BB exhaust seats

[jlatessa]

Has anyone had trouble with hardened ex. seat leaks (water).

I wanted the performance shop to machine and install hardened Ex. seats.
This on 906 heads.
This shop originally did the heads, 2.14 In./1.81 Ex. with bowl contouring and multi-angle seats
said heads have problems with water jacket leaks after seats installed...any comments?

Thanks, Joe Latessa

[elacruze]

If the heads work well and you've sunk a bunch of money into them, use some Liquid Glass block sealer. This old farm remedy really does work as well as claimed. There are risks, however.

First, as you might suspect, your cooling passages must be as clean as possible so the stuff can stick where it's needed.

Second and most importantly, if you use too much it can clog passages. Follow the directions to the letter, and for my $0.02 I've always flushed and rinsed the cooling system thoroughly after I'm sure the stuff has fixed what I put it in there for, just to get out any remainder that could find a home where I don't want it to.

[tan top]

wanted to get hardened seats put in some 906s years ago  , before all these aftermarket heads came about  , machine shop i contacted about getting seats fitted ! said " don't like doing 906s  too close to the water jacket """  
but have seen /& heard lots   of 906s  been fitted ! & as far as i know , none have given problems  

[jlatessa]

Thanks, not what I wanted to hear, so I guess I'll use a fuel additive and minimize the drag racing until I spring for an aftermarket set of heads..

Joe

[firefighter3931]

Joe, use stainless exhaust valves....helps bigtime with metal transfer. 


Ron

[jlatessa]

Valves are stainless, how does that help?
I thought the cast iron seats were pounded into submission because of no lead to cushion.

What metal transfer happens, stainless to cast seats?

Thanks,  Joe

P.S. Valve springs are slight upgrade from stock..came with Racer Brown/Purple Shaft cam (286/286 .484 lift Hyd.)

[elacruze]

I'm not clear as to whether you've already installed seats or not.

If not, SS valves will help iron seats stay good longer because they do not stick to the seats like steel.
Basically the problem goes like this. Steel is basically Iron with Carbon in it. With Iron seats and steel valves, under the right conditions (enough heat and pressure) the valve and seat weld themselves together in tiny spots. Stainless Steel has a lot less Carbon, which is highly attractive to Iron. Less Carbon, less likelihood of alloying to the seat.

Secondly, Stainless valves are harder than Steel valves and the greater the difference in hardness, the less likely is galling which creates pressure points which lead to picking.

Clear as mud?

[firefighter3931]

The oem valves are softer so the increased heat & no lubrication (unleaded fuel) promotes metal transfer between the valves and seats. Stainless is much harder than OEM so it won't pull metal off the cast iron seat. Dissimilar metals work better in that harsh environment. It's not ideal but will last for awhile until you can upgrade. Throw a few ounces of Mavel Mystery oil in each tankful of fuel just for good measure.


Ron

[c00nhunterjoe]

My 906's have had seats replaced with no issues, that was done in 2001

[Challenger340]

Has anyone had trouble with hardened ex. seat leaks (water).

I wanted the performance shop to machine and install hardened Ex. seats.
This on 906 heads.
This shop originally did the heads, 2.14 In./1.81 Ex. with bowl contouring and multi-angle seats
said heads have problems with water jacket leaks after seats installed...any comments?

Thanks, Joe Latessa

I don't understand the rationale behind 906 castings being "prone" to water leaks more than others, after the installation of hardened seats, AT ALL ?
At least,
NOT if the correct "thickness" Seats are Machined for, and Installed ?
If a Guy,
uses TOO THICK a Seat, and hits the water jacket,
well,
then he deserves the leak later ?

As for just running the stock "as cast" soft Valve Seat, we have good success just telling our Customers to run a few Hundred mls of 2 Stroke Oil added to each tank of Fuel.
NO,
it will NOT smoke like a 2 stroke, but it will keep the exhaust seats lubricated sufficiently to prevent reccession, from our experience anyways.

[jlatessa]

No, seats have not been installed, wanted to have them done, but original machine shop balked at the suggestion.

I want to thank everyone for the educational info, still learning/crazy after all these years. (thanks Paul Simon)

I'll go the fuel lube way until I find a shop with the confidence and experience.

Thanks again....Joe

[BSB67]

I'm not clear as to whether you've already installed seats or not.

If not, SS valves will help iron seats stay good longer because they do not stick to the seats like steel.
Basically the problem goes like this. Steel is basically Iron with Carbon in it. With Iron seats and steel valves, under the right conditions (enough heat and pressure) the valve and seat weld themselves together in tiny spots. Stainless Steel has a lot less Carbon, which is highly attractive to Iron. Less Carbon, less likelihood of alloying to the seat.

Secondly, Stainless valves are harder than Steel valves and the greater the difference in hardness, the less likely is galling which creates pressure points which lead to picking.

Clear as mud?

Carbon steel has far less carbon than iron.  Some carbon steels have less carbon than some stainless steels. 

[firefighter3931]

No, seats have not been installed, wanted to have them done, but original machine shop balked at the suggestion.

I want to thank everyone for the educational info, still learning/crazy after all these years. (thanks Paul Simon)

I'll go the fuel lube way until I find a shop with the confidence and experience.

Thanks again....Joe

Good plan Joe  Honestly, if you're considering a set of aftermarket heads down the road just skip the hardened seats and have the heads cut for 1.81 ex valves and call it good. 

I'm not clear as to whether you've already installed seats or not.

If not, SS valves will help iron seats stay good longer because they do not stick to the seats like steel.
Basically the problem goes like this. Steel is basically Iron with Carbon in it. With Iron seats and steel valves, under the right conditions (enough heat and pressure) the valve and seat weld themselves together in tiny spots. Stainless Steel has a lot less Carbon, which is highly attractive to Iron. Less Carbon, less likelihood of alloying to the seat.

Secondly, Stainless valves are harder than Steel valves and the greater the difference in hardness, the less likely is galling which creates pressure points which lead to picking.

Clear as mud?

Carbon steel has far less carbon than iron.  Some carbon steels have less carbon than some stainless steels. 

I see we have some metallurgists amongst us 



Ron

[elacruze]

I'm not clear as to whether you've already installed seats or not.

If not, SS valves will help iron seats stay good longer because they do not stick to the seats like steel.
Basically the problem goes like this. Steel is basically Iron with Carbon in it. With Iron seats and steel valves, under the right conditions (enough heat and pressure) the valve and seat weld themselves together in tiny spots. Stainless Steel has a lot less Carbon, which is highly attractive to Iron. Less Carbon, less likelihood of alloying to the seat.

Secondly, Stainless valves are harder than Steel valves and the greater the difference in hardness, the less likely is galling which creates pressure points which lead to picking.

Clear as mud?

Carbon steel has far less carbon than iron.  Some carbon steels have less carbon than some stainless steels. 

Though I'm not sure that addresses the dynamic involved in seat picking, I'll concede your point.

[jlatessa]

When the heads were done years ago, 2.14s and 1.81s were put in.
Both stainless from Mancini.

Engine has never been run and we have about $1,000 in the heads, bowl contouring, gasket matching etc.
So I think I'll run with them for a while.

Engine is not going to be that wild anyway with that cam.

Joe

[firefighter3931]

Heck ya, don't think twice about running those heads. Just throw some lube in with the fuel and enjoy the ride. 


Ron