396 ?

hello,

i'm hoping somebody can help me out with a problem that i just came accross (one of the many it seems) i've just finished building my engine a 67 396, hydrolic roller. went to set the rockers and the engine turns smooth until a certain spot then it just stops. it will turn back i don't know how far though because i was told never to turn a engine counter clockwise is that true? i know this could be many things....the problem isn't likely in the bottom end because it was pre assembled by a machinist then assembled by me with an experienced person over looking me do it. it rotated fine when the bottom end was assembled. these are all new parts came as a kit. i'd like to hear some suggestions before i start tearing it down again.....sooooo disapointed, i'm getting nowhere fast with this build lol

thanks

could be many..things piston domes hitting head chambers . valves hitting pistons . pistons not hanged right . pistons out of the deck hitting .or valve train.how big is the cam .older trw /speed pro pistons will not take a big cam. was the cam grooved rear cam jounal . some of the older bbc need this done to get lifter oil and top end oil has nothing to do with things hitting but may be another problem

camshaft is a lunati 60211 Duration 272/280, Lift .575/.575. the cam journal was groved. so i guess my first step would be to take the heads off?dunno if it would make a difference but it hits when the #1 cylinder is at top just about to go down. thanks

wrong pistons for the clyinder head chamber type

pistons installed backwards

cam timed wrong and intake valve opening against the piston or exhaust not closing quick enough

pistons wrong CH and out the top of block

i took the cylinder heads off, still doesn't turn. could it still be the timing? maybe i'll take all that apart next?

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Originally Posted by chevygirl396

i took the cylinder heads off, still doesn't turn. could it still be the timing? maybe i'll take all that apart next?

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fly wheel bolts to long hitting back of the block

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Originally Posted by jerry clayton

wrong pistons for the clyinder head chamber type

pistons installed backwards

cam timed wrong and intake valve opening against the piston or exhaust not closing quick enough

pistons wrong CH and out the top of block

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sounds good like post #2 ;)

With the heads off, the cam doesn't care if it's set right or not, it should still rotate. Might take the timing chain and cam gear off. If it doesn't rotate then you have problems with either the crank or rods.......

take the pan off and see if rods are hitting

the fly wheel's not on.....i hope your right dave. i'm thinking/hoping its got to do with the timing chain or cam gear. we rotated the botom end after we put it together and it was fine..i guess i know what i'm doing tomorrow, thanks for the suggestions

take timming chain off lf cam turn s free its not the cam but could be front oil galley plugs hitting on the back of timming gear or the timming cover hitting timming set .i seen this ....bottom end it could be you have caps mix up one rod cap on back wards. there are many thing that can be done wrong

1/4 pipe plugs in front of block must be flush to block or very close to flush

do you mean the ones behing the timing gear? either way i took it all apart and it still doesn't turn. i'll have to pull the engine out and have a look at the rod caps like you suggested.....i could have sworn i double checked that. thanks for all your advice.

I put a Buick engine together awhile back that wouldn't turn. A piston was hitting the counterweight on the crank.

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Originally Posted by BigBlockBird

I put a Buick engine together awhile back that wouldn't turn. A piston was hitting the counterweight on the crank.

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this could happen with the bigger cranks 4.250to 4.750s cranks and has . i seen it with cheaper steel cranks 4.250 marked for stock rod length but not cam cut.big cranks always should do a dry run to make sure bottom of piston clears the counter weights you also need to be aware that the piston skirts can hit the side of the counter weights to .but with the small pin off set of the 366to 427 . 3.765. with this crank it should not happen and they only make a bbc pistons 9.800 deck blocks in that bore size to get it mix up less very cheap off brand ? most pistons not not have alot of pad under the pin boss . they never did a post back on what it was? who know .s it is a old post

Quote:

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Originally Posted by chevygirl396

i was told never to turn a engine counter clockwise is that true?

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There is no problem with turning a motor counter-clockwise, except that if you're turning it with the damper retention bolt, you could loosen the bolt and have to re-torque it. There are tools that will fit the crank snout to turn the crank. Next time you go to the drags, watch the fueler and alcohol guys put a bar on the crank and pull the motor backwards a few times. What they're doing is clearing the cylinders of fuel. When you turn the crank backwards, you're opening the exhaust valve before the intake, so you can't compress fuel in the chamber and maybe break a piston or bend a rod.