Thicker head gaskets?

[MOPAR MITCH]

MrBill426 -- The 8553PT head gasket will work fine... as long as you don't encounter detonation/pre-ignition... then the simple folded over tin-plate cylinder armor becomes the weak-link to combat the combustion.   At 9.5:1 you should be OK... but I'd recommend to only run premium fuel ~92-93.      Most hi-performance engines encounter some detonation/pre-ignition in their life-time.    The 1008 is a superior option as its designed with a stainless steel cylinder armor that wraps around an internal wire-ring to seal the combustion... similar to diesel head gasket designs (having ~16-22:1 CR and higher).

[Mrbill426]

@MOPAR MITCH I have a line on the #1008 so I can switch to those.  A question though, which gaskets are more forgiving of "irregularities" to the mating surfaces?  My heads were milled bu the block deck was not; the shop found it to be straight.


Also... what are the minimum safe clearances for piston to valve or piston to head... anyone??

MrBill426 -- The 8553PT head gasket will work fine... as long as you don't encounter detonation/pre-ignition... then the simple folded over tin-plate cylinder armor becomes the weak-link to combat the combustion.   At 9.5:1 you should be OK... but I'd recommend to only run premium fuel ~92-93.      Most hi-performance engines encounter some detonation/pre-ignition in their life-time.    The 1008 is a superior option as its designed with a stainless steel cylinder armor that wraps around an internal wire-ring to seal the combustion... similar to diesel head gasket designs (having ~16-22:1 CR and higher).

[ek3]

my minimums =  piston to valve .080 intake 100 on exhaust .. piston to head i always used .039 " on small bores .  rpms @ 7k or less on  steel rods w/steel heads . i have been .035" [pth] racing but the piston better be fit well in the block as pistons rock..... 

[Mrbill426]

@ek3 thanks for your input.   I may go with the thinner stainless gasket, if it a better seal for any slight imperfections to the block surface.

my minimums =  piston to valve .080 intake 100 on exhaust .. piston to head i always used .039 " on small bores .  rpms @ 7k or less on  steel rods w/steel heads . i have been .035" [pth] racing but the piston better be fit well in the block as pistons rock.....

[MOPAR MITCH]

MrBill426 -- With regards to your concern about surface irregularities, both gaskets (8553 and 1008) have the same thickness fiber facing.. the difference is in the steel core.   IF your surfaces are out-of-flat (combined head and block to be no more than .003~.004 total), then you may have issues regardless whose ever gasket you'd use.  Also, the surface finish should be relatively smooth without roughness, pits, corrosion, or grooves.... your machine shop should judge that.   The Fel-Pro blue-colored coating provides a micro-seal into small crevices (for fluids), as well as it being an ant-stick release agent if/whenever the gasket needs to be removed.

[Mrbill426]

@MOPAR MITCH thanks... so both of those gaskets have that same coating?  Reading up on them the 1008 sounds like it seals better around the bores; is that right?  Would either one work better with a sealant like copper coat or is that a no no?

MrBill426 -- With regards to your concern about surface irregularities, both gaskets (8553 and 1008) have the same thickness fiber facing.. the difference is in the steel core.   IF your surfaces are out-of-flat (combined head and block to be no more than .003~.004 total), then you may have issues regardless whose ever gasket you'd use.  Also, the surface finish should be relatively smooth without roughness, pits, corrosion, or grooves.... your machine shop should judge that.   The Fel-Pro blue-colored coating provides a micro-seal into small crevices (for fluids), as well as it being an ant-stick release agent if/whenever the gasket needs to be removed.

[MOPAR MITCH]

Simple rule-of-thumb:  fiber-faced gaskets require no sealer;  metal faced gaskets should use a supplementary sealer. 

I wrote all the installation instructions for Fel-Pro's aftermarket gaskets... many years ago (80s--early 2000s)... and was head of the Tech Line.

[Mrbill426]

@MOPAR MITCH ok no sealer, and I suppose at double the cost per gasket the 1008 must seal a LOT better.
Kind of confusing though that when I look up gaskets for my 340 application at Fel Pro it is not listed  ; and even more confusing when I search the part number and check applications it says "Marine" then lists 2 & 3 cylinder PWCs.. what??   

https://drivcat.com/overlays/part-detail.aspx?brandId=FL&pNum=1008&partType=Engine%20Cylinder%20Head%20Gasket

Simple rule-of-thumb:  fiber-faced gaskets require no sealer;  metal faced gaskets should use a supplementary sealer. 

I wrote all the installation instructions for Fel-Pro's aftermarket gaskets... many years ago (80s--early 2000s)... and was head of the Tech Line.

[MOPAR MITCH]

The primary advantage of the Fel-Pro Performance line of head gaskets is for more durable combustion sealing.   These were tested in NASCAR and others when they were introduced many years ago.... the 1008 can replace the 8553... but the sales person has to be aware of that.... and your intended usage.

More info...  The Fel-Pro Performance head gaskets (found and listed in their own catalog) has a thin silicone-type anti-stick coating... helps micro-seal the surface finishes for fluid sealing a little better.   The passenger car type head gaskets from Fel-Pro typically have a Teflon coating for ant-stick and micro sealing (the coating on the FP Performance is more expensive and a slightly better).

[Mrbill426]

I took some more "clay" measurements using check springs on #1 and it's going to be close to the minimums with .039" thick gaskets.   I may do it again with a dial indicator on the valve retainer while at TDC, push the valve down till it hits the piston and subtract the max lift from that reading.  That "should" tell be the clearance too right?  Or am I missing something?

[ek3]

I took some more "clay" measurements using check springs on #1 and it's going to be close to the minimums with .039" thick gaskets.   I may do it again with a dial indicator on the valve retainer while at TDC, push the valve down till it hits the piston and subtract the max lift from that reading.  That "should" tell be the clearance too right?  Or am I missing something?  [tdc wont do it]

Piston to valve clearance needs to be checked by rotation of the engine. the overlap period is when valves are closest... you can stack feeler gauges between the rocker arm  and valve and roll it over to see if its contacting anywhere. if you do , i would use .100" for each valve as a stacked amount.  you should be very good with a mild cam.  piston to head = piston height, deck height, head type, piston dome type. .039" at the closest point will be fine.  looking at photos , i would say use the .039" gasket without any issues......  looks like you are plenty good everywhere to me. 

[Chryco Psycho]

 
The closest point between the valve & piston is usually NOT at TDC
You could also test this with clay or putty .