Fixing over compression on a 2FE (Camshaft analysis?) (1 Viewer)

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Should be a 6mm bolt 10mm in length, with captive lock and flat washers - Part Number 91651-40610.
Mine is a 10mm if I recall. But I have a 2f manual from the early 80’s and many of the bolts are smaller in the book than they are on my truck, which is an 87.
 
So with higher temps I still get that metallic clattering, I retarded the dizzy timing a bit more and installed new spark plugs which helped a little, After about 100 miles on the plugs I did a compression test and this is what I found.

1) 185Psi
2) 175Psi
3) 176Psi
4) 165Psi
5) 175Psi
6) 180Psi

Starting with cylinder #1 on the left and #6 on the right
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I think whats going on is I have leaking fuel injectors and its causing cylinders 3 & 4 to run rich and its what may be causing the clattering at high temps.. I dont think my engine would throw a code as the o2 sensors are not hooked up properly, they are installed in series in front of each-other so the engine is reading an average AFM across all 6 cylinders. I ordered a set of cheapo injectors to test my theory.
 
Welp. I keep thinking I solve the issue and it always comes back.

Compression test as of recent reads
185
175
176
165
175
180

FSM says max PSI is 149. The machine shop cut a bit too much off as I have ~24% more pressure than the maximum the manual says is okay.... Isn't that fun. Pinging is turning into slight thudding.
The one time I let anyone else touch anything on my cruiser and they mess it up.

Cant find any head shims in the states but im not sure how much damage is done. Honestly this rebuild is probably toast and only after 15k miles. The valve rocker arm adjustments are so low I almost have no space to back off the valve clearance. Should of paid more attention to it back when I could make an argument to the shop. The high compression has to be it there's nothing left to check.

My vacuum readings are high, Throttle is responsive, idle is smooth, starts in the cold, new O2 sensors, desmogged, new exhaust, adjusted valves while engine was hot, new air filter, checked air intake for leaks 20x, new vacuum lines, ignition timing is so far retarded I cant see the BB in the viewport window, new spark plugs, professionally cleaned fuel injectors, new fuel pump, good fuel pressure, new fuel filter, no CEL codes but a speed sensor circuit?
 
Looking online nobody shares Head gasket thickness's... I would like to try and save the engine with a thicker gasket or shim but its a matter of finding one. Or making one? I might make one if push comes to shove.

Toyota says Thickness is 1.4mm

I measured a felpro Head-gasket here i had spare and it came out at 1.7mm but that's uncompressed.

Please share any leads if you have any on head gasket thickness's or shims
 
Compression test as of recent reads
185
175
176
165
175
180

FSM says max PSI is 149

Compression test gauges are notoriously not reliable. (Aka inaccurate). I wouldn’t put much credence on those numbers until they’re verified with a high quality compression gauge.
Maybe those high numbers are correct- but you’ve got to verify against another gauge before considering drastic measures.

While the manual states a pressure range up to 149 psi - thats probably to fall in spec using regular octane fuel. If you use premium fuel, the compression can be higher.

I’d just drive it carefully using premium fuel and listen carefully. I don’t think a double head gasket or a thicker one is the answer (my guess not based on experience).
 
Compression test gauges are notoriously not reliable. (Aka inaccurate). I wouldn’t put much credence on those numbers until they’re verified with a high quality compression gauge.
Maybe those high numbers are correct- but you’ve got to verify against another gauge before considering drastic measures.

While the manual states a pressure range up to 149 psi - thats probably to fall in spec using regular octane fuel. If you use premium fuel, the compression can be higher.

I’d just drive it carefully using premium fuel and listen carefully. I don’t think a double head gasket or a thicker one is the answer (my guess not based on experience).
91 octane with octane booster does nothing ive tried it and it still pings. Ive seen online some people get shims the place under the head gasket. I could calulate how much thickness I would need and have one laser cut?
 
91 octane with octane booster does nothing ive tried it and it still pings. Ive seen online some people get shims the place under the head gasket. I could calulate how much thickness I would need and have one laser cut?
Try it. At this point what’s to lose?
 
So, Im unsure of the volume from the cylinder head itself.

Assuming Cylinder Diameter is constant at 3.7" and stroke height is 4" with an initial max pressure of 149psi we can calculate the volume of cylinder #1 at full compression to be 0.289"^3 using Boyles law.

So given my current max PSI is 185, I can compute my actual volume at full compression to be 0.232"^3.

So To offset the pressure from 185psi down to 149, I would need a 0.0562" or 1.43mm thick spacer. Thats just rough math, Im going to dive in and see what metals are avaliable then draft a spacer to be laser cut out of mild steel maybe? Not sure yet.
 
The head gasket has raised metal lips around every opening to act as seals. If a cloned thin metal sheet is placed between the gasket and block or head, the contact surface of thin metal and engine block/head won’t have anything to seal with. Just a flat piece of metal.
It SEEMS like that would be prone to a leak.
 
The head gasket has raised metal lips around every opening to act as seals. If a cloned thin metal sheet is placed between the gasket and block or head, the contact surface of thin metal and engine block/head won’t have anything to seal with. Just a flat piece of metal.
It SEEMS like that would be prone to a leak.
Yeah I was thinking the same thing..... Online looks like some do a gasket - shim - gasket. But then that would be too thick. Im not sure I could source a material as thin as I would need. It would be neat If I could find shorter pistons. I could always maybe throw a 3f crankshaft in it but thats alot of work I want to avoid
 
Another labor intensive job, but an option is to reshape the combustion chamber a bit (adding back volume). It seems like the 3FE could use some deshrouding (I don't know if that's the correct term) around the valves anyways.
 
Stock cam? Longer duration / later intake closure will reduce dynamic compression.
 
Stock cam? Longer duration / later intake closure will reduce dynamic compression.
2f Timing, The 3fe is same cam profile but its a few degrees different
Another labor intensive job, but an option is to reshape the combustion chamber a bit (adding back volume). It seems like the 3FE could use some de-shrouding (I don't know if that's the correct term) around the valves anyways.
I havent heard of that before, I'm going to look into it
 
Stock cam? Longer duration / later intake closure will reduce dynamic compression.
If im thinking correctly, Just throwing on the 3FE CAM gear should help reduce the dynamic compression with its 5* advance. What cam setup did you use?

I just picked up a 2nd daily car so my options on what I can do to my FJ60 just expanded greatly. Im about to hit the nuclear reset on this truck and rebuild another 2F block that hasent been shaved down too much, but if a CAM could help Id be much more willing to try that first. Its recently started knocking the worst it ever has after I put in some Kroger gas...
 
I run a Delta Camshaft regrind with 262° duration. The longer duration (and specifically the later closure of the intake valve, reducing the bore length swept with the valve closed) reduces compression pressure relative to a stock grind camshaft. Advancing your existing camshaft would increase compression.

I'll grab a few pics from a book that has a good explanation.
 

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