283 Big Problem

I bent two pushrods in the number eight cylinder intake valve, after the first one, we tryed another. The valve is now hung three quarter closed. I got a valve job and mill job on the heads. It is only happening at the 8 cly.

heres the specs
283 Bored 40 over
Harlen Sharp 1.5 ratio
Hydraulic lifters with a Summit Cam 254/264 .533/.555
Summit Bracket Racer SFI Harmonic Balancer
Eagle I-Beam Rods with the small journal (5.7 in length)
Original crank, brand new condition, never been cut ( Forged)
Weiand high rise intake
Speed pro forged pistons
Double roller timing chain
375 double hump heads. reworked with the big valves
Rotating assembly balanced and blue printed
650 Edlebrock
headman headers
True duals with no cats.
4.11 posi unit
B and R shifter
350 turbo tranny with shift kit, red line clutches, harden sprag ect....
Summit ignition steet and strip
Rev limiter
hei blue printed distr.
Taylor plugs
3200 stall
3in exhuast

I am sick to my stomach guys please help. Thank it was my machine work the valve seat hung to the valve??????


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bent valve
what size valves did you put in?

283 or 383? that cam is way too big for a 283 pump gas engine.

Did you open up the push rod slots in the heads? double humpers need to be opened up if cam is over .500 lift.

sam-missle

good one! didn't know...

Just curious, when 350 blocks are more plentiful than 283s, why would you just give up 50 plus hp??

I've given this some thought also and can't seem to come up with anything. The only way I would run one is if I needed small cubes to make a certain Comp class at the drag strip. Other than that it doesn't make any sense to me. But hey, with all the practical autos out there for sale, there are still some folks driving Yugos, so.... go figure....

they are 194 and 202 i believe. every thing is clearing, there is no shouting and the pistons are not hitting the heads valves. The 202 valve on cly 8 intake side is hung open. I have takin the head off already. but this is the only one having the problem,, we had it up to about 3500 rpm then we heard the valve hit the piston. but like i said no other cly is doing this.. I believe my machine work was bad,,

i wanted something different, i got the block and some 327 vet heads for a hundred and fifty so what the heck. this is my first motor so i aint worried about making a crap load of horsepower, just want it to run strong.

AHH Yes- there you have it TECH - 327 VET HEADS!! - and you thought nothing would ever surpass to your "Power Packs" (Caution you must be at least 65 to appreciate this).

In your list of parts and modifications I did not notice what you are running for valve springs with that high a lift,care to enlighten us

You stuck a valve, plain and simple. you have probably bent the valve and that is why it is stuck. Take the head off, replace the valve and guide and check to make sure the piston is not damaged. Yes it is a lot of work.

If the piston hit the valve isn't that your answer? Just need to figure out why it hit the valve. Did you accidentally get a piston with a higher crown on it? One or more of the keepers come out?

A 1.94 inch valve is right on the edge of what can be stuffed on top of a 283 bore, care must be taken to insure that all the valves will clear the cylinder walls. A 2.02 is guaranteed to hit the wall.

Normal manufacturing tolerances are more than enough to create a situation where some heads will have problems and others won,t.

Any Hot Rod parts store will have a selection of off set locating pins that are used to align the head such that once the valves are known to clear, the head will return to that position.

Testing is done with the engine disassembled. The heads are installed and located for proper position to the cylinder from the bottom of the engine so you can see up the bores. Minimum clearance to the cylinder wall is our commonly seen .050 inch.

Baring that, the wall needs to be relieved to provide sufficient clearance. This is the technique of last resort in my book, try to get the head lined up first.

Keep in mind you're dealing with tolerances with the bore center position, the valve pocket, port, seat and guide positions. All this can add up to problems. As previously stated aligning the head position can be used to overcome these issues as can relieving the top of the bore where the valve interferes, or the guide position can be moved which of course also moves the seat and possibly the spring pocket. Unfortunately if you're running a 1.94 and certainly a 2.02, the chamber may be out of space in which to machine a new and relocated seat.

Bogie

I agree with Old Bogie... this engine build up was posted in another thread on this bulletin board where I stated 2.02's were not going to work... as has been said 1,000 times with bore sizes under 4".