Topic: 78 L80 engine code help

[Joker (§ir£Ğragon)]

The reason Pontiac engines like the 400 had so many different codes is because there were so many different versions of each engine. Different cams, pistons, cranks and heads to name a few things. Because the 403 was only built for 3 years, and there were no real differences between one or the other there really is no reason for different engine codes.

As he said, they all had 4A heads. It was the block that could either be a 4A or 4B. Supposedly the 4A blocks could be solid web engines. But I've never seen one with either that code OR the solid webs. And as far as I know neither has anyone else. And looking at me last post I see I was a little vague. The 4A blocks (if they exist) would be from early '77. The 4B blocks could be from any of the 3 years of production. So a '77 could have either code.

The heads and exhaust are a great place to start. Helping them breath better and increasing compression that way will help a lot.

I really can't help with the RPO codes on the build sheets.

[T/A Tommy]

Thanks for all your help guys...

[Tra23]

Mondello Olds technical manual has some good info on the 403. He says that the 403 solid main web block came in some Buick wagons built in late 76, some Bonnevilles, and in the 79 T/A with the special towing package only. Also that there were only 2500 or so made. The block casting number (to the right of the oil filler tube) is 49950-4A. I think have found one of these and am going to get it next week. I have not checked the vin on the block, but have my fingers crossed that it is a 79. Unfortunately the guy will not let me open it up before I buy it. May sell it if not solid. I'll post pics if it is. 

[bigty88]

I think that would be the first solid web ever!  Good luck!