Thread: 402-454?

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Originally Posted by back in bus.

got it . u were the only one who actually knew the head casting # were under valve covers.

HAHAHAHAHA, most everybody knows this, they just don't know how to convey their thoughts correctly.

Originally Posted by back in bus.

Is the block # underneath? almost has to be cant see any from eng compt.

As Roger said, it is sometimes obscured with grunge. Get a mechanic's telescoping mirror, a good strong flashlight and a toothbrush soaked in solvent.

Originally Posted by back in bus.

head # 3989241 build date dec 10 71 also has GM 4 T stamped in middle inside.
looked on everything I can find and cannot find that head #.

Probably 3999241, 1972 402, 454 oval port, 113cc open chamber, flows with the best of the cast iron production heads. SCORE.

Originally Posted by back in bus.

intake man # is 6263753

1972 402 240 hp LS3, 454 240, 270 hp

Originally Posted by back in bus.

motor ran like crap. did comp test. # 4-6-5 low at 25 lbs.
on same cyl intake rockers were sideways and push rods bent. exhaust look ok. will have to pull head to look at piston tops , and also get pieces of pushrods, maybe bent valves. don't have any idea what caused this. the heads are clean and look like new under valve covers. going to crawl under to look for block #
thanks again

Suspect valve springs stacked solid, bent pushrod, pushed rocker off to the side. Might also be rocker slot is too short at the rocker stud, causing interference. Also might be valve to piston interference from too much valve lift, not checking clearance in mock-up before actual build. The motor should go together 3 or 4 times to check different clearances and machine work before final assembly. Low compression readings could be bent valves.
Again, block casting number is on the driver's side of the motor, at the rear, just behind the valve cover, on the ledge between the block and the bellhousing. You can see it from under the hood, but like I said above, you may need a telescoping mechanic's mirror and a good strong light. Clean the number with a toothbrush and solvent.
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