Rebuild time on the 230 flat head engine

[Kaegi]

I have shaved as much as .075 off the head. always check valve lift and make sure it will clear first if doing this. the machine shop specs say you can shave I think its up to .110 off a virgin head. i put in larger than stock cams so checking lift is a must for me. getting compression up to 8:1 or more is totally worth it. the stock compression ratio is for 1930s 70 octane. raising it up just makes engine utilize todays gas.

[outpostm37]

I have shaved as much as .075 off the head. always check valve lift and make sure it will clear first if doing this. the machine shop specs say you can shave I think its up to .110 off a virgin head. i put in larger than stock cams so checking lift is a must for me. getting compression up to 8:1 or more is totally worth it. the stock compression ratio is for 1930s 70 octane. raising it up just makes engine utilize todays gas.

Kaigi, When you say larger than stock cams, do you have any available specs? same lift, more duration? purchased from? cost?
What was your cranking compression psi with the 8:1. What was the final valve to cylinder head clearance after the .075" head milling?

[Kaegi]

I have shaved as much as .075 off the head. always check valve lift and make sure it will clear first if doing this. the machine shop specs say you can shave I think its up to .110 off a virgin head. i put in larger than stock cams so checking lift is a must for me. getting compression up to 8:1 or more is totally worth it. the stock compression ratio is for 1930s 70 octane. raising it up just makes engine utilize todays gas.

Kaigi, When you say larger than stock cams, do you have any available specs? same lift, more duration? purchased from? cost?
What was your cranking compression psi with the 8:1. What was the final valve to cylinder head clearance after the .075" head milling?

I have Delta cam shafts regrind my cams in Tacoma WA. They can grind it however you want. i have been having them grind cams for me since the 80s. 7000 rpm v8s included. none have ever failed. They do excellent work. I dont have the specs from the grinds I have used. One was called the torque grind and the other an HP grind. after running both in WC 3/4 tons for combined miles on the two truck of at least 150,000 miles I would go with the HP grind. The 230 has so much low rpm torque already that I could skid logs and yank blazers and toyotas out with ease with the HP grind.
I cant remember the compression but I think with the .060 bore and the shaved head it was around 150 psi?? but its been many years. There is math to calculate it. cam and shaved head really wakes them up nicely.
if I recall I think I left at least .065 clearance between head and valve. I did the measuring without the head gasket so it was actually more.

Cost is less than 100 bucks for just the cam. But, I send them my lifters as well and they redress them. if you get new lifters no need for that. I think the total with lifter work is around 150

[ashyers]

outpostm37,
Here's a thread you may find useful:

http://www.g741.org/PHPBB/viewtopic.php?f=3&t=7489

As far as CR, we used a 218 Plymouth head, it has a much smaller chamber than the "M37" head. It required milling .050" to get it to a reasonable compression ratio. Unfortunately I have no way of knowing for sure if the block was decked or head milled prior to us messing with it so it's hard to help you with accurate dimensions. We went with NOS pistons to get max compression as opposed to the Sealed Power, Silv-o-lite, or Egge pistons available. All have less compression height. FYI: The stock chamber of a stock M37 head is in excess of 100cc.

I do have a spreadsheet I made that you can plug in the dimensions of all the bits to get you in the ball park, I just have to find it . Assuming I can do that I can send it your way, or you can do the math yourself. I'd suggest a spreadsheet, then you can play with the #'s and see what works best with your constraints. I wanted to "0" deck the block for better quench, but the machine shop was none to keen on that due to the hardened valve seats. We settled on cutting the head. I picked up 2-3mpg and around 20ft-lbs of torque across the rev range. The max hp did not change radically due to the governor. The truck has a stock cam and is governed to 3000rpm. With 36.5" tires and 4:89 gears we cruise at 55mph and max at ~62mph. I drive the truck ~3000mi per year, highway travel included.

I'll look for that spreadsheet...

Andy

[outpostm37]

Installed the pistons/rods in the block today. At top dead center, the pistons are .025" down in the holes. The rod bearing clearance to journal is .002"

[outpostm37]

Here is a view of the bottom as piston/rod #6 is installed. Notice the additional metal for Crankshaft balancing (circled in blue)

[outpostm37]

Installed the new manifold studs with lots of #2 Permatex. Test fit manifolds on the studs.

[ashyers]

Looks like a fair amount of material was removed from the deck of your block compared to our engine (~.030"). NOS pistons were .035" down in the hole on ours. I found my spreadsheet, each .01" shaved from the deck works out to ~.1 point of CR increase. The head's more difficult to predict due to the funky shape involved.

[outpostm37]

Looks like a fair amount of material was removed from the deck of your block compared to our engine (~.030"). NOS pistons were .035" down in the hole on ours. I found my spreadsheet, each .01" shaved from the deck works out to ~.1 point of CR increase. The head's more difficult to predict due to the funky shape involved.

The machine shop that milled the 230 deck said that they had never seen a block that was out in the lateral direction, not front to back. The center of the block was "humped" and sloped down on each side.
What I am hearing is that even if factory pistons are used, they will sit in the holes .010"-.015"
I cc'd the cylinder head and found the average is ~95cc's. Maybe my engine will be slightly over 7.0 compression ratio, slightly better than the 6.6? ratio of the original build.

[rickf]

I am looking at that picture of the piston in the hole and I keep getting drawn to the heavy horizontal scratches in the block on the top section when at the same time I see fine circular milling marks at the bottom of the cylinder. What is the story there? These use a metal head gasket don't they? Those deep scratches are not a good match for a steel head gasket. Use a good layer of spray copper.

[outpostm37]

The Felpro head gasket that came in my kit, is copper on the top facing the head, and blue paper facing the deck. I will use the copper spray gasket on both side of the gasket prior to assembly. The block does have some rough areas around the water jackets. The number 5 cylinder had some pitting between the valves and the bore.

[rickf]

Do NOT use the copper spray on the blue side of the head gasket!!! The copper spray is only for metal to metal gaskets. The gasket you have sounds like a hybrid gasket and already has a sealer built into the material on the block side. I would contact Fel-Pro to find out what if any sealer should be used on the block side.

[just me]

No sealer on the blue side!

[outpostm37]

Do NOT use the copper spray on the blue side of the head gasket!!! The copper spray is only for metal to metal gaskets. The gasket you have sounds like a hybrid gasket and already has a sealer built into the material on the block side. I would contact Fel-Pro to find out what if any sealer should be used on the block side.

Thanks! I contacted Fel-Pro and you are correct. No copper spray on the paper side, a retorque is needed after one heat cycle.

[outpostm37]

These showed up today.