Rebuilt 400

todd66442 · April 21st, 2009, 08:01 PM

I went to turn over my 400 rebuild by hand and it will freely turn 180 degrees and then stops. I was wondering what the problem could be. What am I not seeing? What is stopping it from going 360 degrees (full turn) ? Any one?
I have the spark plugs out, the timing cover is on, fuel pump was in and then I took it out to see if that was the culprit but it still stops at 180. Please advise.
Thanks, Todd

cts-v · April 21st, 2009, 08:15 PM

Does it have flat top pistons, decked block, machined heads or anything else that could affect Piston to valve clearance? I hope that's not it....

Coltonis · April 21st, 2009, 08:58 PM

Obviously, its that mouse that ran into the intake manifold when you weren't looking

(lol, this was not a productive comment. I apologize.)

dan2286 · April 21st, 2009, 09:48 PM

It could be many things. You can start taking components off of the engine one by one and check the rotation after you take something off. Start with the easy stuff like oil pan(if its on), timing cover, dist.(if its on), oil pump. Then if none of those things free it up, take off the rockers one by one and see if it will rotate. I would think the next thing would be the cam and timing chain, if its not them remove the heads. Then move on to the pistons, checking the rotation after each one. The last thing would be to take off the main bearing caps one by one. Hopefully you dont need to take the whole engine apart, but this is the only way to find out whats stopping it if you cant see anything physically hitting.

To prevent that from happening again, it is a good idea to see if the engine rotates as you are installing components. That way if you find a problem, you wont have to take apart the whole engine to find it.

todd66442 · April 22nd, 2009, 07:00 PM

Thanks all, I did not build it so I went to the machine shop and asked them, they were no help. If I don't find it doing the first few procedures you mentioned above, I'm taking it back to them. They did a 65 400 for me a few years back and all was good ,so I don't know whats going on here.

Thanks, Todd

todd66442 · April 22nd, 2009, 07:03 PM

Quote:

Originally Posted by cts-v

Does it have flat top pistons, decked block, machined heads or anything else that could affect Piston to valve clearance? I hope that's not it....

No, as I told him to build to original specs. Except for the usual hardened seats...etc.

Thanks, T

April 21st, 2009, 08:01 PM	#1 (permalink)
todd66442 Registered User Join Date: May 2008 Posts: 51	Rebuilt 400 I went to turn over my 400 rebuild by hand and it will freely turn 180 degrees and then stops. I was wondering what the problem could be. What am I not seeing? What is stopping it from going 360 degrees (full turn) ? Any one? I have the spark plugs out, the timing cover is on, fuel pump was in and then I took it out to see if that was the culprit but it still stops at 180. Please advise. Thanks, Todd

April 21st, 2009, 08:15 PM	#2 (permalink)
cts-v Registered User Join Date: Dec 2008 Location: Central IL Posts: 57	Does it have flat top pistons, decked block, machined heads or anything else that could affect Piston to valve clearance? I hope that's not it.... __________________ 1970 Cutlass Supreme

April 21st, 2009, 08:58 PM	#3 (permalink)
Coltonis Registered User Join Date: Nov 2007 Location: Scottsdale, AZ Posts: 99	Obviously, its that mouse that ran into the intake manifold when you weren't looking (lol, this was not a productive comment. I apologize.) __________________ -Coltonis "Arizona: its not hell ...but you can see it from here." My Project Thread

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April 21st, 2009, 09:48 PM	#4 (permalink)
dan2286 Registered User Join Date: Mar 2008 Location: North Ridgeville, Ohio Posts: 338	It could be many things. You can start taking components off of the engine one by one and check the rotation after you take something off. Start with the easy stuff like oil pan(if its on), timing cover, dist.(if its on), oil pump. Then if none of those things free it up, take off the rockers one by one and see if it will rotate. I would think the next thing would be the cam and timing chain, if its not them remove the heads. Then move on to the pistons, checking the rotation after each one. The last thing would be to take off the main bearing caps one by one. Hopefully you dont need to take the whole engine apart, but this is the only way to find out whats stopping it if you cant see anything physically hitting. To prevent that from happening again, it is a good idea to see if the engine rotates as you are installing components. That way if you find a problem, you wont have to take apart the whole engine to find it.

April 22nd, 2009, 07:00 PM	#5 (permalink)
todd66442 Registered User Join Date: May 2008 Posts: 51	Thanks all, I did not build it so I went to the machine shop and asked them, they were no help. If I don't find it doing the first few procedures you mentioned above, I'm taking it back to them. They did a 65 400 for me a few years back and all was good ,so I don't know whats going on here. Thanks, Todd