Navarro 8ba Heads

[69a]

Originally Posted by KiWinUS

Question. So if H&H built this engine what did Mike say about fouling plugs so often?

I never asked about the plug problem, as I only noticed it a couple of months ago. I had other issues at the time.

[tubman]

Originally Posted by Tim Ayers

They are beautifully cast and machined. Still made in the USA too.

If the Chinese ever get into it, we may see decent $395 finned aluminum heads again. If they can make $109 "shoebox" Ford three row radiators, I don't see why they couldn't make a decent set of cheap heads. Does anyone have any idea of why Offenhauser heads are usually priced hundreds of dollars higher than comparable Edelbrock's? Especially since the latest improvements.

So I guess we're all in agreement that all Edelbrock's use 3/4" reach plugs (and always have). Here's a link to the thread where we determined that Offenhauser heads (used to) need a 5/8" reach plug; which isn't made :https://www.fordbarn.com/forum/showt...ghlight=spacer. I hear that problem has been since corrected.

[KiWinUS]

Originally Posted by Tim Ayers

I will say, and I don't have any dyno info to back it up, the Cyclones I took over ran better. Just seat of the pants and to my ear, the throttle crack was sharper and crisper.

I may put them back on this winter.

I can get you the name of the sealer I used on the original 28 Miller OHV head. It has been driven for close to a year with no issues so far and it was throwaway.
Your wife may not be happy when you bake it in her over though. ��

[69a]

Originally Posted by Shoebox

I asked Mike about this subject, his response below.

On Jun 3, 2026, at 9:23 AM, Mike Herman <[email protected]> wrote:

 The electrode is not supposed to hanging out in the valve pocket or it will hit the valve

When the exhaust valve is fully open there is less than 1/16" gap between the valve and the cylinder head. This means the entire plug is up inside the thread. I have seen some heads where a recess is cast into the combustion chamber. The Edelbrock combustion chamber pictured in my previous post has a CNC machined recess to allow for the electrode to extend into the combustion chamber without hitting the valve. The Edelbrock combustion chamber looks great, the other one, not so much.

[KiWinUS]

Originally Posted by 69a

When the exhaust valve is fully open there is less than 1/16" gap between the valve and the cylinder head. This means the entire plug is up inside the thread. I have seen some heads where a recess is cast into the combustion chamber. The Edelbrock combustion chamber pictured in my previous post has a CNC machined recess to allow for the electrode to extend into the combustion chamber without hitting the valve. The Edelbrock combustion chamber looks great, the other one, not so much.

Only the latest Edelbrock are like that all earlier versions are more like the Navarro. I try to get the valve at .040 clearance to the cyl head. 55 plus years building these gems.
So what did Mike say about your plug fouling issues if he built the engine???

[Tim Ayers]

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Originally Posted by tubman

If the Chinese ever get into it, we may see decent $395 finned aluminum heads again. If they can make $109 "shoebox" Ford three row radiators, I don't see why they couldn't make a decent set of cheap heads. Does anyone have any idea of why Offenhauser heads are usually priced hundreds of dollars higher than comparable Edelbrock's? Especially since the latest improvements.

So I guess we're all in agreement that all Edelbrock's use 3/4" reach plugs (and always have). Here's a link to the thread where we determined that Offenhauser heads (used to) need a 5/8" reach plug; which isn't made :https://www.fordbarn.com/forum/showt...ghlight=spacer. I hear that problem has been since corrected.

Tubman,

Offy still does all of the finish work and final machining by hand in CA. I’d assume the higher cost is associated with the higher labor to finish their products.

[Tim Ayers]

Originally Posted by KiWinUS

I can get you the name of the sealer I used on the original 28 Miller OHV head. It has been driven for close to a year with no issues so far and it was throwaway.
Your wife may not be happy when you bake it in her over though. ��

I’ll text you. Thanks, Tony

[69a]

This is an Offy head, you can clearly see the relief cast into the combustion chamber, to allow the electrode to sit clear. This feature is obviously important to everyone except Navarro.

[KiWinUS]

Originally Posted by 69a

This is an Offy head, you can clearly see the relief cast into the combustion chamber, to allow the electrode to sit clear. This feature is obviously important to everyone except Navarro.

I ask you for the third time. What did Mike say about your plug fouling issues and spark plug shrouding you believe to be incorrect???
Do tell.

[tubman]

Originally Posted by Tim Ayers

Tubman,

Offy still does all of the finish work and final machining by hand in CA. I’d assume the higher cost is associated with the higher labor to finish their products.

Sounds to me like another mis-interpretation of basic economic theory that seems to be prevalent in this country these days. Maybe the Chinese should start making aftermarket finned aluminum heads.

[tubman]

Originally Posted by 69a

This is an Offy head, you can clearly see the relief cast into the combustion chamber, to allow the electrode to sit clear. This feature is obviously important to everyone except Navarro.

and Edmunds.

[69a]

Originally Posted by KiWinUS

I ask you for the third time. What did Mike say about your plug fouling issues and spark plug shrouding you believe to be incorrect???
Do tell.

I answered you in post #21.
PM me if you want more info.

[69a]

Originally Posted by tubman

and Edmunds.

Perhaps I am wrong, but the Edmonds heads look like you could use a longer plug without interfering with the valves. The plug location appears to be between the valves.