403 Olds build Mentor
December 12th, 2016, 07:15 AM
#1
Registered User
Thread Starter
Join Date: Nov 2016
Posts: 23
403 Olds build Mentor
Hey Guys, I am looking for someone who would like to mentor me through my first engine build. Someone who wouldn't mind me private messaging them stupid questions all the time. I am brand new at this so I am going to need help.
I am build a 403 on a limited budget, looking to bring up the HP but not looking to have a 400hp car. I have 330 #3 heads forthe build. Getting ready to order pistons but want to make sure I get the correct ones.
if interested private message me or comment below thanks guys.
I am build a 403 on a limited budget, looking to bring up the HP but not looking to have a 400hp car. I have 330 #3 heads forthe build. Getting ready to order pistons but want to make sure I get the correct ones.
if interested private message me or comment below thanks guys.
December 12th, 2016, 07:28 AM
#2
Registered User
Join Date: Sep 2011
Location: Plano, TX
Posts: 1,847
You can post in one of the other forums and just make it a running discussion. Or pick one of the builders (BTR, Mark, etc) and have them work with you. Or pick an existing combo from ROP.
400 hp on a 403 with decent heads is very easy. I'm at 450 hp with a Lunati 60803 cam. Idle is pretty lumpy in town, but runs great and goes anywhere.
403 piston choices are pretty limited. Stock replacement cast, which mean using an earlier head to get decent compression, or the KB flats and use a big block head. Once upon a time there were forged flat tops made and sets show up from time to time. I'm thinking there's one other option out there - a flat cast?
IMO the cam is the most important choice, but everything has to work together. It's a good idea to start a thread with your planned combo (car, rear gear, tire size, tranny, any engine parts you're set on using) and goals (daily driver, weekend cruiser, bracket racer, max effort, etc).
400 hp on a 403 with decent heads is very easy. I'm at 450 hp with a Lunati 60803 cam. Idle is pretty lumpy in town, but runs great and goes anywhere.
403 piston choices are pretty limited. Stock replacement cast, which mean using an earlier head to get decent compression, or the KB flats and use a big block head. Once upon a time there were forged flat tops made and sets show up from time to time. I'm thinking there's one other option out there - a flat cast?
IMO the cam is the most important choice, but everything has to work together. It's a good idea to start a thread with your planned combo (car, rear gear, tire size, tranny, any engine parts you're set on using) and goals (daily driver, weekend cruiser, bracket racer, max effort, etc).
December 12th, 2016, 10:01 AM
#5
Registered User
Join Date: Feb 2010
Location: Vancouver Island, Canada
Posts: 1,482
This!
There are plenty of us here who plan to embark on similar journeys and the ability to follow along on a build thread is part of what belonging to such a forum is about.
December 14th, 2016, 03:40 PM
#8
Registered User
Thread Starter
Join Date: Nov 2016
Posts: 23
No I have not taken it to a machine shop to be looked at. I know it needs to be maged and then bored if it is good. want to bore it .020 over because there is a scrape in ir from a broken ring. So I am looking to find some pistons for it.
December 14th, 2016, 04:48 PM
#9
Having a good machine shop to work with will yield great results. The biggest thing is pay attention to detail. Buy some micrometers , dial calipers , dial indicator with base stand, buy a degree wheel to degree the cam in, Buy a good torque wrench. Seems like alot to build an engine but having the right tools will not only give you piece of mind but will let you build with confidence. check your machines shop's work. Dont assume anything.
Picking a cam is a big deal but learning to pick a cam or why you are getting the came you are getting is knowledge. You also have to think of the overall combination not just the engine , gears , converter, weight of car suspension etc etc.
Im not trying to discourage you because i build all my own stuff and have been for as long as i have been doing this for a hobby. But a reallt wel thought out combination will shine. I see guys who build a nice engine and then cant get it to perform right because they didnt use the right converter or gears etc etc. IN the end its all about the details. A moderatly built 403 with a good converter and gear should pack a punch. I had a very mild 350 running high 13's in the quarter mile in my 72 and it was just a tick over stock.
good luck
Picking a cam is a big deal but learning to pick a cam or why you are getting the came you are getting is knowledge. You also have to think of the overall combination not just the engine , gears , converter, weight of car suspension etc etc.
Im not trying to discourage you because i build all my own stuff and have been for as long as i have been doing this for a hobby. But a reallt wel thought out combination will shine. I see guys who build a nice engine and then cant get it to perform right because they didnt use the right converter or gears etc etc. IN the end its all about the details. A moderatly built 403 with a good converter and gear should pack a punch. I had a very mild 350 running high 13's in the quarter mile in my 72 and it was just a tick over stock.
good luck
December 14th, 2016, 08:44 PM
#11
Registered User
Join Date: Sep 2011
Location: Plano, TX
Posts: 1,847
One's first engine build is always a wild ride. I started feeling confident around build #4. 
403's are tough because piston selection is quite limited, and the block has some significant weaknesses. Boring over 0.030" is strongly discouraged. The walls are thin and siamesed, so they tend to have cooling problems over 0.030".
IMO, cam choice is the single most important decision you can make. The entire combo (cam, intake, heads, carb, pistons, tranny, rear end, tires, and your goals) must work together, but a mistake with the cam is really hard to overcome, and it has a huge effect on how the engine runs and performs.
I like to browse the engine build forum on ROP and see if anything meets my goals and interests and go from there.
Having a quality machine shop is imperative. It is very hard to detect mistakes made by the machinist without specialty equipment and a fair bit of knowledge. I've had many parts trashed because I blindly trusted shops (valves seized, line hone gone way too deep into the block, broken pistons, rods resized too right, freeze plus blown out .....).
Finding someone local willing to work through the assembly with you is also a huge help. Some things can be very subtle and just take a lot of experience to look for (e.g., how to figure out what went wrong with thrust clearances and how to fix it). And silly things, like getting the stupid oil galley plugs right, or installing the rods in the right orientation, can be surprising with an Olds.
403's are tough because piston selection is quite limited, and the block has some significant weaknesses. Boring over 0.030" is strongly discouraged. The walls are thin and siamesed, so they tend to have cooling problems over 0.030".
IMO, cam choice is the single most important decision you can make. The entire combo (cam, intake, heads, carb, pistons, tranny, rear end, tires, and your goals) must work together, but a mistake with the cam is really hard to overcome, and it has a huge effect on how the engine runs and performs.
I like to browse the engine build forum on ROP and see if anything meets my goals and interests and go from there.
Having a quality machine shop is imperative. It is very hard to detect mistakes made by the machinist without specialty equipment and a fair bit of knowledge. I've had many parts trashed because I blindly trusted shops (valves seized, line hone gone way too deep into the block, broken pistons, rods resized too right, freeze plus blown out .....).
Finding someone local willing to work through the assembly with you is also a huge help. Some things can be very subtle and just take a lot of experience to look for (e.g., how to figure out what went wrong with thrust clearances and how to fix it). And silly things, like getting the stupid oil galley plugs right, or installing the rods in the right orientation, can be surprising with an Olds.
December 15th, 2016, 08:39 AM
#12
Registered User
Join Date: Jun 2013
Location: Macon, GA
Posts: 17
Arias has piston for the 403, here is the link.
https://ariaspistons.com/search?q=oldsmobile+pistons
https://ariaspistons.com/search?q=oldsmobile+pistons
December 15th, 2016, 09:36 AM
#13
Registered User
Join Date: Sep 2013
Posts: 3,574
One's first engine build is always a wild ride. I started feeling confident around build #4.
403's are tough because piston selection is quite limited, and the block has some significant weaknesses. Boring over 0.030" is strongly discouraged. The walls are thin and siamesed, so they tend to have cooling problems over 0.030".
IMO, cam choice is the single most important decision you can make. The entire combo (cam, intake, heads, carb, pistons, tranny, rear end, tires, and your goals) must work together, but a mistake with the cam is really hard to overcome, and it has a huge effect on how the engine runs and performs.
I like to browse the engine build forum on ROP and see if anything meets my goals and interests and go from there.
Having a quality machine shop is imperative. It is very hard to detect mistakes made by the machinist without specialty equipment and a fair bit of knowledge. I've had many parts trashed because I blindly trusted shops (valves seized, line hone gone way too deep into the block, broken pistons, rods resized too right, freeze plus blown out .....).
Finding someone local willing to work through the assembly with you is also a huge help. Some things can be very subtle and just take a lot of experience to look for (e.g., how to figure out what went wrong with thrust clearances and how to fix it). And silly things, like getting the stupid oil galley plugs right, or installing the rods in the right orientation, can be surprising with an Olds.
403's are tough because piston selection is quite limited, and the block has some significant weaknesses. Boring over 0.030" is strongly discouraged. The walls are thin and siamesed, so they tend to have cooling problems over 0.030".
IMO, cam choice is the single most important decision you can make. The entire combo (cam, intake, heads, carb, pistons, tranny, rear end, tires, and your goals) must work together, but a mistake with the cam is really hard to overcome, and it has a huge effect on how the engine runs and performs.
I like to browse the engine build forum on ROP and see if anything meets my goals and interests and go from there.
Having a quality machine shop is imperative. It is very hard to detect mistakes made by the machinist without specialty equipment and a fair bit of knowledge. I've had many parts trashed because I blindly trusted shops (valves seized, line hone gone way too deep into the block, broken pistons, rods resized too right, freeze plus blown out .....).
Finding someone local willing to work through the assembly with you is also a huge help. Some things can be very subtle and just take a lot of experience to look for (e.g., how to figure out what went wrong with thrust clearances and how to fix it). And silly things, like getting the stupid oil galley plugs right, or installing the rods in the right orientation, can be surprising with an Olds.
Thread
Thread Starter
Forum
Replies
Last Post
88hurstolds
Parts For Sale
4
January 20th, 2020 11:39 AM
