Tweet
Was told that the 360 in my J20 was rebuilt by a "speed shop" about 10 years ago. Possible work done was different cam, bored, milled heads, etc... Just started trying to get it running and want to drive it around town a little to see what issues it has. Don't want to tear motor down to figure out what was done to it. Any suggestions on figuring out some of these numbers?
-
Johnny
78 J20 360, TH400 new project
77 CJ5 Straight 6, T-18, 10/14 Bolt, 4.88's, 38's, spring over, stretched rear, fiberglass body, cage
09 JKU Mall crawler
15 JKU Wife's -
No. -
Welp, it would be very hard without digging into it.
You could figure out some of your cam specs with a dial indicator but it would be a pain. the only way to determine if its bored is to pull the head or oil pan and measured. The only way I know of to check if the head is milled is to pull the head.Chuck McTruck 71 J4000
(Chuck McTruck Build Thread)
(8.1L swap questions - PerformanceTrucks.net Forums)
79 Cherokee Chief (SOLD, goodbye old buddy)
(Cherokee Build Thread)
11 Nissan Pathfinder Silver Edition 4x4
09 Mazdaspeed3 Grand Touring
00 Baby CherokeeComment
-
Getting a reading of cranking compression would be easy. I suppose one could pour water through the plug hole with a pipette to measure combustion chamber volume as well. Not sure if the plug hole is at the highest point.
I guess the question is - Does the motor does what you want?Last edited by Mikel; 10-03-2019, 02:12 PM.1969 M715 6x6
1963 J300 Swivel frameComment
-
The water in the plug hole will not work, water will leak down past the rings and you will have air pockets in the chamber. Need to tear it down to find out what is really in there or just don't worry about it till it needs a rebuild.Comment
-
Thanks for the replies, I guess it doesn't matter what was done to it as long as it runs good. Probably still check compression just to make sure it's somewhat healthy.Johnny
78 J20 360, TH400 new project
77 CJ5 Straight 6, T-18, 10/14 Bolt, 4.88's, 38's, spring over, stretched rear, fiberglass body, cage
09 JKU Mall crawler
15 JKU Wife'sComment
-
GREAT idea! Also, add a mechanical oil pressure gauge. Those 2 stats (oil pressure and compression) should give you a good idea of engine condition. The oil pressure gauge on your dash will give you ballpark but that's about it. My mechanical and dash gauge are 8 PSI different. I assume the truth to be the lower of the 2.Originally posted by SgtjoyceChuck McTruck 71 J4000
(Chuck McTruck Build Thread)
(8.1L swap questions - PerformanceTrucks.net Forums)
79 Cherokee Chief (SOLD, goodbye old buddy)
(Cherokee Build Thread)
11 Nissan Pathfinder Silver Edition 4x4
09 Mazdaspeed3 Grand Touring
00 Baby CherokeeComment
-
YMMV but I was able to determine overbore using el cheapo USB camera thru spark plug holes.
Was able to see/decipher part number(s)/size on top of pistons from pics.Tony
88 GW, 67 J3000, 07 Magnum SRT8Comment
Comment