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Engine CID ID

B

BlaKK54Speed

1/2 ton status
Joined
Dec 14, 2006
Posts
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Location
Omaha, NE
how can i tell if i have a 350 or a 305? owner told me it was a 350 but im not so sure. vin says its a 305. looks awful original. where can i find an engine id tag or what can i see for differences???? any help is greatly appreciated.

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I found the numbers on the front...right behind the alternator there is a machined pad where the head and block meet. I wire brushed that part and looked up the numbers on Mortec.

Rene
 
the numbers on mortec are on the rear of the block, between the head and the bellhousing. should be on the drivers side of the engine.

just judging by the exhaust manifolds, and the fact that the VIN says its a 305, it probably is.
 
so yea.....cant get to the numbers on the block, i can feel them with my fingers and just barely start to see the last numbers but there is a wire loom right over them, plus oil and grease and there is a retainer about an inch away so i cant move the wire loom to even see them. man i am so mad right now. how hard can it really be to id the damn thing
 
Prolly faster to pull the oilpan off...305 has a 3.75" bore versus the 350's 4" bore.

Rene
 
Perfect excuse. My VIN also said 305 when i ran it, and i had the same trouble you did getting the numbers. I pulled the pan because I was doing a rear main seal and found 4 bolt mains, check the bore and it was just proud of 4"...

When i finally did get the numbers off the block it just comfirmed what i already knew, 4 bolt main 350.

Rene
 
The one and only 305 I ever had, was external balance. The harmonic balancer had offset weiight cast into it. Real easy to see on the back of the balancer.:confused:
 
3 on the tree said:
The one and only 305 I ever had, was external balance. The harmonic balancer had offset weiight cast into it. Real easy to see on the back of the balancer.:confused:
Click to expand...

no 305 has ever been external balanced, they're all neutral balanced. save for the 87+ 1 pc RMS versions, which have a counterbalanced flywheel/flexplate (due to the lack of material to remove for balancing in the RMS area) , and a neutral balanced dampner.
 
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beater_k20 said:
no 305 has ever been external balanced, they're all neutral balanced. save for the 87+ 1 pc RMS versions, which have a counterbalanced flywheel/flexplate (due to the lack of material to remove for balancing in the RMS area) , and a neutral balanced dampner.
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X2 305's or 350's aren't externally balanced. Only the 400 had the "notched" balancer.
 
tRustyK5 said:
I found the numbers on the front...right behind the alternator there is a machined pad where the head and block meet. I wire brushed that part and looked up the numbers on Mortec.

Rene
Click to expand...

Do this. Surefire, as long as the block has never been decked. They are called "suffix codes". This can be accomplished (apparently) on all engines when installed, but it may be more difficult depending on equipment in the way.
 
JpEater said:
X2 305's or 350's aren't externally balanced. Only the 400 had the "notched" balancer.
Click to expand...
Well, I know the motor was a 305. I tried to use the balancer off my 70 350,so all the accessory pulleys would line up. It shook like a bastard! I pulled it all back apart, and compared balancers. The 350 unit was flat on the backside, and the 305 was channeled, except for one area that looked like a big square. The 305 came out of a 78 Impala, BTW. It was NOT fun changing over all the brackets and pulleys.:(
 
78 Impala... could've very well been a 400, since they were produced from '70-'80. that would have an externally balanced balancer and flywheel. :thinking:
 
beater_k20 said:
78 Impala... could've very well been a 400, since they were produced from '70-'80. that would have an externally balanced balancer and flywheel. :thinking:
Click to expand...
The reason I said I KNOW it was a 305, is cause I had to replace head gaskets 1 year after I installed it.:confused:
 
i already looked behind the alternator, there arent any plates or stampings anywhere on the head or block there. i looked hard too
 
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