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Discussion Starter · #1 · (Edited)
403 olds versus 350 target master rebuild

i was just told this is not a big block so sorry about the title guys. i have a 403 olds motor that has been prevously bored .30 over by the person that had it before me. it came out of a 85 olds cutlas, the origional origin of the motor is unknown. the whole engine appears to be in good condition, except the crank. it has grooves spun into it. i will have to replace it. the rest was in good shape when i put it back together to keep rust out. the 350 runs but has some problems and will need to be over hauled if not rebuild. it will be in a 79 trans am. my question is, by each of your own experiences or oppinions which motor will be better for the time money and power that will come from the motor rebuild for my car. i have a th 350 tranny for the 350 and it is allready in the car. i will have to get a tranny for the big block. it has the stock gm 10 bolt posi rear end and the car orrigionally came with a 403 to start with. any help or comments are appriciated.
 

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Old(s) Fart
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dustin.campbell3 said:
i have a 403 big block olds motor
No, you don't. The 403 uses the same short deck height and crank as every other SMALL BLOCK Olds motor. The big block Olds motors have a taller deck to accommodate the longer stroke of those motors. If you buy an aftermarket intake for your 403, it will be a small block Olds intake.

i have a th 350 tranny for the 350 and it is allready in the car. i will have to get a tranny for the big block. it has the stock gm 10 bolt posi rear end and the car orrigionally came with a 403 to start with. any help or comments are appriciated.
Sorry, but I'm still not clear. Is the the trans currently in the car a Chevy bolt pattern, a BOP bolt pattern, or a unisex case?
 

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Discussion Starter · #3 ·
(Sorry, but I'm still not clear. Is the the trans currently in the car a Chevy bolt pattern, a BOP bolt pattern, or a unisex case?)

the tranny is currently in the trans am. it is a gm 350 turbo. i only has one set of bolt boles and bolts to the 350 motor. works and runs fine.
 

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You would need a different trans then, if you went with the chevy.
But, for the cost difference, you might be better off with the chevy, as far as performance parts go at least.
I've always had a fondness for oldsmobiles though, so I'd recommend keeping that, as long as the main journals are still good, and only the crank needs replacing.
Olds can make plenty of power, and don't have that belly button factor.
 

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Old(s) Fart
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dustin.campbell3 said:
the tranny is currently in the trans am. it is a gm 350 turbo. i only has one set of bolt boles and bolts to the 350 motor. works and runs fine.
GM made three different TH350 cases and four different 350 motors with two different bolt patterns on the back of the block. Is it a Chevy 350, Olds 350, Buick 350, or Pontiac 350?
 

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Discussion Starter · #6 ·
"403 olds versus 350 target master rebuild "

it is target master is a gm motor. it came out of a 77 chevy truck that had a swap to a crate target master. so im gonna guess its a chevy, im not too educated on targetmaster.
 

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dustin.campbell3 said:
which motor will be better for the time money and power that will come from the motor rebuild for my car.
That you are open to using the 403 in the first place is good, shows that you are willing to see the possibilities in something that's not wearing a bowtie.

That said, by your own criteria of "time money and power", I would also opt for the SBC engine/TH350 combo. But hang on to the 403- as you grow more knowledgeable in the sport, you may want to do something w/that 403 before you're done. ;)
 

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Old(s) Fart
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dustin.campbell3 said:
personally i dont think the 403 is worthless cause it is the origional motor for the ta but i dont know which one would be better for the money and power
I was being more than a little sarcastic, given the prevalent attitude that Chevy motors are so much less expensive to build than other GM brands. Seriously, I'm always looking for 403s for sale.
 

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Discussion Starter · #12 ·
i got the 403 through a trade about a year ago. i traded an old beat up 89 chevy truck for a 308 rifle and the 403 motor, there was no tranny for it cause he wanted to keep it for the car he had. the guy that had it before me had the crank ground down after the first rebuild and didnt blow out the journals and the crank ended up gettin grooves in the main bearings and now it is to far gone to have reground so im gonna have to get a new one.
 

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i love the 403 olds engines they run really strong in the lower rpm and pull hard i miss the one i had in my 77 electra low miles

it was a runner

also the 425 in the 79 deville limo i had as well

good engines


rare now here

finally got to see anopther 403 recently running really good in a 79 t/a out here we had for a bit



rest are all demo derbied gone

the 40s was in the late 70s trans ams, electras, and such


top of the tran case on the chevy and dual pattern cases are pointed up

BOP and caddy only are curved downwards at the top of the case

where the bolt pattern is

dual pattern multifit cases are 10 bolt housings

i have a TH350-C this way right now frm an '81 c-10 pickup with 350 olds diesel

original

it fits all 90 degree pattern engines from gm including the little v-6 such as the 200 chevy
3.8 229 chevy
3.8 231 buick
and the 4.3 chevy

also the old 1960s gmc v-6 truck engines like the 305 and 351 and 478 etc.
 

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Grumpy Old Goat Herder
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Since we're talking about an engine to go in a TA, why not think about a stroker 400 (stronger than a 455). Same bell housing bolt pattern as an Olds, and the starters are interchangable. I know that Pontiac came out with an Olds powered TA, (corprate politics) but I think a Pontiac should have a Pontiac engine, an Olds should have an Olds, and a Chevy should have a Chevy.

 

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target master 350's use really poor flowing heads.

if you are keeping the stock highway gears and stock converter then use the bigger engine.

if you can stroke it to a 455, even better!!

8 to 8.5:1 cr, 400 to 455 cid, mild cam (205 to 212 degrees at 0.050"), used with a stock converter and highway gears (low numeric gears) makes a good running car
 

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403 olds

just two cent--be like every other teenage girl on the strret with a 350.. or take the 403 and make the beast it is--seriously there are some great pontiac sites specing the 403 ... it can easily be a kick *** motor--bore and stroke on that "lil" sm block is insane--just cant handle high rpms for extended times--siamese cylinders--but if your not hitting 7000 or 1000hp wont matter

 

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talon73ta said:
Is the photo of your motor? Very nice.

I'm curious as to why you kept the 4A heads instead of going to a big block Olds head like a C or E. Chamber size should be about the same, ports and valves are bigger. I assume you've got flattops to get the CR up to something reasonable.
 

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403

aaa sorry joe not my engine,, had the owner listed on the pic but i didnt send it right...was trying to motivate the lad into building the 403 :) ..

now I have a 73 ta clone on a 79 ta frame--1/2 way done and we still have the 403 in the bay..now we went with 72 olds 350 heads-to raise compression. orig i think it was 8:1 now were 10:1 with the heads mill 0.030,, and a 0.040 head gasket.. we drilled the heads for additional cooling--4 additional holes since the 350 heads dont have em..

lol now we did this before i even thought about big block heads-which i would think it would be a fun way to go-we got a mock SD 455 build which is taking some time-and a 68 gto 400 which we have ready to drop today if need be--just not positive which way i want to go..

now the 4a heads--i can only assume its because they have the same size cc as a bb olds--so why change em. :D

 
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