DETONATION killed my motor 2 times now... distributor?

[mighty spx]

I had the motor rebuilt 3 months ago, put it in the truck and got it street legal 2 weeks ago. hit the interstate thinking it was all good and didnt get a mile before this happened
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pulled the motor and sent it back thinking it was mechanical failure, they warrantied it got it back put it back in the truck got it running good and took it down the road. then bam!! it happened again trying to maintain 55 mph round 2
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so needless to say, im not going to send it the machine shop for my screw up. so im stuck fixing it. no problem there.. but what im looking for is the root problem to this. i run 93 in the truck, with a new weber. set to factory timing specs.. Bad distributor? im at a loss

[camoit]

Thats a lean burn. You would have herd it ping like crazy the first time you tried to drive it if the distributer was the cause.. If the cam timing was off you can do this. It would have been advanced by a tooth. But I would say a vacuum leek or way too much advance.

[mighty spx]

Yeah this has been a head scratcher for me, brand new carb (weber) i set timing to factory spec. One thing that i forgot to mention is that it only happens on number 2, the rest of the cyl look great, plugs looked rich..

[Andy 2]

Is the valve train working properly? No bad lifters or valve springs? If the intake valve on #2 is not opening all the way.....

[mighty spx]

All new lifters, great compression when i first got the motor back.. I'm wondering if the egr passage in the exhaust side of number two is not some how causing it..

[Andy 2]

Have you checked your intake manifold for cracks, and the sealing face for flatness. Perhaps your not getting a good seal at #2. #3 looks pretty lean as well. A warped intake manifold might do that. if you bolt it on without a gasket(just finger tight) and shine a flashlight on it you will be able to see the gap. If the manifold is warped slightly it can be machined flat.

[mighty spx]

checked with straight edge, lightly coated intake gasket with silicone to insure no leaks..

[mighty spx]

ok so i got the motor tore down, the head is at the machine shop getting checked, new piston being pressed on the rods. i bought a new carter 4070 fuel pump, and a new regulator with gauge to set for 3 psi for the carb, then i also picked me up a air/fuel ratio gauge kit so i can keep a eye on the running of the motor, plan on making a pillar mount for the gauge for a clean look. and with any luck i should have this truck up and going!!

[mighty spx]

7071I was trying to find a regulator with return outlet so it will not burn my pump up, but i ended up with a holley 12-803 (1-4 psi)