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V-8 Engine Tech

Carter TQ on Chev 350

Mopar Big Block Talk

by Philip Lochner » Mon Feb 11, 2019 8:03 pm

Just for kicks (and hoping for a good outcome...) I fitted the TQ from my '73 Jensen 440 to my Chevy C10 truck with a 350 Chevy V8.

All I had to change was reduce the idle speed. Choke is now non-functional.

Result: Fantastic. Quicker start, smoother idle, more responsive on light throttle, SOUNDS better on partial throttle (more steady V8 throb), pulls harder on full throttle (although not hugely so).

I not saying the Holley 2744 that was on the engine is bad, but I am saying it was not optimally tuned for the engine.
Best regards
Philip
Mk3 7.2 #128/8120 Jan 73 http://tinyurl.com/hsjucm5
Mk3 7.2 #2240.9677 May '74 modified:
Fuel injected: http://tinyurl.com/qyrx93f
GM 4L60e 4-sp transmission: http://tinyurl.com/qxlwk95
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by Grant » Mon Feb 11, 2019 9:46 pm

Hello Philip :P
Good to hear from after so longImage
Happy that you are happy with your new T/Q replacement on your Chevy :wink:
After reading so many praises of the T/quad from you I managed to pick up a New Old Stock a long time ago and had it stock for a good while, anyway I thought I would try it on my 383, so I got an alloy spread-bore inlet and wacked it on, I am so impressed with it Philip, it's bloody greatImage, I'm glad I listened to you Image, I haven't really spent anytime as of yet setting it up on the umbrella jet yet as it seemed to run a treat but I will when I get a chance to get on the local rolling road, but... It does smell rich on Idle with the mixture screws set on the weakest setting/even tickover,... are there Idle jets available for T/quads that you know of please Philip?Image
Thanks Philip :wink:
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by Philip Lochner » Tue Feb 12, 2019 5:21 am

Hi Grant

Lovely to hear you are getting pleasing results with the TQ.

There are three things I would suggest you try to lean out the idle:
1) Remove the thick heat insulator between the carb and the manifold and replace it with a gasket you make from 4mm (or so) cork gasket BUT, cut it so that you retain a strip of gasket that runs along the center separating flange of the intake manifold thus completely separating the two sides. I have found the engine runs better like this and its easier to tune the idle screws, because now one screw is not influenced by the other;
2) Implement #1 first;
3) Turn the needle tree scew anti-clockwise (leaner) half a turn at a time, counting the number of half turns you are implementing to be able to return to the position that works for you. I'm not too sure about this action but I do believe the primaries main jets are also in play to some extent at idle.
Best regards
Philip
Mk3 7.2 #128/8120 Jan 73 http://tinyurl.com/hsjucm5
Mk3 7.2 #2240.9677 May '74 modified:
Fuel injected: http://tinyurl.com/qyrx93f
GM 4L60e 4-sp transmission: http://tinyurl.com/qxlwk95
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by RayR » Wed Feb 13, 2019 12:03 am

Hi Grant/Philip,

Good to hear from the TQ fans!!

Agree with Philip's comments and a few more on a rich idle
- I have tried the primary tree screw for idle and found the effect on mine to be very small
- The PCV has a strong effect on idle, if it is blocked or too small will give a very rich idle
- I agree on keeping the seperating rib on the spacer, I have also made a custom phenolic spacer that has a radiused and tapered inlet to the 4 bores - I have found it to be very good and helped response everywhere. I'll get around to putting a post out one day!
- if the above don't fix it it is probably from a miss-sized bleed hole if you don't have exactly the right carb for the engine.
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by Philip Lochner » Wed Feb 13, 2019 5:57 am

RayR wrote:- The PCV has a strong effect on idle, if it is blocked or too small will give a very rich idle


I always want to know WHY?? In this case I suspect that air via the PCV valve forms a significant portion of the engine's idle air and this air comes in unfueled, which would lean out whatever is coming through the carb.

An aspect easily overlooked. Very good point Ray!!!

Easily checked by pulling the pipe off the PCV valve and then gradually choking it till the idle AFR can be set by the idle mixture screws. Then, how to get the PCV to supply that much air???
Best regards
Philip
Mk3 7.2 #128/8120 Jan 73 http://tinyurl.com/hsjucm5
Mk3 7.2 #2240.9677 May '74 modified:
Fuel injected: http://tinyurl.com/qyrx93f
GM 4L60e 4-sp transmission: http://tinyurl.com/qxlwk95
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by RayR » Thu Feb 14, 2019 5:26 am

Hi Philip, that's my understanding also. I ran across how sensitive it is when trying to manage engine blowby and different PCV's. In my digging I found an adjustable PCV but haven't gone to that extent!

http://mewagner.com/?p=1706
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by Grant » Thu Feb 14, 2019 10:06 am

Thank you for your thoughts ChapsImage
Funnily enough when I fitted the new T/Q I did change the PCV valve for a new one, but.. are you saying Philip and Ray that your thoughts are if there is not enough air being passed through the PCV then that would make the idle circuit richer? which does makes senseImage, although.. It is probably as Ray 1st mentioned that it could be the wrong model Carb, and may have bigger idle circuit passages/orifices, I didn't really check the model and I should as I just saw it years ago being new old stock and bought it.. not really intending to even put it on a 383ci, I guess I need to do some homework on the model number etc and check its application, which was my point originally can I reduce the idle jet size?.. although I haven't attached an AFR meter to it and checked the mixture on Idle,Image but I can smell it is rich on idleImage.. It Stinks!!, but don't we allImage
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by RayR » Fri Feb 15, 2019 3:47 am

Hi Grant, to try and answer your original question!!

I believe the idle fuel orifice (jet!) is a pressed in tube in the plastic main body - I do not believe you can buy them as spares. On some of the mopar forums I have read about people who have removed them and then replaced/modified but obviously a bit of a pain especially as you would want to go smaller.
I had a similar problem when I bought my TQ from Summit but the opposite way, mine was a lean burn carb. I elected to persevere with mine and ended up using thin wires in the different air bleed orifices to richen up the idle and part throttle. Now I am very happy with the carb but it was a bit of a mission juggling the different circuits to get a good mixture on all conditions - I would not attempt it without an AFR gauge. That yours is rich though would lead me to try a different PCV and see what it does.

Good luck.

Ray
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by Grant » Fri Feb 15, 2019 8:55 am

Hi RayImage
Many thanks for your thoughts and advice.. that all makes sense, I do have access to AFR meter so I shall go and get that and bring it home hereImage.. so if I am running Rich on idle your thoughts are to have a larger hole in theory in the PCV valve isn't it?.. that should give more air to the idle circuit YES?
.. Thank you again Ray :wink:
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by Philip Lochner » Fri Feb 15, 2019 5:43 pm

Grant wrote:so if I am running Rich on idle your thoughts are to have a larger hole in theory in the PCV valve isn't it?.. that should give more air to the idle circuit YES?


I agree with that. If the additional air will be enough to get your AFR to where it needs to be (12.5 - 13), remains to be seen.
Best regards
Philip
Mk3 7.2 #128/8120 Jan 73 http://tinyurl.com/hsjucm5
Mk3 7.2 #2240.9677 May '74 modified:
Fuel injected: http://tinyurl.com/qyrx93f
GM 4L60e 4-sp transmission: http://tinyurl.com/qxlwk95
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Posts: 1228
Joined: Thu Feb 28, 2013 12:29 am
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