what modifications does the xj have at this point? lift, oversize tires?

we used to have a work van that was geared too low. at 65 mph the 440 v8 would spin over 4500 rpm. the muffler looked like a third brake light underneath. think it was running lean also but ? the manifold (glowing bright orange) melted a hole in the dog house (engine cover inside cab). was realy hot on passenger's leg. by the way- cardboard does not make a good insulator when it catches fire inside the cab!

 

Specs.

i'M BORED OVER .30, MADE MY OWN INDUCTION "SOUNDS LIKE A WIND TUNNEL" ,POWER AID SPACER, 8.5 MSD WIRES, MSD COIL, HOLLOW CAT, 6 INCH LIFT, 33'S, "TECHS OUT FINE GOING DOWN THE HIGHWAY" AND RUNNING TRIPLE PLATINUM PLUGS . wORKING ON PRESSURE TESTING EACH CYLINDER AND CANT GET PRESSURE TO HOLD. I HAVE YET TO FIND WHERE ITS GOING. THANX

 

Kinda grasping at straws here. is your O2 sensor after the cat? If by hollow you mean no catalyst it's possible that your O2 sensor is causing the engine to run lean or something like that. hopfully somebody with more expertice will chime in.

 

Glowing

O2 SENSOR IS IN THE DOWN PIPE RIGHT AFTER THE MANIFOLD. I HAD IT IN THE SHOP AND MECH. SAID THAT "EVERYTHING" IS WORKING RIGHT,SENSOR(S) THAT IS, o2 SENSOR IS OPENING AND CLOSING THE WAY IT SHOULD. I HAVENT FOUND YET ,BUT IM WONDERING IF THE AUTO PARTS STORE GAVE ME A CAM FOR A 4.2 INSTEAD OF 4.0, DONT REALLY KNOW IF THEIR INTERCHANGABLE, OR MAYBE THE CAM I HAVE IS BADLY MACHINED. GETTING CLOSER TO A SMALL BLOCK 350 EVERYDAY :laugh:

 

Re exhaust glowing

If you tried to do a compression test & it won't hold pressure and your exhaust manifolds glow. Sounds like you burn't your exhaust valves which allow exhaust to pass due to the fact the valve won't seal in its seat. This would cause glowing. oo:

 

Glowing

I just finished air testing each cylinder w/ the manifolds off and sure enough every exhaust valve is leaking ! im still a little concerned, air sounds like it is leaking into the block. the rings have got to be right because the air pressure is pushing the pistons down if their at the top. Ill just have the mach. shop grind the head down or resurface. milling it down should be better performance any how, giving a better comp. ratio Ill let you guys know what comes of this. later

 

Re exhaust glowing

Must of looked pretty cool at night glowing.

 

Glowing exhaust continues

WELL, I TALKED TO THE MACHINE SHOP TODAY AND THEY SAY THE EXHAUST VALVES ARE SEATING FINE, WHAT THE .

 

Re exhaust glowing

If the valves are seating fine then check for weak spring pressure@closed position and the seals are sealing.

 

Glowing

PICKED UP THE HEAD FROM THE MACH. SHOP. HE TELLS ME THE VALVES ARE SEATING CORRECTLY AND ALL SPRING TENSIONS ARE GOOD. I JUST DONT KNOW. HE SAID SOMETHING ELSE MUST BE WRONG IN THE ENGINE ,BUT WHAT,THERE'S NOT MUCH MORE THAT WOULD CAUSE THIS

 

So you're certain the presure loss is out the exhaust, but the valves seat properly off the engine. Re-check valve preload. Something has to be wrong there. Whether it is; wrong cam, lifters, push rod length, rockers, or rocker shims I don't know.
Good luck!

 

Re glowing exhaust

MACH. SHOP SAYS THE SPRING TENSIONS ARE GOOD. IM A LITTLE CONFUSED BECAUSE HE SAID THAT MOTOR SHOULDNT HAVE A HIGH COMPRESSION. HANES BOOK SAYS I SHOULD HAVE 125 PSI. OR BETTER W/ A MIN. OF 30 PSI. DROP BETWEEN EACH CYLINDER. WHEN I DID THE COMPRESSION TEST BEFORE REMOVING ANY THING I ONLY GOT 90 PSI. W/ HOT OR COLD ENGINE I TESTED EACH CYLINDER AROUND 100 PSI. W/ COMPRESSED AIR AND EVERYONE OF THE EXHAUST VALVES LEAKED, BECAUSE IT BLEW OUT THE DUCT TAPE I HAD ON THE MANIFOLD SIDE . NOW IF THE COMPRESSION IS SUPPOSE TO BE 125 PSI. DONT YOU THINK THE VALVE SHOULD HOLD 100 LB. OF PRESSURE . I DO BELIEVE I WILL GET A SECOND MACH. SHOP TO LOOK IT THIS HEAD BEFORE PUTTING IT BACK TOGETHER :smirk:

 

W/ A MIN. OF 30 PSI. DROP BETWEEN EACH CYLINDER.

I have no idea what that means. I've never done a leakdown test. here are a couple links I Googled.

How to do Cylinder Leak Down Testing- Car Craft Magazine

What is a "leak down" test? - Yahoo! Autos

Also did some searching re: lifter pre load (did not read very much of it. getting tired)

CraneCams

If I understand what it says, it goes like this: too much play = noisy lifters, too tight = lifters pumping up = valves not closing fully. By the way, are you running a high pressure oil pump? (could agrivate the preload thing)

 

GlOwInG !!!!!!

NOT REALLY SHER WHAT THE PRELOAD WOULD BE. THIS MOTOR IS SAT UP WITH HYDRO. LIFTERS WHICH HAVE BEEN PRIMED TO REMOVE AIR, AND NON- ADJUSTABLE ROCKERS. AS FAR AS THE PUMP I'M RUNNING STOCK PRESSURE. PICKED THE HEAD UP FROM THE SHOP YESTERDAY AND SOME SEATS WERE BAD BUT IT WAS THE ANGLE ON THE VALVES MAINLY. HOPFULLY WE'LL SEE BY THE END OF THE WEEKEND :laugh:

 

Check out this link starting about 3 paragraphs down.

CraneCams

about 3/4 of the way down the same link, also read the section titled: "Do Hydraulic Lifters Need to be Primed with Oil?" I think it is pretty easy to follow and would explain your exhaust valves not sealing.

GOOD LUCK!

 

Preload

THANKS ALOT FOR FINDING THAT! COME TO FIND OUT THE "EXPERIENCED" ENGINE BUILDER THAT HELP ME BUILD THE MOTOR HAD ME SOAK THE LIFTERS AND PRIME THEM TO REMOVE AIR THIS MIGHT BE THE WHOLE PROBLEM SON OF A . IM GOING TO KICK HIS