Hi everyone, I'm a newbie and have a 68 firebird that I'm trying to bring back to life. I just recently got a 403 motor with a 400 trans. I was looking for a pontiac 400 but was unable to locate one. My question is what application should I go with to get the most out of this 403 block. Currently the motor has an elderbrock 292 RV CAM, Preformer intake amd 455 Cast heads on it. I plan to take it to the machine shop and just would welcome any advise to get the most HP out of this block for street use. thanks for any help.  

talk to barneyformula he can give you great advice if he doesnt see your thread send him a message with details of exactly what your looking for... i.e. do you want this thing street legal or not? lol how much money you have to work with so he can figure what you can work with... all that stuff that too and you say 403 im figuring olds right? let him know all that and more so he can figure something out for ya...  

Thanks for the help I sent a message to Barneyformula..

I was told that the block came out of 78 grand Safri Wagoon. The numbers on the block are 557265 4B. I plan on taking it to the machine shop to get cleaned up and fixed, and just would welcome any advise to get the most HP out of this block for street use or should I just scrap this block and keep looking before I put money in it. Oh before for I forget im working with a budget of around $1500 to get the block stong. thanks for any help or advise you can give.  

Crazybird, I've pasted the rest of the info you gave me here so everyone can see the details, hope you don't mind.

Hello, I'm a newbie and have a 68 firebird that I'm trying to bring back to life. I was sent in your directions for help for another member. I just recently got a 403 (#557265 4B) motor with a 400 trans for $200. The guy I got it from works on cars and had it in a Cutlass and stated that it only has a spun bearing #1 or #2. I was looking for a pontiac 400 but was unable to locate one. My question is what application should I go with to get the most out of this 403 block on a budget. Currently the motor has an elderbrock 292 RV CAM, Preformer intake amd 455 Cast heads on it (#554717). I was told that the block came out of 78 grand Safri Wagoon. The numbers on the block are 557265 4B. I plan on taking it to the machine shop to get cleaned up and fixed, and just would welcome any advise to get the most HP out of this block for street use or should I just scrap this block and keep looking before I put money in it. Oh before for I forget im working with a budget of around $1500 to get the block stong. thanks for any help or advise you can.

BarneyFormula's reply: first things first, you only paid $200 bucks with agood th400 trans so you haven't lost any money. Tear down the 403 and have a machinist determine what it will cost to fix the spun bearing. The crank or rods may be too far gone to fix, if it needs the crank turned, rods resized and new bearings and gaskets, that may blow your whole budget to start with. Otherwise the 403 will respond well to a slightly larger cam and good exhaust, but lets address that after we know what is wrong in the bottom. By the way, the olds pattern th400 will bolt up to a Pontiac v8 so it's still a good deal.
Steve  

Thanks for the info. I will be taking the block to the machine shop and have them go through it to make sure we are working with a sound block. The RV cam that I currently have is not good? Or a bigger cam is just a possible suggestion to get more output of the Block?

I hope that is not a stupid question, just not trying to learn the heard way.  

It's a good question and one that requires a few other questions to answer. What gears and tire sizes are you running or planning to run? How do you intend to drive the car- highway trips or strictly around town cruising? What compression ratio is the engine(455 heads on a 403, not sure what chamber size and piston design you have), your machinist can help figure out the CR. For a strictly mild cruiser with highway friendly gears, I would stick with the RV cam, if you plan on deeper gears and more CR, you can go with more cam.
One other thing, for motor mounts I would think the frame brackets and block brackets from a 68-74 Olds Omega with a 350 olds should fit the bill, the subframes are virtually identical to the 67-69 Bird and Camaro, same goes for headers, rad hoses and accesory brackets. Let us know what you find when you tear down the motor, and answer the questions above and we can go from there.
Steve  

The 403 block was no good. Bad crank and metal inside.
I purchased a 400 bare block with a crank yesterday. and need to get all the goodies to go inside.  

All is not lost, you still have the 400 trans and you can sell the 455 Olds heads and the Edelbrock intake on E-bay to finance the 400 build-up. If you only got a block and crank, you will need lots of stuff to build a motor. My suggestion would be to try to find a cheap, complete 350 and use all the parts off it, you wouldn't believe how much easier that will be than trying to buy all the little stuff "one piece at at time", it was a cool Johnny Cash song, but no way to build a street machine!
Steve  

Crazybird, here's the answer to the PM you sent me. As I said above, find a cheap 350 (preferably a 75-77) for parts, you can use the connecting rods, balancer, timing cover, flex plate, valley pan, oilpan, valve covers, distributor, accesory brackets, push rods, rocker arms and if it's a 75-77, use the 5C or 6X heads. They will have the 2.11" intake valves, 1.66" exhausts, screw-in studs and guide plates. Maybe even the stock 4bbl intake manifold and carb if you don't get a 2bbl engine (the 2 and 4bbl engines are the same except the intake and carb in these years). Summit Racing sells a rebuild kit with forged pistons, moly rings, all bearings and gaskets, oil pump and freeze plug kit for $610. It is the way to go and is available in all piston oversizes and bearing undersizes. Add a cam/lifter and timing set and pay your machinist for the machine work and assembly (unless you can assemble it yourself) and you will have an honest 250hp (with good dual exaust) that will be reliable for years to come, runs on 87-89 octane gas and can be upgraded later if you want aluminum heads and intake. I know this might stretch the old budget a bit, but if you do the long block right the first time you won't regret it.
Steve