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LJDB

tuning with o2 gauge

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No screw in air bleeds. What sly said about the pinging I did have pinging issues before I sorted it by changing thermostat, colder 6 plugs and took timing out I think it is at 28-30 can't remember and octane booster. If I went back to the 5's and took more timing out would that get a better burn and better af at wot?

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I'd stick with the 6's and leave your timing where it is and just get a bit more time with that set up and make sure it can handle everything a street car has to deal with (idle at lights - high and low air and water temps etc etc.) 

 

The hp difference between 11.7 and 12.8 afr is really not that great and unless you are chasing every last bit out of an engine I'd be happy.  I would be more inclined to play with the timing in 1 degree increments to see if you get a better 'seat of the pants' hit from the engine.  I have found these engines to be very timing critical and 1 degree (especially with locked timing - yuk yuk poo) can make a very big RWHP difference - try 10hp on more than one occasion.  That is a big difference a would easily be felt in the car.

 

If you have your idle mixture sorted and your WOT afr's in the ball park then you will have a happier engine that uses less juice and doesn't foul up the oil.  Both of which are a good thing.  Oh and you have done it yourself and learnt along the way - what could be better than that?

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6-7's IMO and tighter plug gap.Fuel is your limiting factor here. I ran 98 and booster and spat head gaskets @ 27-28 degree's.Replaced with a good permaseal wound it up to 32 and spat the gasket in 1 burnout and 1 launch LOL. Since gone to AvGas and ZERO issues but still only 28 degree's from memory but 30-34 it makes it LIFT.

 

Colder plug will take more timing and give cleaner top end RPM but they can foul pretty easily around town. 

 

If you have room can I suggest a 1"open spacer under the carb and a extreme air cleaner top helps to.     

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The best wot af I have got so far is 11.0. I used to run alittle more timing but it feels stronger at what it is on now. Car doesn't run hot or ping ATM. Are u suggesting I try advancing or retarding the timing. Il worry about the fuel first then play with timing

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Adding timing CAN trim AFR's but if you have it where it is happy forget about timing. Where it is set is just a number and some people get caught up in where others say it should be. Every engine is different and each have there own happy spot.

 

Mine trims AFR's by adding timing but mine is safe to add via the AvGas it now runs. 98 and booster (nulon is the best I have found) is still limited but again you need to find the limits.

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Perhaps leave the timing and plugs and just pull another 2 jet sizes off the secondary circuit - see what that does - or perhaps open the high speed air bleeds a fraction. 

 

You are pretty close now by the sounds

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Definitely can back up what ando said about the sensitivity of ignition timing. I moved the timing 2 degrees and although made around 4 or 6 rwhp peak (can't remember exactly), I got an average of 26rwhp throughout the good part of the rev range, albeit on a high comp motor so it was very sensitive

 

 

Sent from my iPhone using Tapatalk

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Ok so i finally got back to driving/tuning the car. The carb is currently set up like this. 60 primaries, 61 secondaries, 6.5pv with wire restriction, 31 squirter, white pump cam and split pins in idle air bleed circuit, silver secondary spring. I've still got a little rich WOT at 11.7, idle is high 13 to 14 and cruise around high 14. Ignition timing is at 30. Im trying to sort a lean bog when i floor it at cruising speed. The gauge drops to around 17/18 when flooring it for a second then quickly makes it way to 11.7 wot. I cable tied the secondaries and the bog is still there but not as bad. I changed out the white pump cam to the green in hole 2 and it made it alot better still with the secondaries closed but still evident. I played with ignition timing but no change, I'm in the process of trying pump cams but theres a lot of conflicting info online about pump cam volume and profiles. I have the cam kit minus the blue cam, I'm going to try the pink cam in position 1 next as it seems to have more volume. The bog gets slightly worse when the secondaries are as normal and heavier spring only delays the bog alittle, lighter makes it worse.

 

Also while the secondaries where cable tied shut i still had a rich WOT at 11.7, should i take more out of the secondaries or lean out the pv further on the primaries as i would like a a/f around high 12

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Yep as sly said - your engine is telling you it needs more fuel - sooner, so give it what it wants.  try a bigger squirter to get more fuel in sooner AND play with your cams- I liked the red cam on position 1 from memory but the brown one used to work as well.  draw the cam profiles out onto paper - using the 1 position as a reference point.  That will tell you which is going to ramp sooner. 

 

Your afr is not stupidly rich and is well in the safe range.  You could try some 58- 59 jets (found in 320 Holley's from memory) but really if it is a streeter that may see high outside temps I would be leaving it as it is or maybe just pumping another degree of timing into it - If it will start happily on 31. 

 

Get your lean on acceleration (bogging) sorted first BEFORE adding timing.  I would think that 31 will clean up the AFR's nicely and 32 would be good when you want to really give it some. 

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You need more fuel in the primaries (can do this with idle mixture screw)

And less in the secondaries (You can do this with jets)

Dont muck around with air bleeds YET

Playing with air bleeds can do some very strange things

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Why would you touch the idle mixture screws when he has perfect idle air mixture?  It could go to 15-16 but really 14 is fine.

 

Primary mixture is controlled by the jets and he had 11.7 so why would you change that?

 

The problem is enrichment on 'flooring it' so that is controlled by the accelerator pump and squirters and has nothing to do with primary jetting.

 

As to air bleeds - they control the real high speed and idle as well and have nothing to do with his issue and yes if you play with them with no clue you will stuff things.

 

The problem is clearly in the enrichment on acceleration and any google search on Holley carbs will back up what I have said and what I know from tuning these things.

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If there's a flat spot coming onto the mains then you could try raising the float a little. This makes the mains come on sooner and harder. I'd prefer to adjust that than to pump more fuel in through the squirters. Some will argue that you shouldn't play with float levels but then why would Holley make them fully adjustable if there was a hard-and-fast rule about float settings?

 

Your engine doesnt care about where it gets fuel from. If raising the level cures your flat spot, so be it.

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Is it ok to run smaller jets in the secondaries than in the primaries. Im also going to try a different air filter set up as i've manage to fit a 12x3 drop base under the cortina bonnet with a 1/2 spacer and its tight under there. I've notice after setting the idle and refitting the filter the ratio changes quite a bit. Hoping to have a play tomorrow and try out everyones tips.

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The spacer should help, especially if your manifold has a sharp turn from the primaries into the plenum. Are you saying you had the spacer in all along or did you just fit it now? If so, this could be why you appear to need bigger primary jets than secondaries: the sharp turn out of the primaries could be affecting your vac signal to the boosters, making you jet up to compensate. Is it an open or closed spacer?

 

Also reading back: what secondary spring are you running, and what rpm does it open at? For your size engine, I'd expect them to come in at around 4000 rpm. Any earlier and you'll drop velocity through all four barrels when the secondaries open, and that's your dead spot. Purple or plain is mid-range, but yours really needs stiffer than that, say a brown or black. Using the primary acc pump tuning to cover up the secondary bog is just that: a cover-up.

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Why would you touch the idle mixture screws when he has perfect idle air mixture?  It could go to 15-16 but really 14 is fine.

 

Primary mixture is controlled by the jets and he had 11.7 so why would you change that?

 

The problem is enrichment on 'flooring it' so that is controlled by the accelerator pump and squirters and has nothing to do with primary jetting.

 

As to air bleeds - they control the real high speed and idle as well and have nothing to do with his issue and yes if you play with them with no clue you will stuff things.

 

The problem is clearly in the enrichment on acceleration and any google search on Holley carbs will back up what I have said and what I know from tuning these things.

Yes you are right

Sorry i just saw his first post and replied when it was 17:1 at idle and 10:1 WOT

Sould have read more

No offence to LJDB but someone with these questions should not touch air bleeds

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If there's a flat spot coming onto the mains then you could try raising the float a little. This makes the mains come on sooner and harder. I'd prefer to adjust that than to pump more fuel in through the squirters. Some will argue that you shouldn't play with float levels but then why would Holley make them fully adjustable if there was a hard-and-fast rule about float settings?

 

Your engine doesnt care about where it gets fuel from. If raising the level cures your flat spot, so be it.

 

Yeah higher float level gives fuel quicker

I play with the level a bit on mine at the drags

Is it ok to run smaller jets in the secondaries than in the primaries. Im also going to try a different air filter set up as i've manage to fit a 12x3 drop base under the cortina bonnet with a 1/2 spacer and its tight under there. I've notice after setting the idle and refitting the filter the ratio changes quite a bit. Hoping to have a play tomorrow and try out everyones tips.

Prob not a good idea, when your secondaries are working you are getting a fair bit of air coming in

So you need the extra fuel to compensate

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No offence taken Ronny i have basic knowledge of tuning a holley but have an understanding of the principals. Many of my post are mearly me experience with playing around with the carb and its effect on the a/f. Most of the time i try something and if it improves keep going in that direction if not go the other way. Il explain why i asked about the small secondary jets. If i have a good cruise a/f which is driving on the primary side and a rich WOT with is primary and secondaries open then the rich WOT is partly due to the secondaries, if i lean out the primaries more it will lean out my cruise a/f more. Is this correct? 
 

By the way i tested the car with pink pump cam in hole 1, 35 squirter and and changed from a 6.5pv to 8.5 and increase primary jetting to 62 and my bog is gone but WOT a/f is a fat 11.

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How long are you on WOT bro ? Takes a little time to clear usually...Are you changing 1 thing at a time when testing ? You could drop your main jets and see how it is now or give it some more timing to trim AFR's if it's safe to do so .

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As sly said, how long at WOT cos the extra fuel from the squirters takes a bit to clear

 

Also i still wouldnt go smaller than primaries with secondary main jets, id try to reduce the fuel from the PV circuit first

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The smaller PV idea worked well for me plus a square jetted carb is the best place to start in my findings. Same primary and secondary size,then tweak pump's PV's cam and squirters. With the restrictive filter it may be a idea to go to a extreme style top. 

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The WOT doesn't clear up, I normally hold it in 2nd or 3rd to 6000rpm when checking the a/f. Ive restricted the PV a little more and will see how she goes over the weekend. I don't think its a squirter issue as it doesn't go rich straight after flooring it.

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Drove down to a local car show yesterday and the car went pretty well. With the car the way it is now with the pink cam i have no flat spot when flooring it and it now has a rich spike for a split second. The wot is now high 11 but it has developed a lean surge at constant speed under very light throttle just off idle. Its not a real big issue as i'm rarely at that throttle position and it richens up either side of it.

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Sounds like you are getting pretty close

Lean spot at constant throttle no problem

High 11 still bit rich for wot, if you can get it to 12.5 to 13 it will be quicker and better economy

Takes a fair while to set a carby up close to perfect

 

Are you just watching the gauge while wot?

I found that hard so I velcro'd my phone to the steering wheel and recorded it

Then I could watch the replay and break down what's exactly happening in slow mo

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