I've a few questions to ask the 335 series engine guru's (this is for a 1978 f150 4x4 w/ NP435, 4.56 geared axles and 33" tires [36" tires somewhere in the future]). I plan to convert this truck to a pre-runner type [fast speeds over bumpy terrain]. currently 3,000-3,400 rpms at 65-75 mph and running on 87 octane.

I've a 5-year old ford 400 rebuild (~30,000 miles) with mtf2 cam, silvolite 1160-040 pistons, edelbrock 2171 manifold, edelbrock 1406 carb, stock manifolds, dual exhaust. All work was done by a machine shop and installed by my mechanic (I lived in an apartment...so no auto work for me).

Three weeks ago, there was some moderate pinging on an uphill road (during a rainstorm) and when I parked in the driveway, I noticed that the idle had dropped really low and vacuum was ~11-12" (normal is 15-16"...I live at 5,000 ft). From what I remember, the engine functioned near normal at off-idle rpms.

I couldn't find any vacuum leaks (although my mechanic used teflon tape on an AN fitting from the vacuum gauge to rear carb port) , so I tested compression (cylinder - initial reading - final reading after 5 revolutions):

1 - 85 - 115
2 - 65 - 120
3 - 90 - 120
4 - 85 - 130
5 - 85 - 105
6 - 75 - 110
7 - 85 - 115
8 - 85 - 120

I put everything back together to see if anything had changed. My vacuum gauge was registering an intermittent drop at idle (which was extremely low, the exhaust smelled semi-rich and sounded really different than normal...usually thump-thump-thump type...now almost like it's spitting) <-- (the sounds are what I remember from last week, so it may not be completely accurate).

First I took the intake off (I could turn some of the bolts by hand), then the valley pan

This weekend I removed the heads to see if I'd punched a hole in a piston.

First was the drivers side head and block ...

then the passenger side head and block ...

I've never opened an engine before, so if you see something weird/abnormal, please tell me.

Is it normal to have this much carbon buildup on a young rebuild (there was an Edelbrock Vara-jection installed, which I thought would alleviate most of the carbon buildup)? This engine is required to pass the smog gas test, so it is jetted lean (Edelbrock 1406 settings - 75x47 rod, orange spring, 95 primary and 92? secondary). This setting allows me to pass with 295 HC and 1.47 CO (idle) and 113 HC and 2.49 CO (2500 rpm)

This engine had 80 psi cold and 30psi hot (40 psi on a good day...not quite so hot). I can still see some cross-hatching where the pistons are recessed in the block.

If eveything looks okay, I was going to rebuild the heads and install a comp xe256 or xe262 setup (cam/lifter/springs/timing/etc.)

Or should I get a set of CHI heads from TMI?

Or a full rebuild from TMI?

Or???

I need an engine that won't leave me stranded in the middle of nevada.

Thanks,

Chris

 

Just talk to Tim and get a set of heads from him. That may help even out those compression numbers.

You may also just have an ignition problem. A misfire will make your exhaust smell rich. A marginal ignition will also build carbon deposits.