83-84 L69 305 H.O. - Camshaft and Lifter Replacement

Looking at the pictures it’s possible to see the bottoms of several are gone. The rubbing surface needs to be convex on surface shape not flat nor concave which I see on some of them. air the lifter face is gone so is it’s mated cam lobe to some extent extent.

The way these cast iron parts wear is more like grinding the pieces are extremely small to microscopic. There isn’t going to be a flood of pieces big enough to be stopped at the oil pump pick up screen and probably small enough the average 30 to 50 micron filter won’t catch them. So to a large extent these partials are to small to do much damage, where they do it will look more like the mating parts were wet sanded rather than carved and gouged.

As for new cam you can put in anything you like with in the limits of having to change stall of the converter so the high idle RPM isn’t pulling hard against the brakes. That is a condition where even with power disk brakes it becomes physically tiring applying enough force such that the engine isn’t spinning the rear tires while standing still or drags you past the intended stopping spot. This is dangerous as one lapse in concentration or the slip of your shoe on the pedal will quickly put into a crossing pedestrian or cross traffic. So if your Monte has a 1350 stall converter the typical lopey cam with a 900-1000 RPM idle is going to be pulling very hard and the closer it gets to converter stall speed the harder it will tug against the brake till it exceeds the brake’s holding power then the rear wheels will spin if the vehicle is unable to move. The rear brakes being drum this they are not as powerful as the front disks. In the “good old days” doing this at the start of a drag race was known as “torquing it up”. In this condition when the brakes are released the vehicle leaps forward with a vengeance. As Paul Stookey a mid to late 20th century song writer, singer and humorist said in his routine of Mr Business Man meets the Kid at a stop light. A semi quote follows——The car is internally hemorrhaging as Mr. Businessman steps on the brake and floors the accelerator to get an extra fast start.

So to get a cam that provides a lopey idle the converter stall is the upper limit. So with the tight converter you have a 900 RPM idle engine will tug hard against that 1350 stall to get to the idle rpm it wants or the engine well constantly stall at these low in gear RPMs The more you speed the engine’s in gear idle to keep it running the harder the pull as the engine speed closes in on the stall speed. This is not an all or nothing situation. For the most part the factory sets the converter stall speed at about half the RPM of in gear hot idle speed of the engine. So your 305 has a cam that is designed for a 650 RPM idle against a 1350 stall. At this RPM the hydraulic transfer force through the converter is easily held with light brake application. From here the force output through the converter geometrically increases with RPM until the stall speed is met. At that point the hydraulic coupling acts like a solid connection. If the output is stalled as in locked then the engine‘s RPM gain is halted with all the twist force the engine is mustering contained in the converter. Needless to say this is nothing less than an oil filled bomb. A stock converter outer case at the least can balloon from the hydraulic forces, with a big enough power input the converter can be forced to explode in a gush of torn steel and scalding hot if not flaming oil.

So these are the constraints on your desire for a lopey cam. Without a converter stall change you can kind of press into the bottom limit of a cam where the idle picks up a little bit of stagger. That point is about has a cut off of about 215 degrees intake at .050 inch lift. If you tighten up the LSA so it is less than 110 degrees the stagger idle sound is more pronounced for that intake duration. After about 215 @.050 duration things get hairy very fast. While cams in this 215 degree range are sold as acceptable with a stock stall converter this is pushing hard on acceptable drivability.

As far as lifter life and spring strength limits are low the older factory cam designs of the 1960’s where durations are fairly long and lifts are pretty low. These old cams used a lot of ramp to ease the coming and going of the valve train with fairly low lifts so spring pressures didn’t eat cam lobes and lifters.

So basically you can’t have a rough idle cam without a lot of other changes.

Bogie

I agree several lobes look wiped or on their way.

Front cam bearing is pretty worn, just how many miles are on the odometer I assuming the engine is native to the vehicle so vehicle miles should equal engine miles.

Good news is the cam gear thrust face of the block is in decent shape.

I’d put a new more than less stock cam with new lifters and call it good. Adding cam will get you into stronger springs and that nets more load on the cam bearings which are already tired.

Replacing cam bearings on an assembled motor is a PIA as your working blind they have an order of assembly with an oil hole orientation which what you see on the number one bearing is correct for all. The force vector is down so you want to introduce oil just ahead of that point so the oil hole goes in the 3 to 4 o’clock position looking from the front. There is a soft plug at the rear of the cam bore that will have to be replaced. Plus since you can get around the engine and into the back normally closed by the bell housing you might as well do all the coolant soft plugs while it’s easy.

Keep in mind that on installation the torque converter needs to be fully seated in the pump. It’s a good idea to fabricate some brackets that bolt to the corner bolt holes of the bottom cover attachment to keep the converter in place during reassembly. It also can be useful to make some guides from a couple long bolts with their heads cut off to act as guides to align the bell housing to the engine. I don’t recommend threaded stud for this as the exposed threads get caught in the bolt holes of the housing making for a herky-jerky operation.

Bogie

Chevy makes general cast parts by casting number and that is how the general or popular press tracks them though this data is usually incomplete.

When you go to the parts counter you buy parts by part number. Here a particular casting can be finished in different ways and given a unique part number. Think of a casting as a blank slate upon which some different things can be written. Common things you find is a block casting can be finished as a 2 or 4 bolt main which then drives two different part numbers.

Generally numbers that are cast on an item are partial to full casting numbers and can be simply mould numbers or pour time numbers where numbers stamped on an item are part numbers or fabrication dates and end user codes which a common example is found on the engine ID pad at the right front of the block just ahead of the cylinder head. Here you find two rows of date the row shortest in length and closest to the head is the engine assembly plant stamp it gives in code the location of the plant the date the engine was assembled and a two or three usually a letter set that details the engine assembly configuration for a particular end use. Ahead of that toward the front edge of this pad is the stamped partial VIN number of the original vehicle the engine was installed to. This is not done on the final assembly line all of this is coordinated with the assembly lines by production control organizations that map all of this out across the corporations numerous facilities so that all the matching subassemblies arrive at the proper place at the proper time in the proper sequence. None of this in these huge corporations happens by effing accident.

Now for your cam these are always problematic to identify sometimes there is a part number in part or total engraved on the back of the rear journal. But usually what the hobby or professional engine builder does is to use a degree wheel attached to crankshaft or the cam if it’s out of the block on a pair of vee blocks along with a mounted dial micrometer. The micrometer measures where lift begins and ends plus lift while the degree wheel indicates duration. Between measuring intake and exhaust lobes you can determine the lobe centers which leads into calculating overlap, obviously opening and closing points, the Lobe Separation Angle (LSA).

Bogie

If the engine is out of the vehicle this can be drilled.

Start by filing the part sticking up flat, it doesn’t need to be flush with the casting just flat.

Then carefully center punch it, you want this a pretty deep indentation so a drill bit will not wander.

Then measure the depth from a good bolt hole, as these are blind bolt holes and you don’t want to penetrate the casting if you can avoid it.

Starting small with about a 1/16th to 3/32nd put a pilot hole down the center.

Check for center, take your time, we’re trading time for money here, and your learning the needed skill as you go so keep in mind mistakes are expensive.

In two or three steps up drill the hole larger till your at the inside diameter of the bolts thread. At this point there should be nothing left of the bolt but the engaged threads.

Now with a sharp pick shape tool start to peel the old bolt’s threads out.

The problem with easy outs is they want to expand the already stuck threads into the wall around them so they usually break or strip out.

You’re learning the cost we should have talked about in the beginning that the price of working on cars is not just the cost of parts and services but also buying tools as you go along and that includes those to fix the diasaters that you encounter along the way anf those needed to avoid disasters like a damper removal tool and installation tool to avoid hammering the thing to death. The damper is always worked from the hub. The outer ring is essentially glued to the hub with rubber, beating on the outer ring will tear the rubber’s bond if not actually breaking it the result will hinder its function.

1800 ppm is about the upper limit for ZDDP in oil around that point and higher it poisons the oil and stops working the way we want it to. probably 1200 to 1600ppm is the safe range for maximum protection of lobes and lifters.

I always use Isky Rev Lube for flat tappet cams and lifter feet, lovingly rubbed into the lobes and lifter feet not just slopped on. You want to work the moly and it’s suspension oils into the metal’s pores.

Magnets of the super type to large to fall through the oil drain back holes can be spotted in the valley to catch failed rocker bearing material and busted valve spring shards. Back when I was a kid in what then was San Diego County farm country we went to the farm supply store and bought ruminant magnets used by the ranchers to catch metal getting into cattle stomachs. Today all of that is gone under housing developments. Last time I went home was for my mother’s funeral, it’s just too sad to see everything of my youth gone including now my parents place which now is all condo’s, they have a big Olympic size swimming pool where the barn once stood.

Bogie

Tynan918 said:

@2001Blazer4x4 Setting engine timing during break in.

OK, if the engine can't idle whatsoever and has to fluctuate from 2000 to 2500 rpm AND timing should be set correct, does that mean I'm just setting total timing a soon as the engine is started ? If so, 34 degrees is what it's set to ?

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No you don’t need to worry total timing at this point. The object is to get it started and keep it running for cam breakin. All it needs at this point is setting the base timing that is about 10 degrees.

Doing the distributor on the SBC can be a hassle as it has to mesh with the oil pump drive which may not be in position for the distributor to engage it without miss timing the distributor. The correct factory install would have the rotor and distributor aligned as the rotor points to the number 1 cap terminal which points at the number one cylinder. At the same time the vacuum advance canister points at cylinder number 6. Cylinder number 6 is half way through the firing order so there’s some logic in this configuration.

Total timing is a mixture of base, centrifugal and vacuum. Base is what it is, it will vary by cam selection where facrtory cams including factory performance use between 4 and 12. Aftermarket race cams will want from 12 to everything as they get crazier. Centrifugal advance is the weight and spring system in the top of the HEI shaft under the rotor it applies advance as a function of RPM more RPM gets more advance because events happen in less time as RPM increases so once leaving base proceeding to total is an automated function.

Vacuum advance is a function of throttle position in the more closed the the throttle the more vacuum advance is applied because at low RPM the mixture density is low so the distance between molecules of air and fuel slows the burn speed. As RPM picks up the throttle is being opened so the vacuum advance goes away as the centrifugal is coming in.

All of this is done because the cylinder regardless of throttle position or RPM must deliver its maximum pressure on the piston at 14 to 16 degrees After Top Dead Center (ATDC) of the power stroke. Anywhere else early or late to that point results in poor running through a bunch of crappy characteristics including poor fuel mileage, detonation, low power, overheating, high vibration, etc.

Bogie

Tynan918 said:

OK, so right at start up I just keep it steady at 2000 RPM and just turn the distrubutor until I get it running smoothly and continue the break in process ?

Or quickly set initial timing to 12 degrees BTDC and continue the break in process ?

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It’s best to be positive of your timing position before cranking it up. Once running it’s fine and usually necessary to adjust the timing so the engine runs smoothly. Tuning isn’t a network one shot, you’ll be back to fiddle it in more than once as all of this goes along so don’t worry the knat‘s details on fire up these will change some as you go through tuning.

I usually aim for some thing in the range of TDC and about 10-12 degrees. At this point your visually aligning the rotor to the the cap terminals with any idea where the high voltage will jump from rotor to terminal so at this point your setting is a close approximate but probably not exactly on. It’s always like this and always has some fluctuation which is one of the why’s that the industry got rid of distributors and went to computer controlled coil-on-plug as that removes the mechanical and electrical timing variations. another result from this configuration is each coil has the time of two crank revolutions (720 degrees) to rebuild its magnetic strength where a common coil firing 8 cylinders in 720 degrees only gets the time to rebuild its magnetics in 90 degrees of crank rotation.

These being a couple of the reasons Gen 3 and up engines make so much power as among many olther improvements their spark is on time and strong every time at all engine speeds. The mechanical distributor, as much as I love them, just can’t come close to that.

Bogie

I use and have for decades run diesel oil in everything from the Harleys to the lawn mower. Most often Chevron Delo but frequently use Shell Rotella or Mobile Delvac. But their heavy loads of ZDDP from the past is going down as is their viscosity since catalytic converters and efficiency mandates came to the trucking industry, so I’m not sure it makes much difference anymore.

GM used to Parkerize their cams but dropped it in the 1970’s as a cost cutting measure and they stopped using their hard faced lifter, since then cam lobe and lifter wear has been a thing. The only stop gap has been ZDDP which was an oil additive since WW2. This got them a class action suit which they prevailed against in a Michigan Federal court, similar to how Harley prevailed with the suits over their early twin cam engine’s cam drive problems. I have one of those, a 60th birthday present from my wife, it runs S&S gear drive and Andrews cams instead of the chain drive Harley used. The not so funny thing is Harley would honor their warrantee on the cam drive failure then turned around and told me if I fixed it myself it would void the warrantee. Leaving me stuck with a one year old unusable 18000 dollar bike with the options she put on it for me. So I figured if they won’t warrantee the cam drive, I’ll fix it myself since the warrantee didn’t appear to have any value. Anyway I still have it and in the 23 years I’ve had it though it really doesn’t have many mikes for its age it‘s never had any other problems.

Bogie

Tynan918 said:

Ok, so there is no specific position the crankshaft or camshaft needs to be in to install the camshaft or I need install it with the crankshaft in a specific position, like TDC ?

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The Chevy has a trick up its sleeve, not as bad as the Ford Y blocks with 12 chain pins between the timing marks or the International V8 timing on cylinder 3 instead of one but the Chevy is a little goofy nevertheless.

In the number 1 cylinder starting the power stroke from TDC the crank and cam gears are in the noon O’clock position putting a fair amount of distance between them to set their alignment.

The trick to simply get straight across from each other timing marks is to set up for cylinder number 6 sitting at TDC of it’s power stroke. This has the crank gear mark at noon and the cam gear mark at 6 O’clock. So now your set being able to eliminate guessing about gear timing marks no fiddling and assuming the gears are synchronized as now you can plainly see it. Then you rotate the crank one full revolution to where TDC again appears so now it is timed for the number 1 power stroke.

Remember that number 6 is exactly half way through the 720 degtrees cycle from number 1.

Bogie

Tynan918 said:

Should I soak the lifters in oil ?

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Not needed. Way more important to put EP lube on their base and just oil or assembly lube on the body.

Pumping them up can make life difficult if you don’t know what to expect when setting them up the first time as they can take some time in a non running engine to bleed down to your pre load position. When you first crank the engine up they may hold the valves off the seat till they bleed down which will make the engine difficult to start complete with fire works out the intake.

The technique is to install just with external lube as I previously described. Going through the firing order one cylinder at a time with both valves closed so your on the power stroke but beyond overlap to insure both are closed. For each in turn your gently capture the push rod between thumb and index finger to rotate the push rod back and forth till it just offers resistance to being rotated. Then you adjust the number of turns the manufacturer recommends. This will on initial crank up allow the plunger to at first sink onto its internal seat, this allows enough valve open motion to fire the engine. Once the engine is operating on its own engine oil pressure will fill the calibrated void under the plunger moving it to the preload position you previously set.

Then you check for top end oiling and button it up once you satisfied enough oil is splattering out the push rod ends of tge rockers to keep everything oil wet.

Bogie