I finally got around to getting my Holley on my car. I was waiting for some decent weather and a time when I don't need my car. Its going well, no paticular problems, and everything has bolted up nicely. It runs and idles quite well, but I feel as though I lost power. If I didn't lose power, I sure didn't gain any. My low end feels better, marginally. I do have a Holley Red pump, and I'm running a high flow fuel filter. I'm thinking the carb is getting plenty of fuel, it seems to be running a bit rich. The choke is not hooked up, but I find it hard to believe that choke plate could kill my power too much. The car was running about as good as a stock nikki can run previously.

Now obviously this carb is not tuned at all, I haven't messed with the secondaries or the accelerator pump yet, but I'm less than impressed at the moment. I must be missing something, as I've heard multiple times that this swap should be a night and day difference. What am I missing here?

 

vac seconday spring too stiff. The engine may not be pulling enough to open them. If you do not have a spring kit, than swap the spring from your nikki into it.

 

While I will certainly look into getting my secondaries opening more freely, there must be something more to the picture. RB supplied it this way and if it doesn't net more power out of the box than the nikki can I'm sure it would be well known among the community here.

 

a vac leak would contribute to this as well.

 

The only way a carb works good out of the box for all altitudes is if it is tuned too rich for all.

 

Uh there should be no vacuum leaks, there really isn't any ports on the RB Manifold for vacuum to leak from, there is only power brakes and ignition advancement, both of which are hooked up.

And I know the carb is running a bit rich, but I guess I wouldn't have to chase down a perfect tune before it makes more power than the stock carb, whether it is tuned very well or not I would have thought it would be more powerful than the stock nikki.

 

It should have more power than the stock Nikki. Check the secondary spring (as was stated above). Do the "screw trick" as a temporary test to see if it's your secondaries opening.

 

For the record, the sping out of the Nikki is incompatible with the holley, and actually feels stiffer, if it isn't it sure isn't softer.

I just took out the spring. Its faster, but I'm still not blown away. I also disconnected the choke in an effort to see if the choke plate was holding it back. I feel like I must be missing something here.

 

Top end is really where you should notice the difference with a Holley.


You're right in that there are few opportunities for a leak with the RB Holley setup, and if the carb is new (and definitely modded by RB, as opposed to a stock Holley), then you should see results, praticularly in the mid-high range. So my first guess is fuel delivery.
What's your fuel pressure at? Just because it's rich at idle doesn't mean it can't be running out up top.
New filter? Could you have sediment in the filter?
Timing? This is the other variable, but not my fortee.

 

Maybe I'm expecting too much, but I'm not seeing much gain in mid to top, infact I noticed a bit of extra kick in the low end but thats about it.

The carb is newish, hasn't been used much from what I know. It is an RB carb. I'm using a Holley Red fuel pump, which should be at 7PSI. I do not have a regulator, I'm just running one feed line into the carb for now. The fuel filter is a brand new Fram G2, the high flow filter that RB recommends. I haven't touched the timing, and I know that I can get more power goofing with that, but I don't want to touch the timing considering the car was running perfect before I put this carb on.

The strange thing is that this carb drives very well. I have about 100 miles on it now, and it doesn't stall, bog, or do anything goofy like that, but it lacks power. Exact opposite of what I thought it would be like. Like I said, perhaps I'm expecting too much of a gain, but from other testimonials this carb should have added alot more kick to my car, and I fail to notice that.

 

I think you're expecting too much. You need exhaust and porting to see big gains. There have been dyno tests with flow reading that show a v8 consuming about 750 cfm regardless of whether it has a 750 or 950cfm carb on. If your engine demand cannot benefit from the larger carb, then it won't. You're only about 100 cfm over stock, do you have a header and free flow exhaust?? If not, than that's next.

 

I have a header and a RB muffler.

It doesn't feel like a lack of fuel, there is no definate bogging.

 

Could be too much.

 

i too did not feel the power. It took me quite awhile to tune my holley to get it just right. As for the secondaries, i used wire to rig my secondaries to open. that also takes awhile to adjust as you dont want them opening too soon and bog down. i have a stock header, 6 psi at fuel pump and no return line. i can now feel the difference between my setup and the stock setup on my girls car.

 

I don't know if this is relevent but I did not hook up my timing as RB suggested. I hooked both advancements to the vacuum port on the carb body. RB suggestes doing this just for the trailing and manually change the leading to a different timing. I wasn't sure how well this would work, and so I left it with both advancements.

Apples to apples I don't see how this carb isn't flowing more air into my motor. I think I feel a bit of a difference now, but it isn't any more than muffler added.

 

You will not feel much of a difference until you work on the tuning of the carb.

 

Does anybody have suggestions for what jets I should be using? I haven't gotten a chance to look at them yet.

Also, does anybody have pics of the metering pump linkage? I DIY'd my own and I'm not sure how good it is.

 

Bump. What jets should I have? I haven't checked the primaries, but the secondaries are built into the metering plate. Do I need to go with bigger secondary jets?

 

On mine I was good with the 50s on the primary and I left the secondary alone.

 

i don't know how to tune holley's, i'm a weber guy, but 7psi is too much for it. Put a FPR on the car. I havea holley returnless FPR i'll give you got $25 shipped. i think they only like 3-5psi max.

 

RB recommends 6psi for the Holley. That is what I have mine set to and it works great.

 

How could too high of PSI be hurting high end performance? My carb isn't flooding, and the float level is good.

http://www.holley.com/12-801-1.asp

Right there holley says the Red fuel pump should work well on a holley without a regulator.

 

I don't think that would be a problem at all.

 

Hmm, this is getting to be a confusing issue for me. I'm really not sure what to do, and I don't want to drop any money into the carb until I have evidence that it should help. Everything seems to be up to spec, I just wish I knew how to tune better.

 

Get a wideband, or at least a narrowband, then ask for help. There's no real way to help you out unless you know what the problem. It's either lean, rich, or the secondaries aren't fully opening. With out eliminiating 2 out of the three of those problems there's nothing any further chat can do to help. If it's got too much fuel pressure it could make it go 10:1 pig rich and the car will fall out on it's face if it's not timed for it. Check your timing and make sure leading it at 20*BTDC at full advance, then go from there. If it's too rich it's either too big of jets, too much fuel pressure, or the carb needs to be rebuilt. If it's too lean then it's just tuning to get it right, or there are vaccume leaks and the carb might need to be rebuilt. If the secondaries aren't fully openeing then the carb might need to get rebuilt, or adjusted. You can't decide what to do until you identify the problem.