Head gasket..

Discuss fixes, upgrades and modifications to your M37

Moderators: Cal_Gary, T. Highway, Monkey Man, robi

longshot2171
PVT
PVT
Posts: 38
Joined: Sat Oct 20, 2007 6:34 pm
Location: Ballston Lake, NY
Contact:

Re: Head gasket..

Post by longshot2171 »

For now I put the old one back. Tested it 190 degree water and it opened up nice and wide.
The Napa ones are standard thermostats that fit way up in the neck and a "cup" that is supposed to fill the rest of the opening to allow water to flow through the bypass elbow before the thermostat temperature is reached. It didn't want to seat properly, and I didn't know if it needed to be pressed in. I will hold on to it for now.
jjw
Marmalute
PFC
PFC
Posts: 78
Joined: Sun May 01, 2016 11:45 am
Location: Northern Vermont

Re: Head gasket..

Post by Marmalute »

Longshot-
How much did you have milled off of the head?
Let us know what the new compression numbers turn out to be if at all different.
Where did you get the new coolant distribution tube?
Good luck with it, let us know how it turns out.
Doug
longshot2171
PVT
PVT
Posts: 38
Joined: Sat Oct 20, 2007 6:34 pm
Location: Ballston Lake, NY
Contact:

Re: Head gasket..

Post by longshot2171 »

It lives......will test drive tomorrow. I found an old flathead enthusiast who whipped out an old book with machining limits. It gave a maximum total machining limit of 70 thousands on a dodge 230 with 6.7 compression ratio to raise it to 7.5 c.r. The new felpro head gasket was 10 thousands thicker than the copper one removed. I went conservative with 60 thousands removed...so in theory with the extra 10 on the gasket, I ended up at -50 thousands total (est approximately 7.25 c.r.) I did test fit the head with a coil of solder on top of the valves and hand rotated the engine to check valve clearance.
Has anyone else ever experienced a grounding or lack thereof with the pertronix unit in the distributor? When I tried to first start, there was no fire. I pulled plug 1,grounded it and cranked the engine and found no spark. I had pulled the distributor while waiting for parts to replace the long disintegrated cork gasket. I disassembled the distributor and as per pertronix tested the unit. It seems fine but the truck does not like it at all...figured what the heck..dropped the points plate back in, set gap, dropped it back in the truck . With just a blip of choke, it fired right up. No leaks, no steam..retourqed head bolts/studs. Set timing back to 4deg. Btdc. Idle seems higher and smooth, restarts quick
Will post tomorrow after drive.
jjw
longshot2171
PVT
PVT
Posts: 38
Joined: Sat Oct 20, 2007 6:34 pm
Location: Ballston Lake, NY
Contact:

Re: Head gasket..

Post by longshot2171 »

Drove around today. Truck ran great...good pickup, no leaks-steam or smoke,steady temp,no stumble or hesitation. Seems to prefer the timing at about 2 degree btdc. Let it sit to try restarts after various lengths of time and restarts quick with just a little throttle. I did not attempt to put the pertronix back in at this time. The points are new and since it is running so well at the moment, I want to develop a performance baseline before I start changing parts.
Needless to say, very happy.
Thanks to all for knowledge and help.
jjw
ashyers
MSGT
MSGT
Posts: 820
Joined: Mon Jan 05, 2015 8:20 pm
Location: Oakland CA

Re: Head gasket..

Post by ashyers »

Now that you have a few heat cycles in it I'd suggest checking the head bolt's torque.

We used a NOS copper/asbestos gasket due to the Plymouth head on our motor and it was surprising how much the bolts turned after a few heat cycles! The old style gaskets compress around .060" on install and must relax a bit too. Not sure about the newer designs.

Andy
longshot2171
PVT
PVT
Posts: 38
Joined: Sat Oct 20, 2007 6:34 pm
Location: Ballston Lake, NY
Contact:

Re: Head gasket..

Post by longshot2171 »

I have checked them....bolts we're good but the studs I used to replace the bolts that also mounted accessories were a tad loose. I took the torque wrench with me on the drive.
jjw
NAM VET
1SG
1SG
Posts: 1118
Joined: Mon Aug 22, 2016 6:27 am

Re: Head gasket..

Post by NAM VET »

with milling your head, did you re-do the valve tappet clearance? Hot? Cold?

nv
longshot2171
PVT
PVT
Posts: 38
Joined: Sat Oct 20, 2007 6:34 pm
Location: Ballston Lake, NY
Contact:

Re: Head gasket..

Post by longshot2171 »

Used manual 9-1840a and set them @ .015 with the engine warmed. Pita....was very careful to not break off the v/c screws..they were stuck good. Valves are a little sloppy sounding cold but truck runs/ idles good.
jjw
Marmalute
PFC
PFC
Posts: 78
Joined: Sun May 01, 2016 11:45 am
Location: Northern Vermont

Re: Head gasket..

Post by Marmalute »

So now with a freshly milled head and adjusted valves, what kind of warm engine compression numbers do you get? I have been considering doing something similar to one of my motors, but my experience has shown me that all too often "tightening up" the upper end of a motor tends to accelerate the wear potential of the rings. That said, I have seen that more commonly in overhead valve engines where valve work is done when head gets milled.
With a compression ratio of 7.25:1 I'd expect low acceptable compression to be 108psi.
Thanks for the information and the update.
Doug
longshot2171
PVT
PVT
Posts: 38
Joined: Sat Oct 20, 2007 6:34 pm
Location: Ballston Lake, NY
Contact:

Re: Head gasket..

Post by longshot2171 »

Have not done a compression test since reassembly. Raining today...
Other than checking head bolts/studs, i don't want to play around with it too much or make additional adjustments until I get to run it a bit for reliability.
jjw
Post Reply