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head rebuilding mods

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Hoghead

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What is involved in a "lead head" conversion - stellite exhaust valves only, or another varient of stellite valves and seats.

Can modern valve seals be installed and if so from what car or PN
Does the head need machined to fit the seal?

Cam is stock as are the springs
 
Ther are other options available .However, I used Oldsmobile 442 valves and seats when I did mine. The valve stems had to be machined as well to take the Healey collets.--Fwiw--Keoke
 
Hoghead said:
What is involved in a "lead head" conversion - stellite exhaust valves only, or another varient of stellite valves and seats.

Can modern valve seals be installed and if so from what car or PN
Does the head need machined to fit the seal?

Cam is stock as are the springs
Click to expand...

My head conversion (1999) involved Stellite exhaust valves, cast iron valve guides, and hardened valve seats. All parts except the hardened seats were from Moss Motors. The machinist preferred to provide the seats himself to accommodate his cutter. The complete valve job included the above, plus new stock intake valves, seals, and new springs. Those parts came from Moss, too.
I have had no problems with the head for 76,638 miles.

It is not necessary to machine the head to fit the valve seals. It is necessary to machine the head to fit the valve seats.
 
The 442 valves are 2.072 In and 1.625 Ex

the AH is 1.745 In and 1.555 Ex

Stem diameters are the same

If new valves are needed then I am all for bigger is better. The 442 valves are a lot bigger and raises a few questions:

Can the stock BJ8 carbs flow enough for these bigger valves, given a little pocket porting and port matching work to go with the new valves? I am using the stock cam and manifolds

Will the bigger valves lose bottom end power in such a low reving engine?

What valve seal can be used that fits right over the valve guide boss without any machining?
 
Velocity is far more important than volume.

Without enough velocity, you cannot keep the fuel entrained in the emulsion, and the liquid droplets land on the port floor.

"Wet" fuel doesn't burn.

I'll go on record saying that more cylinder heads have been ruined by an ameteur with a die-grinder, than were "improved"

If you don't have access to a flow-bench to measure your progress, you have no way of knowing if you're working in the right direction, or creating a boat anchor.
 
Hence my question of using larger valves as my first impression is that these 442 valves are pretty large, and the velocity will be low in our engines. You OTOH have these valves in a Healey engine and presumably with sucess.
What other mods did you do to make the larger valves work?

I know all about ruining heads and this one will be done by an expert.
 
Hoghead said:
Hence my question of using larger valves as my first impression is that these 442 valves are pretty large, and the velocity will be low in our engines. You OTOH have these valves in a Healey engine and presumably with sucess.
What other mods did you do to make the larger valves work?

I know all about ruining heads and this one will be done by an expert.
Click to expand...
While the engine in my car has flow-matched combustion chambers and port-matched manifolds, it has stock valves and ports (as cast). The flow work was done by a pro on a flow bench.

Keoke's the one flexing the muscle car valves. :wink:
 
Pretty inexpensive to install hardened valve seats, but there's plenty of info on the web saying its not needed for normal use cars. The Lead in the fuel was the the reason for why hardened valve seats were really needed at one time.
Here's a quote with a more detailed explanation
Actually, tetraethyl lead was developed in the 20's by GM (Mr. Kettering, the designer of the famous '49 Oldsmobile 'Rocket' OHV engine, among others) and Standard Oil, only to allow the use of higher compression ratios, and NOT as a valve seat lubricant! Contrary to popular belief, the additive was actually very hard on cast iron exhaust valve seats, burning pits in the seats and valves, not to mention fouling s/plugs and creating deposits on the valve heads, etc. This was the reason for developing the hard alloys for use in valve seat inserts, as well as tougher alloys for exhaust valve heads, not the other way around. It was produced under the brand name 'Ethyl' by DuPont, added to gasoline and sold as leaded gasoline by the Ethyl Gasoline Corporation. In the 30's, it was finally sold as an additive to other gasoline companies. Since the re-introduction of unleaded fuel, much has been made of the disasterous results of unleaded fuel and 'soft' valve seats. Well, your cast iron seats would have a far shorter life if you were using leaded fuel! True, hard seat inserts will last longer than cast iron, but the question is it worth the expense of inserting a cast seat for unleaded fuel use in a normal use road engine? No, not really. Only if the cost is not a problem, or you're going to drive it hard, and put on a lot of miles. Otherwise, the cast seats will be fine.
 
I don't disagree with what mwagon posted, however I would add one consideration.

As the seats wear (and are reground) over time, the valves will get deeper and deeper in the head - called seat recession. This seat recession can reduce airflow and therefore power. You should have your machine shop consider how deep the valves are - you may want hard seats installed as a way to bring the valves back to the correct height to ensure good flow characteristics, ie power/performance.

Earlier you asked about valve stem seals. I use rover seals - eurospare part # ERR1782 (unfortunately they come in packs of 10 but your local parts house may be able to sell you 12, or you may have to buy 20 and have 8 spares). You do have to turn down the tops of the guides to fit them but they are small enough to fit inside stock Healey double valve springs, are good positive seals and last well. I would use good quality silica/bronze guides - your machine shop should be able to provide them and turn them to fit the seals.

Hope this helps.
 
Dave, missed you at Mission, B.C. Hope your health is better, looking forward to seeing you at the track soon. Oh ya, on topic, I run DW large stainless comp. valves and bronze guides, did the porting myself having Loynings Engine Service check the flow as I progressed. https://www.loynings.com/
 
My valves are 214N stainless steel with stellite tips and plasma nitrided stems,
Inlet = 1.811" (46mm)
Exhaust = 1.614" (41mm)
 
I purchased mine from Dennis Welch a few years back.

https://www.bighealey.co.uk/category/catalogues/austin-healey/engines/3000-top-end

VALVES

All our valves are made from one-piece forgings in 214N stainless steel with stellite tips and plasma nitrided stems for increased life. Suitable for both leaded and unleaded fuel. These are made to the lightest design using standard size stems and collets.

Inlet Valve Large - CompetitionCENG720Price: ÂŁ18.95

Exhaust Valve Large - CompetitionCENG721Price: ÂŁ16.95
 
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