Carb set up

cobraboy · September 21, 2009 at 6:59 AM

Just got back from Goodwood circuit revival meeting, great weekend you should be able to watch a programme on the net soon. If I find a link I will post it.

No Mustangs racing this year but lots of track action and a wonderful pre 1966 atmosphere.

The car ran superbly on her first 'big trip'.

We covered about 400 miles over the weekend and averaged about 16.5 mpg cruising at around 70mph, but this is UK gallons.

So on this basis the tank holds 13.3 UK galls which should give me a range of 220 miles.

You guys seem to get an average of around 17mpg US galls, so 17 x 16 gall tank gives a range of 272 miles.

This was all steady sedate stuff, so I think she is a little bit thirsty.

The 4100 is all stock for a HiPo, I have checked all the jets etc, but the power valve is unmarked so I dont know what that is. I wondered how you guys set up the secondary stop screw.

I tried setting it so the plates are just off the venturi and set the idle on the primary idle screw, but the car does hunt and the revs cycle up and down.

This weekend I opened up the secondary screw a little more and lowered the primaries and have a steady idle.

But in doing so I wonder if I am using too much gas thru the secondaries.

If anyone can tell me how to go about it or any other ideas I would appreciate it.

Edited by - cobraboy on 09/21/2009 07:00:40

dunc289_old · September 21, 2009 at 8:36 AM

Does it still hunt when driving at a steady state? have you checked for vacuum leaks? Also, the mileage you are getting might be close to our mileage. If you have the 3.89 rearend, this would also point to greater consumption..... I can't speak directly to adjusting the 4100, others might, but if the tip in is smooth, with no stumbling, then you have a good thing going. In the states, many of us with " restomods", that is, Mustangs that we have modified to meet our needs and wishes without regard to authenticity, have installed lower ratios. I have a 3.25 LSD in my convertible, 'cause I have a C-4 automatic. That lower ratio can have a very big impact on mileage, lowering your revs per mile. Performance suffers of course. The slight loss of mileage is the cost of performance. I wish you good luck in your quest. I dream of bringing my car to travel to Goodwood and experience this wonderful event.<img src=images/icon_smile_big.gif border=0 align=middle><img src=images/icon_smile_big.gif border=0 align=middle>

cobraboy · September 21, 2009 at 9:17 AM

Duncan

The car does not hunt at cruise in fact it runs really good. The only little prob I have is trying to get a smooth idle.

The mixture screws are about 1 1/2 turns out, and it seems to get the engine to even out I have to run a higher idle speed than I would like.

I have fitted a NOS PCV Valve with a hex base that it is clean and 'new' but I did remove the pipe to the inlet manifold and plugged the stub on the nanifold with a finger and the idle evened out.

It seems that the pulsing idle is when the toggle in the PCV lifts and gives the motor a dose of air.

Oh 3.50 rear, stock 25.3" tyre

I will give you a heads up about the Goodwood prog

Thanks Mark

Edited by - cobraboy on 09/21/2009 09:20:39

Mu5tanggt_old · September 21, 2009 at 3:49 PM

In all the years my dad drove the Koupe the best she got was 18.2 mpg and he circled it in the book as "best mpg", usually avg. 15 to 17 mpg with 3:50 gears

66gtk · September 21, 2009 at 5:38 PM

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>

In all the years my dad drove the Koupe the best she got was 18.2 mpg and he circled it in the book as "best mpg", usually avg. 15 to 17 mpg with 3:50 gears

I'm sure that was with "real" gas, unlike the crap we have to feed our 'stangs today with all the Ethanol and what-not.

zray · September 21, 2009 at 6:43 PM

In 2008 I got 22.5 mpg average over a 1600 mile trip. It was with a stock Hi-Po engine with the usual Shelby add ons ( 715 Holley, Cobra manifold, and Tri-Y headers. I did have a 3.00:1 gearing. I used Shell premium gas the whole way. When not in a town I tried to keep the speed between 75 & 85 mph (that worked out to 3000 to 3400 rpm), though temptation got the better of me a few times.

Z. Ray

66gtk · September 21, 2009 at 10:12 PM

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>

speed between 75 & 85 mph (that worked out to 3000 to 3400 rpm), .

Translation: 3.50:1 gearing would be 60-70 MPH at those RPMs. Still very respectable gas mileage!

cobraboy · September 22, 2009 at 1:51 AM

Thanks for the replys

I am getting 224 miles to a tank that = 14 mpg US gallons

With fuel costing 6.51 USD for a US gallon over here I will try to improve things a little.

But hey its what your right foots for <img src=images/icon_smile_big.gif border=0 align=middle>

dunc289_old · September 22, 2009 at 10:48 AM

over the years, I've driven quite a bit in the UK [ well, for a yank ] and there are times when on the motorway, that I drove for quite a stretch and the steady throttle would give optimum mileage. But inevitably there is much town driving and traffic is pretty slow, as in BAD. I would think your mileage is in the ball park. JUST DRIVE IT AND SMILE....<img src=images/icon_smile_big.gif border=0 align=middle><img src=images/icon_smile_big.gif border=0 align=middle>

cobraboy · September 22, 2009 at 2:01 PM

Today I have played with the PCV valve and got a smooth idle and re set both the stop screws, so am looking forward to a run out.

Goodwood is on Brit TV channel ITV 4 on 20th Oct at 15.00 hrs and repeated on 21st Oct 17.00 hrs Brit time. http://www.itv4.com This site has a feature to let you watch progs again.

Cheers Mark

cobraboy · September 29, 2009 at 1:00 PM

Guys

I had duff gen on the goodwood prog. it is on in 1hr from now (see post time) http://www.itv4.com

But you can probably watch again on the net

dunc289_old · October 1, 2009 at 5:03 PM

OOPS....MISSED IT!!! dang.....Any small block fords on the track???<img src=images/icon_smile_big.gif border=0 align=middle><img src=images/icon_smile_big.gif border=0 align=middle>

cobraboy · October 2, 2009 at 2:27 AM

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>

OOPS....MISSED IT!!! dang.....Any small block fords on the track???<img src=images/icon_smile_big.gif border=0 align=middle><img src=images/icon_smile_big.gif border=0 align=middle>

COBRAS!!! GT40's

Its still up there to watch, but a bit of a job to find it, I'll try my best to direct you.

http://www.itv.com

click on ITV player

look for and click on catch up

Click on the A-Z , then click on the GHI button

you should see Goodwood revival 2009

Enjoy

Participate now!