holley on a stock 12a manifold
04-15-06, 11:15 PM
#1
holley on a stock 12a manifold
Well a friend of mine needs to get his camden rebuilt (it's a few years old now) and it's a daily driver he cannot do without. He is running a half bridge 12at block and I figured a way to mount a holley on a stock 12a intake with only a few mods. In a couple of days I'll post pics and once we try it out I'll post results. I had a carb spacer in my toolbox, a little bit of JB weld also and a buddy had an FB 12a intake. Net cost, maybe 15 bucks out of pocket. Net cost to do if all you have is the intake, about $60. Updates and pics to follow.
04-16-06, 06:55 PM
#2
You'll see here what I did with the 12a intake to fit the Holley or Edelbrock. I ported out the top of the intake to match the tapered spacer I had. I mounted the spacer to the top of the intake by drilling it to match the factory carb stud pattern and then counter sunk bolts into the spacer and bolted it to the 12a intake after modifying the intake. I removed the shutter valve and JB welded a bolt into the shaft to seal it up. Cut the emissions tubes, sealed with JB weld and crimped them. The only left is to intall the block off plate I have in my toolbox and it's good to go! I did this to help out my buddy so he can run his car while getting his 4 year old Camden rebuilt. Cost, intake $0, tools $0 (have compressor and air die grinder), carbide bit $18, JBWeld $8, space $20 (but I had one so it was 0 to me), misc bolts $0 (junk kicking around that happened to fit), Total= $46
04-16-06, 10:28 PM
#7
More restrictive than a RacingBeatintake for sure. But for a $60 project, it's good. On a stock or streetport engine this will flow well enough and it can hold a 500cfm carb well. I'm an old dog, and in my big block days you would get more torque and midrange out of a good dual plane small port manifold while a large port single plane manifold wouldn't flow well until 2500rpm. So I expect this modification would produce great off idle and midrange performance and torque while still satisfying a 7000 rpm redline.
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04-17-06, 06:57 AM
#8
Old [Sch|F]ool
Have fun getting it to clear the water pump. 
You will need a chokeless carb with mechanical secondaries, there won't be enough room for the choke linkage or the vacuum diaphragm unless you mount the carb "primaries out" and then the throttle linkage won't clear.
I have been there and done that about five years ago...
Furthermore, when you get the carb on the car and running, you might find that it runs like complete crap, running richer the faster you go. If this is the case, you'll need to cut communication channels between the rotors on the primary and secondary sides of your adapter, so that the carb sees the type of booster signal that it was designed for. (If you're running a bacuum secondary carb, you'll need to open it up all the way, the small primary ports probably will not flow enough air to get the secondaries opening much, if at all. This is even true with the stock carburetor, there HAS TO be communication between primary and secondary with a vacuum-secondary carb!) You will also need to have a carb with the grotty sidehung float bowls, the centerhung bowls' side feed won't clear the water pump unless you do something weird/silly with custom lines.
I started working on a similar project last month, figuring on making this one offset rear enough to clear the water pump. I found that with the rare 450cfm mechanical secondary carb (it's chokeless) it WILL clear the water pump, BARELY, with the adaptor centered over the manifold. It's got the sidehung float bowls, too. The only problem is that the adaptor BARELY *BARELY* clears the temp switch in the back of the water pump housing. The carb will have to be assembled to the intake manifold first, then the manifold set onto the engine.
Also, just a heads-up to anyone working on porting aluminum: Sanding rolls will eat aluminum much faster and more controllably than carbide bits. Low RPM/high torque and really force it in there. This *is* possible with an air-powered dir grinder. I wouldn't attempt using a drill, they are too hard to control delicately and forcefully at the same time, and the bearings wear out quite rapidly with the side loads.
You will need a chokeless carb with mechanical secondaries, there won't be enough room for the choke linkage or the vacuum diaphragm unless you mount the carb "primaries out" and then the throttle linkage won't clear.
I have been there and done that about five years ago...
Furthermore, when you get the carb on the car and running, you might find that it runs like complete crap, running richer the faster you go. If this is the case, you'll need to cut communication channels between the rotors on the primary and secondary sides of your adapter, so that the carb sees the type of booster signal that it was designed for. (If you're running a bacuum secondary carb, you'll need to open it up all the way, the small primary ports probably will not flow enough air to get the secondaries opening much, if at all. This is even true with the stock carburetor, there HAS TO be communication between primary and secondary with a vacuum-secondary carb!) You will also need to have a carb with the grotty sidehung float bowls, the centerhung bowls' side feed won't clear the water pump unless you do something weird/silly with custom lines.
I started working on a similar project last month, figuring on making this one offset rear enough to clear the water pump. I found that with the rare 450cfm mechanical secondary carb (it's chokeless) it WILL clear the water pump, BARELY, with the adaptor centered over the manifold. It's got the sidehung float bowls, too. The only problem is that the adaptor BARELY *BARELY* clears the temp switch in the back of the water pump housing. The carb will have to be assembled to the intake manifold first, then the manifold set onto the engine.
Also, just a heads-up to anyone working on porting aluminum: Sanding rolls will eat aluminum much faster and more controllably than carbide bits. Low RPM/high torque and really force it in there. This *is* possible with an air-powered dir grinder. I wouldn't attempt using a drill, they are too hard to control delicately and forcefully at the same time, and the bearings wear out quite rapidly with the side loads.
Last edited by peejay; 04-17-06 at 07:01 AM.
04-17-06, 06:12 PM
#9
Thanks for the lengthy reply Pejay, you have some good history. I did not figure I would be the first with this idea (kinda like the ones that think the air pump would make a good turbocharger). I did cut channels in the stock manifold between the primaries and secondaries under the spacer (ports for first rotor had them already, so I cut a similar channel for the second rotor). If I have fitment issues with the Holley my other buddy has an Edelbrock we can use. Main point here is this is "temporary" while the Camden gets sent out for a rebuild. I am optimistic about it though, the tight runners should offer good intake velocity. I know it will not do the half bridge justice above 7000 rpm though! I can't help but speculate that this would work well on a stock or streetported engine with a 500 cfm Edelbrock Thunder series carb (incredibly simple carb to tune). If it offer a good idle, nice throttle response and midrange power than I consider it a success given the budget and creativity involved.
04-17-06, 06:20 PM
#11
Rotary Freak
It's much easier to use one of the custom sheet metal manifolds I'm selling for holleys.
These work far better for holleys on rotary applications than anything else I've found:
Get one and your troubles will be over.
These work far better for holleys on rotary applications than anything else I've found:
Get one and your troubles will be over.
04-26-06, 01:45 PM
#18
Rotary Freak
Originally Posted by Alex-7
It's much easier to use one of the custom sheet metal manifolds I'm selling for holleys.
These work far better for holleys on rotary applications than anything else I've found:
Get one and your troubles will be over.
These work far better for holleys on rotary applications than anything else I've found:
Get one and your troubles will be over.
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