The Stovebolt Site Forums The Shop Area Engine Shop trips vs duals on a 235

pros and cons?

trips look better! According to the old hotrod books the trips make more hp... how much more is debatable.

To fully answer your question, we need to know more than 235 trips vs duals. What are you trying to achieve? Daily driver? Weekend warior? Retrorod?

synchronizing multi carbs is a PITA

If you do a search you will find lots of advise on this. I seem to remember that most opinions were that three is overkill and you should block one off and get the look without the problems.

Make sure the carb bodies, fuel lines, and air cleaners will clear the firewall. I think this is why most 3 or 5 carb set-ups seem to have narrow diameter air cleaners?

Also, on a 47-55 Chevy truck, the firewall to fender rod can be bent/contorted to still be used with some 2 carb intakes (Offenhauser, for example) but cannot be use with the 2 carb Fenton (I do not know about the Clifford). 3 and 5 carb intakes would most likely eliminate that rod (I have gone without it, but some people might be concerned about not having the firewall-to-fender rod in place).

Tim

PITA really sums it up, usually this set up is for racing. Having said that, there are some carbs around today that could make this project work nicely. Those are the progressive two barrels that Tom Langdon sells, Holley-Webers or Carter-Webers. First stage is very small, 32mm then as you open the throttle the second stage 36mm opens. You would surely have to play around with jet size and getting any multi carb set up in sync is a challange.

Also over on www.inliners.org site in the rides section, search for Bob Malin's 40 Chevy coupe, runs three of these carbs on his 292 ci inline. Also check out Langdon's Stovebolt web site (www.stoveboltengineco.com) and check out his cool items.

And see the duals on my 46, Holley-Webers.

Having run Langdons Carter/Webers on my built 235 for almost 10,000 miles without any major adjustments since they came out of the box, I highly recommend them. However, aside from the fact that they give excellent, carefree performance, dual carbs are not going to give you any great noticeable "kick-in-the-pants" sensations when you put your foot down and open the mechanical secondaries. Granted, you eliminate all of the issues encountered with a wornout Rochester, but I'd have to say that the "visual" effect is paramount. Having run a single Holley/Weber on the same engine with just as good performance/fuel mileage, I think you need to consider the cost of a dual setup, the initial installation, and what you're trying to accomplish by adding duals.

IMO, running triple carbs on a 235 with the center carb blocked off, with the linkage and firewall/shift box/fender support rod clearance issues just seems like a waste of time and money.

Dave

I have had 3 Holley 3 bolts on a GMC 302. I ran off the center one and didn't open the other 2 until the center one reached 50% open. I plan on building a 302 like that, but it won't be in anything I drive regularly. Ever once in a while it is a good feeling to have more hp and watch the gray smoke roll out the back. I am of the opinion, however, that most most multiple carb setups are for bragging rights.

daily-mileage-retro-performance

and from what i've read, can't locate it right now, using a laptop/software/tricky de-vice for carb balancing is available

I run 3 Rochester's on my 250, they are off a Corvair and are quite small, somewhere around 70 cfm each. It runs OK but nothing to brag about. Fuel mileage might be just a bit better at lower speeds, but worse out on the road. They are a pain to get jetted right.
Mine changes with the weather more then a single carb does, now that its cooler, I am going to have to pull the tops off and re-jet or lower the floats. Either way I go, its an hour job! Even day to day it runs different.

Joe

rednate: http://www.minimania.com/web/item/UNI-SYN/invDetail.cfm

On some 235/261 carbs, I have had to use a riser-tube (a short piece of plastic plumbing pipe).

Tim

well, it's certainly less expensive and less involved than what i found at $2200.00 and efi. cb performance makes an efi kit for dual carb veedubs that's interfaced with a laptop/software that allows you to monitor and adjust timing and jetting where the screen becomes a 'dashboard'. cold start and acceleration enrichment can be adjusted and saved into a profile for future use. i haven't researched it completely, but maybe it can be adapted/used on other vehicles

i have dual rochester b's on my 235 and a 2.73 rearend , 15 inch tires and an s10 5 speed trans. on my trip to KC two weeks ago running 70 most of the time i got 23 mpg. my average as close as i can figure was 20mpg. really hard to tell because it went in the shop and the mechanic ran it for two hrs at idle before i had time to fill up the last time. also at the show my gas tank was siphoned. ron

Ron,

Do you think it was one of those sketchy looking, beady-eyed stovebolters that siphoned your gas in KC?

Tim