Good starting range of jet sizes on holley carb?

Discussion in 'Engine Topic' started by AllGoNoShow, Oct 18, 2019.

  1. AllGoNoShow

    AllGoNoShow Veteran Member

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    It is a dual plane intake (Dart Sportsman- I think it's a knock off of the Performer EPS). Haven't done cranking pressure yet...will throw one on it this weekend. Bought a pump cam assortment and some .35 squirters (just in case- I will try to tune with cam first). The idle air fuel was set at operating temp fully warmed up (also did the vacuum gauge thing and got it to max out at 13 from 12 or so). Cam definetly sounds lumpy for what it is but I guess that's what a solid cam leaves you.
     
  2. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    I "think" the only dual plane Dart is making for a sbc is the SHP intake. It's the same as the RPM Air Gap, which is a very good intake for the street. I went 6.9x in the 1/8th with the RPM intake on a 355, HR cam, and a small shot of juice.
     
  3. AllGoNoShow

    AllGoNoShow Veteran Member

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    Oh this intake is at least 20 years old. It says "Dart II" on it and "Sportsman"....it's a pretty high dual plane (when I thought i was cool and was going to run nitrous the plate put the 3" drop base air cleaner into the bottom of the hood).

    On a completely different note and to save a whole new thread...I've drained the 15 gallons of 8 year old gas out of my tank using an old electric pump I had laying around hooked off the feed line before the mechanical pump. Didn't see any contaminants at all the whole time. I was originally going to drop the tank but it looks so good I was just thinking I would drain it as much as possible, put 5 gallons of new gas in it and pump it through until I see the new stuff....thoughts? Trying to get this thing to hit the streets before it snows!

    Nick
     
  4. G72Zed

    G72Zed Veteran Member

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    Well, the races I am referring too were on a 1/4 mile & (1/3) track, but not drag, DIRT oval, so like 125 1/4 passes with corners LOL.

    And yes, It was a kick in the teeth when NASCAR went EFI with the exact same intakes submitted as the year before with the carb, EFI down 11+ HP right off the hit, but it appealed to the general public and head office brass needed the sales and to get the needle moving on the EFI market.

    This years EMC I worked on was going to be carbed, but engine sold. Last years G3 Hemi entry was in fact converted to carb, and to solid FT, nice combo.

    One of the biggest "eye openers" was the 2014 EMC entry of Bischoff's Gen3 Hemi. All work and development done with a top performing EFI, only to show up with a basic 4150 Holley, and killed the field with it.

    But, it's easier to find a laptop guru than a carb guru these days, that's for sure.
     
  5. G72Zed

    G72Zed Veteran Member

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    I think that has the divider cut down a bit, correct? Try the 330 "Pink" on holes 1 and 1.
     
  6. Z28zz383

    Z28zz383 Veteran Member

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    By 50cc squirter, I meant the accelerator pump assembly. It feeds fuel to the squirters.. Mine needed the bigger capacity.
     
  7. G72Zed

    G72Zed Veteran Member

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    Yes, kind of figured you were referring to the 50cc REO acc. pump.

    Looking at the OP's combo, he should be fine with the 30cc acc. pump, unless something is out of the norm.
     
  8. AllGoNoShow

    AllGoNoShow Veteran Member

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    Well I got the thing registered and took it out on the road for the first time in ten years (not a typo). It was a ton of fun...engine is running pretty good. I went up to a 35 squirter in the primary and put a red cam in it (which I thought was already in it but it was actually a sun faded pink cam which is holleys mildest acc. pump cam). A couple questions:

    1. To get the engine to idle when it's cold I have to set the idle air fuel pig rich when its warm (like 12.0 air fuel). This also gives me highest vacuum reading at idle (got it to nearly 15). I assume there is no way to get around this with the exception of buying a new carb that has a choke, right? (Mine does not)

    2. If cruising at or under 2k, engine is running about 15.2 A/F ratio (over 2k it is in the mid 14s). Assume I should go up jet sizes on primary? 1 or 2 sizes?

    3. Mashing the gas causes a split second lean reading on the A/F ratio before it goes rich. You don't feel it when you drive, it just starts pulling, but should I be concerned about this or is it normal?

    4. Power valve choice? Currently running 8.5? Should I go to a 10.5?

    5. Engine was running dead set at 210 coolant temp. Electric fan is from an old Ford Taurus and that is going on early but doesn't seem to cool it any lower than 210. I don't know what thermostat is in it, but I want to replace it as I imagine that is the issue, should I go with 170 or 190 degrees?
     
  9. G72Zed

    G72Zed Veteran Member

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    1- If the idle circuit is setup and tuned with full engine/coolant temp with intake heat soak, you will be on the rich side at first startup and until you get some heat into it. If you drive in cold temps, you could unplug the heat crossover port on the intake if you have this available, if not, you could work on the IFR's and IAB to dial it in.

    2- Sounds like your still on the idle and transfer circuit under 2k, you could try and go down on the HSAB , go up on the IFR, move them to the bottom location, and raise the float slightly in front. Mid 14's- low 15 on highway cruise is nice, make sure you have all your timing in for this lean cruise.

    3- Nope, it's a carb, it will have these quick little spikes.

    4- Look at a 10.5, you mention very good vacuum signal in the 15hg range, the 10.5 PV may help your #3 question

    5- I would try a 170 first to see what it does. Test it first to make sure it works and opens at the right temp. I test all of mine, especially NEW ones, have found many duds out of the package.
     
  10. AllGoNoShow

    AllGoNoShow Veteran Member

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    Thanks for the reply. Did some tuning with it today and ended up putting a 10.5 PV in it which really helped the acceleration from low rpm cruise. Also went up to 74 jets in the primary's.

    Can't really get the idle air fuel ratio right without a choke. If I set it warm and get it into the mid/high 13s the engine won't even idle when it's cold (it will be too lean and die at anything under 1500 rpms until it warms up). Right now it's right at 12.0 warm to get it to start and idle cold....and, interestingly, this also gives the highest vacuum reading. Seems pretty pig rich at idle but without adding a carb with a choke I don't see a way around it. I also don't understand how it can be so rich at idle, then lean out to a 14.0-15 AFR at low RPM cruise when it should be mostly on the idle circuit.

    But, to the point, without staring at the AFR gauge I don't think I would even notice it....it is driving great, accelerates when you want it to, and WOT blows off the dry rotten tires in second gear. Don't recall it ever running this good. Still need to put in the 180 thermostat I got....it's 50 degrees out here and it still was stuck at 210.

    On another note, I'm tuning this carb when it isn't high 40s, low 50s out....are things going to change and in what direction when it's 75 degree summer weather?
     

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