Ok. Have a few questions about worthiness, value and some other things. To start with, have a 70 Cutlass Supreme ragtop with a 77 403 in it. Originally had 350 with 310 HP. Not sure about why it disappeared. Several owners through the years. 403 is running fine, just a bit doggy. Have opportunity to purchase a 2 barrel 350 with #5 heads. Pulled running, sitting for "2years". Would it add/change value to have a 350 back in the car? Would at least go with new 4 barrel intake. Everything else has been redone, (wheels, seats, carpet, paint, glass, etc.) Also read a previous thread about an Olds engine builder in NKC, Mo. Anybody with info or direction to the thread would be appreciated. I appreciate the input, you guys are full of great information. Thanks in advance, Kip.

 

Put #5 heads on your 403 with a mild cam. You will not know it is the same engine, from 7.8 to 1 to around 9 to 1. Then you can build the 350 if you want. The value won't be there unless numbers matching. Even then being a non performance version, it would matter less. Great car, would own one if I could afford it.

 

I would throw a set of W-31 sized valves in those heads first (2.000/1.625). For that matter, you can go the full 2.070/1.625.

 

dreel thee head bolt holes out to a snick over 1/2" and the swap will go a lot smoother

 

Both very good ideas, one being necessary. Don't forget to enlarge the one dowel hole too.

 

310 advertised HP, which was not really 310 HP. I had a bone stock 70 Supreme 350-4bbl (310 hp) and it ran the same as a friend's bone stock 72 Supreme 350-4bbl (200 hp).

So I wouldn't sweat the loss of the original engine and do as other said and put better heads on the 403.

 

Of course, the 70 was 310 GROSS HP, and the 72 was 200 NET HP.