Adding JAM

[AltaKnight]

I'm considering my options to add a little jam to my TR6 stock motor this spring. I want to keep it mild enough for normal street use but add a bit more grunt.
Having read quite a bit on the forum here I'm planning on upgrading the cam to a GP2 (Goodparts) c/w new lifters. I'm also considering shaving 100 thou on the head to raise compression to about 9.0:1?
So here's my questions.
1) Is the GP2 cam the right one to use, is the GP3 too aggressive?
2) Should I change out the timing chain, sprockets and tensioner while in there, or is the 55K mile old one likely ok?
3) Would just the cam change improve performance much without the CR adjustment or vice versa.
4) If I mill the head I'll need shorter pushrods; is there anything else needed on the valve train which seems in good shape otherwise.
I'm a bit concerned with milling the head to raise the CR since it's kind of irreversible. Everything else is stock including the carbs.
Thanks for the help.

 

[amcboy]

Given the stock sounding condition of your engine, I'd say (IMHO) that you would get more benefit from good headers.

Engines are systems.

If you put in a cam and do nothing to the exhaust and intake the cam's effects on the system will be lessened.

The C/R raise to 9:1 will definately improve things, however as you stated it is not simply reversable.

The stock TR-6 intake is actually pretty good. The exhaust is an area where small changes can benefit.

Even if you just Extrudehoned the stock piece and mirrored the ports, you would feel gains. (IMHO)

In the Detriot musclecar world the idea of simply tossing on a larger carb is popular, but a 900CFM carb does nothing for an engine system that will only ever flow 700CFM...


So, my .02 is really if you simply want the overlap induced rumpety-rump idle, cam away....

Buuuttt, if you really want to improve things I'd change the cam and exhaust (matching them if at all possible, I'll explain below) and shave the head.

Matching a cam: Cam makers have to assume alot of variables, so grind XRZ123 will work when plopped into an engine that has mis-matched bits (exhaust, etc.) for the cam profile.

Now, I do not have experience finding cams made for TRs.

Again: I do not have experience finding cams made for TRs.

But, I have had plenty made for V-8s. Reed cams is one that was very eager to help over the years. Custom AMC cams were $150 or so.

In fact here is their custom cam form.

https://www.reedcams.com/camform.htm

Lots of stuff that most of us (me too) don't know.

But, for street you want a torque cam, not a HP cam.

You feel torque in your butt, and see HP in the speedo.

We have essentially a single-plane intake.

And a stock exhaust is pretty restrictive.

These guys had me measuring header collector lengths...

BTW longer collectors move the torque curve down the RPM range. (Dragging HP with it.)

So after all that drivel here are your points:

1. Dunno the profile of either , so can't answer
2. Change 'em.
3. The cam will benefit from better flow rather than C/R changes.
4. External oil line and roller rockers for ultra-durability, and improved rocker ratios/durability.

 

[TRED]

A turbo would be a better way to go, almost no change to the driving manners except when under boost.
Moss now has the supercharger kits.
https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=47648

 

[BryanC]

You might want to get Kastner's Truimph Prep. Handbook and look at the dyno plots. They show 10:1 CR with stock cam, stock carbs and stock exhaust (early style intake and early 6 to 1 exhaust) improved torque at low rpm and raised power from 103 at 4800 rpm to 112 HP at 4900 rpm. 10:1 CR with his S2 cam (similar to the GP2, I believe) and stock intake and exhaust gave torque about like stock (maybe a little less) up to about 3000 rpm. Peak HP was up to 139 HP at 5700 rpm. Adding a good extractor exhaust raised peak HP to 148 at 5900 rpm but there was a little loss of torque below about 3000 rpm. (Good luck finding a GOOD extractor exhaust. I suspect, but don't have data to prove, that many of the headers out there hurt low end torque without helping power any.)

Bryan

 

[Brosky]

Graham,

TR6 Bill, has done his engine, Tom has done his and I'm doing my spare block with the GP2 cam. I believe that Shawn and Shannon may be close to having the same setup. But all of us have headers, most have triple carbs and all have reworked distributors. There are others who will probably add to this list as well.

To agree with amcboy, there are a lot of other things that can make a change worthwhile, but every little addition adds cost.

The engine has to be able to breath, both in and out, as well as burn the air and fuel efficiently to produce more horsepower. The proper mix of compression, intake and exhaust lift and duration, adequate fuel supply, sufficient spark to to burn it and the right exhaust path to relieve it make it all happen in symphony.

As he said, it's a system, but only as good as the weakest part of the system.

I will be beginning a full illustrated tutorial starting with a complete engine disassembly, machine work done, reassembly and right through the final build, installation and tuning for a TR6 over the next few months.

If you are interested, I'll be posting progress pics here, but will run a full package on my website. Every part that you mention above will be used, along with many others, including the roller rocker assembly.

It won't be the perfect build, but it will be what I want to do. Maybe a lot of your questions will be answered both here and with my project before you spend have to any money one way or another.

 

[Guest]

A turbo would be a better way to go, almost no change to the driving manners except when under boost.

Until the wastegate fails...

At least with a supercharger you can let off and it doesn't run away /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif

How is your beast by the way?

 

[amcboy]

Paul has the right idea:It won't be the perfect build, but it will be what I want to do.


Amen.


BTW IMHO the most important part of my post was: You feel torque in your butt, and see HP in the speedo.


It seems everyone forgets that cars that feel fast (accellerate-fast) generally have pretty low (RPM) torque curves.

Cars that are actually speed-fast have the TQ and HP way up there to overcome.... aw shucks, this post would be longer than the one above...

/bcforum/images/%%GRAEMLIN_URL%%/wink.gif

 

[TRED]

A turbo would be a better way to go, almost no change to the driving manners except when under boost.

Until the wastegate fails...

At least with a supercharger you can let off and it doesn't run away /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif

How is your beast by the way?

Theres a huge number of stock cars with turbos and if you use the car regularly the wastegate should be fine.
The TR6's low compression is idle for boost.

My beast is fine, cranked up the new 487" motor the last day of the season and took it to the dyno, 689 HP to the wheels and there is still a bunch of power left.

 

[LastDeadLast]

OK, my 2 cents:

From your post, it sounds like you'd like to increase power without completely rebuilding the engine. Based on that assumption, here are my comments:

I would go 9.5:1, I'm running 10:1 with no ill effects. I've said this before and I'll say it again: Compression builds power, everything else builds on that one thing.

The GP2 is a nice torque cam. I like it because the idle is just a little lopey but still gives a nice low end punch and still pulls all the way to 5500rpm. With the GP3 cam, you're going to get a lopey idle with less power at low rpm, but a big increase in power from 3000-6000rpm. Consequently, I wouldn't mess with the GPS unless you build your bottom end to support the extra revs... at the very minimum a balanced assembly.

If you change your cam, I would get a new timing chain, sprockets and tensioner. It's cheap insurance.

I wouldn't mess with the cam unless you increase the compression of the engine. Adding a hi-po cam to a low compression engine may even decrease it's power.

I didn't have to run shorter push rods, but I'm running R. Good's roller rockers too. I think TSI sells shortened push rods and a cam that is pretty close to the GP2. A machine shop should also be able to shorten them as well.

With all this said, a GP2 cam or something similar and a pump in compression will give you a nice street-able setup with a VERY nice power increase. The intake and exhaust manifolds are actually pretty good items, although the stock muffler stinks. Replace that first if you start messing with the exhaust. Headers will only help if you keep your engine running above 3500rpms so I would put that item at the bottom of the list.

Other items to look at: Electric fan, roller rockers, dual SU carbs (yes dual, not triple), and an alloy flywheel (one of the best upgrades for a TR6 you can do IMO).

Hopefully this helps!

I'm considering my options to add a little jam to my TR6 stock motor this spring. I want to keep it mild enough for normal street use but add a bit more grunt.
Having read quite a bit on the forum here I'm planning on upgrading the cam to a GP2 (Goodparts) c/w new lifters. I'm also considering shaving 100 thou on the head to raise compression to about 9.0:1?
So here's my questions.
1) Is the GP2 cam the right one to use, is the GP3 too aggressive?
2) Should I change out the timing chain, sprockets and tensioner while in there, or is the 55K mile old one likely ok?
3) Would just the cam change improve performance much without the CR adjustment or vice versa.
4) If I mill the head I'll need shorter pushrods; is there anything else needed on the valve train which seems in good shape otherwise.
I'm a bit concerned with milling the head to raise the CR since it's kind of irreversible. Everything else is stock including the carbs.
Thanks for the help.

 

[swift6]

The GP3 cam is definitely more agressive, I know, its what is in my engine. Shannon covered that one pretty well. It won't idle smoothly below 1100 rpm. Below 1300 rpm idle it has a definite 'bad boy' lope to it. On the dyno, the HP and Torque curves crossed at about 5500 rpm and the HP curve kept climbing, though it was nearly level at that point, right up to the 6000 rpm limit I had set for the dyno operator. Oh, and the toque curve was nearly flat from about 2900 rpm all the way to 5500 rpm where it finally started to drop off.

The grin factor is huge, but with a big cam and lots of carbs, you have to really pay attention to keep the carbs from loading up too much at low rpm, standard traffic slogging stuff. PITA to drive in heavy traffic, total hoot when the road opens before you.

If you do upgrade the power. Do us all a favor and toss the stones you call tires for something that will actually stick and help haul you down safely from the resulting increase in power and speed. /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

 

[TR3driver]

On the dyno, the HP and Torque curves crossed at about 5500 rpm

Exactly 5252, just like every other engine. HP is always (torque * rpm)/5252 so at 5252rpm, HP = torque.

 

[70herald]

4. External oil line and roller rockers for ultra-durability, and improved rocker ratios/durability.

Actually an external oil line will most likely NOT improve reliability. The most likely result of installing an external line is that the bottom end will wear out faster than otherwise. The weakest link on these engines as far as lubrication goes is the BOTTOM, not the rockers.

 

[Guest]

All said and done, if I knew then what I know now, I prolly would have looked into dropping a Ford, Chevy or Buick mouse motor into the chassis with the appropriately beefed-up posterior.

I have done most everything one can do to the darn tractor motor and still don't have the giddyup that I want and still keep it steetable.

Blasphemy, I know.


Shoulda had a V8.


(This coming from an old coot who probably needs some Cialis in his morning coffee.)

 

[Brosky]

Richard Good highly recommends additional oil this for the roller rockers. Maybe with stock it's not needed.

Is there a beefier, higher output oil pump for the TR6 other than the stock unit available from Big 3?

Or is this a case of volume/pressure restrictions due to passage designs in the block/head?

 

[Guest]

I have done most everything one can do to the darn tractor motor and still don't have the giddyup that I want and still keep it steetable.

Sounds like someone needs a supercharger...

 

[Brosky]

Shawn,

The last thing that I want is drivability issues in traffic when I have none now. Do you think that there will be any with the GP2 and 1.55 roller rocker setup?

I plan to go with the GP2 to mimic the design of the TR6 PI engine. The cam specs are nearly the same and compression will be equal, so I'm hoping for decent results with the tri-carbs, headers, ignition and engine mods. Maybe not exactly the same, but I think that it should be close.

 

[LastDeadLast]

Paul,

I've the the GP2 and the 1.55 rockers with no issues other than having to set the idle at 1000rpms. I've had a couple stock TR6 owners that drive my car and all have commented that my rig had much more low end power than their TR6's and that's with an alloy flywheel.

 

[Brosky]

Thank you very much Shannon. My parts order list is getting closer to completion.

I can't post a pdf, so here is a reduced jpg showing the different cams profiles available with the stock on top.

 

[swift6]

Paul, the GP2 should not give you low rpm driveability issues. The GP3 is definitely more aggressive.

I had been told the same thing about strongly suggesting the external oiler for the roller rockers. Otherwise, I agree that its probably not needed. Though I did use one on my stock engine for 60,000 of its 150,000 miles and all the lower end bearings looked fine when I took it out. Probably the difference between a street car and a race engine.

I think the best you can do with the oil pump is to make sure the clearance is spot on. Maximize its capability to pump as much as possible at the appropriate pressure.

Getting back to what AMCboy said about low rpm torque engines vs high rpm horsepower engines. There is a reason LBC's tend to have 'torquey' long stroke engines and it has absolutely ZERO to do with agricultural equipment. The family of engines that the TR6 I-6 comes from has no roots in farming. Neither does the TR2-4 four cylinder. The Ferguson Tractor has an engine shared with the early TR's that originally came from a Standard Sedan.

Small rant over.

One of the major reasons that most LBC engines are long stroke, low rpm, torque engines has more to do with tax structures from the day than performance engineering. The cars were taxed on the bore of the cylinders, not the total displacement. Remember, most of the cars we deal with were economy based sports cars. Even back in the day.

There are a few examples of short stroke rpm engines. The English Ford Kent engines are one. Incredibly stout little, over-square, four cylinders that rev and make power at those higher rpms till the cows come home. They didn't need much torque because they cars they were put into were much lighter than the competitors. For example, my MkII Cortina GT, with a 1600cc Crossflow Kent engine, weighed in at a shade over 2000lbs with all the fluids full. And it would seat four adults in relative comfort.

Lastly for this post, it sounds like Bill needs a Corvette, not a supercharger. For me, one of the biggest identifiers with a TR6 is the sweet sweet sound of that engine. Not the overall performance or lack thereof in some cases. The rumble of a V8 from a TR6 is just out of place for me. But, to each their own. Afterall, some can't stand that I painted my TR6 a non-factory color. /bcforum/images/%%GRAEMLIN_URL%%/whistle.gif

 

[swift6]

On the dyno, the HP and Torque curves crossed at about 5500 rpm

Exactly 5252, just like every other engine. HP is always (torque * rpm)/5252 so at 5252rpm, HP = torque.

DOH, Right. No, what I meant to get across was that by 5250rpm a stock TR6 both the HP and Torque curves dropping off dramatically and meet well below the max HP numbers. A stock TR6 makes max torque right around 3000rpm (and then heads directly to the basement) and max HP around 4500 rpm, then tries to race the torque curve to the basement. With the GP3, the torque curve was pretty much flat from around 3000rpm to the cross over point at 5250 rpm and then began to drop off, while the HP curve kept climbing.

From what I have heard about the GP2 and seen from RG. It makes torque from a lower rpm but still exhibits a fairly flat curve to 5250 and the horsepower climbs to meet it again. Much like the GP3, it just happens at lower rpms.