The original heads on my '73 were machined for dual plugs about 16K miles ago by the previous owner. I want to replace them with the same castings that have a date code between 12/72 and 3/73. The replacement "S" heads must be serviceable and have casting numbers of 911104307.1R and K1819h.
Bit of a long shot, I know.
Why don't you just plug the hole and leave yourself open to later using a dual plug ignition?
David
'73 S Targa #0830 2.7 MFI rebuilt to RS specs
Ditto.
Have the heads fly cut to make up for the itsy bitsy loss of compression from the extra eyebrow. 2.4's need some compression added anyway because they're totally lame when stock.
If I were building any other car, I would just find another dual plug distributor to stick back on it. But it's a first series RS and I'm really trying to make this one just like it rolled out of the factory. My initial thoughts were to buy the correct date coded replacement heads and keep these dual plugged ones for a future project, but I've had no luck in buying loose heads, so I'm now trying this trade approach.Originally Posted by RSTarga
Ahhhh...
That changes things.
Ship to Ollie's. Ike will make them like new.
Thanks for the lead. Talked to them - they can certainly fill the extra plug hole, but couldn't repair the external cosmetics where the fins were machined away.
???
That cannot be seen with a stock valve cover in place?
You are much further ahead having this harmless STD and being able to claim original cylinder heads than replace them.
If you're worried about the second spark plug machining that won't show I assume that you also don't have one speck of plastic filler on the car?
Obviously my point is that restoring a car as it rolled out of the factory is impossible. I could show you 100 cylinder heads and every one of them will have some type of defect. (broken fin, corrosion, etc.) Finding a set of properly date matched 2.4S heads that are virgin is a unicorn. Finding someone who has a set and wants to trade is a herd of unicorns.
Last edited by Frank Beck; 09-15-2016 at 03:55 AM.
Sadly, this isn't the first item where my buddy and I have spent silly money on this car for something that no one will see. Like the crazy money spent with the metalworker so that we wouldn't need to use any plastic filler (he did use lead in a couple places). We have had an ongoing debate about the value of leaving the original heads in place. But because of the mods made to the combustion chambers and the high-dome 2.8 pistons, it will never run right without functioning dual plugs. That, of course leads to having to mount a second CD unit and coil - getting even farther away from stock.
One direction we may go is to have a set of E heads we just found with the correct date code re-machined to RS specs by opening up the ports and adding the piston relief chamfer. The casting number (that you also can't really see) will be off, but if we ever sell the car, we can disclose that, and still have the original heads go with the car in a box.
It's unfortunate that the value of these cars has led many like us to this sort of behavior. We're both looking forward to our next project which will undoubtedly will be a hot rod that we can do whatever we want with. Anyway, Thanks for your input.
Let me get this straight, you are planning to to use a single plug head with a high compression 2.8 piston?
This to avoid going twin plug?
Your engine is already non standard, as it has been bored out for a 2.8, so its like being a little pregnant. IMHO
David
'73 S Targa #0830 2.7 MFI rebuilt to RS specs
Funny; I assumed he was going back to the stock 90mm RS spec P's & C's.
But it does beg the question: What changes were made to the combustion chamber? If they're the Mahle 92mm street upgrade for the RS there would be no head mods necessary for those pistons.
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