Engine Set Up, The right tuning and timing |
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Engine Set Up, The right tuning and timing |
CG-914 |
Aug 13 2013, 11:43 PM
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#1
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Member Group: Members Posts: 323 Joined: 27-December 10 From: LA/OC CA Member No.: 12,526 Region Association: Southern California |
I have a 74 2.0 with the following engine setup:
Stock displacement Euro Pistons 8.3:1 Compression 9550 Camshaft and valve train etc Ignition is a Mallory Dizzy from Chris with wires and the Mallory Ignition box is not installed yet. Fuel, Weber Carburators new 40 IDF 28 Ventures 55 idle 115 Emulsifier (not looking for a discussion about the 9550 with carbs) Timing now 25 degrees adv I set the car at 2500 feet above see level with 27 degree timing and 93 octane fuel. I drove the car cross country to CA and trough different altitudes and then with 91 octane, so my heads started getting too hot, actually never too hot, so I had to go down to 25 degrees, with the consequents of power loss. (IMG:style_emoticons/default/headbang.gif) Lately I have even more power loss and the car is loud and misfiring. (IMG:style_emoticons/default/confused24.gif) So here my question, what would be the best carb set up for that engine and how can I tune it right, to the power it should have? Thank you guys! (IMG:style_emoticons/default/pray.gif) |
monkeyboy |
Aug 14 2013, 09:47 AM
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#2
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Senior Member Group: Members Posts: 808 Joined: 8-June 08 From: Los Angeles, Ca Member No.: 9,147 Region Association: None |
I would have to say first off, you need an O2 sensor and gauge. Everyone here can make stabs at what jetting you should have, but your motor will tell you what it wants if you install the gauge.
You didn't say what main jets you have, but I bet that if you fattened them up a bit your temps would go down. |
CG-914 |
Aug 14 2013, 02:01 PM
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#3
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Member Group: Members Posts: 323 Joined: 27-December 10 From: LA/OC CA Member No.: 12,526 Region Association: Southern California |
The mains are F22, if that even makes sense...
And I wasn't planing on putting an O2 sensor on it for a while but it's my daily driver... What throughs me of is that the timing is of so far... |
Elliot Cannon |
Aug 14 2013, 02:19 PM
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#4
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914 Guru Group: Retired Members Posts: 8,487 Joined: 29-December 06 From: Paso Robles Ca. (Central coast) Member No.: 7,407 Region Association: None |
F22 sounds like the emulsion tube. I have 44idf's and it is probably a bit different and I am far from expert. The main jets and air jets I thought should be a three digit number. Make sure you have the numbers straight because there are a lot of folks here who will be able to help.
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monkeyboy |
Aug 14 2013, 02:32 PM
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#5
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Senior Member Group: Members Posts: 808 Joined: 8-June 08 From: Los Angeles, Ca Member No.: 9,147 Region Association: None |
You jetting can cause the heat. Retarding the timing will not help poor jetting.
You need to get the timing set to where it should be, then start looking at the O2 sensor. |
CG-914 |
Aug 14 2013, 07:40 PM
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#6
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Member Group: Members Posts: 323 Joined: 27-December 10 From: LA/OC CA Member No.: 12,526 Region Association: Southern California |
You jetting can cause the heat. Retarding the timing will not help poor jetting. You need to get the timing set to where it should be, then start looking at the O2 sensor. I agree that i need to start with the timing: TIMING: What is the magic number? FI was 27 and carbs should be 32 or 34 right? Over 30 I get predetinations… (IMG:style_emoticons/default/dry.gif) So I'm sure someone is running a 9550 with 40 carbs and a Mallory dizzy on only 91 octane with ethanol… What is your number?????? Then back to Jetting: On the mains I have these three numbers: see pics If it is 20 or 22, that seems awfully small for a 2 liter engine, for the little I know about carbs. I heard though that the F series is not chronological… Anybody? How are the stacks/towers/chimney on the top of the carbs called? What would be the right size for my carbs? With the red line filters? |
stugray |
Aug 14 2013, 07:55 PM
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#7
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Advanced Member Group: Members Posts: 3,824 Joined: 17-September 09 From: Longmont, CO Member No.: 10,819 Region Association: None |
Stock weber setup is:
Main jets: 115 Air correctors: 200 Emulsion tubes: F11 Idles Jets: 50 Pump jet: 50 |
r_towle |
Aug 14 2013, 08:13 PM
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#8
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Custom Member Group: Members Posts: 24,574 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
Have you cleaned the idle jets since it started running poorly?
Valve adjustment? Valve to tight will do this. Timing should be 27 degrees at 3500 rpm,s |
pilothyer |
Aug 14 2013, 09:02 PM
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#9
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Member Group: Members Posts: 838 Joined: 21-May 08 From: N. Alabama Member No.: 9,080 Region Association: South East States |
Cornelius.......The carburetors that were installed when your engine was new had the following as standard new 40 IDF carburetors:
AIR CORRECTION 200 EMULSION TUBE F-11 MAIN JET 115 PUMP JET 50 IDLE JET 50 VENTURII 28mm I would bet that you have been running a bit lean for quite sometime. I hope the integrity of your new rebuild hasn't been compromised after all this time and all those miles. Jerry |
CG-914 |
Aug 14 2013, 11:24 PM
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#10
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Member Group: Members Posts: 323 Joined: 27-December 10 From: LA/OC CA Member No.: 12,526 Region Association: Southern California |
thank you rich and jerry!
the idle jets are 55… always where…. So what would be the next sizes of main jets? When I change those, what do I have to do to the other jets in relation? Which would be the right velocity stacks? |
CG-914 |
Aug 15 2013, 09:54 AM
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#11
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Member Group: Members Posts: 323 Joined: 27-December 10 From: LA/OC CA Member No.: 12,526 Region Association: Southern California |
What is the exact adjustment for the floats?
I did adjust my valves and I did clean my idle jets since the power went down. |
pilothyer |
Aug 15 2013, 11:30 AM
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#12
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Member Group: Members Posts: 838 Joined: 21-May 08 From: N. Alabama Member No.: 9,080 Region Association: South East States |
thank you rich and jerry! So what would be the next sizes of main jets? Next up would be 1.20 get 4 of them...if you happen to get used ones, or even new ones for that matter, always check that the number matches the actual measurment. Main jets are available from 1.00 to 2.55 mm |
pilothyer |
Aug 15 2013, 11:48 AM
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#13
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Member Group: Members Posts: 838 Joined: 21-May 08 From: N. Alabama Member No.: 9,080 Region Association: South East States |
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CG-914 |
Aug 15 2013, 07:32 PM
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#14
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Member Group: Members Posts: 323 Joined: 27-December 10 From: LA/OC CA Member No.: 12,526 Region Association: Southern California |
The 27º adv at 3500 is too much at for the mallory Distributor.
Too much predatination. We ended up setting the timing at idle with the "0" mark. At "0" in idle it is 16º adv at 3500 rpm So we set it at 4º, which was not quiet enough and 7º was too much (each time at idle), so I'm gonna try 5º tomorrow and adjust the carbs after finding the timing sweet spot. When reading the Haynes manual the 5º at idle have something to do with the adv at 27º at 3500 rpm with the original distributor, but I have the feeling, that that does not work with the mallory set up. |
r_towle |
Aug 15 2013, 07:53 PM
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#15
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Custom Member Group: Members Posts: 24,574 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
Mallory has different advance curve springs, but if you bought it from foley, I believe he sets them up with the gray weights which are damn close to correct.
Seems like something else is wrong. Rich |
pilothyer |
Aug 15 2013, 11:27 PM
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#16
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Member Group: Members Posts: 838 Joined: 21-May 08 From: N. Alabama Member No.: 9,080 Region Association: South East States |
Has the distributor been removed since the original install ? If so I would suggest that the ignition shaft got moved from the correct position. I believe it may be off by only a little, (A tooth or so) but you must get it back to where we had it when we first fired up that engine (It was perfect at that time). Unless you do this you will not be able to use the red 27 degree timing mark at 3500 RPM. Let me know if you need to know a good way to do this.
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stugray |
Aug 16 2013, 07:25 AM
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#17
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Advanced Member Group: Members Posts: 3,824 Joined: 17-September 09 From: Longmont, CO Member No.: 10,819 Region Association: None |
QUOTE Unless you do this you will not be able to use the red 27 degree timing mark at 3500 RPM. Having the distributor gear drive off does not invalidate the timing marks. It just means your cyl#1 does not point in the usual direction. Stu |
CG-914 |
Aug 16 2013, 09:46 AM
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#18
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Member Group: Members Posts: 323 Joined: 27-December 10 From: LA/OC CA Member No.: 12,526 Region Association: Southern California |
Setting it at 5 degrees adv at idle is close to 27 degrees adv at 3500 rpm according to the Haynes manual. I just wonder why I can set it up better at idle...
The distributor was never removed. Now next question: Why do you set the valves at 0 clearance with the 9550 cam and the tabu valve train? I get the point with the 911 svival heads, But the valves are still going to expand under heat... I'm asking because I have power loss once the engine really warmed up... I'm asking because the 911 has a 004 clearance... |
nathansnathan |
Aug 16 2013, 10:05 AM
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#19
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Senior Member Group: Members Posts: 1,052 Joined: 31-May 10 From: Laguna Beach, CA Member No.: 11,782 Region Association: None |
I've always run the Mallory Unilite at 28 total advance, 12 initial, with the grey springs, like everyone else does.
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stugray |
Aug 16 2013, 10:15 AM
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#20
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Advanced Member Group: Members Posts: 3,824 Joined: 17-September 09 From: Longmont, CO Member No.: 10,819 Region Association: None |
QUOTE Why do you set the valves at 0 clearance with the 9550 cam and the tabu valve train? It has nothing to do with the cam. It is the pushrods. Since you mention 9550 & swivel feet, I assume you have Jakes cam kit and you cut your own pushrods. If that is the case, then you have Jakes chromolly pushrods. They get set to zero lash because they will expand/contract differently from the stock rods as the engine heats. Stu |
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