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Triple SU Setup in LC Torana

Started by _COSH_ , Feb 02 2015 12:53 PM
Triple SU Manifold LC

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#1 _COSH_

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Posted 02 February 2015 - 12:53 PM

So the time has come to get rid of the Holley and fit a set of Triple SU carbs to the 202 in my LC.  I'm after some advice on the setup.  

 

I've decided to go 1.75" but I'm not sure which manifold to go with.  The engine specs are as follows:

 

Red 202, .060 overbore, fully balanced.

Camtech CT35 608; 241 243 @ 108 LSA

Ported Yella Terra head, 9 port.

MSD 6AL and Bosch HEI dizzy.

Supra 5 speed.

 

I know there are several types of manifolds, but I'm not completely sure on the differences between them.  I also want to make sure that they'll fit in my engine bay, I've included some photos of the current setup below.

 

The main issue I have with the Holley is that the idle quality is crap due to the cam.  So I'm hoping that the triples will smooth it out and make it a lot more pleasant to drive.  I've read that the old style Armours long runner manifolds will be the best for low to mid range power and idle quality, but they are hard to find and I'm not sure they'll fit without relocating the battery to the boot.

 

I'm also not sure if I can re-use the accelerator cable that I currently have, or if I'll need to change it to a linkage setup.

 

IMG_0406.jpg

 

IMG_0407.jpg

IMG_0408.jpg


#2 _Bomber Watson_

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Posted 02 February 2015 - 01:38 PM

Linx 179.

#3 _HRG735_

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Posted 13 February 2015 - 08:17 AM

Hi Cosh

 

Not sure if have sorted it out yet, however generally the shorter the runner the better low end. There are many variables though, some longer runner set-up's use smaller diameter runners to aid in increasing velocity of the air/fuel mixture giving better efficiency at low RPM as well. As stated above the Lynx is very popular and allows leaving the battery in situ. Redline make a "cable linkage kit" for the LC-LJ (approx $75).

 

Couple of questions regarding the idle of the Holley. Do you know what your vacuum at idle is? Are you still using vacuum advance on your distrubutor?

 

Scott


#4 _COSH_

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Posted 13 February 2015 - 10:46 AM

Not yet, I'm trying to get the setup sorted in my head before I start ordering parts. The idle vacuum of the holley is between 9 and 9.5 inches. Vacuum advance is connected. I'm ditching the single carb setup due to the inadequacy of the manifold and poor fuel distribution

#5 _HRG735_

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Posted 13 February 2015 - 11:28 AM

I think you are heading in the right direction, I'm sure there are a lot more efficient triples set-up's out there than 4bbl for the reasons you mention. With that idle vacuum your power valve should be no higher than 5.5 and curious to know where your vacuum advance is running from (manifold or ported)? If vacuum advance is running from ported (above the throttle plates), then try it from direct manifold vacuum. Your idle will probably increase, but you can wind it back, don't alter your timing, test drive and see if there is any difference in idle and low throttle smoothness and response.


#6 _oldjohnno_

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Posted 13 February 2015 - 11:57 AM

I don't know who first came up with the idea that the powervalve is somehow related to idle vacuum, but I wish to christ that they didn't. The powervalve only has to do two things: stay open at WOT and stay closed at a part-throttle cruise. It's part of the main circuit which is inactive at idle so whether it's open or closed at idle doesn't make any difference.


#7 _HRG735_

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Posted 13 February 2015 - 01:25 PM

You may wish to take that up with Mr Holley, as it is his suggestion that the power valve size should be approx half the idle vacuum (starting point for tuning)! I am not sure what you have read into this but, Mr Holley, like me, make no reference it will alter the idle! I am not sure where you read it would change anything at idle, it wasn't in this thread. If your finished........... we can now continue the helpful posts.


#8 _COSH_

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Posted 13 February 2015 - 01:42 PM

You may wish to take that up with Mr Holley, as it is his suggestion that the power valve size should be approx half the idle vacuum (starting point for tuning)! I am not sure what you have read into this but, Mr Holley, like me, make no reference it will alter the idle! I am not sure where you read it would change anything at idle, it wasn't in this thread. If your finished........... we can now continue the helpful posts.

Or you could whack a vacuum gauge on it, take it for a drive and see when the power enrichment is required under load. OJ is correct; setting the PV size based on the idle vacuum is Holleys way of making sure numpty's don't end up with a PV that opens up at idle.

 

I've been through all the tuning steps and it's running as good as it's ever going to.  Now on to a setup with a proper manifold and more sophisticated fuel metering.


#9 _COSH_

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Posted 13 February 2015 - 01:45 PM

I think you are heading in the right direction, I'm sure there are a lot more efficient triples set-up's out there than 4bbl for the reasons you mention. With that idle vacuum your power valve should be no higher than 5.5 and curious to know where your vacuum advance is running from (manifold or ported)? If vacuum advance is running from ported (above the throttle plates), then try it from direct manifold vacuum. Your idle will probably increase, but you can wind it back, don't alter your timing, test drive and see if there is any difference in idle and low throttle smoothness and response.

So what your saying is that I should hook up my vac advance line to Manifold vacuum and NOT the ported vacuum that the carb has been designed for?  I'll leave that idea where it belongs.

 

Any more info to add to the original topic?


#10 _Lazarus_

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Posted 13 February 2015 - 02:14 PM

Have you considered going 12 port while you're at it ?


#11 _oldjohnno_

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Posted 13 February 2015 - 02:22 PM

You may wish to take that up with Mr Holley, as it is his suggestion that the power valve size should be approx half the idle vacuum (starting point for tuning)! I am not sure what you have read into this but, Mr Holley, like me, make no reference it will alter the idle! I am not sure where you read it would change anything at idle, it wasn't in this thread. If your finished........... we can now continue the helpful posts.

 

Mr Holleys men have written quite a lot of garbage over the years, some of which defies the laws of physics. I'm not saying the Holley engineers are stupid at all - they've built some great stuff - just that their tech writers aren't as well informed as they should be. Add to this the fact that their marketing men seem to have taken over and now we have the situation with a lot of their products where no-one is quite sure what they really flow at the traditional pressure ratings.

 

I'm sorry if I appeared to have put words in your mouth - it's just that there is a widely held belief that an open PV at idle will cause problems. Five minutes with a vacuum gauge connected while driving will get you exactly the right PV number first time every time.

 

As for the manifold, as others have said just go for the Lynx. It'll work well and you won't have to butcher the sheetmetal.


#12 _COSH_

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Posted 13 February 2015 - 02:53 PM

Have you considered going 12 port while you're at it ?

No, I haven't.  I'd rather fit the triples and see how good I can get her going.  When I bought the car, the previous owner had just spent a bucketload of money on the engine, head, and ignition; but chucked a cheap 4 barrel on it as a "temporary" setup.


#13 Ice

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Posted 13 February 2015 - 02:58 PM

With the triples on it should pull quite hard no need for 12 port

#14 _HRG735_

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Posted 13 February 2015 - 03:12 PM

No offence taken and thanks for the apology. I'm only new to the site and I see you are a long time member and would have read lots of things that aren't correct. I am trying to be cautious with any advice and try to base it on my knowledge and experiences. I have been working on Holley's for almost 40 years, they are a great carb and haven't changed all that much in that time.

 

Adam, vacuum advance is widely misunderstood. Yes, your Holley is ported vacuum mainly aimed at reducing pollution, not enhancing performance, as are most Holley's from mid 70's on utilising ported vacuum. Your cars original vacuum advance would have probably run off manifold vacuum (this is why you had to disconnect and plug the vacuum line when setting the timing). All I am suggesting to do is try it, you may be pleasantly surprised.


#15 EunUCh

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Posted 13 February 2015 - 05:10 PM

:dontknow:  :dontknow: I thought the ported vac.adv. was to coverup a slight lean transition from transfer to main as well as aid in

economy at light  throttle/high vac. cruising?

you won't have that port with SU or some Weber carbs. which will mean a modified dizzy or some lectronic setup that

will replicate the ported set up...or just lock the timing depending on application.

 

 


#16 DMLC71

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Posted 13 February 2015 - 05:15 PM

The battery is in the way for triple set up
DazM

#17 _COSH_

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Posted 13 February 2015 - 06:21 PM

Got any dimensions I can use to relocate the battery tray so that it's out of the way?

#18 Ice

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Posted 13 February 2015 - 06:41 PM

Got any dimensions I can use to relocate the battery tray so that it's out of the way?


Whip that tray out and buy an XU1 tray from Rares and battery to suit easy fix

#19 _COSH_

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Posted 13 February 2015 - 07:07 PM

I just got a new battery! Arrrgh

#20 _Bomber Watson_

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Posted 13 February 2015 - 07:10 PM

THen put it in the boot. 


#21 _Agent 34_

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Posted 13 February 2015 - 07:48 PM

Got any dimensions I can use to relocate the battery tray so that it's out of the way?

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Edited by Agent 34, 13 February 2015 - 07:49 PM.

#22 _Agent 34_

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Posted 13 February 2015 - 07:52 PM

sorry spastic post - but thats how much i needed to cut out of the standard battery tray to clear the fuel bowl on a 1.75 su on a lynx.

 

I dont have another photo but you can get the drift of what needs to be removed by the bolt and lug to hold the battery in 


#23 _threeblindmice_

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Posted 13 February 2015 - 08:23 PM

We moved the battery on russet , just don't go quite as far as we did if you want to run a Holden battery clamp as it hit on the under bonnet ridge ,
Attached File  105a - Copy.jpg   206.06K   15 downloads

#24 _macdou_

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Posted 14 February 2015 - 09:24 AM

Whip that tray out and buy an XU1 tray from Rares and battery to suit easy fix


+1

#25 _Lazarus_

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Posted 14 February 2015 - 09:52 AM

No, I haven't.  I'd rather fit the triples and see how good I can get her going.  When I bought the car, the previous owner had just spent a bucketload of money on the engine, head, and ignition; but chucked a cheap 4 barrel on it as a "temporary" setup.

 

 

Fair enough, I was just thinking of this quote from my favourite thread -

 

"The 12 port motors are particularly well suited to IR manifolds as it's possible to use longish runners with a fairly constant cross section all the way from the carb to the valve. This can result in a useful boost to midrange power."

 

 

http://www.oldjohnno.id.au/page22.html

 

 

 

.


Edited by Lazarus, 14 February 2015 - 09:53 AM.

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