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Discussion Starter · #1 ·
I have a 1986 f250 460 it has a holley sniper tbi with the holley hyperpark ignition and distributor it has flowtech headers no smog pumps or egr weiend stealth intake manifold and top dead center timing gears it was running great but I decided to swap the cam out for a little more power I ordered a comp cams xtreme 4x4 camshaft with lifters and valve springs after replacing the camshaft and ordering pushrods I started the motor today it is crazy loud out the exhaust and not in a good way it sounds like it went from a full exhaust to a straight pipe the idle is not good very choppy feels like it is misfiring and the engine is shaking whole truck I checked timing multiple times and have the base timing at 16 degrees wich is what it was before the swap I tried adjusting it from 10 to 20 degrees and no change getting to 5 it starts having a hard time running and 25 it starts getting worse and louder the afr is 13.5 to 1 at idle wich is where it ran before I have not tried giving it more/less fuel at this point as I didnt feel it was the problem I have no vacuum no accessories and no power brakes I have checked multiple times for leaks and everything appears to be sealed up I tried driving it and it sounded like a straight piped idi diesel it has no power past 1300 rpms and it runs terrible chugging and really loud but the sound seems to be all from the exhaust not from engine bay when I put the cam/crank gears on I turned the crankshaft till I felt pressure pushing my thumb from the spark plug hole then put the crank gear on and turned the crank a little more till the dot was directly up I then put the chain on and installed the cam gear with the dot facing down towards towards the crank gear dot I then installed timing cover etc. I put the engine back to tdc cylinder 1 and installed the distributor I had made two timing mark's one on ot and the engine when it was tdc before removing so I put it back in the same spot i removed it. Could I have the crank gear 180° out? Would that actually effect anything? Could my pushrods be to short or long? I didnt feel very confident when measuring them. Also I have stock rockers non adjustable the pushrods I installed are 8.450

Please help!!!
 

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this may sound odd but it happened to me i have a 545 with fitech fuel injection and it started fine cold and as it got warm started doing the same thing till it just shut of it was my 02s that just went bad i replaced it and it runs perfect
 

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Check lifter preload. New push rods a fraction longer will make a big difference with bolt down rockers.
 

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Did you change your cam selection in the sniper hand controller?You might try turning on the learning feature and see if that helps.
Sounds like there is a problem with the cam install.
Greg
 

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Discussion Starter · #5 ·
I did change the cam selection in the sniper. I will be checking the lifter preload and will report back. Taylorteamracing did you reading look bad or did they appear fine? I am curious because mine is reporting good AFR numbers but I dont know of that means anything.
 
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