Holley 12A Question.
 

Hi All,

I have not been posting that much since I took delivery of my 1979 Rx7 in the Fall. I did some work on this beautiful car and ultimately gave it to a Mazda mechanic who has been working on these cars since they came out. While he made a lot of progress, the car just did not run well enough to be street worthy.

So, I decided to install the Racing Beat Holley kit (stock block) along with their exhaust.

I cannot say how enjoyable it has been for me to be back with a car that is virtually identical to the 1980 Rx7 GS that I owned when new. On my old car I had replaced the intake with Weber 42DCOE and Rotary Engineering headers. How I did that with limited tools and a set of ramps I have no idea. I think it's because I was so young at the time!

Racing Beat has been really great to work with by phone on getting my car dialed in right. I made some rookie mistakes and they talked me through diagnosing and fixing the problems.

Overall, the car seems very reliable with 140 miles and not a single stall or problem. It does hesitate a little bit but it runs well. When you get on it, it pulls beautifully up to redline in the first three gears. It cruises on the highway nicely.

I am so pleased to have this car running.

I do have one problem that I'd like Holley people's input on. When I go out for a spirited drive, the secondaries do not seem to fully close and the idle stays up around 1500-2000. If I gently nudge the linkage for the secondaries I can almost feel a slight click as they close and the idle settles down to normal. Also when the idle is high, if I shut the car off and restart, the idle is normal.

I took the carb off the intake but did not see anything binding. I'm wondering if I should adjust the secondary idle screw (on the underside of the carb although it does not seem to turn with the carb on the intake) or if a different spring in the secondary vacuum diaphragm might help.

I also noticed that if I put a cloth just over the secondaries that the car stalls. Is this normal? Should there be this much air going through the secondaries at idle????

THANKS

Your lucky the Holley works so well. I hope you kept the original Nikki and intake manifold. With
some work you could make that nikki perform better than the holley.

I realize there's a lot of hate on this forum for the Holley set up which made me reluctant to ask my questions.

So far so good and RB has been very easy to deal with.

I'll reach out to RB with my question and let the forum know if we can figure it out.

No hate here, just reflecting what I have seen in discussions recently with regards to RB holleys.

It's just that for so long we though the only way to get any performance out of a 4bbl on a rotary was from the holley.

Times have changed and it turns out the stock Nikki, properly modded, makes more power and runs better on a rotary than any aftermarket carb. And then we figured out how to add boost.

It's far easier on a Nikki than on a Holley, though some would argue against that notion. They would site the double pumper mod, and the well documented boost prepping material easily found on the net. To that I would counter and say, yeah, but does RB do a boost prepped Holley for a rotary? Nope.

You're on your own to somehow blend a boost prepped Holley with something that will still run well enough on a rotary that you won't feel like throwing it into the neighbor's yard.

Some have had success here. They can make a whole lot of power. That's fine. But it's usually for drag racing only. I like the better drivability of the Nikki on a daily and it handles enough to power that my chassis feels really light. :) Can't get traction on stock size tires.

Good luck.

^He might not hate them, but I do.

I wasted a lot of money and time getting the RB holley to do as advertised. Its a basic carburetor, nothing about it is high performance.

You'll find with time and putting more miles on it that it is not at all a good design. Fuel mileage is awful, cold starts, hot starts, plug fouling, fuel slosh problems, idle circuit transition problems (you already mentioned this in the hesitation) and the damned things love to flood.

When they are brand new, sure. They'll work. Wait until that set up is 5 years old. You'll get to be a pro at rebuilding your carb every spring.

Seriously though, good luck. Assuming your RB holley is defect free (I bought 2 in a row with cracked main bodies, lol) It should be a hoot in a straight line or cruising.

Has no one taken a throttle body fuel injection system and adapted it to work for rotaries? There is the Holley Projection, the MSD Atomic, etc that are built like carbs that fit on a Holley flange... I know they are somewhat expensive but there are some used ones to be had...

Holleys work great Rotaries! Just need to know how mod them for Rotaries. A well tune Holley is great on the HWY and from light to light.

https://cimg9.ibsrv.net/gimg/www.rx7...7e9a6b8aa7.jpg

Like this one? Literally every mod you can do to an RB holley.

You're looking at over 2000 in parts/labor, and that excludes the cost of the many trips to the dyno and brass.
Still idled differect one day to the next, shit cold starts, hot starts, flooding, couldn't take a corner left or right over .6 g, went pig rich on decel.

This carb yielded slower lap times than a factory carb. Literally sputtered and died multiple times in turn 7 at mid ohio.


https://cimg8.ibsrv.net/gimg/www.rx7...c78b4cd016.jpg


^Note the custom machined exchangeable air bleeds that were REQUIRED to properly dial in the fuel curve.

https://cimg0.ibsrv.net/gimg/www.rx7...8632f681d6.jpg

I had a holley setup on my old car is it worked great. I had the car tuned on a dyno and had it running great.

It sounds line the secondary carb linkage is binding. Send me a PM and I might be able to talk you through your problem. I'm not on here much.

also this is the carb RB uses: https://www.holley.com/products/fuel...parts/0-1848-1

also a lot of good info here: https://www.holley.com/support/resources/

Thanks Chris! I think the linkage is sticking somehow but I can't figure out what to adjust to fix it.

I never had a bad experience with a Holley. As far as the cornering issues race float will fix that.

This is just not true. Period. If youre thinking of buying a carb for road racing do not waste you time. The race floats were on my race carb, with foam aeration baffles, jet extensions, center hung bowls, extended vent baffles, etc. Still couldn't handle a corner. The carb is mounted the wrong direction for any sort of holley float to function properly

Yeah I think some folks idea of handles corners versus doing it on the track may be the reason
for the disconnect here. Around town and in spirited driving on the street the special floats may
help some but in long constant sweepers at high speed on a track I can see why the carb
would have issues. When mounted on a rotary its basically rotated 90 degrees from the
orientation its designed to run at. Hence the cornering issues.

I stalled mine on an exit ramp at 45 mph once.