We are currently running on the new domain and server: www.Speed-Talk.com

IMPORTANT: Update your bookmarks to https://www.speed-talk.com/forum/
(Right-click the URL and select "Bookmark this link")

Dominator - can't even get it to idle

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Freddie
New Member
New Member
Posts: 37
Joined: Sat May 30, 2020 11:57 pm
Location: Terrill

Re: Dominator - can't even get it to idle

Post by Freddie » Fri Jun 05, 2020 1:38 am

No it hasn't and I've been thinking of doing exactly that...I live ina quiet area so I can get miles on it with no hood without issues. Might even do that today

shoedoos
Expert
Expert
Posts: 623
Joined: Wed Aug 09, 2006 3:14 am
Location: New Zealand

Re: Dominator - can't even get it to idle

Post by shoedoos » Fri Jun 05, 2020 1:43 am

back the timing down to 30 and take it for a spin......you can check the beginning of the advance curve by using your timing light.....not sure if you will be able to view your tach though at the same time.....maybe video it with your cell phone so you can see what advance is at 2000 and at 2500 etc etc.....see if you can keep the maximum advanced number around 36 degrees when you're driving it......

Geoff2
Guru
Guru
Posts: 1289
Joined: Mon Nov 09, 2015 4:36 pm
Location: Australia

Re: Dominator - can't even get it to idle

Post by Geoff2 » Fri Jun 05, 2020 5:38 am

The engine likes & wants more idle timing. Big mistake that many tuners make, not giving big cammed engines enough idle timing. Your starter doesn't like 42* initial??? Who could blame it? There is a simple, inexpensive fix: use a dist that has an adjustable vac adv. There is a reason that so many dists are sold today....with adj VA units.....
The VA units can add up to about 30* of timing. So you could run 12* initial [ static ] &, with the VA connected to MANIFOLD vacuum, the engine will idle at 42*. You could use more static initial & less VA by adding a limiter to the VA actuator. Any combination you want. The beauty of using VA is that it is load sensitive & will drop off under load, which is what you want.

Freddie
New Member
New Member
Posts: 37
Joined: Sat May 30, 2020 11:57 pm
Location: Terrill

Re: Dominator - can't even get it to idle

Post by Freddie » Sat Jun 06, 2020 12:33 am

OK so today's update.

Tried bigger air bleed on the idle air. Only had 85s (I was running 75s). LOL..so lean I was getting massive exhaust backfire. Quick shut er down and put the 75s back in.

Still rich at idle.

Oil (break in oil with roughly 30-40 of screwing around with the carb time on it) is looking a bit black and I'm getting black liquid squirting out the exhaust.

I bloody hope I havent burnished the bores, that would suck.

That said I needed to get the rings seated. So fired it up and out we went.

It is currently set up as
Primary jets are 80's
Secondary jets are 94
Primary PV = 25
Secondary PV blocked
IAB = 75
HSAB = 33
IFRs = 35

Fuel pressure 5psi
float levels knocked down a bit.

Better at idle but still rich.

On the road.

I get a stumble after the pump shot has completed. Momentary but definately can feel it

Also once I get to about 4,000rpm it really stops pulling and basically won't go any higher in RPM.

so I still need to focus on the idle.

But for now I'm going to drop the oil and filter and replace both as current oil is clearly full of fuel.

On Idle I'm thinking I need to reduce the IFRs some more. Currently 35s I think I need to go to 33 or maybe even 32

Off pump shot stumble I'll deal with later and peak RPM I suspect I just need to jet it up a bit, especially primary...my old 1050 AED has 102 secondaries and that pulled way harder

econo racer
Expert
Expert
Posts: 611
Joined: Mon Nov 26, 2007 11:44 pm
Location:

Re: Dominator - can't even get it to idle

Post by econo racer » Sat Jun 06, 2020 9:17 am

My friend I would get that carb off of that motor ASAP. Its gonna ruin your motor. :(

Freddie
New Member
New Member
Posts: 37
Joined: Sat May 30, 2020 11:57 pm
Location: Terrill

Re: Dominator - can't even get it to idle

Post by Freddie » Sat Jun 20, 2020 8:14 pm

not giving up yet.

Waiting for o2 sensor to arrive

have not had an AF gauge on this yet and I know they aren't that helpful at idle but I need more info.

Took the carb off to go after then next round of settings.

Decreasing IFR's from 35 to 33 and upping secondary jets to 98s (ran lean at WOT). May need to go higher again but will start there.

But while off I just did a triple check of everything. Found an interesting outcome on the transition slot.

Primary no prob. Both bores set at 0.020" perfect
secondaries. One bore is perfect at 0.020" yet the other is closer to 0.050". Throttle blade is not sticking, everything is buttoned up tight. It's just the transition slot in that bore is longer.

So what to do, half them out (one at 0.010" and one at 0.040") or have the long one at 0.020"?

I'm thinking half them out so I don't create an overly excessive lean idle on one side. Or I can even drop the IFR again on that side that is longer to reduce fuel to that bore.

Thoughts ?

Freddie
New Member
New Member
Posts: 37
Joined: Sat May 30, 2020 11:57 pm
Location: Terrill

Re: Dominator - can't even get it to idle

Post by Freddie » Fri Jul 03, 2020 3:59 am

for those following. O2 arrived last week just haven't had a chance with work to get to it. Did so today.

OK so this is where we are at.

23 degrees initial timing
38 degrees all in by 2800 RPM
mechanical adv only, no vac.

T-slots perfect

80 Primary jet
100 secondary jet

Idle air bleed 80
High speed air bleed 33

IFR's 33 front and back

PV 2.5 in primary and blocked in secondary

I can finally tune the Idle AFR using the mixture screws.

I can tune it from 13 AFR to 17 AFR with 2 full turns of the mixture screws.

I had to put my O2 sensor at back of car, so not ideal position but it works. Just means my results are a tad leaner than perfect.

My goal is an 15 to 15.5 : 1 Idle AFR.

Once I dial that in (tomorrow) then I'll dial in cruise and WOT.

Only getting 8hg/In vac and idle speed is around 950 RPM but it seems to be fine at that.

Haven't checked plugs as plugs in it are fouled in anyway. Didn't want to kill a new set till I had idle dialed in. Once I get idle dialled in, I will change the plugs and do a plug check also

Surprising how far off the "out of the box" settings were.

steve cowan
HotPass
HotPass
Posts: 1095
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: Dominator - can't even get it to idle

Post by steve cowan » Fri Jul 03, 2020 7:19 am

be careful with placement of your o2 and don't rely on it to much as it should be in the collector,things to consider-if you are to lean at idle there will more than likely be a stumble off idle or driving around a corner at low speed meaning this is the transfer slot,Jmarkaudio put up earlier about drilling ,tapping and jetting T slot circuit in the main body-this is the first mod I done on my holleys and BG demon makes a huge difference but it is daunting the first time.20 jet sizes is a huge spread ?? I would be running power valve front and back and I do on all my carbs,i have spent a lot of time and effort setting up a 1:1 linkage,power valves front and rear and square jetting and tuning the PVRC for WOT with good success.i have rebuilt only 1 x holley dominator so I don't have the experience on those carbs.sometimes at the track I will only put in one brand new sparkplug and remove it after a pass for inspection or if I separate the sparkplug for closer inspection,this might save you some $$ on spark plugs until you have your engine running up to speed.
steve c

Freddie
New Member
New Member
Posts: 37
Joined: Sat May 30, 2020 11:57 pm
Location: Terrill

Re: Dominator - can't even get it to idle

Post by Freddie » Fri Jul 03, 2020 2:57 pm

Steve, yeah only using the O2 as a guide as I had no idea where I was lean / ricjh wise. It just kep fouling plug after plug no matter what I tried. Using Vac Guage and plugs as my tuning devices. O2 just to get me in ball park. I am doing the 1 plug at a time swapping at the moment. Thanks for the tip.

steve cowan
HotPass
HotPass
Posts: 1095
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: Dominator - can't even get it to idle

Post by steve cowan » Fri Jul 03, 2020 3:40 pm

sounds like the idle circuit is responding so thats good news,i am interested on how your car drives,and then the fun part of tuning the entire fuel curve,i am still curious on only 8 inches of vacuum at idle,do you have vacuum readings previously as in light cruise/WOT,idle in gear engine hot etc.
I am just wondering if there is cam timing issues.
steve c

Freddie
New Member
New Member
Posts: 37
Joined: Sat May 30, 2020 11:57 pm
Location: Terrill

Re: Dominator - can't even get it to idle

Post by Freddie » Fri Jul 03, 2020 10:31 pm

Steve, just had it out on the road for a bit of tuning. I'm at 14.2:1 idle IFR @900 RPM and 8 in of Vac. Still a tad rich.

But damn it was hard to start, seriously hard. Spitting out the carb, etc. Even kicked back on the starter twice and it made an ugly grinding noise. Hope I haven't killed some teeth. I bumped up timing to 24 initial and 38 all in by 2600

Drivability. Off idle stumble but that really doesn't surprise me at all.

at cruise (1800-2100 RPM) it 14.5:1 AFR. Did not have vac gauge on it but will be doing that next.

at wide open it leans way out to 16-17 : 1 AFR.

So I'm going to up the primary jets which will richen cruise a bit but not much I definately need to richen up WOT.

Still need to lean out idle a bit (as it still smells which is one of the things I'm trying to address)

Guy who built the engine I trust, he's built heaps, so I expect cam is degreed fine.

So now it's cleaned up a bit at idle, but too lean for cold start and to smelly / rich when warm. Almost like a need a choke

steve cowan
HotPass
HotPass
Posts: 1095
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: Dominator - can't even get it to idle

Post by steve cowan » Fri Jul 03, 2020 11:46 pm

Freddie,
All my stuff wont idle cold,in my opinion a engine is to rich if it does without a choke set up, i would advise putting a power valve back in the rear and take main jets down in size,i am not convinced when people say the mains dont pull fuel at idle,just my opinion.do you have provisions for vacuum advance?? Probably mentioned before but I have forgotten. Make no mistake this carb will be on and off a few times as it is time consuming but stick with it, you will learn alot. Forget about WOT at the moment.
steve c

Freddie
New Member
New Member
Posts: 37
Joined: Sat May 30, 2020 11:57 pm
Location: Terrill

Re: Dominator - can't even get it to idle

Post by Freddie » Sat Jul 04, 2020 4:04 am

Thanks Steve, actually enjoying the process even if taking longer than I planned. Learning tons.

No provision for Vac adv. But guessing I could, tap a port in the carb, have to check if my Dizzy will accept a vac adv.

Not too worried on WOT yet either.

I want to lean the idle just a bit if I can.

Cruise seems good but will need to address the off low cruise stumble. It has #30 shooters in it now with the yellow cam. At light throttle it dribbles out the squirters so it's already into the acc pump and suspect it drains the bowls so then when I get on it, not enough in em. But they are 50cc pump bowls.

Will put a PV in rear and lower the rear jet. I think I will increase the primary jets to 84 and lower the secondaries to 96

steve cowan
HotPass
HotPass
Posts: 1095
Joined: Wed Jul 27, 2011 5:22 am
Location: brisbane AUSTRALIA

Re: Dominator - can't even get it to idle

Post by steve cowan » Sat Jul 04, 2020 6:11 am

Freddie,
looking at your carb spec that was on that Holley link
needle and seat 0.130'' what size did you replace 0.110''??,0.130''??
it says 37 squirters
I would check your accelerator pump adjustment,traditionally you open to full throttle and make sure the pump arm is not over extending into the pump diaphragm but I actually adjust my carbs with a bit of clearance at the pump arm with throttle closed as I think the pump shot can change when engine gets hotter with expansion.
look at the secondary linkage because it is adjustable.
I am curious what adjustments your metering block has,i know it has IFR adjustment but what about emulsion or power valve restrictors.
I would not be surprised if your engine wants more timing at idle but using a start retard or interrupter switch would be required.
steve c

Freddie
New Member
New Member
Posts: 37
Joined: Sat May 30, 2020 11:57 pm
Location: Terrill

Re: Dominator - can't even get it to idle

Post by Freddie » Sat Jul 04, 2020 6:37 pm

Steve. Well thank you. I did not even know that needles and seats came in different sizes. I had a dominator rebuild kit. Turns out it’s a 110 seat needle and seat. Will replace with proper 130

Squirted is a 37. I can’t read poor eye sight swear it says 30 on it but poorly stamped. I just measured it and yep it’s a 37

Pump arm is adjusted so 15 thousandth gap when fully closed. I have not checked wide open adjustment will do that.

Metering blocks are fully adjustable. Everything. I’ve only changed IFRs at this point

Post Reply