tunnel ram

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aaronk785

aaronk785

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Going tunnel ram on my drag car. I have 2 600 holley vs carbs. I would like to make these work since I have them. Car weights 3450. Engine is 440, pro comp eddy rpm copies, 10.75 compression, howards 272 , at .050 and 660 lift after lash. 5000 stall converter and 4.30 gears. Best time is 10.51 at 127. Current carb is holley 850 dp and m1 single plane. Will the 600s work or should I look for something else. Anyone have any experience or tuning suggestions. Would be greatly appreciated.
 
They should be fine. Tuning tip? What every primary jets one has, the other gets. For starters, delay the secondary opening. No need to get aggressive off the bat. Get the primary sides first.
 
Thanks Rumble. I have lots of jets. Both carbs have 66s now. Ill go from there. Sounds like I need to get 2 sets of secondary springs. I guess I have all winter to think it over.
 
What 600's are they?

Those are very small. I know many will argue but let them.

You should have no less than 750's that are set up by a competent carb tuner. You should buy a cam ground for the tunnel ram.

Off the top of my head, to keep engine speed the same, you will need 8-10 degrees LESS @ .050 than what you have, on no more than a 110 LSA.

If you don't get the cam correct, it will be a pig off the tranny brake, or even worse if you foot brake it, it will be lazy in the gear change and want to drive the RPM up.

The tunnel ram, when done correctly, will make more HP and torque all over, without having to twist the guts out of it.
 
YR, he all ready has the 600's.
They will be good for the heavy car.
NOT that I'm arguing the use of your suggestion.
 
600vs carbs are fine, don't change them. install them inline, linkage is simple. jets and plates have to be the same. the vacuum cans have to be tied together, holley has the tops for this. buy two spring kits. your motor should pull enough vacuum to require the black spring in both cans. when using the lighter springs should you feel the motor studder it's the cans opening the secondaries to soon and you need to try the next stronger spring. the motor isn't making enough vacuum to pull gas up the emulsion tubes yet and needs to slow the blades down a little. you need to also buy two nozzle cam kits, try the quick green one first, it should be the correct one. the ram likes a very quick shot. your cam is just fine you don't need to change it. you'll find out the coming off a 1000 rpm idle will work real good.
 
The problem with a vacuum secondary carb on a tunnel ram is the secondaries don't open until high RPM and sometimes they NEVER open. May as well run a single 4.

The cross mounted carb linkage is not that complicated.

Like I said, too small with other issues, like no metering blocks in the rear, if they are 1850's. We are not even sure he don't have something like a 450 that were used a bunch and never worked worth a damn.
 
Thanks for all the replies. Like I said I have all winter. If I find some cheap 750s ill get them. Otherwise ill use what I got and try to make it work. I'm a poor boy so no way I can afford new 750s let alone pay someone to tune them. I know this is the right way just not affordable for me. The carbs I have are 1850s payed 15 bucks apiece so I'm not out much if it doesn't work.
 
aaronk785 said:
Thanks for all the replies. Like I said I have all winter. If I find some cheap 750s ill get them. Otherwise ill use what I got and try to make it work. I'm a poor boy so no way I can afford new 750s let alone pay someone to tune them. I know this is the right way just not affordable for me. The carbs I have are 1850s payed 15 bucks apiece so I'm not out much if it doesn't work.
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What intake is it? The problem with the inline deal is most of the time you can run metering blocks on the secondary side. I never liked trying to tune by changing that plate out. If they are sideways you can put blocks on them.

Be prepared to change the idle feed restriction on both carbs. You doubled the area but not the airflow. Even on the 1850's you have to take some fuel out on the bottom. May even require you open the idle bleed up a bit.
 
Thanks YR. I'm not opposed to turning them sideways. I see your tuneability point. I also have extra metering blocks so free, just have to buy the longer tube for the bowls. Intake is a newer weiand. Thanks for the tips on the bleeds and restrictors.
 
Put them on a dyno.

It take a bunch of air speed to get them all the way open.

That's really where the 660 center squirters came from (Holley number 4224).

Even with the lightest springs in the can, they may not open all the way until almost max RPM. I've seen them never come all the way open.

The problem with the 4224's on the street was the dead fat idle circuit. Which, is an issue with any TR set up, because you doubled the idle feed restriction area without doubling the air flow.

And really, at WOT, you didn't double the air flow either. So you need to be able to tune MAB's as well, among other things.
 
I just remembered a pretty nice 327 on a dyno back in probably 1990ish. I was at a shop to rent some flow bench time (we ended up comparing notes and testing each other's stuff when I bought my own bench) and that thing was on the dyno. It was a pretty well warmed up 327. The owner brought in a 3310 Holley. They beat on it for a while and then realized the secondaries didn't open fully with the lightest spring. I remember the owner and the dyno guy discussing if the spring was too light, letting it start the secondaries open a bit, opening too early and then never getting the secondaries open all they way.

They changed springs a few times and then put a 750 DP on it. It picked up a bunch of power and some RPM as well. The engine owner blamed the single plane intake for not having air speed to open the secondaries. Looking at the numbers, the DP made more power lower and longer than the VS carb did.


I'm just not a fan of VS carbs on anything. Unless it's a Carter. Those are different.
 
Well looks like in can put metering blocks on and still go inline. That makes linkage a lot easier. Going to get the pod tops to connect them together. Thanks again for all your input.
 
IF the OP had some bucks, then a pair of DP's would be in order.
The Carters are mechanical secondary carbs with ether the weighted air velocity door (not a fan) or the spring loaded secondary choke plate (LIKE!) that open up with air demand.

Those AVS's would be pretty OK up top a TR. while not so tuneable next to a Holley, they do well for what they are. Basically, stock replacement carbs.
 
aaronk785 said:
Well looks like in can put metering blocks on and still go inline. That makes linkage a lot easier. Going to get the pod tops to connect them together. Thanks again for all your input.
Click to expand...

That's good. The inline linkage is cheaper and espalier to do.

The thing is, you can use what you have, add the metering blocks and learn to tune without spending big dollars. You can always buy something else later.

I advocate making them run and drive and use them, and upgrade as you go.
 
Use what ya got!!!!
Where NOT like the U.S. Government! Throwing bags of money at a problem.
(Real problem or not!)
 
His engine originally has a 850 dp can't he just sell the 2 600 and buy another 850 ??
 
273 said:
His engine originally has a 850 dp can't he just sell the 2 600 and buy another 850 ??
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Sure! But, it is about balance. How many big blocks have you seen run twin 850's on a TR?
If so, what was there engine like that it could actually consume/use 1700 cfm?
 
rumblefish360 said:
IF the OP had some bucks, then a pair of DP's would be in order.
The Carters are mechanical secondary carbs with ether the weighted air velocity door (not a fan) or the spring loaded secondary choke plate (LIKE!) that open up with air demand.

Those AVS's would be pretty OK up top a TR. while not so tuneable next to a Holley, they do well for what they are. Basically, stock replacement carbs.
Click to expand...

Rubmlefish I ran 10.50 in the 1/4 with pretty much stock 750 edlebrock carbs on my big block M1 tunnelram.
 
I wish Joe dust was still on here. He had a big block 906 headed duster with the wieand tunnelram with 2 600 hollers. If I remember right he was also runing mid 10 in the 1/4 with the car.
 
On my old 73 dart I was runing a wieand tunnel ram on my 440 and was using 2 650DP with the pro form mainbodys added. On 93 pump gas my best time was 10.49 in the 1/4. At the time I had the wrong converter in it.

But I agree if the op has the 600 might as well use them. Just like everything Elese it's just going to take tuning and time
 
mopar65 said:
On my old 73 dart I was runing a wieand tunnel ram on my 440 and was using 2 650DP with the pro form mainbodys added. On 93 pump gas my best time was 10.49 in the 1/4. At the time I had the wrong converter in it.

But I agree if the op has the 600 might as well use them. Just like everything Elese it's just going to take tuning and time
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Yup, if the OP let ME spend his money his *** would be in bankruptcy court tomorrow.

It's always easier to spend other people's money for sure.
 
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