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I'm choosing carb's for a mostly stock BBC with a street tunnel ram. Are some 450's with a single acc. pump enough, or do I need to get the 600 / 660's. What throttle linkage do you recommend for forward facing carbs? It seems like it would be pretty simple to connect the throttle linkages of the 2 carbs and hook the throttle cable to either one. Why are the linkage kits so damn expensive?
Without chokes, is it difficult to get a tunnel ram motor started? I would think that since the carbs are a foot away from the combustion chamber, it would be difficult to get it to fire and about a half an hour until the carbs get warm enough to work well. What do you think?
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The linkage kits are expensive because they are usually designed to be used with a bell crank system and sideways oriented dual feeds. In this situation, a ton of inflexible linkage is needed, and the kits are spendy. If you are able to orient them front/back you will capitalize on two things, first, the carbs work better upon acceleration, and second that the linkage is basic, just run a pair of heim joints on a rod between the carbs and make sure you take out all of the slack. E-mail me if you have any questions.
P.S. They warm up just fine at the river!
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I run a tunnel ram with dual 450's that have been modified and tricked by Dave at DNE motorsports. I know there small, but they seem to work great on my mild 454 punched 30 over. I run in the low 70's right now. Once the timing and carbs were dialed in by Dave, my boat has been turn key everytime. When it's cold or been a while since running it, it does take longer. Once on the water, never a delay or problem. Good Luck!
HBjet
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HBJet,
Holley has a very inexpensive 450, but the pix in Jegs / Summit make it look like a single acc. pump. What've you got? I don't know why, but the 600's with the same center hung, small bowls are more than 2 times the money.
thanks, JB
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I am not a carb guy! I repeat... I am not a carb guy! But... I think that the center hung's are more expensive for a variety of reasons.
1. More parts. You have two inlets, two filters, a lot more linkage, two accelerator pumps, high performance internals and removeable jets for the secondarys.
2. Demand. They are not smog legal and have to be sold to only hot rodders. The others can be marketed as performance replacements to the smog crowd. Much larger volume.
3. Legend baby, legend.
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I had nothing but problems with my 660 center squirters. On a tunnel ram (weiand) on a BBF. The boat ran differently every day. Even the most reputable shops couldn't get them to run right after I got frustrated. The new owner of the boat just replaced them with new (I think 750's) and notices "a world of difference."
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I purchased the tunnel ram set up from summit racing with the dual 450's that they offer. they have the single accelerator pump on them. have yet to find out jet size, accel pump size, and power valve size. with the cable linkage bracket, velocity stacks and dual fuel line with gauge. aprox $800.00 in to it so far and find out the fuel pump I have doesn't deliver enought pressure. had the set up on at the tail end of last year,fired it up in the driveway and the main bearings went on the crank (stupid me, not knowing that there should be keepers on the oil pump rod, which where missing). when I installed the distributor, must of lifted up and slid the rod out of the top of the oil pump. 3000.00 later I have a rebuild in the boat, but I'm now uneasy about putting the tunnel ram back on.
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I have a set of those 450 cfm Holleys. They are mech. secondary w/single squirter carbs. I've never seen a Holley like that before. I guess the assumption is that the single squirter is adaquate for all 4 barrels and has the duration of squirt too.
The nice thing about that is Holley offers bigger squirters and pump diaphragms along with pump cams to tailor the hit of fuel
Got mine from Summit with the 10% discount. they are usually $175 a piece. Haven't tried them yet, but I like to go conservative on carb size and 900 cfm should work for me.
Edelbrock & Mr. Gasket sell inexpensive ($40 range) linkage for in-line carbs.
Correct me if I'm wrong, but carbs don't need to get warm and run bette when cool. It's the motor that needs to warm up.
