Couple of things...I had a slight interference with the drop base and the throttle bracket on a Qjet. I think the Holley is shorter than a qjet. Also I'm pretty sure you are going to have to run without an under hood insulation blanket. I know I will.

Since this thread is about the RPM manifold it may be a good place to pose this question.... I am going to modify an RPM manifold a bit this winter to install on my 462 . when I did the exhaust crossover modification on my car the first time I documented it all with pics for the website (of course)
I received an interesting email from a fellow a few weeks ago with some information on his views on blocking off the exhaust crossover. I put his emails on a page for folks to read. If there are any mechanics or knowledgable folks out there with opinions to share.. I would love to hear what they have to say about it. I am actually considering leaving the exhaust crossover open this time around just to see if it does make a difference in the cars cold-running manners. which to be honest have always been pretty crappy. I just put up with it because once it warms up it runs soooo gooood. :-)
http://www3.telus.net/68bird/engine_intake02.htm
what do you think about it?

kelly

Everyone has an opinion and what works for one person may not work for the next. Any engineer should know about variables and assumptions.
About the balance thing. Remember that the heat crossovers are only connecting 3&5 cylinders to 4&6 cylinders with a tiny port which is not nearly the same as having a balance tube or x crossover in the exhaust system.
Besides every manufacturer used a heat crossover on their engines for heating the intake manifold.
That's my thoughts.
I fill my heat crossovers in my heads.

I am bringing this back to life since I still have some more questions. Bluebird you said at one point that you had a Edelbrock EPS 800 on a performer RPM manifold with a drop base cleaner, that looks to be a Moroso? Is that the same set up you have now? Does your carb have an electric choke? I was going to go with a Edelbrock AVS with elect choke and everything I read says you cant use a drop base cleaner with it. Help? Anyone using a RPM manifold with an Edelbrock Carb with a Elect chock and drop base cleaner???? If so I need to know what cleaner they are using and what is the drop? One inch, one and a half inch drop?

PM sent

I finished the work I mentioned earlier in the post.. the rpm is a good 1.25 to 1.5 higher than the stock manifold for sure. do not know about the edelbrock height compared to a holley but you can see how close it is with a regular drop base air cleaner installed.
https://www.youtube.com/watch?v=GF__sQQbhbo

Ordy, Yes that is the same air cleaner and carb I have now. It is a Moroso. It is not an electric choke, manual choke with the choke lock-wired open, when I get a chance I will take the choke right out of the body. No use having it in the way if I don't use it. I will check when I can about clearance for an electric choke.

Kelly, Great website, I have it on my favorites list, good work. My heads don't have cross over in them so it's a moot point for my application

OK so lets change this up, so anyone using a Edelbrock Performer RPM and Holley with a electric choke and a drop base filter?

May not help much.

Don't even get me started on engineers...

TO LATE!

Working in GM dealerships since 81(?) Know/known/dealt with many over the years.
And deal with one most every day now working at his fathers AC Delco warehouse.
Like any other career, some good, many not. Do to thought process(?), common sense seems to be absent. And don't waste time arguing, their never wrong . Ya, right!
Done with rant about them people...

According to GM, the heat x-over is for faster cold weather heat up, and choke coil operation.
Like mentioned above, the location is wrong for exhaust pulses.
But will say this.
Heat = energy. So the higher the engine operates at(up to a point), the more power it will produce.

To OP.
I had a RPM intake, 1" n2o plate, 850 Demon with E-choke, Moroso drop base a/clnr just like in pic above.
There was about 1/4" clearance on passenger side of hood.

yes , USMC_ordy, that is exactly what i am using now, edelbrock RPM, Holley with electric choke, and drop base air cleaner....
question?

Yes, heat does = energy but not when you're talking about the A/F charge. Cooler air and cooler fuel charge= more power. That's why the best track times are made later in the evening , generally, as the air temps drop.

Thanks for the pics Bluebird. That shows me what I suspected, that there isn't enough room for an elect choke.

Thanks Medhat68, what drop base cleaner are you using and do you have a link for it? How much is the drop and how much filter is above carb? Thanks for the good info!

Look three posts up the page, Medhat68 says he uses just that, an RPM, a Holley with electric choke and a drop base air cleaner.