Dual Quad lesson learned

[masterlock]

So I wanted to have the coolest looking engine, I wanted to have all the fancy looking parts under the hood. I am new at this whole truck restoring thing and I really didn't know what I was doing. I figured I would buy a sweet dual quad setup along with all the fancy things that go with it. So i saved up and bought it all, took my time and installed it all. I was very impressed with myself. I looked at it and thought wow what a good job you did making that boring old engine awesome. So a friend who has been building cars since he was a kid stops by today. He looks at the engine and I am all proud of my work. He then asks what kind of rebuild I did on the engine and my response was that it was stock. Well, he explained that the engine was NOT going to be able to handle that kind of system. So in the end I need to buy a new intake and take all my fancy looking waste of money off. At least I have a nice paperweight. Lesson learned!!!!

[frog210]

dont get down man things like this happen, just think about it like this at least you got everything for the futrue
at least you can improve your truck so more

[masterlock]

Yeah thats how I feel, try explaining that to my wife

[INSIDIOUS '86]

If you want to use it you can use dual quad holleys with vacuum secondaries. This way you can be full throttle and the other four centuries will not engage untill the engine absolutely needs it.
This will alow you engine to handle more carb than it needs.

A simple cam change can make things better too
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[Hulk Will Smash]

Sounds like an awesome opportunity to build a big bad stroker motor! Good luck skiing down the slippery slope of performance mods!
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[88Jimmy4x4]

great looking project

[geezer#99]

Leave it on there. It'll run great even with a stock motor under it.
Limit your fuel pressure to 4.5 lbs. Set up your linkage to run the back carb as the primary and the front one to open all the way when the back one is 60% wide open.
Run at least 12* intial timing with your vacuum pot hooked up to manifold vacuum.
I ran a similiar set up on a 56 chevy. Stock 9 to 1 350 with factory cast iron exhaust manifolds.
I ran a pair of carter AFB's. Twin 600cfm carbs.
Hauled butt and pulled down 20 mpg with a turbo 350 and 3.70 rear gear.

[Pyrotechnic]

Your friend is wrong. It'll work just fine. Assuming those are regular AFB style Edelbrocks, they have a weighted air door for the secondaries so they should be fine. If you are rolling along at 30 MPH in the highest gear and you stomp the pedal as hard as you can it may cough and wheeze, but if you use a little common sense with the gas pedal and keep it in the right gear when you hammer the throttle it will work.

Now if you topped that motor with a tunnel ram and a pair of 800 double pumpers, you would definitely have a problem.

Keep what you got. It will work fine now and it will be even better when you do some upgrades later on.

[masterlock]

Thanks for the words of wisdom, Im really in the dark here as far as compression and cams. What is the compression and cam set up on a stock 350 SBC. Is there a way to figure this out without tearing the engine apart? My friend said he thinks that the engine would just get flooded every time the engine ran.

[meter swinger]

Like my old man used to say...well cross that bridge when we get there. Im with rest of the guys on here. Get it buttoned up and running and then go from there. No need to jump to conclusions when we dont have it running yet. Your friend may be right. He may be wrong. Youll know when its running if it cant be dialed in. We have have all done stuff like this. Educations are expensive sometimes.
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One of the first engines i rebuilt was a 22r in a toyota 4x4. I spent a lot of money on the rebuild except for the rod bolts. After I turned it into shrapnel a week later I understood why you dont re-use rod bolts.

[THE "10" SILVERADO]

I don't know if it will work or not, so I'll leave the technical stuff to the experts but I have to say that looks really cool!

[masterlock]

Yeah I think it looks great I just hope it works and works well, I would hate to have to take it all off and go back to stock

[irishman999]

I got a strip kit for my AFB and have tinkered with the Jets and metering rods trying to find a good combo. I wonder if you could lean out both the carbs and set up the linkage as mentioned above.

[BigBlocksRule]

I've seen guys running 750 Dominators on 350's on the street without huge flooding issues...pretty much any carb can be tuned to pretty much any engine. Do some research at Corvette and other muscle car sites, they'll have some good advice.

[mopar346]

Originally Posted by BigBlocksRule

I've seen guys running 750 Dominators on 350's on the street without huge flooding issues...pretty much any carb can be tuned to pretty much any engine. Do some research at Corvette and other muscle car sites, they'll have some good advice.

Yep, what he said, the biggest problem I have with the set up is the fact that you used Eddy carbs. Your set up can be tuned to be too little gas if you fiddle with it. At worse case you set it up were the secondaries wont open and you are just running on primaries and 2 sets of primaries aren't gonna be too much for even a smog motor.


As far as what your engine has go to your engine builder and get the specs of the parts he used, pistons, head casting number, head gasket thickness and cam specs along with any readings or modification info they have. From there you can figure out everything else. Compression has to do with the top of the piston (dish, flat, dome), the size of the combustion chamber of the head and the thichness of the head gasket. The 3 combine to create a certain size are in which the original amount of air (cylinder volume) is compressed into. The ratio between the starting area and final area is the compression ratio. (Before the engine gurus get after me I am well aware that stroke/rod length and deck heigth also play a major role but for the sake of simple explanation I'll leave that alone.) Cam specs control valve opening and the amount of air that is taken in and allowed to escape before completely sealed.

Anyway, the bigger better badder theory usually doesn't work nearly as well as a well thought out balanced approach to matching the components during an engine build. Your's can be made to work just not optimum of what the intake set up is capable of, sounds to me like you were going for looks not power anyway.

[masterlock]

Oh don't get me wrong I was going for power I just didn't know what I was doing. The looks thing is a plus.

[mopar346]

Oh...............then you definitely went about it wrong.


Build a solid bottom end to take what ever you want to through at it and make power with your heads. Intake set up (cam, manifold, carb and even air cleaner) to match the head flow and an exhaust capable of getting it out fast enough.

[masterlock]

Im gonna call a carb shop here locally and get their best guess on my situation