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Forgot to break in cam SBC. runs okay? should i worry?

10K views 24 replies 13 participants last post by  caminoguy 
#1 ·
Hey all! im new to the site and new to hot rodding. i just finished my first engine build.
heres some specs:

1972 GMC 350
4 bolt mains
Stock bore
Mods:
Dart iron eagle heads (cast)
72 cc
2.02 int valves
Lunati Voo Doo street performance cam/lifter kit.
melling double roller timing set.

1986 El camino 7004R automatic.


I had no oil pressure on initial start up. it turned out I had galley plugs missing behind the timing set so i put them in. somewhere along getting oil pressure i never thought to break in the cam. I have normal oil pressure now and the motor seems to run decent. I have one or two slightly noisy lifters. not loud enough to hear from inside the car windows up. ive tried adjusting the valves to no avail. (0 lash and 1/2turn) How worried should i be? what can i do if anything to prevent any failures? Ive been driving it to work for a few weeks. about 20 minutes each way nothing extensive. My commute is mostly 40-50mph stuff around 1500 rpm. hasnt gotten any louder or quieter. driveability is good but not shockingly different from my old 305 but then again its the stock carb.
 
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#2 ·
More then likely your ok, if any damage it's already done, but you really do need to re-adjust the lifters, i usually go 1/4 turn and they are fine but some do go 1/2 also.JMO
Had you ever adjusted lifters before ? And what type oil do you have in it did you put any zink additive in it before hand ?


Cole
 
#3 ·
Im running quaker state 10w-40. my dad is a hot rod guy and swears by it. i was thinkin of getting some zinc stuff though. Ive never done lifters before but ive got it down pretty well except for a couple that just wont quite shut up. the cam instructions say half a turn after 0 lash on the stand. i would assume the same running. losened em till they clatter tightened til they quiet down then a half turn tighter. And its not like they're wicked loud just tick tick tick. its one of those noises ya dont hear unless your parked next to a wall or driving next to a barrier.

also, the oil coming out of the pushrods doesnt spray like I expected. just kinda blurbs out. but theres oil. Everyone ive mentioned that to says its fine. Im still worried about it though. oil pressure is 40 psi cold start at idle. 22-30 hot idle. thats in drive. round 700-800 rpm. High volume oil pump. fram filter.
 
#4 ·
Do yourself a huge favor and switch to at least an ac delco filter and valvoline oil. Its almost the same price. Also, when you adjust your lifters, tighten until it quiets down and leave it there, no extra half turn. Voodoo cams are sometimes noisy, which one did you use? Are you running a stock intake and exhaust manifolds? If so that will severely restrict your power.
 
#6 ·
I once had a persistent ticking noise similar to the flat tappet noise that bothered me, because I'm very careful when I set the lifters. This was on a newly rebuilt SBC. After four times of adjusting the lash someone suggested that the fuel pump may have a broken return spring. Sure enough, it was broken and the arm must have been bouncing slightly off the push rod or the push rod bouncing off the cam eccentric. Replaced the pump and no more ticking noise. BTW - I use 1/2 turn past zero lash. Good luck.
 
#7 ·
I know you ask a hundred people and you get a hundred answers but I started adjusting my lifters only an 1/8 turn( I forget why now,lol) but haven't had any problems in years. You sound like you got lucky on the " break-in" but I still keep an "ear" on it.
 
#8 ·
I used to work for valvoline and will never buy their products again based on experience. not saying they arent good but deffenitely over price for whats in it. Ashland is extremely corrupt. delco i will do though.

heres the cam: http://www.lunatipower.com/Product.aspx?id=2323

Im running a stock carb and intake. I just got a set of headers from a friend but they fit a caprice. not sure if that will work but his caprice manifolds were the same as my elcamino manifolds so il have to try them i guess.

Fuel pump is brand new made by airtec but il check it out any how it was really cheap but has a warrantee. problem is the ticking is on the opposite side. Meh il check it anyways.

the valves make noise no matter where i put them it seems but they do get quiet for a few seconds and then the noise is back. i figure the lifters fill up with oil while theyre lose.

Ive gone about 250 miles il change the oil at 500 and see what it looks like i guess. maybe sooner if it gets loud.
 
#9 ·
This may sound like a silly question, but are you sure its not an exhaust leak? Brand new gaskets with no broken studs? The reason being is an exhaust leak can sound similar to valve chatter.

Another idea is if your having trouble finding the noise is to put your fingers against the side of the rockers to find the loose one. They do move, however are not going to hurt you.

When idling with the valve covers off, the oil sometimes squirts, but not always. Because it isn't spraying all over the place doesn't necessarily mean its not lubricating properly.

Its been a few years since I have adjusted valves, however I had the lovely experience of buying an engine from a man who installed the wrong push rods that were not guide plate compatible (pontiac 389). And as a bonus, the rocker nuts would back themselves loose. It gave me lots of practice adjusting before realizing what a circus it really was. Man was I pissed. :spank:

I can tell you this much... valve chatter should only last a second or two on start-up while the oil fills the tolerances. Some cams are indeed noisy.

Also a spun bearing can sound like valve chatter, however it is followed by a loss of power and eventually engine failure. Very unlikely in this case it sounds.

I wish you good luck finding the sound.
 
#15 ·
Oh yeahhh almost forgot to mention that! im running comp cams pushrods and roller tipped rockers. 1.5 ratio.

rockers: http://www.summitracing.com/parts/SUM-141506/

pushrods: http://www.summitracing.com/parts/CCA-7812-16/

Im not sure what kind of lifters they are they came with the cam in a kit. Ive looked but cannot find any specs on the lifters only cam specs.

Exhaust leaks are present and identified. I think the torque convertor makes a bit of noise though but there is deffinitely lifter noise seeing as how it changes when i adjust lash. It mega phones through my sunpro oil pressure gauge in the car now that i put a copper line in after melting a plastic one.. i can hear alot but it sounds like one lifter stands out. theres the usual churning and an outstanding tick.

I guess My main question is if I have noisy lifters is it causing damage to something? I still drive to work and i almost just want to park the thing because im afraid il break it.
 
#16 ·
IMO, camshaft break in is the worst thing you could do to a new engine. Steel will expand .000006" per 1 degree increase in temp. Starting a new engine and running it till it gets hot will cause the crankshaft to expand tight against brand new bearings, rings will expand and face more than they should, etc.

I start the engine and let it run for less than 1 minute and then let it cool completely down and repeat the process in increments of 1 minute or less. That allows everything to break in at normal clearances without too much expansion all at once.
 
#18 ·
If you have not flattened a lobe by now you are probably ok. As far as adjustment I have always done them with the engine running, back off antil it clacks, bring down until quiet and go 1/2 turn more 1/4 at a time. This has worked for me since the 70's.
Some go 3/4 but I thin 1/2 is enough.
 
#19 ·
jason777 said:
IMO, camshaft break in is the worst thing you could do to a new engine. Steel will expand .000006" per 1 degree increase in temp. Starting a new engine and running it till it gets hot will cause the crankshaft to expand tight against brand new bearings, rings will expand and face more than they should, etc.

I start the engine and let it run for less than 1 minute and then let it cool completely down and repeat the process in increments of 1 minute or less. That allows everything to break in at normal clearances without too much expansion all at once.
I like that idea. Will that type of break in be safe for flat tappet cams? I'm nearly ready to start up a rebuilt SBC 350 with a Melling CTC-1 cam.
 
#21 ·
Never heard of that.
BTW, a little math, with 3/8''-24 rocker studs, each 1/4 turn pushes the lifter plunger down .010''.
24 threads per inch at the top of the stud. 1'' divided by 24 = .04166'' for 1 turn of the nut. .04166'' / 4 = .0104''
You said turning the rocker nut moves it so much when you turn it. What about the rocker arm that makes a cam lift a valve more than the size of the lobe. Does the same thing happen when the nut is turned. I mean that there is more movement because of the rocker arm is there?
 
#22 · (Edited)
jason777 said:
I start the engine and let it run for less than 1 minute and then let it cool completely down and repeat the process in increments of 1 minute or less. That allows everything to break in at normal clearances without too much expansion all at once.

I wouldn't recommend getting any engine hot on the first start up.
I wouldn't agree with that procedure, unless it's a roller motor, then no serious break-in is needed, rings will seat with normal driving. If you're motor is getting hot during break-in, you have other issues, such as not moving enough air. Again, JMO, you'll find different opinions I'm sure, do some research.
 
#23 ·
If the cooling is good on the car and the motor has enough timing it shouldnt get that hot any ways. you got to keep check on temp gage if it goes to high for some reason sure then shut it off. if I see its no higher than 200 or so I keep it lit until broken in. every one does it there own way i guess.
 
#24 ·
Okay i was running 210 degrees. my radiator is aftermarket junk . single(one big) core, advance auto parts special. I put a 180 degree thermostat in and it runs 190-195 right on. warms up nice and quick too. when i get rich and famous il spend money on a radiator. maybe next month il go bigger. for now that works.

I adjusted my carb idle air mix, air bleed and then advaced my timing just a touch. my vacum gauge is a little off but its reading between 24in. and 26. it doesnt zero out so more like 22. its nice and steady once and a while it moves a tiny bit.

Today i have to drive from worcester to framingham with a tractor in the back. wel see how it goes. its all 55 mph for about 40 min. noises havent changed.
 
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