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Location:
Castle Hill, Sydney
Registered:
February 2004
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Location:
Castle Hill, Sydney
Registered:
February 2004
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Re: why does my 3tg act like a 3tc
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Sat, 11 September 2004 08:49
 
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by the way
did a compression test on it a couple hundred km's ago
got roughly 140psi from each cylinder
i think a run in engine is around 160psi
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I supported Toymods
Location:
Perth, Western Australia
Registered:
December 2002
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Re: why does my 3tg act like a 3tc
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Sat, 11 September 2004 09:59
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Might help if you incl;uded induction and exhaust info, timing info, build info, ..., more info in general. You wont gain 20psi once the engine's run in, what pistons, compression or head did you use?
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Location:
Tasmania
Registered:
May 2002
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Re: why does my 3tg act like a 3tc
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Sat, 11 September 2004 10:16
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I have a 3T-G. I estimate it has about 160hp. Does a 15 second 0-400m in my 940kg car.
This is with:
3T-C pistons, 1mm over = 86mm
2T-G 88222 head
Wade 305.5 degree camshafts (this is where the real difference is) timed to about 105 degrees.
lightened stock flywheel (makes a difference in acceleration)
Solex Mikuni carbs, old gen. 40mm throttles.
Jets 160 airs, 160 mains, 57.5 idles
32mm main venturis
Ignition: 2T-GEU distributor, standard, vac advance not working, base timing at about 12 degrees. Nothing special here.
good power from 3000-8000rpm. Works best from 4000-7000rpm.
This motor has 150psi on all four. (Expect a higher number with stock cams). Compression ratio is about 9.9:1, or maybe 10:1. Also have Iridium plugs, not sure of the difference. Run premium fuel 97? Would run Optimax if I could get it.
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Location:
Land of Oz
Registered:
June 2004
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Re: why does my 3tg act like a 3tc
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Sat, 11 September 2004 10:18
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Hi,
Are the carbs set up properly? No leaking gaskets on them? Also, how's your ignition? Has the engine been to a tune-up specialist and run on a dyno to see what's happening?
You got carbs, then take it to Kleinigs. I took my car there, and it was running like crap, but now it's a little beauty. Worth every cent.
seeyuzz
river
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Location:
Tasmania
Registered:
May 2002
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Re: why does my 3tg act like a 3tc
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Sat, 11 September 2004 10:21
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Yes, a ordinary 2T-G will only be as good as a good 3T-C. What can you expect? The 2T-G has bigger valves, no rockers, and sidedrafts. So if you can rev it cleanly to 7000rpm then the sidedrafts should suck in more fuel/air then the 3T-C carb, and give more power. But, it needs to be running right.
Kepp trying things. You will probably need to take the carbs apart, work out whats what, make sure you have some good linkages (not the dodgy ones you are using), and learn to ballance them. Then, after a while, you may learn to select different jets to tune it right. This takes alot of trial and error sorry. Few mechanics can do it so you will have to learn yourself. 
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Location:
Castle Hill, Sydney
Registered:
February 2004
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Re: why does my 3tg act like a 3tc
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Sat, 11 September 2004 10:38
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yeah, it aint a 2tg! it has to have more power there!
1812cc
88260 head, fully rebuilt (polished ports, lapped valves)
10.05:1 compresion
twin dellorto 40mm sidedraughts ramflo foam filters
(32mm chokes, 150 mains, 24o air correctors, 35 pump jets, 60 idles)
288 degree cams 34/74 overlap
bosch GT40 coil, ignition is at 12 degrees, NGK BP6ES plugs
genie 4-1 extractors 2 1/2 inch to first muffler than 2 inch
ACL 3t pistons and rings (86mm bore, 1mm oversize) brand new
new bearings, crank was ground
all in a 960kg T-18 + me 65kg
EVERYTHING has been stripped and if slightly damaged, replaced! everty single part was in prime condition when we built it
so i dont think its any components letting me down.
i've put through a couple tanks of optimax, not a big difference
we are alright to tune the carbs, been silver soldaring/drilling jets here and there last couple of weeks, according to exhuast gas anyliser its made a big difference but not much change in performance, have been having trouble with one bit inparticular, when i punch it it gets VERY rich but i think we fixed that today...by bringing down the mains from 170 to 150
i've tried so many things, no noticeable differcnes anywhere, quite sure its not iginition, i was running 3tc coil but changed to the gt40, didnt make any difference...still running the 3t-c points distributor though
could it be the engine timing? it's the only thing i havent experimented with since ive had the engine running.
only problems we've had is some chronic running on, and cylinder 1 wasnt fireing but gapping plugs again seemed to fixed that
linkages work fine, im definately getting full throttle when my foot plants
maybe im expecting more out of it than it has, but this engine should spank the pants off what the 3tc had, it pulls really well at around 3500rpm, so it should have twice the balls it has there up high, especially with those cams! shouldnt it?
i had a go along side of a modern stock camry, couldnt get in front! shifting around 5 grand.
maybe i should take it up to 7000rpm and see what happens, but at about 5 grand it sounds like im forcing it and it doesnt wanna rev any harder! hence me not wanting to take it on a dyno or a drag strip yet!
this pic is the engine at the moment, only difference since i took the pic is i took out the resistor on the ignition to bring it up to 12v, that didnt make a differnce either.
[Updated on: Sat, 11 September 2004 11:17]
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Location:
Castle Hill, Sydney
Registered:
February 2004
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Location:
Tasmania
Registered:
May 2002
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Re: why does my 3tg act like a 3tc
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Sun, 12 September 2004 02:07
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OK this is very interesting to me. I have almost the same motor, and mine goes very well. Mine has bigger cams, but yours should go almost as well.
The difference is, mine can ONLY be driven at part throttle up to 3000rpm. And the power comes on strong from 3500 - 7000rpm. Plus it will freely rev to about 8000rpm, depending on the day.
Thie difference is cam timing. I have mine set roughly to 105 degrees on both intake and exhaust (home made degree wheel, not very accurate). This is very mild and has good torque and is very driveable. A standardish motor will have the cam timing set to about 110 degrees, torque will come on early but it won't rev. A more race orientated engine will have the timing closer to 100 degrees.
Your 288 degree cams with 34/74 timing, are set at 110 degrees.
(288/2) -34= 110
Reset the cam lobe centers to about 100 degrees (or 104 degrees if you want to try something conservative first). This will give you more overlap, and open the engine up for good rpm.
In your case this will be 44/64 timing for 100 degrees.
I'm not yet an expert on this, but this is the best info I have from what I have read, and seams to fit with my experience.
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Location:
Tasmania
Registered:
May 2002
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Re: WHY does my 3tg act like a 3tc
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Sun, 12 September 2004 02:12
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Don't go by the notches in the cams. You have regrind cams, you NEED to set them up with a degree wheel, and a dial gauge, and someone that knows how to do this. Don't go by marks on the timing cover either, you need to find where true TDC is again.
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Location:
Castle Hill, Sydney
Registered:
February 2004
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Re: WHY does my 3tg act like a 3tc
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Sun, 12 September 2004 07:26
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yeah we set them to 34/74 when we built the engine
with a dial gauge and a degree wheel and everything
but thats going to be a little hard to do now with the engine in the car isnt it :S?
should i just try advancing intake a knotch and retarding exhuast a knotch and take it for a spin, then if it improves repeat process until i find the best overlap?
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Location:
Tasmania
Registered:
May 2002
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Re: WHY does my 3tg act like a 3tc
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Sun, 12 September 2004 08:18
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Yes you can try that. (I think I will try that myself actualy!) But realy, we should be able to get a degree wheel in there and to it propper. Just take the fan off and you should have room.
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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 Re: WHY does my 3tg act like a 3tc
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Mon, 13 September 2004 01:59
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Jesse,
Before you start repostioning your cams at random keep in mind you are dealing with a full impact engine.. IE if your cam timing is out your valves and pistoms will attempt to occupy the same real estate at the same time.. This is generally considered a Bad thing !
Not to sound harsh but I would tend to suggest you are way out of your depth with the Carby set up and itgnition timing. These need to be set under load (ie on a Dyno) and whilst your backyarder style home mechanic may think they can get it right they very rarely do !
A good tune will probablt do the package wonders as it sounds like it should be a good thing. Frank Kleinig would be your man to Tune it and regraph your dizzy ! It won't be cheap but performance is never acheived by the lowest bidder !
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Location:
Castle Hill, Sydney
Registered:
February 2004
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Location:
Hornsby, Sydney
Registered:
October 2002
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Location:
Castle Hill, Sydney
Registered:
February 2004
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Location:
Castle Hill, Sydney
Registered:
February 2004
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Re: WHY does my 3tg act like a 3tc
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Mon, 13 September 2004 09:30
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i dont suppose u know what sort of overlap those cams orignally had?
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Location:
Tasmania
Registered:
May 2002
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Re: WHY does my 3tg act like a 3tc
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Mon, 13 September 2004 13:22
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I have already given the info. Most standard motors will have about 110 degrees between TDC and the center of the cam profile. If you don't know what that means, do some general searching and read up on twincam cam timing. Do lots of reading. Learn the effects of longer duration, different overlap etc. I havn't much experience, but if you want the top end power, set it closer to 100 degrees. But I suspect you have other problems also. Maybe your gas analizer is not reading in a good range, and maybe the engine wants to be a bit rich when you have your foot down. Take note of the jet sizes in my motor, its runs ok, not perfect.
2T-G = 110-115hp
2T = 80hp?
3T-C = 90hp?
3T-G with cams etc. = 160hp
A 2T-G has a greater rev range than a old Holden, so its a bit different. Plus with the 2T-G you can vary the cam timing individualy as you now know.
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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Location:
Land of Oz
Registered:
June 2004
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Re: WHY does my 3tg act like a 3tc
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Mon, 13 September 2004 22:36
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Hi,
Jesse, Rod (El Presidente - Pretty Boy) is right on the mark with this one. As you know, I've got an 18RG which is very similar to the 2TG engine, and over the years I have taken it to many tune-up shops and it's never performed as I would expect. Actually, I was a little disappointed at the performance of the engine.
I bit the bullet and, upon many recommendations, took the car to Frank Kleinig Motors, and, as you have seen my posts, the engine now goes like a little ripper.
Trust me, spend the dosh and get Frank to do it. He knows the old Toyota twin cam engines and their carbie set-ups. He knows the Weber, Solex and DeLorot carbs - 'cos he was talking to me about them. It cost me about $750 to get the carbs pulled down, rebuilt, plugs, points, and dyno tuned. The best money I have spent on the car so far 'cos it's like a new engine. It took about a week for him to do it.
Frank's number is 9896-3672, and he's at 5 Amax Avenue, Girraween.
I'd love to see 2 new posts from you. The first post is "I took the car to Kleinigs", and the 2nd post "Got the car back and I cannot beleive the grunt my engine has!" 
Go on, do it! We all want to see your T18 tearing up the bitumen and scaring women and children almost as much as you do. Hey, I'd like to come over and check it out when it's all done.
seeyuzz
river
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Location:
Castle Hill, Sydney
Registered:
February 2004
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Those in the know.... Know