belt option is for 87 and up.

So i guess my question is...

Can I have three belts running to the crank? It has three belt grooves that seem to line up but Im unsure if its too much stress on the crank.

I can't really see it working any other way. Id really rather not replace it as it will be expensive and I need the truck for work.

Thanks again.

 

I thought there was a thread on here the other day and they showed the air pump driven by a short belt from the alternator the air pump, and then one belt going from the alternator over to the center of the engine and the crankshaft. That's the way some of the v8's were also.

 

Here's the other thread with pictures.

https://www.ford-trucks.com/forums/1393355-belt.html

 

Thanks Franklin.

Post #3 first picture.

My Setup is identical except for the dotted belt which runs to the ac.

I wanted to re route the power steering pump up from the smog pump located below, and reroute it to the first groove closest to the fan, where his dotted belt is.

The two rear belts wrap around crank, smog and then around to the alternator which isnt pictured, but is located below the ac pump, left of crank from front of engine.

I was thinking I could use shorter belts and skip the smog, instead running directly to the alternator.

What do you think?

 

Ill snap some pics of my belt setup tomorrow, You should be able to follow that to bypass the air pump entirely.
Not sure on belt sizes though.

 

You can't run the belts like in post #14? In that diagram you have 3 belts on the crankshaft pulley, and each belt runs one accessory, except the one that runs the alternator and the air pump. But you have a separate belt for the air pump. Don't want to run the air pump? Leave the short belt off. Don't want to run the A/C? Leave that belt off.

 

Ok I'm able to upload his diagram.<br/><br/>I don't have the upper right pulley, and it looks like the air pump is hooked up with three belts.

 

The top-right, the air conditioning compressor? That looks to be its own belt, leave it off if you don't want to use it....?

 

I just run 2 belts to the alt !

 

That's what I'm thinking. Two small belts going from crank pulley to alt.

Here's a better picture. That diagram up top is different.






<br/>This is much closer to what mine looks like.<br/><br/>Both the crank pulley in the middle and the air pump pullet below have three belt grooves. <br/><br/>Instead of having the two belts closest to the engine wrapping around the crank pulley smog pulley and back up to alt maybe two small belts from crank to alt.<br/><br/>The power steering belt connects to the third groove at the front of the smog pulley closest to the radiator. However, there is a third belt groove on the crank pulley that lines up with it.

You can just barely make out that third belt groove at the front of the crank pulley, its vacant on mine as well. It looks a bit smaller than pulley its currently attached to however.

 

I have never seen them run two belts on these truck's alternators, it's not needed. If you run it like the factory diagram, you can get the belts from the store, they already have them listed with the correct lengths.

I would be careful running two belts side by side. Some of these crank pulleys do not have the same sized grooves, one will be a hair different in diameter or belt width. People have had problems on here before with running belts like that and write in saying they don't know what's wrong, their belts keep getting chewed up. They don't realize one belt is trying to go faster or slower than the other one beside it driving the same accessory, and they do not like that for very long.

 

First off, Franklin..

You are a Godsend for those of us struggling with our beloved, old trucks. Its difficult to find a lot of info, especially for the bullnose years. Next time I'm in Kentucky I'll try to make it to Virginia and buy you a steak dinner and help you with whatever you need done around the house or on your truck. Thanks for being a great guy.

That's interesting that these trucks don't want two pulleys on the alt like that. Mine is identical to the picture. I've read two pulleys were needed for when the alt is under load to prevent sslippage but I can't remember where I read that.

Im fairly certain my power steering belt has no alternative pulley to attach to in this case. I read about people doing the dsii conversion and ridding their truck of emissions but I don't see how they bypass or eliminate that smog pump. Its too far out to attach to the middle belt on the crank pulley.

It looks as if Im going to have to just replace the smog pump and pulley. Unfortunately the pulleys don't come attached to the smog pump itself so I'm kind of stuck here.

I would love to get rid of it as its one less pulley I have to worry about failing and I wanted to convert anyhow.

This is about the only time Id rather have an 8cyl small block because information and bypass setups abound.

Thanks again. Maybe I'll have to scour the yards but even bullnose trucks are rare around these parts.

I'm all ears if you've got any other suggestions.