I have an 84 GSL-SE that's been converted to carb w/ the RB Holley kit for a 6-port 13b (600cfm). It runs and drives, but has a pretty bad stumble. It's been rejetted with smaller primaries (62s) but secondaries are still 66s. I don't know a whole lot about carbs but would like to get this car running good (along with learning about carbs)

Any advice on what I needa change is appreciated.

Thanks!
Marc

 

Wheres the stumble? Might be the accelerator pump if its just off idle, or possibly the secondary diaphragm spring if its more in the midrange. I would call RB or Mazdatrix about what jet sizes are appropriate as a starting point.

 

Below 3k it's pretty bad, beyond that it gets better. It makes me think it's getting too much fuel for the low rpms. Also, when you first touch the pedal it stumbles for a sec and then revs good.

I read another thread where 57 primary jets and a 50cc accel pump and mech secondaries worked wonders on a stock port 13b, was thinking of trying that.

What kinda places (local) would/should have parts like jets etc. I was looking online and shipping is more than most of the parts cost so it doesn't seem feasible to buy them online.

Thanks again and I'll try giving RB a call later today (after work) and see what they have to say.

Marc

 

Any local speedshop should have jets, accel pump cams and stuff for a holley. Autozone and Discount/Advance Auto Parts sells holley jet kits and parts.

Check you accelerator pump adjustment. SOunds like thats part of your problem.

 

oh cool I didn't think that Autozone would have them. Never saw them before, probably because I wasn't looking... heh. Anyways, I'll give them a try.

Thanks
Marc

 

The previous owner said the secondaries come on at ~6000 rpm if I remember correctly...

 

Get a holley tuning book and learn how all the adjustments work. They are as simple as the Nikkis really.

 

I got one now. Haynes Holley Carburetor Manual.

 

make sure your floats are set right. if the stumble happens when you barely step into it, it might be the idle jetting. If it's when you step on it harder, it might be more so the accelerator pump. It more likely for it to be a lean stumble if it's a racing beat kit...they jet them on the lean side, reguardless of cfm. Does it get better if you go into higher elevations?

 

i'd say it's the accelerator pump cam. unless u keep alittle grease on it, it tends to wear in that area of normal every day driving/crusing, which will be noticeable during a steady cruise and then slightly accelerate going up hill.

 

Try finding one of these small perofrmance shops that youve drove by a thousand times. I have found that they have everything performance I have ever needed. The one shop I had got some jets from had one of every number right down a board. Couldn't go wrong. I might have some of the jets you need. Contact me at zfrederick@***.net and I will send them to you for free if I have the ones you need. Good luck.

 

I've got; 2 - 56jets, 4 - 57jets, 1 - 58 jet and 2 - 65jets

Just let me know what you need

 

Well, I'm going to take a look at it all today. Jim Mederer (from Racing Beat) suggested looking at float levels first, then accelerator pump linkage for any 'looseness' and if all that is OK, then move on to no load slow rev to 3000rpm. Then adjust idle mixture til you get improvement and if it persists, try different jetting.

 

New problems today...

When trying to start it today after work, it just plain wouldn't start. It smelled pretty bad of fuel, so I assumed it had flooded. I 'unflooded' it by pulling plugs, disconnecting fuel pump and cranking the car for ~15 seconds, twice. I checked the plugs, they look fine and get good spark. Put a little bit of MMO down the carb and turned the car over a few more times to lube it up. After the plugs dried I put'em back in and tried starting it and it fired up but died shortly thereafter. This continued for a few times until it was flooded again. Eventually, after about 3 unfloodings I got it to run for a few minutes, but it wouldn't idle on it's own and eventually died with another great flood. I never got to checking the float level because the Holley manual I have says to do it while it's idling, which never happened. I also tried adjusting the idle mix, but it still wouldn't idle to save my ***.

When I talked to the previous owner I found that it's not a RB modded Holley, but a plain Holley 4160 600cfm carb, DOH!

What kinda mods need done to make this carb work? Or what else should I try to make it work? I didn't try push/pull starting yet, but didn't think it'd help with it flooding so bad. Fuel seriously was POURING out the leading plug holes...

 

call RB and get their specs for the 600. Find out what the jets and everything are from them and replace all the components on your carb with those. It'll be cheap, pretty easy, and (most important) you'll finally know EXACTLY what's bolted to your car.

 

or you could give it to me in exchange for my engineless pretty 89 NA.

 

DO a search on Holleys here. 4160 dont have jets in the secs, they have a metering plate. You cant change jets, only drill out the plate. And 4150/4160's dont have replaceable air bleeds either.

 

I did a search, what I came up with was plugging the power valve, jetting the primaries smaller, remove choke, and plug oil lines into carb. The car is setup to run premix so I'm assuming the Oil lines part is not required in my case?

Sorry for being a pain in the neck, but I don't get a whole lot of time to actually work on the car lately. This weekend should see the fix (hopefully).

Thanks again guys for your patience.

 

Yea if your premixing, then dont sweat the lines. Why remove the choke? And how will you plug the power valve? Good luck, keep us posted.

 

I don't know about the power valve. I just read about the removal of the choke, I was thinking instead of getting one of those manual choke cables from Pepboys and fabbing up a bracket. As it stands, I can't use the choke from in the car.

I messed with the accelerator pump linkage and it seems to be working fine... but from what I read in the manual the pump should be able to move further than what WOT is, but this is not the case. Perhaps that's a part of it?

Also, I think I figured out part of the flooding problem... There's no Pressure Regulator, so my guess is the fuel pressure is too high? It's just running off a Purolator pump, with the return lines still there. Now as far as I have heard, purolator is crap, is this true? If so I can always get a Carter or Holley fuel pump after I get it going again. I went and bought a pressure regulator as well as a set of the secondary diaphragm springs and a few different jets to experiment with. Hopefully something will work.

Be back in a few w/ the carb to see what I can do.

 

You cant just remove the PV. You'll open up a big hole for fuel. Youd have to cap the opening, sounds like a waste to me, leave it alone. Yea a universal choke cable and youll be in business. On the Accelerator pump, it needs to have more travel than full throttle or youll bind or even bend linkage Is it close to making it? Are you sure you didnt over adjust that lever arm?

Ah, too much pressure will mess you all up. Sounds like you need a fuel presure gauge to check it.

 

Well here's the scoop. I bought a Power Valve Plug (who woulda thought it would be so simple) from the local O'Reilley's for $5, along with a choke cable ($4). The plug looks basically the same as the power valves in shape and size, but it's solid. I found the pump that's in the car while I was there, but it doesn't say anything about pressure other than "low pressure fuel pump". Pressure reg is on the way and I'll get a gauge when it gets here.

About the accel pump stuff, I hadn't made *ANY* adjustments to the accelerator pump and it's linkage, so it was like this already. I'll try adjusting it a bit to make it have some leeway.

I think that's all for now. Again, thanks a BUNCH carl, you're helping a carb newb become a carb un-newb... or something.

 

Oh and from what I can tell, the cam appears to be like a pink or orange... something close to that color.

How much further should the pump linkage be able to move after WOT? I got maybe 2mm or so? Good?

 

Easy part is done, fuel bowl and metering block are off. Power Valve is replaced with a plug. Curious though, what's the easiest way to get this f'ing gasket off? heh

NM, talked to a Domestic loving friend of mine and he gave me the secret. Drench them with some Carb Cleaner. yay.

 

About racing beat's setup question, they finally got back to me!

"The information you are requesting is proprietary in nature and, as a matter
of company policy, we do not release any information that is deemed
proprietary."

Yay that helps. *sarcasm* Guess I get to wing it.