Just wondering. It's a little off topic but surely some of you guys have stumbled across cheap marine carbs and considered em for your hot rod. I have a holley DP that I suspect is marine by the weird square squirters and have never dealt with this variation before. So what does make em mariney anyway? And what needs to change for street use? The squirters?
The most recognizable features of a marine carb (Holley anyway), are "J" tubes for the bowl vents and sealed throttle shafts. If the bowls overflow, the J tubes will dump into the venturis killing the engine (or at least keeping the fuel in the engine, as opposed to the bilge). The sealed shafts keep fuel from seeping out of the throttle base at the bores. There are other differences, but as far as running a marine carb on the street, go for it. I have one boat with a HP throttle body and no J tubes.... I need to take care of that. The other boat is open engine and not as critical.
"I have one boat with a HP throttle body and no J tubes.... I need to take care of that." Do it now while your thinking about it. Besides blowing your family/friends to smitherines...your insurance company won't know you. Remember to make sure the blower is working and you run it a couple minutes before lighting the fire. Terry
Pretty much what he said....J tubes (or the newer single drilled tube that connects both bowls), sealed shafts, the anti-slosh baffles inside the bowls (usually), & sometimes the floats are different...and usually the nitrophyl type. There are some calibration differences as well...but, really, no more so than any of the other Holley variations. I've seen the square squirters before...so far as I know it's just an older variation & not marine in particular. Assuming that you are familiar with tuning a Holley, there's absolutely no reason NOT to use it if you like. If you post the list number on the bowl I can probably determine whether it is a marine unit or not.
Ah-ha. That answers it. I'd been told the square squirters were possible marine by someone "more knowledgeable". Turns out it's just an old automotive carb. No J tubes on the vents seals the diagnosis. It's a model 4165 6212 800 DP spreadbore, having a hard time finding anything specific about it, seems long ago discontinued. No mixture screws in the rear metering block. First DP I've seen like that too. Is that an old thing, or a spread-bore thing?
If memory serves, it's a replacement spreadbore for bigger GM applications...B-O-P 455s & Chevy 454 in 'early '70s applications on stock manifolds, with all emissions gear & air cleaner assembly left intact....that sort of stuff...but I need to dig out some older references. In my experience, for whatever THAT's worth, most or all of the 4150-style DPs have rear idle screws for the universal application listings (such as the 4779 750 DP), but the specific application ones may, or may not....generally not. On those, I guess Holley figured it was more likely to confuse the avg. guy/mechanic, who tends to adjust/turn/screw up everything that can be adjusted/turned/moved, and they were required to be a replacement carb...meeting the same standards as the OE carb. It is possible to mod those rear blocks to gain the four-corner idle, but I dunno whether it's worth it. That would be a nice carb on a Performer for a BB towing application. Spreadbores can rule on the street if they are set up correctly.
The Jalopy Journal
