Carb suggestions for TR

[Squirtcha?]

Looking for some input on carbs for a tunnelram. Motor is a 500 hp BBF and I'm currently running a Weiand TR with a pair of Holley 660 center squirters. I'm getting killed at the pump and want to make a change to something a little more miserly on the go juice.
Prior to the tunnelram I was running a Weiand Stealth dual plane intake and a single Holley 850 dp. Since I gained absolutely nothing (except for the piss poor mileage) by making the change to the TR, I figure I could pick some carbs that would put me around that same 850-900 cfm mark.
I'm toying with the idea of vacume secondaries, or possibly the Holley 450
4160 mechanical secondary. I see where Summit and Jegs are selling that 450 for $193 so the price is right. The question is............will I be in the same position I am now (right next to the gas pump) or is the linkage more progressive than the 660s I'm running? Does anybody know about this particular carb? It states in the ad This has a mechanical secondary, but no secondary accelerator pump circuit. It is designed for a mulitiple carburetor application ONLY, it will not function properly on a single carburetor application.
It sounds perfect and the linkage looks to be a lot more progressive than my "all or nothing" on the 660s.
http://static.summitracing.com/global/images/prod/large/hly-0-9776.jpg
Link to the Holley 4160 carb (http://store.summitracing.com/partdetail.asp?autofilter=1&part=HLY%2D0%2D9776&N=700+115&autoview=sku)
I have buddies that are running BBFs with tunnelrams and 600 vac sec carbs. They work o.k. for them and their fuel mileage is way way better than mine so I reckon the vac secs would be o.k. but I'd probably go a bit smaller.
Any thoughts or comments on these two choices. Or any other possible choices to recommend.
Input appreciated.
Thanks
Dan

[sanger rat]

Dan, I've been really happy with my 600 dp's. I don't think you will be happy with the 450.

[wsuwrhr]

Wouldn't a vacuum secondary carb in a TR application cause a lean/rich condition due to the later opening of the secondary butteryfly?
I bought that combo deal from Summit years back for the jetboat and later returned the carbs because I didn't realize the carbs the combo came with were vac. secondary.
Brian

[QuickJet]

I have yet to see ANY vacume secondary carb work from a performance standpoint. I had 660's on my BBC in a jet AND in a v-drive and they worked great. Maybe it's what's under the carbs that not giving you what you need. What series intake is it? I'd switch the intake before messing with the carbs. The only thing a Weiand intake is good for on a boat is to fill it with concrete, tie a rope to it and use it as an anchor. Or you could fill it with potting soil and make a nice planter out of it. Wife might like it. :p

[Squirtcha?]

Not a lot of choices on tunnelrams for BBFs. As for the carbs, the secondaries are tipping in at 3000 rpm. I hardly ever run my boat that slow which means I'm sucking some major fuel.
The boat runs great, it's just a gas hog.
http://jetboat.homestead.com/carbs_done_copy.jpg

[Blown 472]

If you gained nothing why not go back to the 850?

[OverKill]

Dan
Don't even think about swaping motors LOL.

[DUCKY]

We used to run an 850 Holley DP on an Offy single carb T/R (10:1 BBF) in my Dad's jetboat. When he sold it, he wanted to keep that carb, so we put on a 780cfm vacuum secondary Holley. After spending some time tuning it, the overall top end loss was only 150rpm, and the throttle response and economy were both drastically improved. The 450's could be made to work, but it will take some tuning time, and some mods from the way they come out of the box. One key to a pair of vacuum carbs is drilling and tapping the vacuum cans and running a balance line between them, and adding the secondary metering blocks so you can change the jets on the sec. side is also a really good idea. I have done a couple using primary blocks that have idle screw and power valve provisions, and that makes for a nice smooth pull from idle to WOT.

[DUCKY]

Wouldn't a vacuum secondary carb in a TR application cause a lean/rich condition due to the later opening of the secondary butteryfly?
Brian
Not if the primaries are jetted right, and have the right power valves.
I am not professing to be a Holley master, but I have played with quite a few, and it seems that most people automatically discount a vacuum secondary carb, due to a general lack of understanding. They can and do work when they are tweaked right, and I don't mean putting in the lightest spring you can find and throwing away the check ball, or even worse putting a screw in the little arm. The most drastic mistake that most people make with a V/S carb is trying to force the secondaries to open early. The motor will open them IF it needs the air.... Oh yeah, and another good one is when people slap that vac. can together without paying attention to the diaphragm, and tear it with the screws If there is a leak, you can forget about the secondaries ever opening... (I am speaking from personal experience, having made ALL of the aforementioned mistakes :) )

[Squirtcha?]

If you gained nothing why not go back to the 850?
I've sold all the other pieces parts. I still kick myself in the ass for that one. Let em go way too cheap too.
Not if the primaries are jetted right, and have the right power valves.
I am not professing to be a Holley master, but I have played with quite a few, and it seems that most people automatically discount a vacuum secondary carb, due to a general lack of understanding. They can and do work when they are tweaked right, and I don't mean putting in the lightest spring you can find and throwing away the check ball, or even worse putting a screw in the little arm. The most drastic mistake that most people make with a V/S carb is trying to force the secondaries to open early. The motor will open them IF it needs the air.... Oh yeah, and another good one is when people slap that vac. can together without paying attention to the diaphragm, and tear it with the screws If there is a leak, you can forget about the secondaries ever opening... (I am speaking from personal experience, having made ALL of the aforementioned mistakes :) )
I completely agree with this statement. Right down to tearing the diaphragm on the vacume pot, and messing around trying to turn a VS carb into a mechanical linkage.
I know the VS carbs can be made to work on a tunnelram and might even prove to be more fuel efficient than the the little 4160 mech carbs I'm looking at.
Personally............ I still prefer a mech sec carb though.
The 450's could be made to work, but it will take some tuning time, and some mods from the way they come out of the box.
We're talking about modding the VS carbs too so that's not a huge deal. I didn't really expect to bolt em on and have em work perfectly.
Dan, I've been really happy with my 600 dp's. I don't think you will be happy with the 450.
I appreciate the input, but can I ask why? The only downside I can think of is if I build the 557 stroker that I want so bad, I'd have to make another change later on.

[GofastRacer]

There is absolutely nothing wrong with VS carbs on a tunnelram, all it takes is tuning and the worst thing is to turn them into mechanical secondaries since there are no accelarator pumps for the secondaries. The trick is to get the secondaries to start opening at a smoothe rate as quick as possible without a bog right after the primaries are open, also a vacuum line connecting both diaghprams is mandatory to keep both working simultaniously!. Another thing a lot of people do is eliminate the little check ball, that is a no-no because all that does is allow the secondaries to slam open and that will cuase it to fall on it's face!..... Now to eliminate all that BS, throw the carbs in the trash and put a hat on the tumnnelram and forget about it. OH, and it will go on any size motor it don't care!.. :D :D

[Blown 472]

There is absolutely nothing wrong with VS carbs on a tunnelram, all it takes is tuning and the worst thing is to turn them into mechanical secondaries since there are no accelarator pumps for the secondaries. The trick is to get the secondaries to start opening at a smoothe rate as quick as possible without a bog right after the primaries are open, also a vacuum line connecting both diaghprams is mandatory to keep both working simultaniously!. Another thing a lot of people do is eliminate the little check ball, that is a no-no because all that does is allow the secondaries to slam open and that will cuase it to fall on it's face!..... Now to eliminate all that BS, throw the carbs in the trash and put a hat on the tumnnelram and forget about it. OH, and it will go on any size motor it don't care!.. :D :D
Doesn't the vacuum loose it's signal at wot? He should get a vacuum gauge and hook it up and that will help tune where you want everything to work? power valves and give you and idea if you have vac at wot.
I have two 800 holleys with linkage and everything I will sell ya, off my blown motta as I am going injected, hehehehehehe :crossx:

[GofastRacer]

Doesn't the vacuum loose it's signal at wot? He should get a vacuum gauge and hook it up and that will help tune where you want everything to work? power valves and give you and idea if you have vac at wot.
I have two 800 holleys with linkage and everything I will sell ya, off my blown motta as I am going injected, hehehehehehe :crossx:
No because it's venturi vacuum that opens them!..
That's ok, you can keep the carbejemators!.. :crossx:

[OverKill]

I had a single Holley 750cfm on a wieand TR. I would get to about 4500 rpm back off to 2000 rpm then go back up to 4500 and I would get a sputtering sound. I checked the plugs and all were jet black wet. I did a vacume test from the carb. and I was all the way up to 13psi at 4500 and sometimes got it to 15psi at 3900 way to high. That carb. had vacume secondaries. I put an 850cfm Holley with MS and no problems, even added a 1.5 Wilson spacer and got even better response. So I feel there is a signal problem with VS and TR's. Just my opinion.
OverKill

[texas-19]

I'm toying with the idea of vacume secondaries, or possibly the Holley 450
4160 mechanical secondary. I see where Summit and Jegs are selling that 450 for $193 so the price is right.
Dan
You'll have $400.00 + in 2 450's and then have to be tunning on them.Just break down and get the 850 dp.You will be a whole lot happier with it.Troubleshooting will be alot easier and less headache.I'd look for a good used one,you can still run what you have and be looking for a good used one for probobly less than those 450's will cost.
I had the same situation.Had a tunnel ram on with 2 750's,swapped to an 850 and never lost any speed and got better gas mileage.

[Kindsvater Flat]

I have 600 vac sec on my tunnel ram and they work great. No hesitation or anything. Never flood it either.

[OverKill]

I second that

[DUCKY]

I guess I was confused, I thought you were looking at the 450cfm V/S carbs that Summit sells with their tunnel ram combos. Not mechanical secondaries. I seriosly doubt that the mechanical 450's will be much better than your 660's on the economy side, and they will certainly cost you some top end. If it were me, I'd get the 450's (v/s) and run them, and save the 660's for your big motor.

[AzMandella]

If you want to run vac-secondaries go for it.I run a set of 750's on my 514 and when it comes to racing you wouldn't know thwy were vac's.And they get much better fuel milage when cruising or skiing.It all depends on what springs you use.Quick Fuel Technologies has a new secondary diaphram housing that will let you change the opening rate by turning a screw.You also have to run a balance tube to keep them opening equally.
http://i5.photobucket.com/albums/y189/AzMandella/Boat/carb002-2.jpg
http://i5.photobucket.com/albums/y189/AzMandella/Boat/carb003-1.jpg

[67weimann]

AzMandella, at least you could have thrown a quick spit shine on those velocity stacks before you snapped that pic...j/k

[Taylorman]

I've sold all the other pieces parts. I still kick myself in the ass for that one. Let em go way too cheap too.
Greaser and i appreciate you for that Dan.
Seriously, you should go back to a single carb and single plain intake. You could sell all the stuff you have now and pay for a new intake and carb. I recently switched from tunnel ram with dual 600's to a single plain and a 750 dominator. Man what a difference. That dam carb is super responsive and runs great. You can pick them up on ebay for $500.
http://cgi.ebay.com/ebaymotors/holley-750-dominator-carb_W0QQcmdZViewItemQQcategoryZ33550QQihZ006QQite mZ160046005801QQrdZ1QQsspagenameZWDVW
http://cgi.ebay.com/ebaymotors/NEW-750-cfm-Holley-Pro-Street-HP-Dominator-NEW_W0QQcmdZViewItemQQcategoryZ33550QQihZ011QQitem Z320043996668QQrdZ1QQsspagenameZWDVW

[AzMandella]

AzMandella, at least you could have thrown a quick spit shine on those velocity stacks before you snapped that pic...j/k
Yeah I know.I just happen to take those pics to send to someone else before I got to wash the boat after a trip.Besides I know how good it looks when all poliched up. :cool:

[GofastRacer]

Yeah I know.I just happen to take those pics to send to someone else before I got to wash the boat after a trip.Besides I know how good it looks when all poliched up. :cool:
Hey Marvin, I know how to get rid of those flower pots!.. :D :D

[AzMandella]

Hey Marvin, I know how to get rid of those flower pots!.. :D :D
Don't worry Art I'm going to do a MFI setup on the engine for the 21'er.So be ready to help me dial it in. :p Will not be any time soon but it wont be to long either.

[GofastRacer]

Don't worry Art I'm going to do a MFI setup on the engine for the 21'er.So be ready to help me dial it in. :p Will not be any time soon but it wont be to long either.
No problem at all!.. :)

[Squirtcha?]

That's some real good input fellas and thanks for that.
Here's my line of thinking.
1. I've got the tunnelram and it works fine (other than the poor mileage).
At this point in time, I don't have any plans to go back to a single carb
setup. I'd have to buy another intake and carb to do that, and I can change carbs on the TR much cheaper than that.
2. I'm thinking that fuel economy-wise it would be better to go with the
vacume sec carbs and my buddies that run them on BBFs with similar
component get some pretty fair mileage. In fact, they're both pretty much
convinced that their mileage hasn't suffered at all following the TR install.
3. Wishing like hell that someone had some experience with these mech sec carbs I'm looking at, cause I'd sure like to give em a go. I have to admit
that the $200 price tag is inviting as well. Can't touch a new pair of vac sec carbs for that price. By looking at the linkage I can't believe that they'd be as bad as the 660s are on gas.
4. Still not sure just what I'm gonna do here though. I put the 660s up for sale in the spam section, but no bites yet.
I do appreciate ya'll posting up with your thoughts on this deal.
Dan

[Blown 472]

That's some real good input fellas and thanks for that.
Here's my line of thinking.
1. I've got the tunnelram and it works fine (other than the poor mileage).
At this point in time, I don't have any plans to go back to a single carb
setup. I'd have to buy another intake and carb to do that, and I can change carbs on the TR much cheaper than that.
2. I'm thinking that fuel economy-wise it would be better to go with the
vacume sec carbs and my buddies that run them on BBFs with similar
component get some pretty fair mileage. In fact, they're both pretty much
convinced that their mileage hasn't suffered at all following the TR install.
3. Wishing like hell that someone had some experience with these mech sec carbs I'm looking at, cause I'd sure like to give em a go. I have to admit
that the $200 price tag is inviting as well. Can't touch a new pair of vac sec carbs for that price. By looking at the linkage I can't believe that they'd be as bad as the 660s are on gas.
4. Still not sure just what I'm gonna do here though. I put the 660s up for sale in the spam section, but no bites yet.
I do appreciate ya'll posting up with your thoughts on this deal.
Dan
Why not a pair of 750's then you have room to grow motta wise, keep your foot out of it and it might not be so bad on gas.
From what I understand those 660 both throttle blades open at the same time, a drag race carb is all they are and I am sure milage would suck with them.

[DUCKY]

Jeg's 600VS (http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?storeId=10001&catalogId=10002&catalogIdentifier=&categoryId=22549&parentCategoryId=10271)
You can get a Holley Reman #1850 600 v/s for just over $200. I can't seem to find the old 450 v/s Maybe it's been discontinued....

[LakesOnly]

The 660's have 1:1 throttle linkage between the primary & secondaries, so you have no choice but to open up all 8 barrels simultaneously every time you step on the foot throttle. That's where a good part of your gas mileage is going.
Put two mechanical 600's or 750's on it that have progressive primary/secondary linkage. This way, the secondaries don't open until you are 2/3 - 3/4 full throttle...and you can feel the secondaries opening with your right foot. This will be easy to monitor while you are motoring around on the primaries alone. Also, it will be close to running a single 4 (while both carbs are on just the primaries), except that 4 throttle plates will be atomizing air/fuel instead of 2...and this will overall still be less than one WOT 660 center squirter, even if you have two 750's running on the primaries at just part throttle. As a matter of fact, Herc had two 750's on his 466 and he got really great fuel economy, so good that it shocked me because I had become so used to my 660's...which can empty both my tanks in twenty minutes if I really try. You might want to ask Herc how often he had to tank up.
LO
p.s. I don't know for sure, but I don't think the 450's aren even rated for cfm the way the real 4-bbl carbs are, and that the actually flow a lot less than most believe...I think they yuse the 2-bbl vacuum rating, but I might be mistaken on this. (EDIT: Same rating, just that a 2-bbl 450 cfm flows differently than a 4-bbl 450 cfm. LO) One thing for sure, though...those 8 tiny venturis are way too small for a sustained 5000+ rpm 466.