flywheel to balancer weight proportion- inline 6

[Truckedup]

My expereince was mosty with the 302 GMC inline 6, a bit different with only 4 main bearings but still a very long heavy crank. 4 inch bore, 4 inch stroke.For land speed racing with a rare aftermarket head, the GMC can make 500hp N/A. For the street, I always figured, maybe wrong, that a heavy crank and flywheel would be better at "absorbing" tortional vibrations...Becaue of limited room in the 37 Chevy PU truck,I ran a modified stock damper...The engine made about 230 hp or so, maximum RPM I used was around 4800 rpm,...The engine had 80,000 miles on it between me and the guy i sold the truck to too ,he just stop driving it for what ever reasons..There were no mechanical problems...If the engine is not going to be raced or run a lot at high rpm, the harmonic balancer, may be less of an issue..Or not...

[chevyfreak]

Right now, the plan is to have the timing gear that fits onto the crank snout countersunk 0.25" on the front side so the uncut V-8 dampner will go back as it should. The other way being to take 0.25" off the rear of the dampner sleeve that fits onto the crank snout. I am thinking it would be better to countersink the crank gear so that the heavier dampner will have full engagement with the key and keep the weight as far back as possible. Then bolt a small block Chevy V-8 (short water pump type) double groove pulley onto the dampner hub. To align the drive belts, I can machine a spacer that takes up the needed distance between block and water pump and redrill the alternator bracket to allow it to mount the same distance forward as well. Would need to make provisions to accommodate other accessories if I install A/C or power steering at some point. No plans to do so at present, though. And in any case, will need to bring engine to TDC on #1 cylinder and install a new timing pointer (spot weld to timing cover).

I will give your idea some thought, however. If it will shorten the engine enough to help fit it in my chassis and will not place undo strain on the crank snout, I may give it a go.

Best regards and many thanks to all,

Harry

Yip. 153 is same structure. Over here the 153 were used to an extended usage. Even had an High output version with higher cr and weber carb and intake.

You can still move it closer to timing cover and perhaps still get a single groove pulley in there. Saves you with spacer for wpump and alt. And if need be you can add pulley in front for your accesories.
The reason i went a 2groove pulley is so that my std pulleys can still be used.
I attached pics so you can see. (Sorry for the dirty surface. Was a while ago and in a rush)
Next to normal 250 damper.
Only machining done was the lip on the front of the damper so it clears my fan and then the pulley id.

Chevyfreak.

[inline6]

Yeah Fluid damper ...both places that have made me billet I6 cranks said stay away. That was Moldex and Rody Crankshaft.
Scott

[Truckedup]

Did it on my 153. The original hub were toast. And with the tendency of shaking on the 153, i took a chevy v6 damper and fit pulleys behind it.

Chevyfreak.

My expereince was different..I swpped a 1969 153 into my 47 CJ2A Jeep. The was stock except for tightened up quench and the home made headers in the photo. The stock damper is minimal, maybe 3/8 to 1/2 inch x 6 inch diameter. It did not have shaky idle and with the low Jeep gearing it was always turning high rpm and was smooth, Maybe it was my hillbilly motors... The orignal 134 cube flat head four had no damper and was smooth for what was..

[enigma57]

My apologies. Have been experiencing problems with the server timing out here. Was in the middle of editing my priour post to add a note to Juho and got bounced off the forum here 15 hours ago. Just now got back on......

Juho, my crankshaft weighs about 13 lb. more than the one in your Volvo. Flywheel weighs the same as your flywheel and pressure plate combined, so a bit heavier there, as well. The thing that I can do little to improve with my engine is that it has a relatively small bore (3.875") which limits valve size and breathing and a very long stroke (4.10") resulting in very heavy rods and pistons. Even if I use the longer Molnar billet rods and lighter Ross forged pistons as I plan to...... (This will lighten each rod / piston by nearly 1/2 lb.)...... Each of my rods and pistons will still weigh 1 lb. more than those in your Volvo. I believe the combination of long stroke and heavier reciprocating parts has a lot to do with the harmonics issues these Chevy 292 inline 6 engines are noted for. So I will do all that I can to address this, but will keep redline RPMs under the range where these engines encounter the bad harmonics and count on any improvements to lengthen engine life rather than increase redline RPMs.

Tony, I'm planning on limiting redline to around 5,000 RPMs much as you did with your 302 GMC and my solid lifter cam is similar in (equivalent) duration to your hydraulic cam from what I recall your saying. Yes, I believe a heavy crankshaft and fairly heavy flywheel and dampner if teamed up with lighter rods and pistons should help minimize the bad harmonics. At least somewhat. We'll see.

What you found with the 153 inline 4 makes perfect sense, Tony. The inline 4 with its shorter crank length, shorter stroke and lighter rods and pistons would not need as heavy a dampner as the 292 inline 6.

Chevyfreak, that's a slick looking rig you've got there. I'll definitely give it some thought.

Scott, I agree. The more I hear about the fluid filled type dampners, the less I want to use one on this particular engine.

Well, better post this before I get bounced off here by the server again.

Best regards,

Harry

[chevyfreak]

Did it on my 153. The original hub were toast. And with the tendency of shaking on the 153, i took a chevy v6 damper and fit pulleys behind it.

Chevyfreak.

My expereince was different..I swpped a 1969 153 into my 47 CJ2A Jeep. The was stock except for tightened up quench and the home made headers in the photo. The stock damper is minimal, maybe 3/8 to 1/2 inch x 6 inch diameter. It did not have shaky idle and with the low Jeep gearing it was always turning high rpm and was smooth, Maybe it was my hillbilly motors... The orignal 134 cube flat head four had no damper and was smooth for what was..

Over here in south africa the chevy inline 4 and 6 were used in relabeled gm products. Opel , vauxhall and holdens, so Gmsa made their own mounts(soft compound which makes it shake) and brackets most of the times.
Gmsa even made a 119.6 ci ( based on 194 bore and 153/230 stroke) and a 141.5ci (based on 153 bore and 151 stroke). We never had the 151 iron duke here.

As for the jeep, perfect place for a 153. I love it. Over here its a popular mod in old swb land rover series 1 and 2.

Chevyfreak.

[Truckedup]

The GMC's were solid lifter, .990 diameter....The cam was a one off tight lash reground from a the NOS cam done the by the late Lazer Cams..212 dgrees at .050 lift and ,440 valve lift....The engine had 9.5 static compression, but not the best with .060 quench that gave me some detonation issues with a the large 112 cc chambers even though had a decent quench band. In hind sight a cistom made .035 thick custom gasket might have solved the detonation...The engine idled with a slight lope at 700 rpm, wide power band that fell off suddently beyond 4600 rpm...The head had Chevy SBC 1.94 intakes and 1.6 exhausts ,other than a bit of bowl work, was not ported...I tried a variety of 4 bbl carbs, Holley 390 and 460, but the best results came from a 400 CFM AFB .....The engine seemed to have higher fueling reqirements than a typical V8 when the throttle was opened fully at 2800 rpm or so in the upper gears, 5 speed manual...With the Holleys I had drilled out the PV channels a bit and it helped but the engine was too rich at higher rpms...I had more success playing around with the AFB, maybe it just suited my limited knowledge...I used a water heated intake and when tuned correctly it has excllent street manners and really good fuel milege..But the heated intake did cause some of detonation issues. Full time vacuum advance limted to 12 degrees, total timing was 36 all in by about 3200.I experimented with timing also.I also use a Snow brand controlable water/alcohol injection but I was relutant to flow the amout of fluid necessary to totaly kill detonation with no other changes.And it did not seem to offer a power advange..I was active in Inliners at the time and wrote a few articles about the engine tuning..In the 2900 pound stock looking 37 PU it had no problem beating other old GMC, Flathead Ford or the occasional 80-90's stock 302 Mustang...
the GMC has different combustion chamber design than a 292 so not much of this may apply to your build.....It's certainly more challanging than building a SBC with the huge knowledge base to make it easier....Odd people like odd engines eh?

[strokersix]

The more I hear about the fluid filled type dampners, the less I want to use one on this particular engine.

Why? Please post links or explain. I am not arguing, just want to learn.

As I've said before, I'm running a modified SBC streetdampr on my inline six. If that is a bad choice I want to know why.

[Truckedup]

Over here in south africa the chevy inline 4 and 6 were used in relabeled gm products. Opel , vauxhall and holdens, so Gmsa made their own mounts(soft compound which makes it shake) and brackets most of the times.
Gmsa even made a 119.6 ci ( based on 194 bore and 153/230 stroke) and a 141.5ci (based on 153 bore and 151 stroke). We never had the 151 iron duke here.

As for the jeep, perfect place for a 153. I love it. Over here its a popular mod in old swb land rover series 1 and 2.

Chevyfreak.
[/quote]

The old CJ Jeeps has 5.13 gears and the 151 could sing along at 4500 rpm with no problems.They are used in small boats and are run at high load and high rpm..There are problems with cracked blocks or heads but almost always because the engine was subject to freezing with lake water in the engine or overheating caused by poor tuning..I believe they also did well in midget circle track cars ....Pontiac built the 153 Iron Duke and while it could make more power than the 151 , it suffered from a lot head cracking problems, probably because GM USA trying to save a few dollars

[Dan Timberlake]

It doesn't take much damping to suck the energy out of a resonant system .
A squishy finger tip on a ringing noisy cowbell shuts it right up.

There are several types of dampers that have been used effectively to tame resonant vibrations in industrial systems.

The common car dampers with an inertia ring secured with rubber work best when the the springiness of the rubber and the weight are tuned to REALLY start doing the hokey pokey at the same frequency that the crank wants to wind-unwind. But I bet they do SOMEthing at any RPM that the hub rpm is pulsating plus/minus. Like even when the flywheel is too light and the cylinders too few for even torque creation. Note the sucked-out and dissipated energy turns to heat internally, so running right at the problem rpm conceivably could really heat up the rubber after several/many minutes.

In theory and in practice viscous dampers ( Fluid damper) go to work whenever the hub/shell rpm is pulsating plus/minus and the inner inner weight disk rpm is ~ constant the same as the engine nominal rpm. The greater the plus/minus, the greater the energy dissipation (heat creation withing the oil, just like the heat created with rod and main bearings at high rpm, or the oil being squished around in an off-road motorcycle suspension). If, as reported , Fluid dampers have not performed well, I'm guessing something is going on to bind the inner weight to the outer shell. So the crank saving energy-dissipating shearing action of the oil between the inner disk faces and the shell just ain't happening.

Note the attached image from the Studebaker SAE paper "tsvep451.jpg" equates the end-to-end crank twist when using no damper to a 540 lb-ft torque equivalent to twist the crank that amount. The nominal max torque of the engine is 190 lb-ft with a peak instantaneous value probably about twice that. http://www.epi-eng.com/images/Engine/ET-X-8%20Cyl.gif
The unfortunately timed power pulses nose-tweaks are able to pile on top of each other to twist the crank about 50% further than engine torque could all by itself. Oil shearing action of the bearing and pistons etc may serve to limit the maximum amplitude achieved at resonance. Real life Mechanical systems with minimal damping can vibrate with 10X amplitude amplification.

[Truckedup]

WW2 piston combat aircraft ha serous issues with harmonic vibration at high power . It was mentioned in orders of 1st, 4th etc modes or orders....The vibration dampers were mechanical, hydraulc and some sort of penulum weights, more than one usually..The objective was always the same, move the vibration out of the normal rpm range....

Inline sixes ,at least the US OHV ones, tend to loosen up flywheel bolts when modifed and run at high rpm like drag racing..I had the GMC 302 damper "rebuilt" by Dal Manufacturing.I asked the guy over the phone how he does it..The new elastic is a silcone rubber...Ok, but is that anywhere as effective as the damper was when new...Supposedly the damper rubber is tuned for a particular engine, yes? Or it doesn't really matter?

[PackardV8]

My experience with dampner/snout failures, cam gear fretting, keyway damage, and flywheel/crank interface issues have been the same as yours- terrible!! (I6 265ci) . . . . 1. Spending as little time as possible in the known rpm damage zone (in this case 6200 to 6400rpm) by either short shifting or running through/past as quick as possible

.

The objective was always the same, move the vibration out of the normal rpm range.... Inline sixes ,at least the US OHV ones, tend to loosen up flywheel bolts when modifed and run at high rpm

This has been a forever problem when trying to race a long stroke inline six. Ford's inline flathead six was introduced in 1941. The first attempts at racing it all ended with broken crankshafts. Then. the late, great Clay Smith built and began winning in hydroplane racing with the supposedly terminally flawed engine. When asked how he'd prevented the destructive harmonics, he said, "We run past the problem before it has a chance to develop."

[modok]

The more I hear about the fluid filled type dampners, the less I want to use one on this particular engine.

Why? Please post links or explain. I am not arguing, just want to learn.

As I've said before, I'm running a modified SBC streetdampr on my inline six. If that is a bad choice I want to know why.

Rubber mountings work so well because the rubber tends to act as a very progressive spring. It is like a spring, because the majority of the energy put in bounces back out, but a spring with no particular frequency itself. Am I talking about dampeners or suspension mounts or reducing machining chatter....all. nothing beats rubber at doing that particular trick.
Far as a crank dampener it is true the rubber type work best if tuned to the frequencies of the crank, but they also work well out side that, and most importantly.... they really can't HURT.
A fluid type is more like a frictional damper in that a lot more of the energy it absorbs is converted to friction.
There is a greater chance it COULd hurt, by reducing your power output and/or overheating itself, now or later.
I am sure they use some very special oil, but even then the oil is still going to reduce viscosity as it heats up, and will become sheared thinner with age. so, you don't really know if it's working, and tho they say they don't need to be tuned, they still do. Tuned so they are working in the range where you need to be, somewhere in between doing nothing and overheating itself, which in a modified engine, nobody really knows what that's going to be.

[enigma57]

The more I hear about the fluid filled type dampners, the less I want to use one on this particular engine.

Why? Please post links or explain. I am not arguing, just want to learn.

As I've said before, I'm running a modified SBC streetdampr on my inline six. If that is a bad choice I want to know why.

Hi, strokersix! Firstly, I am no expert on torsional dampers. Just researching them so I can make the best choice for my 292 inline 6 engine.
From my readings...... As you might expect, each type of dampner (OEM bonded rubber inertia ring type, mechanical type such as ATI and fluid type such as Fluidamper) has its pros and cons.

The main advantage of the fluid filled type is that they are said not to need to be tuned for a specific RPM and that they are effective over a broad RPM range. This is why initially, I was leaning towards this type for my 292 build.

However, after reading several links on the subject including the one Kevin posted here earlier......

viewtopic.php?t=31442&start=15

...... I understand that when a fluid type dampner reaches the RPM range(s) where it encounters harmonics issues, internal friction generates heat and this heat causes the silicone based fluid to loose its effectiveness at dampening. This being compounded with each use over time until the properties of the fluid are eventually compromised to the point where the dampner is less and less effective with each use.

This, in addition to the crank snout failures experienced by builders who have commented on various other threads I have researched indicating that the majority of failures they have experienced were with fluid type dampners.

That is why I have decided for my own engine, I will either use the new high perf. OEM V-8 malleable iron dampner I have here...... Or the ATI type recommended by Mr. Molnar when he and I were discussing a custom billet crank for the 292.

This is similar dampner to the one I have here marked 'MALL' (no, I would never beat a dampner onto a crank snout using a hammer as this one apparently was, so please disregard the hammer marks). Just posting this photo to show the type dampner I have here. ......





In short, I came away from my research with the impression that the fluid style would work fine on a 'built' 292 for a while, but with time and usage, would work less and less effectively as the fluid is compromised by the internal friction and heat generated over time. And being hermetically sealed, there would be no way to test nor to change out the fluid.

Considering that this engine will be in a driver rather than a drag car used only for periodic short runs at the track...... Unless I wanted to periodically install new fluid filled dampners based on a 'guesstament' of how long they would last before being compromised...... My best bet would be to go with one of the other types...... And to build my engine to make the most average power below the RPM range where the worst harmonics issues come into play.

Hope this makes sense. I'm not bashing a particular manufacturer's product. Just saying that in my case with this particular engine and its intended usage...... I believe I will have better luck with the other type dampners over the long haul.

Best regards,

Harry

[enigma57]

The GMC's were solid lifter, .990 diameter....The cam was a one off tight lash reground from a the NOS cam done the by the late Lazer Cams..212 degrees at .050 lift and ,440 valve lift....The engine had 9.5 static compression, but not the best with .060 quench that gave me some detonation issues with a the large 112 cc chambers even though had a decent quench band. In hind sight a custom made .035 thick custom gasket might have solved the detonation...The engine idled with a slight lope at 700 rpm, wide power band that fell off suddenly beyond 4600 rpm...The head had Chevy SBC 1.94 intakes and 1.6 exhausts ,other than a bit of bowl work, was not ported...I tried a variety of 4 bbl carbs, Holley 390 and 460, but the best results came from a 400 CFM AFB .....The engine seemed to have higher fueling requirements than a typical V8 when the throttle was opened fully at 2800 rpm or so in the upper gears, 5 speed manual...With the Holleys I had drilled out the PV channels a bit and it helped but the engine was too rich at higher rpms...I had more success playing around with the AFB, maybe it just suited my limited knowledge...I used a water heated intake and when tuned correctly it has excellent street manners and really good fuel mileage..But the heated intake did cause some of detonation issues. Full time vacuum advance limited to 12 degrees, total timing was 36 all in by about 3200.I experimented with timing also.I also use a Snow brand controllable water/alcohol injection but I was reluctant to flow the amount of fluid necessary to totally kill detonation with no other changes.And it did not seem to offer a power advantage..I was active in Inliners at the time and wrote a few articles about the engine tuning..In the 2900 pound stock looking 37 PU it had no problem beating other old GMC, Flathead Ford or the occasional 80-90's stock 302 Mustang...
the GMC has different combustion chamber design than a 292 so not much of this may apply to your build.....It's certainly more challenging than building a SBC with the huge knowledge base to make it easier....Odd people like odd engines eh?

Tony, my 292 will be built much along the same lines as your 302 GMC and should have a similar power band except HP peak should be pretty much flat between 4,500 and 5,000 RPMs then drop off steeply, so little need to rev it much past 4,500 and torque should be nearly flat from 2,000 to 4,000 RPMs if this old dyno program a buddy gave me in 2003 is any indication. Should be a stump puller.

I played with the dyno program a lot using various cam lobes, my goal being to redline the engine at or below 5,000 RPMs to stay out of the range where bad harmonics become an issue. And to cam it so that it would have a broad power band and make the most average power in that operating range, rather than having higher HP and TQ peaks, but less average power where the engine will spend the majority of its running time.

Solid lifter flat tappet cam I had Isky grind...... 210 deg. (intake) and 216 deg. (exhaust) duration @ 0.050", ground on 108 deg. LSA. Valve lift 0.495" for both. Running 1.7 big block Chevy rockers on 7/16" screw-in studs.

For some reason, I was thinking you said you ran a hydraulic cam having 218 degrees duration @ 0.050" (which should perform much like a 210 - 212 degree @ 0.050" solid lifter cam). Must be getting old.

The '63 - '84 inline 6 heads have combustion chambers much like open chamber V-8 heads of 70cc to 74cc volume. There were smaller chambers available in the early 194 engines but all the tests I have seen indicate that you can make more power with the larger chamber heads. Like your GMC, I will be running 1.94" / 1.60" valves and will rework the valve pockets. Will do a limited amount of porting (cleanup and blending mostly) and will cut out the metal the head bolt goes through in the center of the siamesed intake ports and add bolt-in 'lump' kits to the floors of the intake ports. Will run flat top pistons having only a small (12cc) reverse dome to keep static comp. at 9.5:1 and hold quench to 0.045".

Running modified Langdon split exhaust manifolds and 2-1/2" dual (chambered) exhaust. Intake is a Brazilian sidedraught type modified to fit (3) Weber DCNF downdraught carbs. Actually, it is made from (2) of these manifolds, the inboard manifold half being pretty much as cast and the outboard manifold half having had the mods made. There was insufficient room for DCOE sidedraught carbs with proper trumpets, air cleaners or an airbox (clearance issues with my steering column and master cylinder), so I am using two manifolds for the conversion to downdraught and this will give me longer runners whilst 'just' clearing my steering column and master cylinder.

I would like to add water heating / cooling to the intake, as well. Looking at ways of doing that.

Also want to run a V-8 torsional dampner if it doesn't present a clearance problem due to added length of engine. I believe running the V-8 dampner with crank pulley bolted to the hub rather than the inline 6 dampner having the drive pulley grooves as a part of the inertia ring will help with dampening.

Best regards,

Harry