HottSS

I'm looking to purchase a bone stock 68 Z28 with the original DZ 302 engine. The current owner tells me he has to run race gas in it mixed with a small amount of 92 octane pump gas. He says this is because the engine has never been rebuilt (40,000 miles). Does anyone have any experience with this? Will it run OK on just 92 octane? Do I need to use a lead additive?
Thanks

ZZMike

First off, the carb should have a DZ designation, but the block should be an MO code if it is the original 68 engine. He is running leaded race fuel through the engine to offset the lack of tetraethyl lead in modern gasoline. This is fine, I run 114 octane in my 68 crossram Z/28 though. The lead in the fuel coats the valve seats and valve faces to allow for some cushioning effect. If regular unleaded is to be used, you will want to ****** the heads off and have hardened exhaust seats installed. This will keep the valves from recessing themselves into the heads due to lack of cushioning from the absence of lead. Good Luck with the car.

angel71rs

DZ is for 69s. With engine originally having high compression and 40k worth of carbon build up, engine is going to require better than 92 for sure. I've run 10.7 with iron heads and had to add race gas when I took it to the track to get rid of high speed ping.

I've run pre 71 engines on unleaded. Recession wasn't a problem. I think they are ok as long as you don't run under heavy load constantly, like a tow situation.

jcstew02

If its a DZ, you need to run racefuel or a lead aditive. Better safe than sorry. I know alot of people have run avgas 100oct. Aviation fuel. It says 100LL the LL stands for low lead content. But its actually full of lead. Its also cheaper than race fuel. You should be able to run 50/50 100LL and 92 pump. Hope this helps..........

HottSS

Thanks guys. I went to look at it yesterday. It does have the DZ carb. Another question: The car is REALLY nice but it has been repainted. It was originally Corvette Bronze and is now Matador Red with black stripes. Does anyone have an opinion how the repaint to red should affect the value?

ZZMike

Is the block truly an MO code?? If so, congratulations. The 1968 corvette colors, such as Corvette Bronze and British Racing Green were introduced mid-year and did appeal to buyers at the time by touting the camaro as a "blue collar corvette". Red cars typically do very well at the locally sponsored and amateur car shows, and in some instances may help for a quick sale (a.k.a. "re-sale red"), but the big money is in originality, and besides, that bronze is just something you don't see everyday. Just my .02