Oversizing valves.

[muh'stang]

In my 351w heads that are going on my 302 mini-stroker (317 w/pinto rods) I want to do the 1.94"in./1.6"ex valves. Where do I find them in a junkyard, and once i get them out what do I have to do to the valves? I know i have to unshroud the bowl in the head.

 

[TOM B]

Its not worth the hassel. Think about it.
I dont think the 351w had any valves that size.
69 -74 had 1.84 Intake and 1.56 exhaust if your serious.

 

[Edbert]

I think you are talking about the Chebbie valves from their 5.7L. They can be easily fitted into the 351W heads by a competent machine shop, but you do NOT want used valves.

 

[muh'stang]

I think you are talking about the Chebbie valves from their 5.7L. They can be easily fitted into the 351W heads by a competent machine shop, but you do NOT want used valves.

Yeah thats what I was saying. I guess ill stick with some ported windsor heads instead.

 

[brianj5600]

Unless you do MAJOR porting, the valve won't be the restriction with early 351 heads. I would just clean up the bowls, take out the hump in the exhaust port, and back cut the valves. Any more work than that and you should be looking at aftermarket heads.

 

[BC_Ace]

but you do NOT want used valves.

Why not used valves?

 

[dodgestang]

Why not used valves?

If you went to walmart and they had a sale on used underwear would you buy some?

If you were having a romantic moment with your significant other, would you use an new condom or pull out the one from last night?

Would you drink used beer?

Vavles IMO can be considered a wear item on a car, they mate to the heads they are installed in. Pulling a used valve out of one head and slapping it into another there is a very high chance it won't seal (both have to be machined for them to work) and there is also a chance that it came from an abused motor, has been stressed and could very well fail cauing an implosion in your motor when it goes 'plink' at 4000 RPM.

 

[BC_Ace]

So, would you think this could cause my engine to smoke(burn oil) when I punch it?

My engine has about 3000 miles on it since rebuild, and I'm running used chevy valves in my stock 289 heads that were machined and assembled by an experienced shop. Since the rebuild, I've replaced the valve seals, with no success.

What you say makes sense. I never gave much thought about getting new valves though.

 

[BC_Ace]

I thought I'd also add that the engine runs great, I regularly rev it to 6000+(maybe I shouldn't??), and it has high oil pressure.

Oh yeah... sorry to hijack this thread.

 

[Edbert]

So, would you think this could cause my engine to smoke(burn oil) when I punch it?

My engine has about 3000 miles on it since rebuild, and I'm running used chevy valves in my stock 289 heads that were machined and assembled by an experienced shop. Since the rebuild, I've replaced the valve seals, with no success.

There are three places where a valve will wear. The seat, this can be ground and polished for a good seal before being re-installed. The retainer groove(s), IMHO once there is wear here they are trash. But they can also wear on their shafts where the oil seals are. In the old days of leaded fuel the lead served as a lubricant, but many an old engine was run with unleaded gas and caused excessive wear. This could be the source of your blue smoke too.

 

[289power]

Yeah I had to add lead in my '66 with the 289 whenever I filled up with gas. Once I rebuilt it though I did some major head work and got the oversized chev valves and now I dont need the lead, just premium gas.

 

[slapper]

If you went to walmart and they had a sale on used underwear would you buy some?
If you were having a romantic moment with your significant other, would you use an new condom or pull out the one from last night?
Would you drink used beer?

That's good! Most decisions can be this simple.