i recently ran into a couple of problems with my newly rebuilt 350. low compression and low vaccum in had because after i took my heads to get a head job for time, the second machine shop took apart my heads in front of me showed me all of the things they did and didnt do! the valve job was non-exsitant and the heads were resurfaced with sand belt all in all, my heads should be good to go after they were done right but when i looked to see how my cam broke in i noticed one lobe looks flat. im not sure if im right and i also found that the lifter has a straight pattern but is there hope being that the 350 has no more than 1 hour of run time or do i start over with a new cam. also i checked my preload and came with .072" preload and the lifters are not caved in nor are they flat but would that cuase this... tell me what you think and is it as bad as i think or am i worrying too much?
I guess you bought the car from someone who told you they rebuilt the engine? Lifter preload should be between .030 and .060 maximum. The stock Buick valve train is non adjustable. Anytime you use a replacement cam, you should check push rod length and preload. Cheapest way is to use adjustable push rods. Current oils on the market are not flat tappet friendly, they lack a zinc phosphorous compound called ZDDP, an anti wear, high pressure additive that is not needed for today's roller valve trains. During the cam break in period, it's a good idea to make sure all the push rods are spinning. The lifter has to spin, or the cam will not live. Looks like you have a problem. Who knows what else was done wrong.
well Larry i did rebuild the engine my self but its my first in 15 years and that was 455 but i failed to check my preload when i in the process of the rebuild and if the pushrods were spinning because of a fuel leak i had during the breakin and know i should have but i didnt. now i just want to know if i anyone tell, by looking at the pictures i posted earlier, if i have a flat cam or not and what caused it if i do, like too much preload. also the pattern on the lifter, do i need to get a new cam and new lifter or would it begin to spin because i can tell its spinnig by looking at the wear marks on the side but its not spinning a lot like it needs to.
From your picture of the lifter, it IS NOT spinning as it should. That is the reason for the flat groove in the face of the lifter. Replace the cam and lifters. Make sure when assembling that ALL the lifters spin freely in the lifter bores, typically an edge of a lifter bore is a bit tight and will keep a lifter/s from spinning freely. A lifter that IS spinning properly will have a grayish round wear pattern on the face of the lifter, NOT a definitive line like the one pictured.
Call TA and ask them if they warranty the cam for this,or maybe they can regrind the cam for you to save you some$$? CAll them to see if they will work with you for this issue,and their recommendation of what to do. Although it does'nt look to bad (in the picture anyway) it still doesn't look right,and you should not run it. They are very knowledgeable at TA,and should be able to help you. Goodluck.
I'm not sure if TA uses new blanks to keep the base as in stock or grinds the base to achieve the new profile but...I would imagine that if you had exessive preload to wipe out a lobe you would break a rocker first. My guess would be some bad oiling or poor machining that caused the lifter to not rotate. Besides cam lobe does not hit the center of the tappet, it is offset to cause the rotation. A cam and lifters are cheap......metal shavings mixed with bearing surfaces and rotating surfaces is expensive.
ok, well i called TA and they told me if the lifter still had its crown on the botom, it would still have a chance to start spining again. I checked all of my lifters and they all had their crown and they all did but i did find two others that had a similar pattern as the one in the picture above but were not as bad. TA said to run the engine at idle and watch for the rods to spin and if they were not then to hit them or spin them with my fingers to get them going, but when i did that, only one of the three non-spining started to move but very slow and it would still stop every now and then, and as for the other two, they wouldnt move no matter what i did. TA said to call them back on monday. and also for the record i was running a vacuum gauge and i was only getting 12in of vac at 850 rpm but every now and then it would drop 2 inches out of nowhere... i dont know if that would have and corilation to a flat cam or not. i think the vac is kind of low for that cam and Ta told me that cam should have 15inches of vacuum. i dont know where i stand right now but it would be much appreciated if someone can kinda tell me anything that i am missing or why the vac drops or why the vac is so low. any help or comments are would be helpful.
I still say you have a bur or burs in one or more of your lifter bores keeping the lifter/s from spinning.
I ,like Larry, think that what you have is lubricant failure.... you have to have zinc added to the oil to keep from wiping the cam.... also at this stage, you need to pull the engine and look at the oil pump/rod bearings/mainbearings ect.. because the oil filter will not, will not , catch all the metal chips .... and those chips go to and are imbeded in the bearings.... you need to revisit the whole engine rebuild.....sorry,,,,,
