Olds 403 Head Upgrade

[FE3X CLONE]

I've never heard anything about steam holes, but you'll also need to drill the locating pin holes on the heads slightly larger for the pins on the 403. You'll also need the valve covers with the correct number of bolts.

I could be wrong, but I thought the 403 heads had the steam holes similar to the Chevy 400 because they're both siamesed cylinder blocks. I don't want to give out the wrong info, so feel free to chime in.

We didn't drill any steam holes on my brother's 403 when we swapped to the 7A heads. Just drilled out the head bolt holes for the larger head bolts and like you said, enlarded the dowel pin holes slightly.

 

[olds307 and 403]

The steam holes a sbc thing. With 6cc KB pistons, you will be around 10 to 1. Electric fuel pump will be needed, as said. The new, out this year, Edelbrock heads have a better chamber, port design and flow. The original design flows around 240 cfm intake and 175 cfm exhaust. Much better than midly modified "factory" 4A heads.

 

[foxtrot]

Thanks for all of the info guys! I'm starting to think that I'll try to find a pair of the 1971 "7" heads instead.

 

[foxtrot]

Does anyone know of a source for a good core set of 1971/7 heads or even better a rebuilt set?

 

[foxtrot]

<BUMP>

 

[G-Body_Vet]

<fart>

What's with foxtrot? Are you a military guy as well?

Well anyway, you might want to try searching the classifieds on
http://www.oldspower.com
http://www.realoldspower.com

You could also try http://www.car-part.com