Frusturating 68 F100

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Jan 10, 2014 | 10:59 PM

#16

orich

Lead Driver

Joined: Aug 2003

Posts: 7,592

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From: **** hole San Jose ca.

Try hot wiring it by by passing the ign. switch If it's bad it will or should start up and run. Run a small jumper wire from to Batt hot +side too the plus side of the coil+.. ORICH

Jan 11, 2014 | 01:07 AM

#17

Aesop

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Joined: Nov 2005

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The piston sporting the dropped valve might have a hole in the piston and a bent valve head. How many pistons are dead? 1 is good and 2 is dead. What about the rest?.
verify cap rotation and check every plug wire for correct hookup
I would pull the head. then pour a little fuel down the intake and exhaust ports and examine how well each valve seals. It should be fuel tight. If there is slight wetness - then lap the valves. Any drips or streams and it needs a valve grind. sticky valves need guide work but you can get them unstuck with a rubber mallot. rotate the cam and ensure full lift at each valve position.

Look for a blown out head gasket, a likely culprit.

You can have stuck rings, broken rings, and just plain old worn out rings.

If the head checks good, clean up the pistons and rering and hone, cheap valve grind. get same size rod and main bearings.

Ford 300 1967-1983 Engine Master Kit | Northern Auto Parts $347

Jan 12, 2014 | 11:00 PM

#18

trozei

Postmaster

Joined: Nov 2012

Posts: 2,806

Likes: 8

From: Langley, BC

Quote:

Originally Posted by Gembone

The vacuum advance on my '70 300 i6 is pointing at the firewall.

Not that it's of much assistance, but mine's pointing towards the rear as well.

Jan 13, 2014 | 03:23 PM

#19

CougarJohn

Fleet Mechanic

Joined: May 2001

Posts: 1,396

Likes: 4

From: Cupertino

Methinks Orich is right. He often is.
Regardless of the shape of the pistons and valves a motor would not start and then die when the ignition comes off start.
Try what he says and report back.

Jan 13, 2014 | 03:53 PM

#20

orich

Lead Driver

Joined: Aug 2003

Posts: 7,592

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From: **** hole San Jose ca.

Also a bad condenser could keep it from starting up..orich

Jan 14, 2014 | 11:19 AM

#21

jgavac

Thread Starter

Cargo Master

Joined: Oct 2010

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From: Lost In a Pit of Despair

Finished the compression test today.

#1: 90 psi
#2: 0 psi
#3: 0 psi
#4: 80 psi
#5: 0 psi
#6: 0 psi

Jan 14, 2014 | 11:48 AM

#22

orich

Lead Driver

Joined: Aug 2003

Posts: 7,592

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From: **** hole San Jose ca.

Quote:

Originally Posted by jgavac

Finished the compression test today.

#1: 90 psi
#2: 0 psi
#3: 0 psi
#4: 80 psi
#5: 0 psi
#6: 0 psi

Not a good sign.
I've seen a few with I6 having cam lobe troubles. Also see a lot in the JY with the heads removed with burned out exh valves. could be a bad Head gasket possibly...
But what ever it is I'd pull it down and inspect it
orich

Jan 14, 2014 | 09:49 PM

#23

Ben-jamin

Tuned

Joined: Dec 2006

Posts: 291

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From: houston,tx

seeing that the cylinders that have zero compression it's most likely a head gasket that's blown between them. Whats odd is you have 2 pair that are like that, which leads me too believe the head gasket blew on one pair and they kept running it until the other two blew out. The problem with that is, depending on how long it was run that way it would erode the block at the sealing surface area of the blow-out. You could pull your plugs and then back off your lifters on the affected cylinders until loose then using a rubber tipped blow gun, inject air into a cylinder with no compression. If im right air will come out of the neighboring cylinder. If you pull the head,be sure to use a true flat edge to check the sealing surface on the block and a .0015 feeler gage for flatness.