Hey guys
happy 025'
As a last thing in 024' I picked up a 403CI OLDS SB.
​​​​complete engine. Casting 557265 4B.

I'm very familiar with BUICKS, CHEVYS and also build Mopars, I am a fan of pushrod V8s and so I'm sure I can make a decent BUDGET performance engine out of this 403.
I was always intrigued by the 403ci Sb and always thought that this could have been GMs best SB.
The guts are there I think.

So here is the BUDGET plan ( 400+hp)
the engine rotates very good , I will inspect the rod and main bearings as well as the pistons.
I want to reuse the oem pistons ( budget reasons).
maybe re- ring them and give the bores a dingleball hone.

I understand that the Heads suck.
I also know that I can swap 350 (#5,#7) heads fairly easy to pump up the compression .
455 heads would fit as well but would make the intake options a headache.

cam wise I have tge local option to get the iem cam re grind as well as tge oem lifters resurfaced.
so I'm looking for cam suggestions!!!
( NO I don't have aproject yet but I consider a GM Squarebody TRUCK as option)
trans BOP TH350.

Are there any good valve spring part # to upgrades the 350 heads? ( up to .600 lift )
Also any 5/16to 7/16 rocker studs?
I would like to use roller rockers If they are really a good upgrade, or should I stay stock rockers?
how much can I mill 350 heads before I get intake or clearance issues?

The engine came with a great shape EDDY 350 intake. That I can use.

ANY 403 recipes are very welcome!

 

Welcome. Unfortunately the tiny runners in that E-brock Performer are inconsistent with your goals. Sell it and get a Performer RPM. The 403 has windowed main webs that require a girdle for high HP builds. Your best bet is a set of aftermarket heads that will flow appropriately for that engine. Talk to Mark Remmel (cutlassefi on this site) for details. He's build a few of these.

 

Thanks great info.
I had good success with speedmaster parts and scored some great deals at the Black Friday sale,maybe i wait and try to score Olds heads, roller rockers and intakes at upcoming deals.

 

Hey Guys
I found this Aftermarket heads , they seem to be Speedmaster brand but modified with enlarged Head bolt holes
and they claim they have a 69cc chamber for the 350.
i assume this are BBO heads from speedmaster since they dont have a "real" SB olds head.
https://oldsrocketparts.com/index.ph...luminum-heads/

has anybody used the Speedmaster intakes with the Speedmaster heads or any OEM BBO heads.
Wondering if they fit well with the 403 block.

I had good success with Speedmaster parts int he past , across all engine brands ( chevy, Mopar mainly ) i dont mind the parts

 

Those might work but they have been measured and fall short of their 69cc claim. Are you planning on using the stock or cast replacements? Honestly a Performer RPM intake, new small dish forged pistons and the Procomp or BB Edelbrock heads might be better to reliably reach your goals.

 

thats what i thought this heads look exactly as there "procomp"BBO heads.
so i assume this are the same and tge 69cc is just a claim.
The speedmaster heads have 77 have but great flow.

I try to not do pistons at all if I don't find severe damage and/ or a great deal on oem replacements .

I'm ok with a 9:5:1 ish engine

 

Speedmasters have NEVER been 77cc’s. And their flow numbers out of the box are just slightly better than a large valve BB iron.

 

Good to know.
I heard you have good experience with 403 builds,

What are your suggestions with oem SB or BB heads.
Does it make sense to Port and upgrade the 4As?
mill the heads?
I have a local source source for the work.

Also with this mods in mind I would love to see a cam grind suggestion for a FT cam.

 

Mark has done really nice 403 builds with near stock C casting 455 heads that have big valves and hyd roller camshaft

 

With stock pistons .025" below deck, you need about a 25cc smaller chamber. The 65 to 72 Olds 330 and 350 heads, #2 through 7a heads are mid 60 to 70cc stock. You need about a 60cc chamber with Felpro 403 head gaskets to reach 9.5 to 1 on a factory short block.

 

yea if I get a lil advise I have no problem using the #4 heads...
however I sourced #5 350 heads locally already, which is a better head. And i am sure i let Lloyd touch them ...​​​​​i might port them myself before they get a rebuild and a milling.

I will also see how much I can possibly port/work the eddy intake I have to match the heads well...

and i get tge cam re-grind locally as well as tge lifters resurfaced.

 

Lloyd no longer does iron heads , I mentioned above. 68-69 #5 is nice clean casting but if they don't get bowl work and bigger valves there is little to gain actually you also have to enlarge the head bolt holes to 1/2 from 7/16 too , a pocket port on the smog 4/4A heads 403 stuff will clean them up to do well but a stock 455 C E or G head will out performer either small block head , what is this going in ?

resurfacing lifters and regrindig cam, just no no no no no

 

Not going with BBO heads if the intake is a shitshow....
its a budget build so i dont spend 500$ on a intake for a 50$ motor just because I use BBO heads.
further this BBO heads have to be worked as well especially on the compression side to offer a gain...
so its apples to apples
re grinding FT cams and resurfacing is by todays cam core supply and failing lifters left and right a good option. especially the sources I use. ( use them for a long time).

Ps: headbolt on the #5 heads are already 1/2

And i consider bigger valves since i take the heads appart anyways and instead of reworking the valves I can upgrade
what size is recommended on the 350 heads?
I know the #4 heads have bigger size than #5 heads

 

So shitshow appears to be the plan , good luck with it

 

yes sir , that's what I'm aiming for.
that makes the most sense $/purpose ratio.

I got #5 heads lined up (thanks to amember)