I was only able to make one pass at 11.12 / 118. It was a good pass for the first of the day. No issues. During shut down I heard the tick of an header gasket leak. By the time I left the track and made it 3/4 the way back to the lanes, I had major exhuast leak sounding noise, the motor was running rough and stalled on me. The attempt to re-fire was met with bucking but it did fire so we brought the trailer around and loaded up. The trip home was full of speculation on what broke.

Got home early enough to take a quick look and found a 1/8 hole in the header gasket on no 3. This fit for the tick i heard. Still curious I pulled the plugs and all look great.... Ok now i can get some sleep. This am I ran a cold cranking compression test the results were

Cyl 1 190 2 192 3 198 4 180

Cyl 5 182 6 183 7 180 8 180

Note: low tension rings, gas ported pistons

And here is the issue

When cranking the motor over with the plugs out, all sounds are normal. As soon as I install the compression tester on no 3 ( the one that had the highest cranking compression), I hear air chuffing out some place. The chuffing is NOT in sync with the compression pulses i can feel in the guage hose. Its a second later.

All signs say head gasket issue, but why is the chuffing later than the cylinder pulses and the no 3 compression higher? Cross cylinder compession exchange would be a possible thought but all the plugs are out. Any idess ??

Bob

06 Dodge Ram CTD
72 "Mach 1" V Drive 390
69 Mustang SCJ 10.86 121.83 1.494 60 ft.
65 Comet 428
53 Willy's P/U 390
32 Ford P/U
30 Ford Bantam project 427 Sohc

the carb(s) throttle plates wired wide open?

Is so, wonder if you have a leakdown test gauge to check each cylinder with air pressure? Does sound like a head gasket issue but that should have appeared even with a simple compression tester and your results don't necessarily show that. Also, I wonder about an intake gasket leak but then again, it doesn't sound like it. One could tape/seal off the all intake ports, remove the rokcers and apply vacuum (Mighty-Vac pump?) to a home-made plate blocking the carb intake pads.

i Know they should be open for this test, but i was looking for some major loss of compression on one or more more cylinders. I dont have a leakdown tester, but I can pressurize each cylinder, as i have done in car valve springs changes this way in the past. I think thats what i will try before starting dis-assembly.

Bob

06 Dodge Ram CTD
72 "Mach 1" V Drive 390
69 Mustang SCJ 10.86 121.83 1.494 60 ft.
65 Comet 428
53 Willy's P/U 390
32 Ford P/U
30 Ford Bantam project 427 Sohc

Could it be the intake valve opening early and bleeding off compresion?

Throw a leakdown gauge on it, or even just air to the cylinders with all the plugs out, you'll hear it coming out of another plug, the carb, or the tailpipe if something is leaking down


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- 70 Fastback Mustang, 489 cid FE, TKO-600 5 speed, 3.70 9 inch
- 71 F100 shortbed 4x4, 397 cid FE, headers, Street Dominator, 280H, 5 lug Dana 60, 4 speed

I had an old 352 with a couple exhaust lifters rusted in the down position and it behaved like this - hi compression vs the other cylinders, but it was dropping these couple cylinders. The exhaust couldnt get OUT fast enough so it was causing a miss due to poor mixture.

Just a guess!?

Solid roller on the lifters. Bent valve might not seal or even hang open, Compression is good, so i dont thats the case.

Since the manifold is coming off, i have a couple different intakes im considering trying. If i do decide to change to 1 of these, would you gonk my combo with the different inductions for me?

Bob

06 Dodge Ram CTD
72 "Mach 1" V Drive 390
69 Mustang SCJ 10.86 121.83 1.494 60 ft.
65 Comet 428
53 Willy's P/U 390
32 Ford P/U
30 Ford Bantam project 427 Sohc

of course, a bent valve wouldn't do what you are seeing, a collapsed lifter or bent pushrod might, but if solids there goes that theory. Sounds like your theory of a leak from one cyl to another is onto something.

Sure, happy to Gonk possible combos, since gas will be under $3.00 soon (party on!) we might just drive up to Sears Pt / Infineon and see how the real et's then compare when it's done!

I didnt have the right fitting to pressurize the E bock plug thread size.. but i did try something else. By quick bumping of the motor until the first sign of needle movement on the compression tester in no 3 hole, and with my thumb over no 4 plug hole, i found that 4 has its valves closed and is also building pressure. Im thinking now, that shortly therafter one of no 4's valves opens and the compression bleeds off allowing no 3's pressure to jet thru to 4 thru a gasket break between the two., giving me the chuffing sound that im hearing. I'll try to find a fitting to pressurize no 3 tommorow to confirm.




Bob

06 Dodge Ram CTD
72 "Mach 1" V Drive 390
69 Mustang SCJ 10.86 121.83 1.494 60 ft.
65 Comet 428
53 Willy's P/U 390
32 Ford P/U
30 Ford Bantam project 427 Sohc