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4JH1T timing gears

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4JH1T timing gears

Postby rabidrabbit001 » Sat Jan 23, 2016 10:38 am

Does anyone have access to a full set of 4jh1 timing gears including the twin scissors gear, and the injection pump timing gear pully that bolts to the corosponding gear?
Like the ones pictured here Image
Image
I am thinking of making this setup work on my 4jg1t setup. So I will need anything that will be related to bolting the gears to the case or block...spacers, bolts, all of it.
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Re: 4JH1T timing gears

Postby Roderunner » Tue Jan 26, 2016 11:06 am

No replies Rapidrabbit! Are the 4jg2 gears not suited to the new engine combo?
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Re: 4JH1T timing gears

Postby rabidrabbit001 » Wed Jan 27, 2016 2:17 am

Roderunner wrote:No replies Rapidrabbit! Are the 4jg2 gears not suited to the new engine combo?

I'm actually running a combination gear combo. 4ja1t cam gear, 4ja1t crank gear, 4ja1t idler gear A, 4jg1t gear B, 4ja1t pump gear. And they all mesh perfectly and the engine runs great. I am looking to use a quieter running set of gears. The 4jb1t gears that I originally ran were extremely loud. I have a 4ja1t gear B scissor gear but the aluminum spacer plug that goes behind the gear is too tall and machining it is not an option since returning to a standard gear would be out after machining. I am unable to source the correct aluminum plug since it is an out of USA part only. Any suggestions?
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Re: 4JH1T timing gears

Postby Roderunner » Wed Jan 27, 2016 12:37 pm

Have you thought about getting a new aluminium spacer machined up by a local machine shop?....
I haven't actually got any experience with the gear drive, but would assume that each engine would get a "matched set" of gears from the factory as there would probably be minor variations in the various gears dimensions/keyway locations after casting and machining. The belt drive is one option, and is fairly quiet and usually reliable if the belt/idler bearings are changed within the specified service interval, but if you have your heart set on the gear drive then maybe you could source the insulated cover that comes standard on the Aus spec. 4jb1T engine if yours doesn't actually have one fitted.
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Re: 4JH1T timing gears

Postby rabidrabbit001 » Wed Jan 27, 2016 3:34 pm

Roderunner wrote: The belt drive is one option, and is fairly quiet and usually reliable if the belt/idler bearings are changed within the specified service interval.

I converted over from belt drive and am not impressed with belt components. The gear drives seem to be the most reliable with the longest service intervals. The term (bullet proof) has been used in reference to the gear drive and direct injection of the 4jb1t motors and that is what I'm really trying to achieve in this setup.
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Re: 4JH1T timing gears

Postby Dinger95 » Sun Feb 07, 2016 6:17 am

Would 4JX1 timing gears work, there is a UK guy on ebay with them http://stores.ebay.com/Internetscrapyard
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Re: 4JH1T timing gears

Postby stardog » Sun Feb 07, 2016 5:22 pm

pretty sure 4jx1 runs double cam shafts 4jg1 and 4jg2 run single cam shaft.
Could be a problem if im right I am not a fan of 4jx1 engines but they do make good target practice for a 458 win mag or a 460 weatherby mag is even better.
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Re: 4JH1T timing gears

Postby Roderunner » Sun Feb 07, 2016 8:08 pm

I just remembered something that might be relevant to your noisy gear drive.....the distance between the centres of the crankshaft/camshaft/injection pump tunnels vary a small amount from engine to engine, I think that using gears off a different motor might result in incorrect mesh when they are mixed together, much like a diff crown and pinion that doesn't have the correct heel and toe- they howl a bit. I wonder if a diff centre specialist could use engineering blue to verify correct meshing?
Another possible cause of valvetrain noise could be caused by unusual engine harmonics which can be transferred from the crank to the valvetrain / drive. This sounds unlikely, but I wonder if the swap to pistons that don't weigh the same as the originals might have upset the engines balance enough to get a vibration going. I don't suppose you weighed the new pistons before they went in?
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Re: 4JH1T timing gears

Postby rabidrabbit001 » Thu Feb 11, 2016 10:08 am

4jg1t and 4jg2t from what I can tell have the same crankshaft and rods.
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Re: 4JH1T timing gears

Postby Roderunner » Thu Feb 11, 2016 4:17 pm

rabidrabbit001 wrote:4jg1t and 4jg2t from what I can tell have the same crankshaft and rods.

I don't know how Isuzu balanced these engines in their manufacturing plant, maybe they weigh the pistons to get matched sets, or maybe they just drill some holes into the flywheel. That's what we're up against when modifying unusual brands/models. If this were a small block Chev or ford engine there would be 10 guys who could pass on this type of information, not to mention at least 10 books on how to hotrod them too.
BUT, where is the fun in doing what 500,000 other guys have already done! :D Unfortunately (or fortunately depending on how you look at it) fooling around with the isuzu diesel engine is fraught with apparently unsolvable problems which really try out ones mechanical aptitude (and attitude), I usually get beaten by the tough technical questions, not finding out the answers until the particular engine/vehicle is passed on to the next owner when I upgrade to something more powerful and reliable. (That's why I purchased the Isuzu)
I only offer the harmonics theory as a possible contributor to the valve gear noise, probably because I destroyed 3 sets of conrod bearings in my last diesel performance build because no-one (including myself) had a clue as to what was happening in the engine via crankshaft harmonics. While I'm ranting (I've been drinking lots of bourbon today), did you peeps know that a 4 cylinder inline engine has a bad vibration band at 3000 and 6000 revs...which is concentrated onto the no.3 bearing, well, now you do, so if you can avoid it don't run your hopped up engine at 3000 revs for an extended period of time (like at cruise speed), also don't shave the flywheel for the same reason- vibration is satan's spanner!
Maybe the gearnoise that you can hear is at the normal sound level, and the change from belt drive to gear drive has made the gear whine more noticable. I can't hear the gear drive noise when I listen to my 4jg2 at idle or at any revs for that matter, but my hearing is a bit dull these days, all I hear is some mild combustion knock at idle, and the fan when it is engaged. I did a short video of my engine running, and posted it on you tube so that you can compare it with yours, Maybe the insulated cover over the geardrive muffles the noise a bit ( that's what it is there for so I think that's a reasonable assumption). This video makes the engine sound louder than what it is when the hood is closed, at 100 km/h I can't hear the engine at all over the tyres and wind noise. The buffeting noise in the vid is the fan engaged, and it dis-engages toward the end of the vid. https://youtu.be/6Xg1pLmCDSY
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Re: 4JH1T timing gears

Postby geeves » Thu Feb 11, 2016 7:06 pm

"did you peeps know that a 4 cylinder inline engine has a bad vibration band at 3000 and 6000 revs...which is concentrated onto the no.3 bearing, well, now you do, so if you can avoid it don't run your hopped up engine at 3000 revs for an extended period of time (like at cruise speed), also don't shave the flywheel for the same reason- vibration is satan's spanner! "
Interesting Surely though the revs this happens at would alter due to stroke and piston mass. My old 4jb1 had a very definate harmonic at 2200 If you search back 10 years on here you will find my posts about it Only know about it because of an intercooler bolt that was too long meaning it was tight be the washer on it wasnt. Between 2150 and 2200 it fair screamed.
As far as Im aware these motors are just built from a parts bin where all parts have been weighed measured etc to within tolerances. They are not race engines and only rev to 4k so thats good enough. As it is modern techniques probably are better on mass produced parts nowdays than an expert blueprinter would of been 20 years ago.
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: 4JH1T timing gears

Postby Roderunner » Fri Feb 12, 2016 11:32 am

geeves wrote:Interesting Surely though the revs this happens at would alter due to stroke and piston mass.

From what I understand the 3000 and 6000 vibration band is inherent in all inline fours, no matter what the stroke or piston mass, and is not really a problem until the engine is being stressed by loads that are beyond the engines design spec, like very high peak pressure spikes.
My old 4jb1 had a very definate harmonic at 2200 If you search back 10 years on here you will find my posts about it Only know about it because of an intercooler bolt that was too long meaning it was tight be the washer on it wasnt. Between 2150 and 2200 it fair screamed.

I don't doubt your claim at all, apparently there is a wide range of harmonics that can affect an engine, especially a diesel. The 4jg2 has a bad vibration at about 1000 revs, so going around a slow corner in top gear nearly vibrates the fillings out of my teeth, not that I like to lug the engine, I'm just trying to avoid a gear change.

As far as Im aware these motors are just built from a parts bin where all parts have been weighed measured etc to within tolerances. They are not race engines and only rev to 4k so thats good enough. As it is modern techniques probably are better on mass produced parts nowdays than an expert blueprinter would of been 20 years ago.

I wouldn't want to work on the later design engines after hearing how careful the assembler has to be, for instance when fitting a head gasket onto a certain late model Ford engine you arn't allowed to leave any fingerprints on the gasket's surface as this contamination can lead to another blown gasket. Finicky to the extreme. I have to say that the 4jg2 is very smooth when operated in the correct rpm band, but the tune plays a part too, injection timing seems to be the biggest factor, not to mention the correct viscosity oil.
There is a lot of info on engine harmonics, it gets a bit indepth though, here's one of the more interesting sites- http://www.epi-eng.com/piston_engine_te ... ngines.htm
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