Got a buddy with a problem 350 chevy engine. It was punched out to 383 + a mild cam, stock push rods & rockers. Later he swapped in a set GM hi per ZZ383 fast burn heads. He now can't get to start. It backfired and bent a couple of push rods. He then swapped in non-shifting rockers, new stock puchrods & still won't start. He has checked the distributor setting several times (it only goes in 2 ways) and it seems right. Was'up?
There are 360 drgrees in a circle and you can be off that many degrees with your distributer. A Big block MOPAR can only go in two ways a small block chevy is gear driven there are a lot of different ways to get it in. Here are common problems with the SBC. people cross the 5 and 7 plug wire, they get them in 180 out they don't roll it up on TDC prior to dropping the distributer in. Start from scratch. Remove a the driver rocker cover. Roll the engine clockwise until the #1 intake just closes. Be sure you are looking at the intake and not the exahaust. No continue rolling the engine until the timming mark comes up align it at the desired timming mark. Now drop your distributert with the rotor pointing at the number on otwer on the distributer cap. The distributer may not drop all the qway because the oil pump shaft is not lined up. Turn the motor while applying light pressure to the distributer until it drops into place. Roll it around to the timming mark again and make sure that the rotor is ligned up with the number one plug tower and ****on it up. Now see if it will start.
Bent pushrods? Sure sounds like the valves hit the pistons. Did he change cams at all? Is it possible the timing chain is off enough to cause clearance issues? Larger valves in the fast burns and the piston eyebrows arent big enough? Higher ratio rocker arms causing clearance issues? Anytime you are bending stuff up I would be more concerned than just timing issues. Hopefully it was just the wrong rockers, but I would be looking into piston clearance issues.
I'm with 42hotrod from what you have written. When you mix and match valve train parts and heads it is wise to 1. make sure that there is no interference between piston and head/valves. The process can be as simple as applying kids clay to the top of a piston and rotating through one cycle. 2.Checking pushrod length, and 3. making sure valve springs will handle the specific cam requirements.
You don"t just throw a high-lift cam in an engine and use stock lifters. Get the lifters that match the cam then find you a Hamb member in the area that will show you how to set the timing before you end up with a pile of s**** metal. From your statement you made that the dist. will just go in two ways,you guys need some help.There is nothing wrong with needing help ,only way to learn how to do it right. Engine parts are expensive,asking for help is free.
Actually never done it with a naturaly aspirated motor but I did have a blower motor balk on me once and bend some pushrods. Fortunately I was ahead of schedual and had time to tear it all the way back down for inspection before I had to deliver it. Sounds like the fella was running the wrong rockers for the heads and that is what bent the pushrods. If it bent all of them I would be worried. Someone e=mentioned asking for help. I am with that if it were hee in town I would offer to come by and get it sorted out. I am sure that there is a local guy that wouldn't mind doing the same.
THe fast burn heads have a raised intake runner, and if using a early style intake, the ports will not match up and sometimes leave exposed holes for vacuum leaks.
As for bent push rods , the first thing you do when you change a cam is check the length of the push rods that is needed for the cam you have . Sounds like you tightened down the rocker arms way too tight and when the lifters got oil in them , it bent the push rods . FIRST get someone that knows what they are doing to check over the work you already did ! Usually a case of cold beer works for that ! NOW do the rest if you don't find someone to do the work for you ! Make sure you have a good fan pushed against the radiator for good air flow ! Check the push rods to see how the rocker arms ride on the valves . Use a drill and pump the oil through the engine for good oil pressure BEFORE you set the distributor on #1 piston ! Make sure you have the correct firing order . 1-8-4-3-6-5-7-2 Get the distributor and set it on TDC on #1 piston . The front piston on the p***engers side of the engine . Now adjust the lifters till they just start to get snug on the valves , NOT TIGHT ! Loose is OK but TIGHT is BAD ! Check the cam card to see what the timing should be at . Start the engine and adjust the lifters . Set the timing . Adjust the carb . If you are using a flat tap can , make sure you use the correct oil to break the cam and lifter in , or you just wasted $300 ! Run the engine for 20 to 30 mins at about 2000 to 2500 rpms . If a roller cam just set carb and idle to specs . Retro Jim
You need fuel, air, spark, timing - remember FAST. Next you need compression. All of that is based on the premise that the motor actually spins over without bending ****. #1 is drivers side front cylinder, the drivers side bank is odd numbered front to back, 1,3,5,7 - p***enger side is even & front to back 2,4,6,8. Jim's comment about #1 being on the p***enger side is incorrect in America or other left hand drive sbc powered vehicles. There are plenty of wrong ways to drop the dizzy in a SBS, not just one. If its a Ford, or anytime you work on one remember this - FORD= Firing Order Really Different. If its backfireing, the valves is open while its sparking. You need to determine if the valve timing in relation to the piston is correct, or if the ignition timing in relation to piston position is correct and the components are in good working order. Now that some of the basics are properly attended to. Did it run before he did this work ? What are the results of a compression test?
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