Store with full tank or empty?

[69hurstolds]

Way back when they first took the lead out of the gas, Texaco sold Gasahol. It was offered to replace the lead and it was a very high octane. It did work quite well. I found that even with high compression Pontiac heads, I had no pinging. A side bonus was the mileage increase. On a road trip from NYC to Pittsburgh, I managed almost 20mpg with a 1969 Pontiac 400 and 3:55 rear gears. The problem was that it still lacked lead and I eventually suffered valve seat recession. It wasn't until 1973 that they added hardened valve seats to survive the lack of lead.

Interesting. Olds V8 heads started using induction-hardened valve seats in '71. Don't see why the other brands didn't either, but Olds was always a bit different.

 

[Bonnewagon]

Pontiac kept it's large valve heads even when they dropped the compression ratio. That would be the '71-'72 heads. Unfortunately they also dropped a couple of exhaust bolt holes on the ends of the heads. Some bean-counter figured they could save $.03 per head by grinding the ends of the exhaust manifolds at an angle so that the single end bolt would press it tight. Stupid idea. In 1973 they went with even lower compression, added EGR passages, changed to the hot air choke, restored all the exhaust bolt holes, went to small exhaust valves, and added the hardened valve seats. That type of heads lasted right on to 1979 the last year of the traditional Pontiac V-8.

 

[spongbob]

Way back when they first took the lead out of the gas, Texaco sold Gasahol. It was offered to replace the lead and it was a very high octane. It did work quite well. I found that even with high compression Pontiac heads, I had no pinging. A side bonus was the mileage increase. On a road trip from NYC to Pittsburgh, I managed almost 20mpg with a 1969 Pontiac 400 and 3:55 rear gears. The problem was that it still lacked lead and I eventually suffered valve seat recession. It wasn't until 1973 that they added hardened valve seats to survive the lack of lead.

I've had a feeling about that seat hardening and , seems like I read that the spring pressure was reduced .I'm persuaded that with many of the old cars with much millage to boot that the springs on board them had somewhat lost enough pressure that they actually acquired a happy medium with the seat's... wear wise ...not saying that valves don't wear or burn.... in vehicles ( most of the cars operating ) at any given time could benefit from a valve job particularly the exhaust ones ( side) for shure"... one gets the idea that high spring pressure may be half the longevity ( lacking) figure ,...excluding higher performance ops aside, and thinking of the occasional comuter ," it's all good.. ethol, tired springs,and carbon sealing,...carbon sealing what am I saying . I'm not I'm just leaving a suggestion...