retarded the timing a whole lot i guess my shop teacher did and then said drive it home and see how it runs. it ran like **** no ***** what so ever and now it knocks i drove it about 2 miles with it knocking. i can feel the vibrations from the clutch pedal and its loud. do you think i did any damage? do you think just retiming it will work? please tell me i didnt just **** up my new engine.

 

What engine and what did you do to set the timing?

Bet after you get the real way to do it, mr teacher will have a red face tomorrow.

 

you should advance it, not retard it. i would put it back to normal and see how it runs. it should run alot better. never retard your timing.

 

we retarded it because it was running hot. do you think i did any damage to the engine. this is a early 70s corvette engine.

 

Running hot so you retarded the timing? If its running hot you need to fix that problem, not patch it.

 

either way it wont stop knocking even after i redid the timing. im getting so mad at this engine. do you think if i put some 91 in it, it will stop knocking.

 

Retard can cause the engine to run hot and ping as well as make the manifolds/headers glow cherry red. I have a problem with my distributer hold down bolt loosening in my performer RPM intake and the timing just retards itself. The engine will run terrible, hot, and ping. As soon as the pedal starts needing to be pushed further and further at cruise on the highway I know it is time to advance the timing. Locktite can't even get the hold down bolt to stay tight.

Moral never retard for performance, set it @ 4* BTDC and it will be much better.

 

Do what I did... don't use a bold to hold down the distributor clamp. Use a stud. Find a stud with the same threads as the bolt, and the right length. Use some permanent stregnth thread locker (usually thick red stuff) to lock the stud into the hole.

Then, you just use a washer and nut (locknut?) to hold the clamp down. It works great!

 

yes you should put on 91 gas in there and some octane booster and advance your timimg and fix that heating problem.

 

its not pinging its knocking.

 

"Pinging" is what people also refer to "engine knock" which is pre-ignition or detonation. It is best described as "erractic" sound when the engine is under load and will sound like you have marbles bouncing inside your engine. Too much spark advance, too low octane and/or too much compression are common causes.

If your hear a "continous or regular" knock, that is a mechanical problem inside your motor and has nothing to do with detonation/pre-ignition. Something is physically wrong with your motor then.

 

its a noise that sounds like something was hitting the fan. some people are saying it might be carbon build up. im not sure tho i sure hope thats all it is

 

What's your compression ratio and what grade of gas are you using? I re-read your original post and I think you have a mechanical problem, not pre-ignition/detonation.

Simple way to test, pre-ignition/detonation seldom occur at idle unless you have extremely high compression or bad gas. Typically, pre-ignition only occurs when the engine is under a load. If you still hear noise at idle, it pretty well suggests a mechanical problem.

Being a new engine, a VERY common problem is improper break-in of the cam. If a lobe gets wiped-out, then you may hear a "ticking sound", similar as you said to a fan hitting something while the engine is running.

But, before I get into a "diagnostic check" of all conceivable problems, you need to differentiate whether the noise is caused by pre-ignition or a mechanical problem. I am leaning to a mechanical problem as the problem started when the distributor was adjusted.

BTW, have you checked what the timing is currently set at? If not, do so.

 

First off i would go kick your shop teacher in the face.

 

yea cept hes like 2x my size

 

In that case hit him from behind with a 2x4 bout 5 feet long and run.


Some questions were asked, try to answer them if you can, other wise say so. Folks are trying to help.

I bet the knocking is detonation because of the timing. Need to know what your timing is set at now and as many details as you can provide about your engine.

 

everyone here at home in cali say that it sounds like its a lifter or a bent pushrod from the details that i have given them. i do not know the timing as i do believe the cam was misdegreed. the engine has approx 4000 miles on it as that is what the guy said. when it was running it was running hot but that was it, it sounded great and pulled well into 5500 5600 range.

 

Never mind what you have been told. You are not listening to the advice you have been given here.

Here is the problem.

You were running hot. Engine ran fine otherwise.

Timing was adjusted. Now the engine is knocking/pinging.

My advice:

Get a timing light/learn how to use it and see what it is set at now. This is VERY IMPORTANT. You can/will screw up your engine otherwise.

A timing light is cheap, perhaps you could even borrow one but this is the first step you have to take before pulling pushrods and screwing up the valve lash in the process.

Don't drive the car anymore untill you can tell what the timing is set at now.

Once you have that then we can chase down the overheating problem.

If you can't do that then have a mechanic look at it. I hope you were not trying to drive the **** out of it while it was making those knocking noises.

 

i have a timing light i know how to use it im almost ase certified for my smog tech license. i cant tell the total timing because the cam was misdegreed. no i wasnt drivinig the **** out of it when it was knocking in fact as soon as i heard the noise i dropped into neutral and coasted for awhile and then left it in 4th at 2,000 all the way home except for the stop signs but i never took it above 2500 accerlating.

 

Cam timing is different than distributor timing. Distributor is referenced to the mark on the harmonic balancer/damper, which is connected to the crankshaft. Ignition timing has nothing to do with cam installation on these engines, just damper and distributor (assuming the damper ring hasn't slipped like on an old stock piece or something).

Misdegreeing a cam is not an easy task. It takes a cam grind error, or a timing set installed incorrectly, both of which are not likely.

 

well then maybe my dampner has slipped. its 60 degrees off. also i tightened the rockers as they were a little bit loose but it still makes the noise my dad heard it over the phone and said it sounded like a main bearing but i dont think its that as its not a thumping sound or a rod bearing.

 

ok had my uncle come over and we used a stethascope to figure out it was coming off of the #7 intake. we used the compression guage and showed 135-145 for pressure. so this rules out the bad piston and piston rings. my question is can i start the engine and idle it for about 20 secs with out the #7 pushrod. or will this destroy the valve. next if the lifter is bad does this mean i did any damage to the cam. since im replacing all of the lifters do you think i should change all of my pushrods.
jond

 

if you have a bad lifter, you DEFINETLY have a whiped cam lobe. There's no "maybe the cam is still ok" it's definite. Sorry, you're going to have to buy a cam/lifters set.

You could remove the pushrod for that cylinder... but you're just asking for trouble then. Imagine this...

intake valve opens, lets fuel and air in, then closes. The piston comes up, spark shoots off, piston shoots down. Exhaust lingers there, creating a high density atmosphere. Intake valve opens again, now with the exhaust gas in the cylinder again, and trys to let fresh air and fuel in. after some exhaust leaks out of the intake valve isntead of the exhaust (because you took out the pushrod for that exhaust).

Then you have hot air, that doesnt have much oxygen in it, and wont have much of a burn. All you'll be doing is drastically decreasing performance, and drastically increasing your chances of detonation on that cylinder. If you reeaaaaally want to have a rebuild on the motor, I'd say go for it.

If you reaaaally want to drive the car still even w/ a whiped cam lobe... atleast take out the intake and exhaust pushrods so that no combustion will take place in that cylinder.

I dont know what side-effects you'd have to that (other than a rough idle) since I dont know much about intakes, but I'd imagine that it would flood fuel behind the intake valve.


Really... I wouldnt even bother driving the car until you get the new cam/lifters (if you're sure that's what is happening).


GOOD LUCK!

 

i just wanted to idle the car with no pushrod or spark plug on teh 7 cylinder. and see if the noise goes away. if the noise goes away wouldnt that point out that it is indeed the lifter.

 

Oh. Just unplugging the #7 spark plug would produce the same results (but better aftermath in a sense) to taking out the pushrods.

 

Until you can pull the top-end off and confirm (and replace) the bad components, DO NOTHING. You are far better off to leave the car alone until you are ready to fix it than start it.

What good will come out of starting your "broken motor" (other than to analyze it)? Last I heard, they don't fix themselves.

 

That's what I was trying to say... but he seems to want to do it his way lol... so nothing's gunna stop 'em... might as well give a little advice.

 

He doesn't listen. Either he doesn't care about his engine cause daddy paid for it or he doesn't care and is an idiot or a troll. I and others have given solid advice. He seems to like to play with it or some other demented perversion.

 

well i figure it this way if i start the damn thing with the pushrods disconnected without the spark plug there shouldnt be any pressure on the lifter so wouldnt the noise go away. if the mtr is broken then running it for 30 secs isnt gonna cause any more harm to it.

 

if you remove a pushrod, the lifter may spit out. If a lifter spits out, I think you'll lose oil pressure to all the lifters. Also, if a lifter spits out, you'll have to remove the intake also. If you want to, you can get away with over-tightening the rocker which will always keep the valvetrain in compression and shouldn't knock (but may run rough).

 

the hole is significantly smaller on the head than the lifter. so how would the lifter pop out unless you mean pop out into the lifter valley

 

I see nothing good about doing what you plan and plenty of bad.

Without any "pressure" on the lifter, it is going to bounce on the cam lobes. What harm can this do? Well, it can wipe out the lobe of the cam, it could pop the lifter out of the lifter bore and bounce around inside the lifter valley, it could lodge itself somewhere you where it was never intended to be ....

Get the picture? Do you hate this motor and hell bent on killing it? This is "up there" with lighting a match and checking your gas tank to see if any gas is left. Just make sure you yell "FIRE IN THE HOLE" when you do it.

 

no i think im just gonna take off the intake manifold and put a new cam and lifter set in with some new crane roller rockers and pushrods

 

Question? How did you "break-in" your cam? I assume it is a flat tappet cam, which needs to be broken in. I say this because the #1 reason for "wiping out a cam" is due to improper break-in.

Based on your description, my immediate reaction is, you wiped out a lobe on the cam and that is what cause the "ticking" sound. What you now need to do, is make sure you didn't ruin the lifter bore, or you may be back doing this again.

 

how do i check the lifter bore? the engine had about 4000 miles or so i was told be4 i got it.

 

To properly check the lifter bore, you need to get a machine shop or a good mechanic to check it. You need to check if for "out-of-roundness"; a very common problem with late 70s/early 80s SBCs with flat tappet cams.

In the those days, GM used a very mild steel cam which would wear out pre-maturely. Very common to have a "bad cam" in those days. So guys would swap the cam only to have the problem reappear shortly.

The reason, the first bad cam, often caused the lifter to rock inside the lifter bore (another reason why you shouldn't run an engine with a problem) and cause the bore to become "out-of-round".

Then when they replace the cam and lifters, the new lifter would rock inside the lifter bore (ruined by the last cam/lifters) and promptly begin to wear out the new cam. The proper fix was to over bore the lifter bores and run a bigger lifter (like an AMC).

Your engine may have had this problem right from the beginning and the reason your first cam wiped it's lobe (though you still don't know for sure).

I recommend you have the engine towed to a good machine shop/mechanic and have them inspect the old cam, lifters and lifter bore. And, for all the work to do that, you MAY just want to consider a new block (350). They are cheap as hell and for all the money you would spend on the 305, it may turn out the cheaper solution.

 

I agree with you all up to that point Glenn. It's not as easy as just getting a new 350 block, and putting everything back in. Would have to have new pistons installed, probably hot tank the rotating assembly while you're at it, and have the rods shot peened.

Then new bearings all around, new pistons since the 305's obviously wont fit. Then you need to have the rotating assembly balanced... then have the machine shop re-assemble the block


I see the machine shop costs skyrocketing compared to over-boring the lifters on his 305 instead.

I only speak up because I kept hearing "well since you spun bearings on your 305 you should just go up to a 350!" made it sound like it was totally cheaper and easier.

It's not, I'm going to be spending around 1500 for the short block itself, not to mention what I'm going to do to the heads....

If I were to just have my old 305 rebuilt, it would have cost me around 700. More than double for 45 more cubic inches... ouch.

Anyhow, Glenn knows what he's talking about, you should bring the engine into a machine shop and have them check it out for yah and see what they'll advise you.

 

its a 70s corvette 350 engine not my l69

 

Hot tank the rotating assembly? Never heard of that one.

 

my bad... you havent seen my "moldy block" ... that'll explain it all to yah

 

I guess it REALLY depends on how much more is wrong with it and how much more would need to be done. I am NOT bring up the old "dump the 305 and get a 350" argument. It's more of a "check the puppy out, figure out what REALLY needs to be done, and then consider your options".

305s are so dirt cheap and plentiful. It isn't hard to find a good, low mileage 305 short block and treat it as "disposable". Just swap on a heads, cam and intake and then "rev the snot out of it and blow it up". When that engine dies, get another.... A guy can have a lot of fun for a few hundred dollars and a little effort to swap the motor.

He could also luck out and find a good 350 short block as well. Plenty of 90s Truck 350s kicking around too. So what if it has 100,000 miles? Too many guys go after a "high buck" solution instead of a "cheap buck" solution (and get nearly the same results). I guess it really depends on how many bucks you got.

But when I was a "youngster", we use to do that all the time because we didn't have much money and it was cheaper than rebuilding a motor. The only difference, was the engines were 327s, 307s and 283s. 350s were still new and not that plentiful.

 

yea lets not jump ahead of the gun im not gonna replace the whole engine for a topend deal