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spreadbore vs squarebore

F

fibersport

Member
In the process of rebuilding a Century Cardel, 22' with a Crusader CH350 454. The carb is most likely garbage as it had some water in it so a replacement is in order. The intake manifold is rusty and heavy. This boat would spend most of the time on the trailer and will be used in fresh water only so a new aluminum intake would not be out of the question, I have one on my other boat for 15 years with no problems.

My question is regarding the choice of a spreadbore vs a squarebore. I have a Holley on my other boat and have not had many problems with it so I am leaning towards a Holley because of the simplicity of them compared to a Quadrajet, as well as parts availability. However, I would like to hear from someone who has switched from the Quadrajet to a squarebore. The boat will be used for pleasure and occasionally pulling skiers, probably more concerned with out of the hole performance rather than top end.
 
I converted to a carter afb/square bore, and run them many years on a 2x 454 inboard. Also, ran the edelbroc Al intake, dual plane. The intake was spread, but the carbs fit just fine with the right spacer. I have no exp. with Holly, but this gets into chevy vs ford talk anyway. I will say the carters are bulletproof, have no trick systems that need tuning and care. I had issues for over a year that sent water into these carbs and they put up with it. good luck.
 
Ayuh,..... I too, love the AFB clones, with the side hung float bowls, Vs: the fore, 'n aft float bowls of a Holley,....

Especially considerin' the massive changes in attitude boat motors go through from at rest, up, 'n over, then on-plane,....
 
the spreadbore with the smaller front throttle plates will give you better and quicker low end torque and throttle response. any time you have to use an adapter to use a carb.....forget doing it.
 
Thanks for the input. Here's a long shot, anyone have any leads on a marine version of the 800 cfm Holley 4011? This was a short lived model, I have a squarebore 600 cfm on my small block, this is just a bigger version.
 
Well the only other size in the 4011 model is 650 cfm, a bit restrictive for a big block. As long as it has vacuum secondaries, it should only take what it needs. Many of the original Quadrajet's were about 750 cfm, and were was used on small blocks and even some sixes I think. With the spreadbore design, the smaller primaries would give me some economy on the low end, the larger secondaries would come into play at WOT.
 
Realistically, unless you run WOT a bunch ($$$) the smaller carb will work just fine.

Most people over carburete (like, ah-hem, me at times).


Jeff
 
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