Timing chain/ Cam reusing question

I guess that sounded like something it shouldn't have. That cam came out of that motor, so the motor and cam both have 5000~ miles or so.

I am not really concerned about streetabililty, for the few months it was running, i have never felt acceleration like that. but then again, i have only driven 4 cars (1991 5.0 stang, 1995 3.4 camaro, 1986 trans am tpi 5.0, and mine - 1988 camaro rs w/ 327 and 5 speed + 4.10's)

How about that timing chain? stretched to much?

If you were me, would you take a 327 with a gm forged crank, forged rods, arp rod bolts, speed pro forged pistons, and 2 bolt mains with arp studs to 7200 rpm???

crane cams is out of business, any suggestions for cams that will get me some good hp/tq numbers in the same powerband without having to change the CR and valve springs???

Biscuit6447 said:

After many many months of adjusting and tuning, and lots of engine oil, i decided to tear my engine apart. The motor is a 327 large journal, 3970010 block, rebuilt in 2007, sat for 2 years, than given to me. It is basically a full race motor, but i didn't know that, so initial tuning was very difficult.

Turns out, 6 of the 8 piston rings' gaps were not 180* off. also, the first initial start up must have sent significant foreign material through the oil system because all the bearings have issues. They aren't spun or extremely worn, but definitely worse than what a 5000 mile motor should be like.

Also, i had horrible blow-by, so i used oil like crazy, fouled plugs a lot, and leaked a lot of oil.

So i am having the shop replace all that stuff, but my question is can i still use my cam after seeing what it looks like?

The distributor drive gear on the cam seams to have significant wear, but all the cam lobes a perfect and smooth.

The cam is a crane cams "saturday night special" cam. #111411 oval track mechanical flat tappet cam. 4200-7200 power band, 292/300 adv. dur, 256/264 @ .050, .545/.563 lift, 105 lsa. according to a chevelle forum i found this cam produces the best ET results in a 1/4 at the expense of idle quality and manifold vacuum.

I have all the lifters organized to go back in the same spots, but i want to know if the gear wear will cause timing issuse, and eventually fail.

As i was tearing the engine down, i noticed that there was excessive slack in the coyles double roller timing chain. (hope the video works)



So do i need a new cam, new lifters and a new timing set???

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The cam's distributor drive gear appears to show a deep amount of wear with a lip present about 2/3s the way down the tooth. If this really exists, the cam is shot. This could be the result of running incompatible materials between the distributor gear and that of the cam. In a competition engine the OEM type steel gear really wears heavily on the cam's cast gear. Although meant for roller cams, a bronze distributor gear transfers that wear onto the more easily replaced distributor gear.

The Coyles looks like it too has taken a lot of wear, so while you're there you might as well replace it. Gear drives are OK for drag engines that aren't expected to run long without maintenance. These drives have a lot of harmonics going on between the crank's and cam's actions that are really hard on the teeth. This would be a big problem for a race prepped engine driven on the street. A high quality crank damper can be of some help here if you use an SFI approved race part such as made by Fluid Damper or the Rattler. The two piece bonded rubber style damper is wholly inadequate to this job if not downright dangerous. A chain driven timing set has the ability to absorb transient vibrations between the crank and cam, but it is a suicide task, as much as they may need replacement, its way ahead of what happens if a tooth on a gear drive breaks or the cam snaps. So this is a place where you've got to decide which issue is the bigger problem to deal with, slightly errant timing or busted major parts. I highly suggest you use a cam thrust bumper, even flat tappet cams when confronted with high RPMs, high amounts of harmonic vibration, and high spring pressures bounce around a lot more than the forces between angled lobes and lifters can restrain. I expect that some of the wear on the cam's distributor/oil pump drive gear is the result of this as the gears have been functioning as a thrust bearing. Using a thrust button will keep the cam in place and relieve the distributor/oil pump drive gears of this task. Everything from the cam, lifters and those backside gears will last longer as might the timing set since it won't see longitudinal twist loads being imposed on it as the cam moves fore and aft in its bearings. An aluminum thrust bearing will last longer than the plastic verity.

Engines such as you have just don't have long life spans, they're like rock stars, they shine brightly, but burn out quickly.

Bogie

Good info, thanks.

I guess i also should have said that when it was rebuilt, it was broken in and then used for a few 1/4 miles passes and 100 miles of street time. THEN it sat for 2 years. So it was already broken in, but i did prime the oil system before i ran it for the first time.

Engines such as you have just don't have long life spans, they're like rock stars, they shine brightly, but burn out quickly. Bogie

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Why do they wear out quickly? If all the part are right, then shouldn't they last? I have had plenty of people say it will last 100k miles if it is taken care of.

I had a mild built 350 once with a gear drive, and i hated it. Also, that motor had 6 spun rod bearing when i tore it apart.

As for my plan with this motor: I plan to use it as a Seasonal driver from may to september (live in Colorado) And during that time, use it as a "weekend warrior" and have it as my fun car. I have no problem putting a lot of time into the engine and maintenance.

Just about everything attached to the motor is aftermarket. The distributor is a procomp, i put in a much better fuel system, all the luxuries have been removed, and i don't ever let the motor go above 190*.

Can anyone suggest a good thrust button? I have need seen or used one, so i don't know which one are the good quality ones.

thanks, josh

Biscuit6447 said:

Good info, thanks.

I guess i also should have said that when it was rebuilt, it was broken in and then used for a few 1/4 miles passes and 100 miles of street time. THEN it sat for 2 years. So it was already broken in, but i did prime the oil system before i ran it for the first time.



Why do they wear out quickly? If all the part are right, then shouldn't they last? I have had plenty of people say it will last 100k miles if it is taken care of.

I had a mild built 350 once with a gear drive, and i hated it. Also, that motor had 6 spun rod bearing when i tore it apart.

As for my plan with this motor: I plan to use it as a Seasonal driver from may to september (live in Colorado) And during that time, use it as a "weekend warrior" and have it as my fun car. I have no problem putting a lot of time into the engine and maintenance.

Just about everything attached to the motor is aftermarket. The distributor is a procomp, i put in a much better fuel system, all the luxuries have been removed, and i don't ever let the motor go above 190*.

Can anyone suggest a good thrust button? I have need seen or used one, so i don't know which one are the good quality ones.

thanks, josh

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The operative word is take care of it. Wear is proportional to dynamic loads on the components. These type loads are proportional to RPM by the square so they get really big really fast as the revs go up. Excersions above 5500-6000 RPM start eating at engine life span very quckly. An engine built to race specs in terms of components and balance can last a very long time as long as you don't exercise the top end too often.

My daily driver is an S15 with a well built Frankenmouse 350 stuffed into it. Frankenmouse as it's an 880 Vortec block with an LT1 cam, stock but balanced crank and rods with forged D dish pistons. The heads were/are LT4s with the reverse coolant passages welded up and redrilled for conventional cooling. The coolant is rounded up externally from what was the vent holes on the ends which are were drilled and tapped for 1/2 inch stainless fittings. The rockers are Miller 1.6:1 mid lift rollers that are not self aligning. The heads carry Isky push rod guide plates. The intake is GMPP LT4, 4 barrel carb modified to accept port injectors and EGR. Injection and ignition is handled by a 1991 L98 Speed Density computer and distributor with a TPiS chip. Exhaust is shorty headers into dual cats and mufflers with a single O2 sensor. Transmission is a mildly built 4L60E.

This thing is creeping up on 200,000 miles since the conversion and so far smogs.

I've built quite a few of these S10/15 conversions which have been pretty similar to this except I don't build Franken-anything engines for paying customers as it takes too long to do and they can be too quirky out in the real world. I save the junk yard dog exercises just for me.

Bogie

DoubleVision said:

Bogie, you gotta be kiddin. You mean you took the time to reweld a set of LT4 heads? If the gain was a 100 horses I might consider it but not for less.

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There you are with piles of stuff and a long holiday with no plans. Next thing you know the Alfa has a small block Ford in it, the Monza ends up with a small block Ford bolted to its Saginaw 4 speed, the GMC S15 parts truck ends up with a Franken Mouse Chevy, the Beechcraft gets an Oldsmobile, the Ford Courier gets a 289 and a top loader, the V-Max gets converted to chain drive, the old Ford pick up with a 292 gets Lincoln 430, the 49 Chrysler woody wagon gets a 440, the Toyota Hilux pick up gets a Olds Toronado dumped in the bed, the old lady's Jag gets a 350, etc. Just can't sit still and piles of odd stuff get my attention, pretty soon the thought, "I wonder if I can do that" gets in my head. Sooo, I crank up the coffee pot turn on KZOK (the kick-*** station) and get to messing around. I love KZOK, back somewhere in the early 1990s Boeing had landed there billionth airplane order in a week. I was out in the shop with the rain pounding on the roof, like that's news around here. Now some genius in city hall back in the 1970s decided that Seattle needed a nick name, so in keeping with everything covered in moss and blackberry vines they decided on the "Emerald City". How original! So the DJ breaks in on the Stones for the news and announces the Big B has more orders than there is aluminum to build 'em, everybody will have to turn in their empties at the recycle center. He concludes this news piece with "Emerald City my ***,,, This is Jet City". For sure dude!

Humm, I've been looking at the wife's Prius thinking that it and the Small Block Chevy by the work bench would look interesting together.

Bogie

Is it possible to find a cam with spring requirements very close to what i already have?? I have found a few cams i like, but i need to know if i need to buy just the cam, or the kit that includes the cam, lifters, springs, and retainers. The cams i am looking at are all isky cams.

I just remembered.... since i had something go through my oil system, i decided to look inside my oil pump. Are the gears supposed to be smooth? Because they seamed to be all scuffed up, and one of the gears has a significant size dent or chip in one of the teeth. It is a high volume pump with taller gears.

can you but replacement gears for the oil pump?? or do you need to replace the whole pump?

Would my 327 be suitable for 7500 rpm? It is a large journal 327 forged crank, arp main studs, forged i-beam rods, arp rod suds (press in with a nut) and forged pistons.

Biscuit6447 said:

Is it possible to find a cam with spring requirements very close to what i already have?? I have found a few cams i like, but i need to know if i need to buy just the cam, or the kit that includes the cam, lifters, springs, and retainers. The cams i am looking at are all isky cams.

I just remembered.... since i had something go through my oil system, i decided to look inside my oil pump. Are the gears supposed to be smooth? Because they seamed to be all scuffed up, and one of the gears has a significant size dent or chip in one of the teeth. It is a high volume pump with taller gears.

can you but replacement gears for the oil pump?? or do you need to replace the whole pump?

Would my 327 be suitable for 7500 rpm? It is a large journal 327 forged crank, arp main studs, forged i-beam rods, arp rod suds (press in with a nut) and forged pistons.

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Gear teeth should be smooth. Just replace the pump.

The cam is better with a kit, especially if you're thinking of a 7500 RPM engine. the reason is that there is more involved than spring pressure. There is also how the spring deals with harmonic vibrations within itself. Two springs of the same pressure may not have the same response to harmonic vibrations in the coils. Harmonics in the spring are sensitive to the wire used to wind the spring and the shape and size of size of the spring. For the wire, the type and grade of the material used , plus wire diameter, and its shape. For the spring; the number of coils, coil diameter, shape, and length have great effect on harmonic response. The response is excited by the rate of lift, amount of lift, and the RPMs of the camshaft. The bending moment of the pushrod, which is another "spring" in the system. The reaction of the rocker which consists of a bending moment and bearing stiction. The weights of the valve, spring, and retainers as well as stiction of the valve in the guide at one end and the weight of the rocker, pushrod and lifter on the other. The effect of getting contol does lead to spring pressure, which is a fair but not absolute guideline to a springs harmonic response. Two springs from different manufacturers with the same extended and compressed pressures may not have the same harmonic responses to the point where with a given cam, one may track events just fine while the other may loose control from the interference of its function by harmonic vibrations. So and especailly in keeping with a cam manufacturer's rather valuable warranty, its a good idea to use their recommended kit unless you have the engineering lab with which to do your own testing.

Bogie