How can i tell if these heads are set up with unleaded seats (stainless)?They are fuelie double hump and are reconditioned,i have no way of tracking down what was done.How long will they last without an additive in fuel under normal driving ?cheers--keeo

id doubt ANY engine builder would build a engine without hardend seats these days, considering ALL fuels on the market needs hardened seats (unleaded and gas)

Stainless seats alone is not going to last, if the inserts are made from stainless steel - they will need to be induction hardened, and allowed to cool slowly in either soda ash, or temperature controlled oil bath.

Stalite seats are the best choice for a high performance engine and one that is to last the distance.

15 years ago? Youd assume they would have unleaded suitable seats as it was 10years into compulsory unleaded. However, if they were done for a hot motor, it might have been running around on avgas, race fuel or similar. Valve seat degredation may not have been considered.

Ill ask the old man tonight. He is an engine reconditioner after all!

"Silly modern cars"

Any 78 model on Chev with cast iron heads had induction hardened seats, as these engines ran on un-leaded fuel. Unfortunately the double or even single hump heads were not in production in this era.

Though these heads were used with unleaded, the seats were not all that hard, and most often seat degradation still resulted. The only real fix is Hardened stainless or Stalite seats.

Cloudy - K-lines are a brand of valve guides.

Many years ago, after completing my Apprenticeship I worked for a company that was a Franchise for MTU Diesel Engines, and we had a large contract for the NZ Government with a Research vessel that had 5 of these engines coupled to generators. My position was reconditioning and machining the cylinder heads. As part of the proceedure for fitting the new seats and valve guides, the head was heated in an oven to 400 degrees C and the seats were dropped into liquid nitrogen. I had to machine these components with a 6 thou interference fit at ambient temperature. As a result of the changed state in the temp of the head and the seat insert, the valve seats and guides would literally drop into place when fitting to the head. The only way to then remove them is to machine them out. Each cylinder had its own head and were fitted with four valves per cylinder, that adds up to a lot of work, especially when the engines are in V-12 and V-16 formation.

Just a little of my history with cylinder heads lol.