adjustable timing gear sprocket

newby here, hello all, have a ? about timing gear sprockets. building new engine,putting in isky z-19 cam,do i need an adjustable timing gear sprocket??? the block is new,head to be shaved to 3.402,reworked valves,stock lifters,stock rockers,dual downdraft webers,free-flow dual exhaust, new crankshaft, and i quess i need to mention vehicle, 74 tr6 ,new block is a 76,----am new to forums so do not know protocol,be patient, thanks, allen.

Wow, sounds like a great motor. Opinion: if your cam were manufactured to be in time, you would not need anything other than line up marks. However, there seems to be many cams manufactured where the line up just does not come up to near perfect. When I changed the timing chain, I installed new timing gears (just as I presume you would). Keeping the idea of purchasing new gears in mind, I would select adjustable ones. What is the $ difference?

the kent duplex gear i looked at on the web was 279.00$ from moss the stock gear is 57.00$ that's quite a jump don't you agree?? but if the thing keeps my engine running smoothly for a longer period of time maybe it's worth it. thank u for reply allen.

Hi Allen,

Stock TR timing gearsets were pretty good and had enough adjustment in them to usually get within 1 or 2 degrees or so of perfect, sometimes better. However, some aftermarket gears aren't nearly so good. (Kent is a good brand, though.)

Personally, I think the adjustable sprocket is a good item to install. But, that's just me. Yes, it's quite a bit more expensive, but allows for highly accurate cam timing.

Now if it were a matter of making some choices, where the money might be spent elsewhere, I'd prioritze headers, porting and maybe a few other improvments higher than an adjustable cam sprocket.

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thanks for the reply alan, the info i recieve here is highly regarded, instead of the adj. t. gear, i had in mind some roller rockers. can't afford goodparts tho, i saw some on e-bay that you could put on your existing rocker shaft, don't know if u know of these, but if anyone has these,or used these before,what do ya think?? thanks for reply's. allen

Hi Allen, I'm new here too. When you put the engine together get a degree wheel and a dial gauge and "degree" the cam according to the instructions that came with it. Isky should have a spec for ya'... If you can get it right with the stock timing gears... you don't need the adjustable gear.
Now, if you're racing with a wild cam, you're gonna want to mess around with the cam timing .. then you need the adjustable gear. And a dyno to figure it out!

Good luck and have fun. /ubbthreads/images/graemlins/thumbsup.gif

hello rusticus, good to meet u, any kin to sparticus? allen.

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hello rusticus, good to meet u, any kin to sparticus? allen.

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I'm his "country cousin"! /ubbthreads/images/graemlins/wink.gif

See the rest of my post above. Hit the button too quick.

thanks rusticus, i have someone who is going to help me index the timing,and i will watch closely. as far as the cam is concerned, i looked up cams for the tr6 without having to use cam bearings, and the one that i think i'll use is the isky z-19. i would really rather use the goodparts gp-2,but i have a budget that says isky. thanks for the info, too bad about ol sparti, we'll get them romans next time!!!!! allen.

just remember that if you change the chain you SHOULD change BOTH timing sprockets.so when you look at the cost of the kent timing set (does it come with both sprockets and chain?)it might look more reasonable.adjustability just makes it easier and more exact.also your engine may respond to a different timing than recommended so it gives you options.i do not agree with others about re-using timing sprockets, especially with a hopped up motor like yours. /ubbthreads/images/graemlins/square.gif
rob

Hello Allen,

you may be aware but no body has mentioned that the Triumph timing (cam) sprocket can be fitted four ways each with a small increment of adjustment. The four holes are not at ninety degrees so you can use a choice of two of the four holes and turn the sprocket back to front all giving a slightly different timing, simple and effective.
This engine benefits from a six-three-one (or two for the standard TR6 exhaust system.) exhaust manifold rather than six to two or six to one.
I wonder why you are going to downdraught carburettors? You gain no power and lose flexibility over the standard instruments?

Alec

Allen, The webers will be good--------another Allan on this site! perfect---this should be enough to drive Tr6Bill crazy!.

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i had in mind some roller rockers. can't afford goodparts tho, i saw some on e-bay that you could put on your existing rocker shaft... but if anyone has these,or used these before,what do ya think??

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Hi again Allen,

Be a little careful about roller rockers. At least, they should be installed on a new shaft, preferably a hardened one, and probably are best fitted with spacers instead of the orignal springs.

Most of the alu rollers I've seen on eBay and elsewhere in the U.S. are Harland Sharpe. These are moderate quality, from what I understand, and I plan to install a set in my TR4. Apparently there have been some failures in serious, hard drivin' and high revving racing, but they are good enuf for street and the occasional auto-x.

Cambridge Motorsport in England has neat double rollers, but talk about pricey! Racetorations, RevingtonTR and other Britsh suppliers have other rollers too, but also are quite expensive.

Do watch out for increased ratios. Stock TRs came with about 1.45:1 ratio rockers. 1.5:1 or 1.55:1 (most H-S are this) are okay and you don't need to worry about clearance problems or messing up the timing of the nice, new cam. More radical 1.65:1 or 1.7:1 rollers can get ya in trouble.

Harland Sharpe rollers use a bushing against the shaft. IMHO, that's a good thing. Some rockers went to needle bearings at the shaft, and that was all the rage for awhile. But, but with the type of motion rockers go through, needle bearings actually caused a lot of problems, more wear wear and gouging on the shaft. Some of the very latest and greatest roller designs are now going back to solid bushings, in some cases with special low-friction coatings, etc.

All this about roller rockers, and I haven't mentioned probably the most important thing. Rollers will give only a little improvement in performance. They will mostly make the engine a little quieter running and will be less stressful on the valve guides. The only real power gain is a little less friction, and that's minimal in terms of HP. In terms of dollars to HP gain, rollers are not worth it. In terms of engine durability and reliability over time, they are more valuable (assuming a good installation and proper geometry... i.e., you probably need to change pushrods too, to accomodate a new cam, head milling, different rockers.)

Try Ted Schumacher at TSimportedautomotive.com. He seems to have about the best price on roller sets for Triumphs. I checked with him and the TR2/3/4 rollers he offers are Harland Sharpe and 1.55:1 ratio.

It's too bad we can't just adapt a rollers set from small block Chevy or Ford, since they are much cheaper and there are a great deal more brands/styles to choose.

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Allen, I ran Goodparts roller 1:65 with a stock cam and upgrade springs with no problem and there was quite a noticible difference in power, with an Isky cam it probably wont make too much difference. I had ordered the Cambridge rollers before the Goodparts and had to send them back (that was a costly mistake) they didnt line up right with the valve stems. If you havent considered cam bearings,it is a must to install cam bearings for the set up you will be running.

Another 2c in the pot for you.

I agree with ALLAN here. If you haven't done it already, cam bearings are going to be one of the best changes you'll make in terms of longetivity.

You'll also likely do better spending $ on a guy with a flowbench and backcut valves than roller rockers - especially if $$ is a consideration.

One other unsolicited piece of advice about the carbs - If you don't already have them read this. If you do, don't. You'll be able to go trips ZS for the same $ as webers if you have the stock two.

https://www.6-pack.org/modules.php?name=F...de485a36740aa79

Again, mo only. Good luck.
Alan

My last two TR6's had DGV Webers on them. I have but one word to describe this setup....yawn.


Bill

Hello all,

I found Alana's link very interesting. Can anyone tell me what the timing is on the GP2 cam as it seems to perform quite well?
Also the other interesting point was that the poster's engine ran better for him at idle on points than the popular modification of Pertronix ignition.

Alec