Team Camaro Tech banner

1 - 9 of 9 Posts

·
Registered
Joined
·
440 Posts
Discussion Starter #1
Hey guys, how do you measure an assembled engine sitting on an engine stand to determine its true displacement? I would like to play with one to see if I can measure it accurately. I'm assuming you can remove the oil pan and take measurements from the bottom but not sure how to measure or where (specifically on the crank for the stroke)?
 

·
Registered
Joined
·
5,073 Posts
Can you get a bore scope through a spark plug hole and get a number off the top of a piston? Gonna be tough to measure everything from the bottom. The flange on the rear of the crank may give a clue to it's stroke as long as it hasn't been offset ground. Of course, if you are going to pull the pan, you should be able to get a number off the crank.
 

·
Registered
Joined
·
10,515 Posts
It would be easy if you were willing to remove a cyl head - measure bore diameter with a caliper and stroke with a dial indicator on the top of a piston. Would be difficult to do from the bottom, esp bore diameter, without removing a piston/rod. Stroke could possibly be measured with a dial indicator at the wrist pin boss or the bottom of a piston skirt.
 

·
Registered
Joined
·
4,826 Posts
It sounds like you are about to buy a "pig in a poke" if all you know about the engine is that it is a Chevy V8. What has been said is an indication of the engine series, but your actual displacement is the measured swept volume times the number of cylinders: which doesn't occur until the intake valve actually closes, so you need to degree the cam as well if you want to know the actual displaced volume.

Checking casting numbers on the crank or looking at the back of the crank to identify the crank configuration applies only to a SBC that has a Chevy crank installed. Just keep in mind that Chevy never made a 383 which is a bored and stroked 350 block. The block casting number as well as the number of freeze plugs cast in the side can tell you if you are dealing with a small block Chevy V8 casting with a 3.736" bore block, 3.875" bore block, a 4.000" bore block or a 4.125" bore block.

Casting Flange for a 283 ...


compared to a 327 casting flange


If you have a round rear crank then it is either a 305 or a 350 block (or possibly a 262 but no one ever rebuilds those engines so it couldn't be sitting on an engine stand) with a one piece rear main seal. Note the casting flange for a 350.



Big Dave
 

·
Registered
Joined
·
54 Posts
It sounds like you are about to buy a "pig in a poke" if all you know about the engine is that it is a Chevy V8. What has been said is an indication of the engine series, but your actual displacement is the measured swept volume times the number of cylinders: which doesn't occur until the intake valve actually closes, so you need to degree the cam as well if you want to know the actual displaced volume.



Checking casting numbers on the crank or looking at the back of the crank to identify the crank configuration applies only to a SBC that has a Chevy crank installed. Just keep in mind that Chevy never made a 383 which is a bored and stroked 350 block. The block casting number as well as the number of freeze plugs cast in the side can tell you if you are dealing with a small block Chevy V8 casting with a 3.736" bore block, 3.875" bore block, a 4.000" bore block or a 4.125" bore block.



Casting Flange for a 283 ...





compared to a 327 casting flange





If you have a round rear crank then it is either a 305 or a 350 block (or possibly a 262 but no one ever rebuilds those engines so it couldn't be sitting on an engine stand) with a one piece rear main seal. Note the casting flange for a 350.







Big Dave

Good info.
 

·
Registered
Joined
·
1,470 Posts
I would pull one cylinder head to get the bore size.

You could check the stroke by inserting a stiff wire (coat hanger) gently down through a spark plug hole. 3.5" = 350 or 305 , 3.25 = 327, 3.75 = 400 crank

But if you are buying an engine, definitely pull one head
 

·
Moderator
Joined
·
14,011 Posts
Rotate the engine on the stand until spark plug hole is at 12 o'clock.

Rotate the crank until piston is at BTC

Fill cylinder trough spark plug hole with oil

Rotate crank to TDC and measure the amount of oil that comes out of the plug hole

X8 give you displacement.:thumbsup:
 

·
Registered
Joined
·
13,337 Posts
As above.. pour careful.. no air trapped...
And a broken spark plug.. centre electrode removed with a tube on the end to control the oil coming up into a measuring cylinder...
Down side...as previous posts allude to, different cranks/ stroke, different bores, over size can confuse the numbers.
Bottom line pull a head as suggested...
Pulling a head(s) not only allows measurements...but also checks wear, scuffing, possible cracked skirts, head chamber size/ condition, valve recession etc.

and if the guy selling objects to pulling a head..... walk away if the engine is intended to be rebuilt etc
If for just a elcheapo runner... well in that case volume , bores etc dont really matter... its a elcheapo disposable runner
 

·
Registered
Joined
·
440 Posts
Discussion Starter #9
Hey guys, thanks for all the info. I was actually able to take some measurements and saw some stampings and have determined that the engine is a 427. I did forget to add that this is an LSX as well. According to the crank it has markings that read 4-LS1-4000-61. When I look that number up it's Scat with a 4 inch stroke. For the bore I cut a metal strip and placed into the center part of the bore (not the most accurate I'm sure but I knew it would put me in the ballpark). Using dial calipers it measured 4.125 so this calculates to 427.

Now, here is why I'm extremely pissed about this. I purchased an LSX 454... or so I thought. I know my measurements on the bore aren't the most scientific but the measurements are pretty damn close. I know this block was a 427 before and the engine builder told me he would have it bored out and have the proper crank installed for a 454. I'm trying to get a hold of the builder now and see what he has to say about this. He did tell me the engine has .030 quench when I first got it, would that change the displacement at all? I'm hoping I missed something here or I did something wrong. I may have to pull a head to see for sure. But the thing of it is for a 454 you need a 4.125 stroke and a 4.185 bore. Even if I'm off on my bore measurement the crank is still .125 short at only 4 inches. So either way I'm definitely not at 454 cubic inches.
 
1 - 9 of 9 Posts
Top