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Dominator - can't even get it to idle

General engine tech -- Drag Racing to Circle Track

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777
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Re: Dominator - can't even get it to idle

Post by 777 »

Your pump arm adjustment is not right

https://youtu.be/w3F3ssOb8lg?t=60
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Re: Dominator - can't even get it to idle

Post by steve cowan »

Freddie,
I would not worry about changing needle and seats yet as you are trying to get low speed sorted first.
Good link 777 thanks for that
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Re: Dominator - can't even get it to idle

Post by Freddie »

Thanks 777 will adjust
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Re: Dominator - can't even get it to idle

Post by Freddie »

close to 7 weeks since I posted. Flexplate lost 4 teeth. Short story no way I was yanking the engine, as major job, have to dissmantle the entire front of car. So I managed to replace it without even taking out the trans. Difficult but got it done.

So back to tuning.

I have idle very close. I need to richen up just a touch which I can do with idle mixture

Cruise could do with a bit of richness also. low speed cruise is quite good at 14 AFR (under 20 miles an hour). 20-45 MPH afr jumps up to 15 so I have to get that down. WOT is still my issue now. 15 - 15.5 AFR.

I'm 88 Primary Jet 2.5 PV
96 Secondary jets 2.5 PV

primaries are bigger than before, secondaries lower (had blocked PV before)

I think I'll take the secondaries back up to 100 and bump the primaries to 90 for richer cruise
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Re: Dominator - can't even get it to idle

Post by MadBill »

Freddie wrote: Fri Aug 28, 2020 8:29 pm...
Cruise could do with a bit of richness also. low speed cruise is quite good at 14 AFR (under 20 miles an hour). 20-45 MPH afr jumps up to 15 so I have to get that down...

I think I'll take the secondaries back up to 100 and bump the primaries to 90 for richer cruise
With a mild cam 15:1 cruise is usually not excessive. If the only issue is the O2 reading I'd leave it as-is (or lean it further until it misbehaves and then back off half a ratio) BTW, the correct sequence (rarely followed) with a P.V. is to tune for high speed cruise with the main jets then tune for WOT with the P.V.C.R.s.
Re WOT, I've found worthwhile gains by tuning F/R separately. Disconnect the secondaries and get the AFR where you want it, then reconnect and do the final tune with only the secondary jets.
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Re: Dominator - can't even get it to idle

Post by Freddie »

Thanks Bill so in that sequence do I square the jets to tune the PVCR??
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Re: Dominator - can't even get it to idle

Post by MadBill »

No, I'd follow this path:
1. Disconnect the secondary link.
2. Size the primary main jets to achieve desired high speed cruise AFR*.
3. Size the primary P.V.C.R.s* to achieve best power/desired WOT AFR. *If they are not screw-in, you can have them converted or drill them larger (a couple of thous at a time), but you might want to skip this step and just go for WOT with the main jets.
4. Reconnect the linkage and tune for WOT, changing just the secondary jets.
Last edited by MadBill on Fri Aug 28, 2020 10:06 pm, edited 1 time in total.
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Re: Dominator - can't even get it to idle

Post by Freddie »

Thanks. Will try that
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Re: Dominator - can't even get it to idle

Post by Freddie »

so I haven't done any of the changes mentioned yesterday. I thought I'd pull some plugs and see what they tell me. Would love some thoughts on these.

I pulled #1 and #2 cylinders.

Note these are NGK6RE's

they have less than 20 mins run time on them.

I'd say 10 mins of that is at idle

5-8 mins cruise

3-4 strong WOT hits

Current timing is 27 base 41 total (mechanical only)

My basic read is:
- still rich, especially idle...even though AFR gauge telling me I'm lean
- plug looks like it could be a touch hot based on the ground strap
- there are no real defined base and total timing marks so very hard for me to check timing at this stage, but very faint marks look like I could take 1-2 degrees out of total
- can't do any porcelain check as dry carbon due to richness

Now part of the issue could be cold starts. I have to feather throttle for a good 2-3 mins at about 1800 RPM (on the T slot clearly) to get it up to temp. Once at temp it idles fine. But before that it dies. This 2-3 mins means it runs stupid rich (my eyes were burning rich). Could that be enough to foul the plugs and as a result kill any ability to use the plugs to get a read out? I may use an old set, get it up to temp and replace the plugs then do plug based tuning.

First 3 pics below are #1 plug

2md 3 pics are plug #2 (right hand bank)


Image

Image

Image

#2 plug

Image

Image

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

Post by steve cowan »

if a engine idles from a ''cold start'' without a choke set up it is to rich in my opinion,its obvious that you are way rich as you stated.with your engine not being able to idle for a few minutes until warmed up is the about right,i am going to say it will be transition slot making it very rich,i am going back to read you thread again.i think your lack of manifold vacuum is playing havoc on booster signal as well.
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Re: Dominator - can't even get it to idle

Post by Freddie »

Steve, T-slot has been checked many time I have it at 0.015" right now so I am pretty sure that's OK.

Lack of vacumm has always been an issue with this engine. I get only about 7-8 Hg" at idle. Always been that way both before and after rebuild.

Thanks for the insight though. I know most engines need to be a bit richer to start up, but this literally will die instantly if I take my foot off the gas. I have idle at 1100 RPM now when hot (in park) and around 950 in gear. But until the engine is warm I need to keep it at about 1800 rpm which I know means I'm running almost strictly off the T-slot
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Re: Dominator - can't even get it to idle

Post by steve cowan »

I think I mentioned earlier in your thread -
all my carbs have adjustable T- slot jets,most carbs are to rich on T-slot at low speed.
if you wanted to send me your carb i can do the mod for you and also move IFR in metering block as well,I am in Brisbane,no pressure just an offer.I think you need to take some rear jet out as well and square jet since you running PV,I understand you are just looking at low speed function at this stage but carbs can do funny things.
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Re: Dominator - can't even get it to idle

Post by Freddie »

I may have to send to you Steve. I’m in Noosa. I’m way out of my depth doing those mods. Let me have one more crack today. If no joy I’ll reach out to get it to you
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Re: Dominator - can't even get it to idle

Post by steve cowan »

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

Post by steve cowan »

20201003_171930.jpg
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Chris ( freddie) dropped of carb and as per photos I drilled and taped a 10/32 set screw at 0.058".As per factory they have a press fit brass jet at around 0.080".
I moved IFR to lower position it is 0.035" may have to bump up to a bigger jet but will test first.
We have set up at a 1:1 throttle,square jet and both power valves fitted.
Starting off at 84 main jet and i drilled PVRC to 0.089" will test and adjust if required.
Emulsion is standard.
MY QUESTION IS-
As per photo the pink metering block gasket is off my 830 holley with proform blocks,the pink gasket came with the 1150 carb as well but was replaced with blue gasket.i have had a idle quality issue previously by using blue gasket on the billet proform metering blocks,replaced with the pink gaskets and problem went away.i use the blue gaskets on my HP HOLLEY CARBS WITH BILLET METERING BLOCKS with no issues.
Can anyone give me a part # for the pink gasket,I have proform 6220 pink gaskets but they are the same as the blue gasket.
Appreciate any help.
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