2.5 inch stroke

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Mar 4, 2023 | 04:48 PM

CarterDawson

Thread Starter

5th Wheeling

Joined: Jan 2023

Posts: 33

Likes: 2

2.5 inch stroke

I’ve tried this 2 times in a row. Where you put the straw down the spark hole and you measure the stroke. I’ve gotten 2.5 inches in a row. The valve cover says it’s a 360, but the guy that owned it was positive it was a 390. He said it’s a hopped up one. Used to be a mud truck that would do wheelies. It’s sat for about 15 years. But this doesn’t make sense. It seems to be very very high compression. I can hardly roll it over when I get it to 180°.

Mar 5, 2023 | 07:52 AM

lee

Laughing Gas

Joined: Jul 1999

Posts: 1,047

Likes: 22

From: Lacey, WA

Hi,
First off, please confirm that you can rotate the crank a full 360*.

Concerning the high compression,... remove all spark plugs when rotating to measure the stroke.

Mar 5, 2023 | 09:36 AM

GPatrick

Tuned

Joined: May 2015

Posts: 413

Likes: 52

Which two cylinders are you checking? Compare #1 at TDC to #4 which should be at BDC. 1 and 4 are the front and rear cylinders on the passenger side in case you are used to numbering from a different manufacturer.

Mar 5, 2023 | 11:20 AM

cbrown9064

Fleet Mechanic

Joined: Feb 2007

Posts: 1,252

Likes: 113

From: Mandan, ND

Could be a 352 also...

This is common. 352/360 truck often magically become a 390 when posted for sale...

Mar 5, 2023 | 12:08 PM

CarterDawson

Thread Starter

5th Wheeling

Joined: Jan 2023

Posts: 33

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Yes. With all plugs pulled it still is impossible to roll over. I’ve come the the conclusion that the cylinder walls are rusted. Im gonna put some mystery oil in it and let it sit for some time. The back right spark plug is seized in its hole. Just soaking it in kroil.

Mar 5, 2023 | 02:39 PM

85e150

Super Moderator

Joined: Apr 2004

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After 15 years of sitting after being a "gently used" mud truck the engine should be torn down. Otherwise a clacking oil burner is in your future.

Mar 6, 2023 | 12:33 AM

CarterDawson

Thread Starter

5th Wheeling

Joined: Jan 2023

Posts: 33

Likes: 2

Quote:

Originally Posted by 85e150

After 15 years of sitting after being a "gently used" mud truck the engine should be torn down. Otherwise a clacking oil burner is in your future.

Yes. If I get it to run and if it’s a 390 inch am gonna rebuild it and have it bored out. It was locked up, but I got it freed up. Tomorrow I’m going to measure the stroke again and see if I can’t see if it’s a 360 or 390.