The 750 Holley vs is on, and my Iroc is running like a champ Never before have I taken the car up to 6500rpm, but it feels so awesome, and it pulls like no tomorrow. I'm still getting over the 1st week jitters, feeling that I'll break something in the drivetrain, haha.


This was the way to go from the start, idk why I opted otherwise. Not only does the car actually RUN now, but other things are way better than the edelbrock. For example, the edelbrock idle was hard as hell to tune, and VERY sensitive to the weather. The electronic choke was a pita to get right with the ever changing weather of New Jersey. This Holley though, manual choke, way more convenient than the electric imho. The idle has been perfect for the past three days, AND I can bring it down to 800rpm, and still have it not stall like the edelbrock carb would (had to keep that at 1200 idle)


The only thing that is killing me now is an off idle bog I have to tune out, as well as fixing my gas pedal and throttle cable so that I can actually get 100% travel (I'm getting like 85% now, and it's STILL got a crap load of power). The only thing left to do is address these small issues and richen up the carb one step or two. Plugs are still white with a tiny tinge of brown/soot.


I gotta say though, thanks to you guys that put up with my crap for this long amount of time. Without the wealth of knowledge available on this forum, I would have been lost so many times. You guys that have been helping me really make this forum, and I can only hope that I've helped others on here the way you've all helped me.

 

Rock on man! Now you gotta change your sig so it doesn't say Edelbrock carb eh?
Off idle bog? Primary blades might be open too far to get it to idle. See how far they are open by removing the carb and checking the idle slots (if it's similar to a q-jet that is). Try adding timing rather than throttle blade opening to get a good idle. And of course play with idle mixture for max vacuum.

 

Haha, good point with the sig.

I'll take a look at the blades this weekend and see what's up in that department.

So with the idle screws, you adjust them evenly until you get a maximum vacuum? Easy enough, I can start there. I just hope it's something simple and I don't have to convert to a 50cc pump kit.

Also one more thing. I haven't hooked my PCV valve up yet. The brake booster is going to the port on the rear of the carb. Where should the PCV be going? There is an open port on the passenger side of the carb, on the metering block that looks too small to go to PCV. Should I get a step down and hook it to there? I was told that I could put it off of the port in the manifold but this would just be more convenient.

 

oh, good call there. The PCV is a big source of unmetered air flow. Once you hook it up you'll be able to close your throttle blades a lot. It'll change your idle drastically. Do that first.

No, you want a big port. There isn't one in the front of the carb eh? Then use a hole in the intake if it's there, remove the allen head plug (should be on the intake manifold) and put in a pipe thread -> hose nipple style convertor and hook it up to that.

And yea, that's what you do for the idle screws. But again, do that after you hook up the PCV, it'll throw everything off.

 

Right right. I figured I could take it out for a few passes to see how it felt with it disconnected without any harm being done.

What is that port on the passenger side for then? Vacuum advance for the distributor? If so, I already have the distributor hooked up to the front of the carb...that fitting that is on the baseplate and angled 45 degrees toward the passenger side.

 

I'm not familiar with that carb, so I can't say.
You probably want vac advance on a ported source. Use a vacuum gauge to verify which is which. Your call which you want to use, but just make sure you know what you're using (manifold vacuum or ported vacuum), so you can swap it if you want to try it the other way.

 

Yeah it dawned on me after writing that that the port on the side is the ported vacuum source and the one I have the vacuum advance hooked to now is manifold vacuum. I'll try the ported and see what it does with the bog, if anything at all.

I gotta run out and get a low profile 90 degree fitting for my pcv source at home depot. Man I really hate going there for a 3$ part that can fit in my ashtray...such a waste of time.

 

Hey it's worse when the car isn't running, so I have to take the friggen bus to go pick up a $2 part for my 350HP hot rod. Yea, that's humbling. It's happened more often than me actually driving the POS... err, *cough*...

 

The ported vacuum port on the side will change the actual timing curve from off idle... That may help the off idle bog. If that doesnt do it try going up in squirter sizes like 2 or 3 steps. I have a Holley on my camaro and had the same problem I also found it best to just use the manifold vacuum port for the advance and just cap the port in the side... Hope this helps

 

Yeah, my first step will be to change ports to see if that alleviates anything. Thanks for the heads up. In all actuality I didn't even think to plug off the ported vacuum barb, so I could be losing vacuum under throttle...I know that's doing something bad for me lol.

If changing the vacuum source doesnt help, I'll look into adjusting the idle and look into squirter sizes. Are they easy to get to and change out? What about cams? Would you suggest a cam that has a bigger initial lope than the stock one?

 

The squirters are very accesible... Pull the air cleaner and look on the top of the carb.. The large Phillips head screws that you see are the screws holding down the squirters. Just dont lose the little gaskets that are on both sides of it. You dont want to drrop i t in the carb... I think i am running the pink cam on the accelerator pump.. and yes the port on the side will suck air under throttle causing a lean condition.. im just not sure how lean that would make it.
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I almost forgot... If you start working through it and find that the squirters are large enough but your not getting enough fuel off the line then you may need to change to a 50cc sccelerator pump... i think the stock ones are 30 cc. When it is about right it should want to blow just a very slight touch of black smoke when you punch the throttle and instantly go away. The biggest mistake a lot of people make is to over carb a motor or make it run to fat. I hope this gives you some insight....

 

It does give me insight, thank you very much. I get done finals here at college next week and I'll actually have time to spend tuning it. Yeah the stock pump is 30cc and the aftermarket is 50cc.

I'm gonna take this one step at a time, starting with the simplest options, but I'm just trying to gather information as of now. But tell me if this plan of attack is smart:

-Get PCV and vacuum advance hammered out (try ported vacuum, and see how that works, cap off which ever barb isnt being used)

-Adjust idle screws for max vacuum

-Get a pump cam kit and swap in cams until I find a suitable one

-Try a bigger accelerator nozzle (the stock one is a .25, maybe try out a .35)

-Then I guess the only option if none of those work is to go for the 50cc pump kit right?

So I am looking to tune to eliminate the bog, AND get a quick burst of black smoke out the tailpipes? If I end up going too big with a cam or squirter, will I know it, based on if more/lots more smoke comes out?

 

yeah that sounds like a pretty good plan.. Just make sure that when you adjust the idle screws and such that you dont adjust it to the point where the base throttle plates start to open to far.. that will end up bypassing the idle circut. and if you get it to rich it will smoke a little bit but you will feel it first.. it will have power but it will feel a little sluggish..

glad i could help.. i have chased the exact same problems and ended up going with a new pump cam and 2 squirter sizes larger in the front and i think 3 in the rear.. still on a 30cc pump..

Good Luck... let me know if i can be of more assistance

 

That sounds like a great plan.
I agree, I think without your PCV this is where you are now. That's why I think you may not need some of those steps.

One other thought, make sure you do each step completely seperate. ie, make sure there's no way you can confuse your results. Do one step, then drive it for a few days, idle, mid range, WOT. Make sure you know what issues you've touched on, and what you haven't. Then go and do another step. A lot easier to go back to a "known good" state if you follow this painfully slow careful way.

 

Thanks guys. Like you said sonix, I'll go one step at a time. I know the aggravation of trying to diagnose a problem with multiple solutions, finding it's only worse and thinking "crap, now why is it doing this". Don't wanna walk down that road again.

And when adjusting the idle screws, it is in for lean and out for rich correct?

What setup are you running camarokracker? I figured that a 30cc pump could handle my application, but I just wanna check it against yours to get an idea. Obviously if you are running a cammed 427 on a 30cc pump then I'll be fine with my 30cc


Edit: Another thing a buddy of mine mentioned was installing a lighter vacuum secondary spring (he has a few on hand). Would a bog be a result of the vacuum secondaries not opening soon enough?

 

What torque converter are you using?
And what gears are in it?
I didn't notice either in your sig..

 

Stock, and 2.73's

They aren't in my sig because it's something I am not proud of. I know that these two are holding me back significantly. My next plan of attack is the rear, and I hope to save up $1000 so I can beef up my 10 bolt and put 3.73s in the rear. I want to switch to a T5 or T56 down the line as well, so I don't want to invest in a stall just yet.

 

No wonder you've been having so much trouble... with those large heads and decent cam you're slow speed torque sucks.. its going to be hard to overcome stumble with large port heads like those.. the velocity is probably horrible. I can't imagine a stock converter on that setup.. 200cc heads are 383 territory.. invest in a 3200 rpm converter or manual trans soon and that will help a lot.

 

Thanks for the tip. I know guys with big ports like me with auto trannies who have tuned their carbs to be perfectly street friendly (minus the fact that the low end power was being held up). I know I'll be able to get this bog out. I wanted to go with the 180cc heads because they flowed a bit better, but the 200ccs came with better springs that I feel more comfortable with, and I got a killer deal on a new set off of ebay, so I opted for them. I plan to keep going more powerful anyhow (looking into a roots blower within the next two years, but with that comes a bottom end rebuild, and I pretty much have to have the trans and beefy 10 bolt by then too.) so the 200s will be useful down the line. I don't plan on launching with slicks, so I think a tanked up 10 bolt will suit me just fine as well.