C heads fit on a 403 olds?

[Bri guy]

Any chance you can measure the valves? I think there were 2.02 and 2.07 versions.

He said they're the 2.07

 

[fleming442]

So, when do you pick them up?

 

[Bri guy]

So, when do you pick them up?

Maybe satudray if I don't work. Is it worth getting? Will I feel any difference in performance?

 

[Bri guy]

Maybe satudray if I don't work. Is it worth getting? Will I feel any difference in performance?

Also picking up a dissassembled 455 on Thursday for 100....it also has j heads. But I don't have a clue what's good and what's junk or what it takes to make it work. I'm going by advice from others...so if c heads are worth investing in, I will pick them up.

 

[fleming442]

Put it this way: C castings are the best flowing, factory, iron heads made by Oldsmobile.

 

[Bri guy]

Put it this way: C castings are the best flowing, factory, iron heads made by Oldsmobile.

I stand corrected. I have 4a heads. My mind is going nuts with all this.

 

[Bri guy]

I stand corrected. I have 4a heads. My mind is going nuts with all this.

 

[olds307 and 403]

The flow on J and 4A are the same, not so good, around 190 intake and 120 exhaust cfm. I believe the big valve C heads are 215 intake and 175? exhaust cfm. The Procomp heads flow 240 cfm intake and Edelbrock's a bit more but requires an electric fuel pump. Bare the Procomp heads are around $300 each.

 

[L92 OLDS]

Also picking up a dissassembled 455 on Thursday for 100....it also has j heads. But I don't have a clue what's good and what's junk or what it takes to make it work. I'm going by advice from others...so if c heads are worth investing in, I will pick them up.

If you decide on a Performer RPM intake keep in mind that most guys running these run in to clearance problems and a cowl hood is required.

 

[Gozer442]

I have a 403, .60 over, J heads, and RPM intake(milled and port matched to fit BBO heads). Ran 11.89 in the 1/4 with full weight '87 442 with 373 gears, 28" tires, and Edelbrock 750.

The idles nice and lumpy at the lights....cruises like a dream...and stays cool on long trips. I love Olds motors!

With the C heads, and added breathing the motor will have, you'll be pushing the higher rpm bandwidth further out... I'd highly suggest strengthening/lightening your crank assembly! Get a girdle, and lighten and re-balance your rotating mass. Those windowed main webs in the 403 will always be haunting you!