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olds 403

6K views 17 replies 8 participants last post by  The Factory Man 
#1 · (Edited)
i am rebuilding an olds 403 and am looking to see what people think of my build. The engine is out of a 79 trans am. The block was bored 0.24 over. oil restrictors in main saddles. moroso high volume oil pump and deep oil pan. I have a forged olds 330 crank with stock 403 rods and kb pistons. Main bearing holes were elongated to line up better with the feed holes. The entire assembly balanced. I also have a 4 cap girdle with stud kit tying the main caps together. i might make a piece that will attach the girdle to the 5th cap making in stronger. The cam is a custom ground hydraulic roller from comp. intake .528 exhaust .547. duration intake 248 and exhaust 254. lsa is 110. behive stiff valve springs. Hydraulic roller lifters. On top i have 72 #7 olds 350 heads with arp stud kit. There not milled but im hoping to get around 10.5:1 compression. im using copper head gasket. They were hand ported and polished. Installed the biggest stainless steel valves i could. comp magnum roller rockers and oil restricted pushrods. edelbrock 7111 port matched intake and holley 750 dp with choke tower machined for improved airflow. headers and msd ignition. I also have a electric fan for it. Engine will be hooked up to 700-r4 from monster transmissions and 3.73 rear gears. Im hoping for 500+ hp. Do you think i will meet my goal?
 
#2 ·
dman0712 said:
i am rebuilding an olds 403 and am looking to see what people think of my build.
Sounds like a good solid build. I would be wary of the restrictors, however. Olds motors send oil to the lifter galleries first, then to the mains and finally to the cam bearings. These restrictors do virtually nothing to help keep oil out of the top end and frequently result in damaged cam bearings if the hole in the main bearing doesn't line up with the hole in the restrictor. The only effective restrictors for Olds motors are individual restrictors in each of the lifter oil feed holes.
 
#5 ·
my only worry is i have the 64cc chamber heads and kb 0.24 over pistons. my compression is going to be around 11:1. i have a good headgasket and a large enough cam to work with the compression but i just dont know if the bottom end will handle it?
 
#6 ·
crank

i have the stock 403 crank and forged olds 330 crank. i was going to have the crank knife edged to lighten it but im not sure which crank to do this too. the forged crank is far heavier but i worry about the mains even with my girdle and the 403 crank could be much lighter. I need some answers
 
#15 · (Edited)
DENCOUCH said:
Maybe he had the block resleeved, and then bored .24?
Do you really think that there is enough cast iron between the cylinders that would allow you to do that? It has been a while since I have seen an Olds 403 engine block so I am going from memory but I still don't think you could go that big on the over-bore. Maybe someone with current machine shop experience will comment.
 
#16 ·
The Factory Man said:
Do you really think that there is enough cast iron between the cylinders that would allow you to do that? It has been a while since I have seen an Olds 403 engine block so I am going from memory but I still don't think you could go that big on the over-bore. Maybe someone with current machine shop experience will comment.
Cut me some slack!

Nice of you to completely edit your post, but you forget that the email notifier sends your reply to this thread to me as soon as you post it.

Did you lose track of the fact that this guy had 9 replies to his post before I pointed out the error of his having an over-bore of .24?

I am attempting to keep this thread "lite" until he discovers his error, and I don't especially feel the need to drag his butt over the coals for it.
 
#17 · (Edited)
I see this type of error all the time on not only this forum, but every other one I visit as well. Maybe if we detail this problem a little, we can keep others from making it....
This is half a thousandth...0.0005"
This is one thousandth...0.001"
This is one and a half thousandths...0.0015"
This is two thousandths...0.002"
This is two and a half thousandths...0.0025"
This is thirty thousandths...as in "I bored the motor thirty thousandths"...0.030"...This is also thirty thousandths...0.03"
This is three hundred thousandths...as in "I bored the motor three hundred thousandths"...0.300"...or as in the case of this particular thread..."I bored the motor Two hundred and forty thousandths oversize...0.240"

While it is entirely possible to bore an aftermarket block two hundred and forty thousandths oversize, you would never get away with it in a factory production block. You'd run into the water jackets way before that. So, we're pretty sure the OP is saying that he bored the block twenty four thousandths...0.024"... :thumbup:
 
#18 ·
techinspector1 said:
I see this type of error all the time on not only this forum, but every other one I visit as well. Maybe if we detail this problem a little, we can keep others from making it....
This is one thousandth...0.001"
This is one and a half thousandths...0.0015"
This is two thousandths...0.002"
This is two and a half thousandths...0.0025"
This is thirty thousandths...as in "I bored the motor thirty thousandths"...0.030"
This is three hundred thousandths...as in "I bored the motor three hundred thousandths"...0.300"...or as in the case of this particular thread..."I bored the motor Two hundred and forty thousandths oversize...0.240"

While it is entirely possible to bore an aftermarket block two hundred and forty thousandths oversize, you would never get away with it in a factory production block. You'd run into the water jackets way before that. So, we're pretty sure the OP is saying that he bored the block twenty four thousandths...0.024"... :thumbup:
I agree and I hope others read this post so they will sound like they know what they are talking about!!!
0.0015 can also be read as fifteen ten thousandths.
0.0025 can also be read as twenty five ten thousandths. Now watch everyone get confused!!!
 
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