questions on 85 model

[Mudd Hawg]

I just got an 85 silverado, picked it up for a grand, not bad shape, but needs some attention, question is the 305 was the stock motor, but was told that this truck has a 350, is there anyway to tell them apart, and what rearend was stock, thought they came with 10 bolts, but this one has a12 bolt.

[454ss]

It should have the displacement stamped into the block near the oil filter.

[Domeskilla]

Some have 10's some have 12's. My 79 original 454 truck has a 12 bolt rear.

[Mudd Hawg]

Originally posted by 454ss
It should have the displacement stamped into the block near the oil filter.

Any idea where abouts? I found some smaller no.s above the filter, but couldn't see displacement no.s

[tonypirate]

well if you can see the code that is located on the passenger side of the block deck just below the head and just above the water pump ,there should be 3-4 numbers and 2-3letters .I have a book that translates the codes so if you find them I will look it up for ya..

[Mudd Hawg]

Thanks, I will try to look for them. I was told it was a 350, but this truck came with a 305, and I didn't get to talk to the guy that owned it before, so I am kinda leary what is in it.

[Captkaos]

12bolts were discontinued in 1982 from the factory. Same goes for the 350 in 1/2T's (until 1987). If it has one in it, it was converted.

[Mudd Hawg]

Originally posted by Captkaos
12bolts were discontinued in 1982 from the factory. Same goes for the 350 in 1/2T's (until 1987). If it has one in it, it was converted.

That's what I thought on the rear, the motor I know was swapped, emissions sticker read 305, but I was told this truck has a 350, the previous owner did some kinda shady work, that is why I question it, but it doesn't matter, I am putting in a different motor anyway.

[JB]

Its no biggie that it doesnt have the 305, hell would you put another 305 in it or a 350?

Mine has a GM crate 350 but the sticker says 305....at least it did till I removed it

[ayev8r]

305's are alright for decent power numbers and good fuel mileage. I'm building one to replace my v6 now. It's a factory roller motor from a 90 Caprice.

There are no visual differences to tell 305 from 350, but if you can see the back of the block just above the tran mounting ears...you can see 5.0 or 5.7 on 86 and later blocks. This would be on the driver side. As for pre 86 blocks you need to know casting numbers. Some of the 350 blocks have 350 stamped on them just behind the motor mounts..but are difficult to read installed. A 400 is easily identifiable by (usually) having only 2 welch plugs(aka. freeze plugs) installed. Hope this helps.

[HEAVY_HAULER]

not trying to cause problems but, the 400 came with 3 freeze plugs as well as two, it depends on the number of bolts in the mains, the 4 bolt main 400 had 3 freeze plugs and the 2 bolt motors had 2 freeze plugs, or maybe the other way around (can't remember which).

if you find the casting numbers on the rear bellhousing of the motor you can look them up on

www.mortec.com

[Dixie]

Originally posted by ayev8r
305's are alright for decent power numbers and good fuel mileage. I'm building one to replace my v6 now. It's a factory roller motor from a 90 Caprice.

I agree. I was talking to a guy the other day and he called my 305 a boat anchor. But his 350 was a Hoss. Now look at the 2 from the same year of truck. What is the difference in the 2 other than bore? They are the same stroke. Is it the heads? If so call the heads a dog. There are pleanty of 350 heads(smog) that suck. To be quite honest I wish I had left the 305 heads on. I would have had better torque lower. Anyway, explain what makes the 305 a dog.
gp

[Mudd Hawg]

Okay,
Next weekend motor is gone, I am putting in the motor from my 78, 350 4 bolt main bored 30 over with edelbrock hyperkynetic pistons, and a 272 comp cam, pete jackson gear drive with a holley contender manifold, and a edelbrock 600 electric choke carb. Carb will probably change, just isn't big enough to feed the motor, but it's all I got for now. Hmm, now for suspension mods.

[ayev8r]

Ya'll right, there was a 2 and 3 freeze plug set up. Also the 305 has smaller bore and smaller head chambers..that is why it's not recommended to use 305 heads on a 350. It shrouds the valves and seriously raises the comp ratio.

[ayev8r]

It's better than a 4.3 being mistaked for a 305. I bought my chevy from a game warden that thought it had a 305 and it turned out to be a 4.3. I was able to kill him on the price after that.

[Dixie]

Now that's sad. He can count your limit but not plug wires... gp