What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Engine questions?

Deuling

Deuling

“I like to make things”
 Premium
GMOTM Winner
Joined
Dec 8, 2010
Posts
25,038
Reaction score
6,239
Location
Muskegon Michigan
So my old 305 block #4010207 has a piston bore of 4.03". We checked it in ever cylinder like 10 times with a known good set of calipers... Wtf??? A 305 has 3.736" pistons. These pistons say .30 on them. Wtf?
 
Last edited:
Your caliper is fubbared plain and simple. A 305 block can't even be bored anywhere near that far. Do you have a piston out of the engine? If you do there is a part number on the inside of the skirt and then you could look up what engine they fit.
 
Can a 350 or 400 even be bored that far? that is BBC territory. I know you have had CI envy for a while now but you need to get a handle on it and just buy a bbc. They really are cheap and even the peanut port head can run hard. SBCs are for circle track cars. If you want power in the sand you need something designed 10 years later.
 
i have a cheepy titan digital caliper. everytime i use it i have to pull the battery after i turn it on to reset it. or it reads .3" more than it should read every inch .
 
Deuling said:
So my old 305 block #4010207 has a piston bore of 4.3". We checked it in ever cylinder like 10 times with a known good set of calipers... Wtf??? A 305 has 3.736" pistons. These pistons say .30 on them. Wtf?
Click to expand...

i just did a quick search and that casting number you have does not exist. However, if you add a 1 in front of it it would be a 350, sometimes its hard to see the 1 in the beginning of the number. a 350 would start with a 4" bore and bored 30 would be 4.030" still not even close to where you are and it would not be able to be bored that far.

The only other thing i can think of is that if you are measuring with a caliper and not a dial bore gauge or hole gauge, is that you can only measure the upper lip and the cylinder might be worn at the top, still seems like a lot though...
 
Caliper works fine. We checked it with a gauge set. Its gotta be a .030 over 350. It had a couple spun bearings But damn if the top end doesnt look perty. Im not doing anything with it. My buddy might now though.
 
Is this a digital caliper, dial, or the old sleeve type?

Sure sounds like the sleeve type and you are reading it wrong. I agree that with the "30" in the piston and the readings, its a .030 bored 350.

Is the 30 stamped in the top of the piston?
 
The 305 does have a bore of 3.736 inches and a stroke of 3.48 inches. No way it could be 4.3"
:dunno:​
 
Oh haha its 4.030 lol. I forgot a zero. Sorry it was kinda late lol.
 
wage92 said:
yea haha there ya go, its a 350 bored .030 making it a 355.

Put a 400 crank in there and ya got a 383 ;)
Click to expand...

I know :D we are going to pick up an 81 k10 with an sm465 in it right now. My buddy ripped the motor apart with me last night and i told him he could have it. So he found a truck on cl thos morning lol.
 
Deuling said:
I know what you meant. The rust and body damage were just extras i thought you would like lol. Ill try to talk him into some hubcaps lol
Click to expand...

It will be perfect. Rust makes trucks faster and manuals are great.
 
Sounds like you gotta machine the crank or replace it anyway. Do a 383 in that case. Would be a fun build. Glad you figured out the right bore. 4.30. Not workin in any old small block I know of. Lol
 
You must log in or register to reply here.

Latest Posts

Top Bottom