Hello, I have not been here for a while, but I remember getting great advice in the past so I thought maybe someone could help me out. My 1980 L82, with 80,000 miles started missing and backfiring through the carb. I have it at a local shop. They told me the first lobe on the camshaft is shot (mostly gone in fact) and that I should consider replacing the motor with a crate motor because the missing metal is probably floating around in the engine anyway. They also said replacing the cam with a roller style cam would cost a lot anyway. They did not recommend putting the same kind of cam back in. They quoted me 5k for engine replacement with a 290 HP GM motor. They wouted me about 2,800 for the roller cam replacement. I'm not sure what I should do. Thanks for any advice.

 

Ok couple things, that quote for the 290 GM motor is WAY high. That motor costs less than $2,000 and is a direct swap for your motor, as in they can probably swap it in less than a day.

That quote for the cam replacement is also way high in my opinion, the roller cam should be in the $600-800 range, so they are saying about $2,000 in labor...

How mechanically inclined are you? I'm assuming not super comfortable with it since you are asking here, but in my opinion a cam swap is not that hard of a job, should be doable in a day. I did mine with the engine in the car by just removing the hood, radiator, fan, and condenser for room.

How trustworthy would you say your mechanic is? If the lobe really is wiped on your camshaft, you need to replace it. The real tell is in the oil. If you drain your oil and see some sparkle to it, you have metal shavings and I would be nervous about running the engine. Have you been using an oil with high zinc levels or at least a zinc additive? On these old motors with flat tappet cams, this is required to prevent wiping a lobe.

If you drain your oil and it looks fine, (no metal shavings, run a magnet through it and see what it picks up, check your magnetic oil drain plug if you have one) I would just replace the cam. If you are on a major budget, you can get a better camshaft than your stock L82 one for about $200. If you have the funds, a hydraulic roller cam would be much better (roughly $600-800). If you have the budget for a new motor, I would reccomend the Blue Print Engines 383. It costs about $3500, will make 430 hp (way more than your L82) and will be all brand new (no worn parts like crank bearings, piston rings, etc... in your current motor). It is a pretty easy swap to switch between to small block chevys if you feel like doing it yourself. But a good shop should be able to do it in a day or two of labor.

 

I agree with everything said above.
I would recommend looking at the specifics for the crate motor. Blueprint is a good way to go. That is where I got mine. Be careful with getting too big of a cam in the crate motor if you have power brakes. It will affect the vacuum system overall really. Maybe the 390 hp 383 from blueprint?

I would be worried about the rest of the motor if it has 80K miles and the cam is that bad. What does the rest of it look like? If it were me, I would go for the crate motor.
And get a different shop. Any shop that offers an engine with no details of what is in it I would be weary of.

 

You guys are jumping the gun here. Who verified the cam lobe is worn? What test was done? Usually that backfire indicates a lean condition or a IGN issue.

I would find a new mechanic. If the cam lobe is worn down wouldn't that keep the valve from opening instead of keeping the valve open? And if the valve is not opening as it should, how can it backfire through the carb?

 

Here's how a bad lobe backfires through the carb. When an exhaust lobe wears, the exhaust valve does not open or opens late, this leaves pressure in the combustion chamber that pops when the intake valve is opened!

 

Or vise-versa. More common to hear a unusual note in the exhaust system.

 

It all depends on whether it wiped an exhaust lobe or intake, exhaust lobe pops through the carb, intake lobe is more noticeable in the exhaust sound. There's no info here to doubt the shops diagnosis, but if they are nervous about installing a flat tappet cam, then it seems funny they want to sell the 290 gm crate engine, pretty sure it is flat tappet also. I guess the gm crate comes with a warranty, whereas the shop would have to warranty a cam change on an engine that's 3/4 worn out already. If you're interested in originality, then you might consider getting your engine rebuilt.

 

This photo is from after I cleaned everything up because it had just been sitting for a few years.
Guys, Thank you so much for the quick replies and advice. I have had this car for many years, but I hardly ever drive it. However, it never gave me any problems on the rare occasions that I did take it out. I got it about 25 years ago with 68k miles, and have put just 12k on it since. I've never added any zinc to the oil. Last time I took it out it started the backfiring, but nothing serious. It only did it when I really got on it. So I made the appointment to bring it into the shop. However, driving it to the shop it started missing more and more. According to the mechanic, when they took off the valve covers, the forward most rocker, on the #1 cylinder was not moving. When they removed the intake manifold, they said the lobe was shot and the bottom of the lifter looked damaged too. I am pretty handy with this kind of stuff, maybe novice level mechanic I'd say, so I thought maybe I could just change the cam my self, although I've never done one.

 

It was not uncommon for GM cams from this era to wipe a lobe. Poor cast quality. Heavy backfire through the carb was usually the first indicator. I bought several late 70's Corvettes where the owner was sure the engine was shot. New cam and lifters, good as new. The lobe disintegrates pretty slowly into very fine particles so there are no chunks of metal laying in wait to dynamite your engine.
Your car looks very clean and original. Matching numbers may not mean too much on a 1980 Corvette today but in a few more years, it may. Remember, in the mid 70's nobody cared at all if C2's had matching numbers......Now they ALL do
I agree completely with mobird, the prices you've been quoted are WAY high.
Cam/lifter install is a fairly common and easy job if you're at all mechanically inclined. A good weekend job at home. All the info you need to do this is readily available in any Chilton/Mitchell/Motors manual as well as on line or simply on youtube.
OE type hydraulic cam and lifter sets can be had for around $150. Rollers can be bought between $300-$400. You can certainly spend more than this but with your stock Corvette horsepower there's no need. You'll need an intake manifold, timing cover and valve cover gasket set. And while you're in there, replace the timing chain and gears, seeing as they will be removed anyway. GM bottom ends are pretty resilient so you should have lots of life left in that motor.
Don't spend more than you have to, to correct this problem.
Good Luck, Greg

 

I have to agree with Greg. Cam replacement is what I would do here. Replaced mine during an overhaul and stayed with the stock cam. I did swap heads but otherwise its pretty much stock looking. You might want to plug the oil filter bypass on the filter mount while you have the engine apart to make sure it does not open during new cam break-in. A good filter will protect you.

 

What is your goal with the car? Back when I had engine issues with my 71, I went the route of a ZZ4 engine. If you are happy with the power the car currently has, I would just replace the cam with another hydraulic lifter cam. That is the cheapest thing to do.

My next question is what all are they replacing in the roller cam quote? I know the cam and lifters, could be around $800-$1000 alone. I would expect them to replace the timing chain as well and you will need new pushrod lengths. My roller cam setup I just purchased for my BBC build cost me $1549. That prices is for cam, lifters, pushrods and rocker arms. The roller setup is more durable and less chance you will wipe a cam lobe.

Let me also add, that is the engine in the car is original make sure and get it back if you go the crate route. Some future owner may want the original numbers matching engine and that would help get the most money should you ever choose to sell the car.

 

There are additional (hidden) cost with roller cams to consider:

You will need a cam button off the cam sprocket to keep the camshaft from moving.
You may need a new timing chain cover or reinforce your present cover for the cam button.
You may need a different compatible material fuel-pump push rod.
You may need a different material distributor gear.
You will need new pushrods due to the different height of roller lifters.
(Disregard all of this list with a Flat Tappet Cam)
Just use oil w/ zinc.

 

As the last 2 posts said, a roller cam gets expensive fast, I priced one for my 327 rebuild and with all the extra parts it was close to $2k. I would get a second opinion on the cam being bad. Then if you have the time, replace it yourself. It will be a learning experience. ITs simple to do. Its cheap because you just need a new cam, lifters, push rods if yours are bent and gaskets. you can throw in a better than stock cam that doesnt need high compression or a stall converter and gain alot of fun and it wont be expensive. If you screw it up or the main bearings go then you can look at goiing to a crate motor or a rebuild. A complete rebuild will cost you about $4500 if you replace everything except the crank and heads, (all bearings, connecting rods, pistons, tools to replace cam bearings, etc..)

I would replace the cam and see how it goes and then worry about a motor later and you can look at one that has the roller cam in it

 

 

[QUOTE=mobird;1597843342]If you are on a major budget, you can get a better camshaft than your stock L82 one for about $200. If you have the funds, a hydraulic roller cam would be much better (roughly $600-800). .[w/QUOTE]

mobird, it is apparent that you have a lack of experience when you post. You should not post bad information. Please look things up!

Just add up the price of all the parts required to do a roller cam. Do you even know what is required?

Parts list for roller cam

timing cover with adjustable button.
new double roller timing set
Roller cam and probably bearings
might even need block alignment boring with 80,000 miles
roller lifters, good ones can be $800 +
shorter push rods
Matching valve springs, keepers, retainers, and seals
roller rockers with screw in studs, you would break stock stamped rockers
probably need a valve job with new guides
all the gaskets

I only work on higher end motors, but go to summit racing and price out good parts. I've always told people $2000 just in parts if you want to do it right.
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[QUOTE=gkull;1597848289]Interesting statement....

I definitely only try to respond with accurate info to help others out, especially since this forum has been very helpful to me. I am no professional, but I've done a couple cam swaps and top end builds recently. I by no means know everything, but I don't post up false answers to things I don't know.

What about my above statement was not accurate? I did a 5 second google search and found this: https://www.summitracing.com/parts/c...yABEgK5b_D_BwE now granted, that costs $100 more than my quoted "$600-800" price range for a roller conversion, but I don't think that being off by $100 on my estimate is reason to try to insult someone.

Unless you were trying to argue that there AREN'T better FT camshafts than the stock L82 one for under $200? As I'm sure you know since you work on motors, camshafts have come a long way in design, both in hardened lobes that are more resistant to flattening and in ramp rates. I was suggesting to the OP that if he is majorly on a budget, the cheapest fix for his current situation (assuming a flat lobe is actually the problem) is to get a FT camshaft, and while he is at it he might as well take advantage of some of the newer cam profiles out there.

I have no reason to get into a war of words with someone on the internet, and I fully acknowledge that you have more experience than me when it comes to building motors, but I stand by what I said and I don't believe it was false.

Have a good one.

 

Okay, You are right about the basic kit being $900. but you still need a timing cover with maybe and adjustable button, probably a Torrington bearing between the cam gear and block, cam bearings, screw in studs, guide plates or self aligning roller rockers, probably a valve job, gasket sets, timing cover seal, and last but not least taller valve covers to clear the roller rockers.

Sorry to get on you, but you get nickel and dimed to death when you buy a basic kit. I would not recommend the cheap heavy lifters and cheaper springs that might only last a year or two. Those kit springs could even be of a larger diameter requiring spring pocket machining to fit them.

 

 

Those guys are puzzies if they are afraid to change a FT cam.
Stay away from teh trendy extreme ramp stuff youll be fine, no special sauce needed. Mild ones last even longer
Sure some of us had a few engines way back then we tried every cam in the book on tired motors, nothing bad happened.

Even an Elgin...Crower Isky, etc are just fine. Only had 1 go flat but it was over 23 yrs old, who is to say a roller wouldnt also? Have a XFI 280 with 18k...that went flat. Yup, roller.

 

if your intake ..... is still all off the cheapest route would be a new cam, lifters, spring set. You can do that with the motor in the car.