SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: SuperDuty on February 26, 2011, 02:35:45 PM
-
So I bought a tunnel ram last season with a motor that I later found out was trash.. Im trying to figure out if I can use the t/r with my new setup but dont know the CFMs on the Holleys and cant seem to find a site with numbers. He said they were 2 850s but that seems pretty excessive for a 468 that was pretty mellow. Not to mention the guy was one hell of a liar I later found out. Problem is... the list number was cut off. Is there any other way to tell what they are? I heard by measureing the base plate but I cant find what measurements mean what carb.. Thanks!
-
So I bought a tunnel ram last season with a motor that I later found out was trash.. Im trying to figure out if I can use the t/r with my new setup but dont know the CFMs on the Holleys and cant seem to find a site with numbers. He said they were 2 850s but that seems pretty excessive for a 468 that was pretty mellow. Not to mention the guy was one hell of a liar I later found out. Problem is... the list number was cut off. Is there any other way to tell what they are? I heard by measureing the base plate but I cant find what measurements mean what carb.. Thanks!
The Holley website has tech information, including venturi bore sizes, although there is some overlap between various CFM and venturi sizes.
You could run 850's on a 468, but tuning and therefore fuel economy may suffer. What engine are you putting it on?
-
Im hoping their alot smaller than 850s so I can bolt em up to a stock bore 454 or 396. If not Ill just have to buy new ones and keep these around for a big motor build next winter.
-
What size are the venturi?
-
Does just under 1 3/4 sound right? I get like 1 and 11/16s with my tape. Number on the top of the venturis is 6R 3745 B if that means anything.
-
I think 1 11/16" bores (both primary and secondary, correct) indicate between 650 and 800 CFM. The 4781 Holley 850 has 1 3/4" throttle bores. I ckecked an older book that I have, but Holley does have all their carb specs online as well.
-
Yah, Thats both primary and secondary. Thanks alot for checkin that out for me.. Really appreciate it!
-
i just bought a boat from texas and it has a 468 in it and two 750 holleys on a weined tunnel ram
-
i just bought a boat from texas and it has a 468 in it and two 750 holleys on a weined tunnel ram
I ran twin 4160 750's on my .030 460 for 2 years with no problems at all. Cammed and high compression though. Ran out great, fuel economy was pretty good really, until you flatfooted the thing extensively. Then.....well......it got a little expensive to run. Even after I blew it up though, plugs were a VERY consistent caramel color.
Nordie and I were talking the other day about one run. Both tanks full, (28 gallons total) from a trip upriver from Pirates Cove to the AVI, Lost Nordie and the rest pretty quick, but held it pretty constant from 4500-6000 the whole way up, Throwing roost on occasion to the beach combers. What is that? 10 miles or less? Anyways, ran one tank out and had 1/2 left in the other............ :screwy:
Ray
-
Im not all that concerned about fuel usage as much as tunning. I just hear horror storys about T/Rs but Im pretty much set on the looks of running one. Im hoping to be able to use this setup instead of re-buying carbs. These carbs also need rebuilt.. Might be a pain to order a rebuild kit without the CFM.. :o
-
Im not all that concerned about fuel usage as much as tunning. I just hear horror storys about T/Rs but Im pretty much set on the looks of running one. Im hoping to be able to use this setup instead of re-buying carbs. These carbs also need rebuilt.. Might be a pain to order a rebuild kit without the CFM.. :o
Take the carbs to the shop. They can figure it out, I'm sure. I think Fuel Curve West is near you. They can even probably 99% dial the carbs if you have all the stats on your engine. Still gonna be cheaper than buying new or buying used then rebuilding those...........T/R's can and will run great! Many of us run them, and once dialed, really as problem free as any single carb setup.
I was not gonna open up my preference for vac sec'y carbs in this instance, but truly, unless its a full out race application, you are far better off that way. Post some pics of the carbs up. ;)
Ray
-
I'm running some trick out reworked 660 center squirter that bench flowed just under 800 cfm Dave at fuel curve west did the build and work great since day one.