C heads fit on a 403 olds?

[pontiacgp]

The only difference with big block, and small block Oldsmobile V8 motors, is deck height.... with BBO having a higher deck. Almost all the parts are interchangeable bolt-ons, with some of the parts requiring some modifications to fit like cranks and heads. All Olds heads are interchangeable...260ci up to 455ci. Many mistakenly call the 403 a big block, and the 350 "Rocket", or 350 "Gold Block", a big block... all small blocks. The 403 uses 1/2" head bolts, and the big block have 7/16" head bolts, so the BBO heads need to be drilled out to 1/2" to be bolted to the newer blocks... along with the port-matching on the intake. So, because the deck height is higher on a big block Olds, the BBO intake is wider, so it won't fit a SBO. Everything else is pretty much interchangeable!

thank you....

 

[fleming442]

I'll add that the biggest problem with putting BB heads on the SB is the interference with a mechanical fuel pump. Other than that, it's a great upgrade, even if you stay with iron heads.

 

[olds307 and 403]

I'll add that the biggest problem with putting BB heads on the SB is the interference with a mechanical fuel pump. Other than that, it's a great upgrade, even if you stay with iron heads.

The fuel pump interference is only the Edelbrock and Procomp heads, I wish they would modify that area and add a 67cc chamber size for the SBO.

 

[fleming442]

The fuel pump interference is only the Edelbrock and Procomp heads, I wish they would modify that area and add a 67cc chamber size for the SBO.

The E-brocks hit it on a BB, too. I had to "clearance" my diaphragm housing with a hammer.

 

[olds307 and 403]

The E-brocks hit it on a BB, too. I had to "clearance" my diaphragm housing with a hammer.

Why they don't change it is beyond me. It also interferes on the early style power steering reservoir return line on the SBO. The owner had to change to a different replacement reservoir that changed the return line routing. Too bad as those heads have a improved chamber or at least spark plug position and actually flow 240+ cfm on the intake, along with better exhaust numbers, unlike stock C or any iron SBO/BBO head.

 

[pontiacgp]

The E-brocks hit it on a BB, too. I had to "clearance" my diaphragm housing with a hammer.

was it a hammer or a precision modification implement?

 

[fleming442]

was it a hammer or a precision modification implement?

Technically, an anti-reverberation precision modification implement (dead blow).
I was 200 miles from home, and the Mr. Gasket pump broke off at the mounting boss as they are prone to do. I had ground a small relief for the Mr. Gasket, but didn't want to hit water, and didn't have said deburring tool in the hotel parking lot. Gotta do, what ya gotta do!

 

[Vengeance]

I also need to find heads for a 403.
Has anyone seen this package?
Ultimate Top End Kit
Is $2,459 a good deal for everything it comes with? It looks like it comes with the performer rpm manifold already port matched. I'd have to ask to be sure. The heads are already opened for 1/2 bolts. We're starting from scratch so I figure the kit might be the best bang for the buck. Would it be cheaper to look for some C heads and piece everything else together? We're going to stick with the stock bottom end since it has low miles, so the 69cc chambers would be better compared to Edelbrock's 77cc. I think it would end up about 9:1. What's the stock gasket thickness and how thin can I go for max compression with stock pistons?

I wish they would modify that area and add a 67cc chamber size for the SBO.

The kit I linked to is close with 69cc.

 

[olds307 and 403]

There have been complaint's that those heads don't measure what they are supposed to, one builder did a motor for a guy who bought those heads, they CC'd at 70+ I believe . They are Procomp heads which would work very well on a 403. Olds Rocket parts has been accused of being Mondello Performance Products, not good if true. Joe's son Benard Mondello does a quality rebuild of those heads, proper clearances, quality parts, whatever chamber CC and could probably be close to that price and you know everything would work as it should and your compression would be where it should be. Another option for those heads is Mark Remmel, Cutlassefi on this site. He sells many Olds parts, including custom cams and has brought many parts to market, including a billet 4" stroker crank for the SBO. Both would be a better choice. The stock pistons while not great should survive reasonable abuse. The big issue besides being cast is their weight, keep the RPM's around 5000 RPM max with a stock bottom end, I spun the bottom end at 5500 RPM but it was not balanced either, a 307 crank ended up in it, due to multiple overheatings cooking the stock one. The stock one had .010" rod bearings, supposedly came out of an old man's 78 Delta 88. Mark Remmel contact at [email protected].
Bernard Mondello
https://www.google.com/url?sa=t&sou...FjAdegQIBBAB&usg=AOvVaw12QVmrQkhysjvR3ANLcUR7
https://www.google.com/url?sa=t&sou...gwHnoECAkQAQ&usg=AOvVaw3xEcZYZoabVUh6js66_q4O

 

[Vengeance]

Joe's son Benard Mondello does a quality rebuild of those heads, proper clearances, quality parts, whatever chamber CC and could probably be close to that price

Close to that price with cam, intake manifold, roller rockers etc.?
I found This guy saying C heads actually aren't the best stock heads, A heads are. He's also milled Edelbrock heads down to 46cc and said there's still plenty of thickness left. 53cc should get 10:1 with stock pistons.