• The Roadster Factory Recovery Fund - Friends, as you may have heard, The Roadster Factory, a respected British Car Parts business in PA, suffered a total loss in a fire on Christmas Day. Read about it, discuss or ask questions >> HERE. The Triumph Register of America is sponsoring a fund raiser to help TRF get back on their feet. If you can help, vist >> their GoFundMe page.
  • Hey there Guest!
    If you enjoy BCF and find our forum a useful resource, if you appreciate not having ads pop up all over the place and you want to ensure we can stay online - Please consider supporting with an "optional" low-cost annual subscription.
    **Upgrade Now**
    (PS: Subscribers don't see this UGLY banner)
Tips
Tips

62 tri-carb tuning question

  • Thread starter Deleted member 21878
  • Start date
D

Deleted member 21878

Guest
Guest
Offline
has anyone out there with a tri-carb ever measured the distance of the jet tube to the bridge?
i realize all engine run a little different but i want to know i am in the ballpark on my set up.

Thanks
 
OP
D

Deleted member 21878

Guest
Guest
Offline
steve
Thanks. i have read in the manual. guess it would help if i said why i was asking for this info.

back when i first got the engine running, i had set the mixture screws 2 turns down as the manual said. the manual also says to adjust to get the fastest idle after that but i got caught up in setting the timing and watching the engine temp so i never really did a lot of adjusting from there. the engine ran fine and idled fine so i was not in a hurry to try another change.

the engine temp had me wondering though. one thing that can affect the temp is running too lean. (my plugs were sure looking quite clean) So in an effort to help my temp concerns, i started to make the mixture richer. i adjusted out a little at a time until i felt the idle was really starting to suffer. then i adjusted back in one flat.

as a base line i had measured the distance to the jet from the bridge when i started (two turns down) and also made sure they pretty much matched from carb to carb. as i adjusted the carbs richer, i also pulled the tops and check the depth of each jet.

a lot of other things along the way but fast forward to this past week. my engine has been running cooler. because of some things i have done? maybe... but i think it has more to do with the engine parts starting to seat. in fact lately on longer runs the engine would run cooler at the end of the run than the beginning.

As i am now getting close to my 500 mile mark on this engine break-in, i thought maybe it was time to adjust the carbs back to where they probably should be. i knew i was running rich. even the plugs showed it now. So i ordered a colortune plug as an extra check for getting the correct mixture. i have never had much luck just lifting the piston and removing the brearthers is a real pain. on saturday i tried the colortune plug. i starting adjusting the mixture leaner until i was getting blue in the glass. i did a few plugs. balanced the carbs and used the colortune once more. the car idled much better, started great when it was warmed up and seemed pretty good on my test drive. maybe not quite as much punch on the accel side but it rev'd easy and ran fine. a couple miles from home, i glanced at the temp gauge. it was about 200. it has not run that hot for a while. when i shut it down, it went to almost 230. again not done that in a while. usually any more, it never runs over 195, usually 190 or a little less. and when i shut it down it might get to say 220. but that is it.

So my first thought was, running too lean? then i wondered, if after the two turns down, do most people have to go a flat or two more, maybe 3? I figured it was easier to ask if anyone knew how deep they set their jets. then i could compare easier.

my engine is still pretty new and maybe it needs to be a little rich to help offset the tightness. also i am running with my valve lash at .015. could the setting be letting less of a fuel mixture in on the cycle and causing some of the heat?

anyway, i was curious if anyone else had taken a measurement to see if maybe i should go a little richer than the colortune plug was showing me.

my engine has run pretty well at all these settings. it does not backfire, it does not miss, it does not hesitate. Just at the richer setting the idle was loping and it was harder to start if it was hot.

odd enough, the colortune plug had me back close to where i started with the two turns down. the depth was .064.... well except the back carb. to get the right color on those cylinders the depth was .035. Not sure why that is. ( i pulled the breather today and cleaned it to make sure it is not clogged with oil or anything since the vent goes in that breather.)

anyway, right now i have lowered the mixtures one more flat so the jets are at .071-.073 depth. i went ahead and set the rear carb to match the other two. i am thinking i will try this setting and see if the car runs any cooler. if not i may try another flat. where it is right now, the car still starts great when hot and idles smooth.

but i wondered if someone else had found, from experience, that everything works better at a certain setting for their engine.
 

mgtf328

Jedi Hopeful
Country flag
Offline
I have a BJ8 with 2 carbs and I'm going thru a similar experience. Please read recent post 'Carb Tuning'. My car runs well and I have adjusted using a Colourtune. However, I recently measured the depth of the jets and got .088" for the front and .04" for the back. I'm still trying to figure it out why they're not the same. General advice seems to be they ought to be around .075". I'm happy with the front as I deliberately set it rich as I've been told BJ8's like to run rich. Can't figure out what's happening with the front yet.
AJ
 
OP
D

Deleted member 21878

Guest
Guest
Offline
AJ, thanks. i have been reading your post but did not want to hijack it with my car since it is a tri-carb.
 

dougie

Luke Skywalker
Country flag
Offline
I dial-in all my tri-carb race motors on the dyno "rolling road" for the optimal performance. It's the only way to get an accurate tune.

'57 Dyno Tune Front.jpg

'57 Dyno Rear.jpg
 

dougie

Luke Skywalker
Country flag
Offline
Reid -

If I thought I could sneak in dyno in the shop without my wife finding out, I might try it. I tried Portland Speed Industries last year, good shop but more for the modern "tuner" crowd. I'm using Fast Specialities in Vancouver, WA this year. Bascically, I rent the dyno and due my own tuning based on the data the dyno tech provides me. https://www.fastspecialties.com/custom-auto-services/custom-auto-tuning/
 
OP
D

Deleted member 21878

Guest
Guest
Offline
Doug
i am sure if you are setting up race motors, your settings are a bit different than mine. guessing different cam, etc.

i ended up lowering my jets the one flat and the car ran cooler today. it does not start, when hot, quite as quickly as the .064 setting but it still starts fine. it also idles fine as well.

i am at the point of 500 miles since the engine rebuild so i am about to go thru my list of items to do. along with oil and filter changes, re-torquing, check and adjust the valves, check and adjust the timing. so we shall see what changes all of that brings before i mess with the settings anymore.
 
Similar threads
Thread starter Title Forum Replies Date
Zitch SOLD!! SOLD - Tri-Carb Exhaust manifold for a 3000 Austin Healey Classifieds 0
T Air Filter Recommendations for My Tri-Carb Austin Healey 7
HealeyPassion For Sale Tri-Carb Complete Set including manifolds Austin Healey Classifieds 13
Healey Nut Tri-Carb Throttle Controls Austin Healey 4
D Tri carb: order of installation question. Austin Healey 5
Healey Nut Tri-Carb Project Austin Healey 213
CLB62 1962 BT7 Tri-Carb for sale on BaT Austin Healey 2
D 62 tri-carb upper fulcrum pins Austin Healey 4
M engine stutter of rebuild BT7 engine [tri-carb] above 2500 rpm Austin Healey 27
lbcspinners 1962 Austin-Healey 3000 Mk II BN7 Tri-Carb 2-Seat Roadster: for sale on BaT Austin Healey 2
D Grose valves / Tri-carb Austin Healey 11
D Tri-carb PCV valve Austin Healey 61
D 62 tri-carb fuel line connection Austin Healey 10
C Tri carb Austin Healey 7
T Tri-carb questions. Austin Healey 10
J BT7 [Tri-Carb] Restoration Upgrades Austin Healey 2
D BT7 Tri-Carb Distributor Cap Austin Healey 9
D BT7 tri-carb linkage set up Austin Healey 23
D BT-7 tri-carb Two more questions Austin Healey 18
D BT-7 tri-carb ring gap Austin Healey 10
D BT7 tri-carb installing my crank Austin Healey 4
D 62 / BT7 tri-carb engine Austin Healey 16
D 62 tri-carb wiring harness Austin Healey 10
HealeyPassion Tri-carb intake manifold balance tube size Austin Healey 10
steveg Rare colored tri-carb BT7 on eBay Austin Healey 13
davidb AH 3000 tri-carb throttle shafts Austin Healey 13
W Barrett Jackson Auction 62 2 Seater Tri-carb only brings 48k Austin Healey 19
Norman Tri carb - overheating issue ???? Austin Healey 10
K Tri-carb help Austin Healey 11
K Tri-carb help please Austin Healey 0
AH67 62 MKII Tri Carb, done with some pictures Austin Healey 9
M WTB: Tri Carb Choke Linkage Parts Austin Healey 8
BoyRacer What are MK II [tri-carb] 2 seaters selling for? Austin Healey 12
D BT7 Tri carb Backfire Austin Healey 2
M Tri Carb Camshaft Austin Healey 4
B tri carb problems Austin Healey 17
B Gas mileage Tri-Carb Austin Healey 2
A tri carb on ebay Austin Healey 14
C Cold air box for Tri Carb 3000 BT7 ??? Austin Healey 9
G tri carb vapor lock Austin Healey 30
J Seeking tri carb help Austin Healey 16
M 100-6/ 3000 tri carb set up Austin Healey 13
Patrick67BJ8 Ruddspeed Tri-Carb Set-up Austin Healey 9
6 BN7 tri-carb will not start Austin Healey 7
6 BJ8-BT7 Tri-carb Conversion? Austin Healey 7
B PCV Valve Tri Carb Austin Healey 11
C Tri - Carb assistance ! Austin Healey 5
Dave Richards WOW! a "RARE" tri-carb Austin Healey 12
C AH 3000 Tri-Carb conversion. Austin Healey 4
V Choke cables for tri-carb Austin Healey 5

Similar threads

Top