Hot Rod Forum banner

Tunnel Ram 327

37K views 57 replies 20 participants last post by  willys36@aol.com 
#1 ·
I am going to order a Duel Quad Tunnel Ram for my 68 SS 327 smallblock. I know what it is and how it works but what will it real do for my 327?

Its mostly a stock 350 Hp 327 (ran The numbers) so im hopeing i can get in to the 13.0s at the track. I would just like to know how and What the tunnel ram would do.

thanks for your help
 

Attachments

See less See more
1
#2 ·
Unless you have a "wild" cam, head work, good headers, gears etc, I wouldn't recommend it. Go with a single 4bbl, you will be further ahead........................

Depending on the body it's in, you should get into the 13s............
 
#4 ·
My cam is a Crane Cams:Energizer
Specifications:
* Advertised duration: 278 intake/278 exhaust
* Duration at .050 in. cam lift: 222 intake/222 exhaust
* Gross valve lift: .467 in. intake/.467 in. exhaust
* Lobe separation: 110 degrees
* Basic rpm range: 2,400 to 5,400
* 9.5 to 10.75: 1 compression ratio recommended

I dont know if thats too wild i just tryed to match it to the orgianl. im also buying a 2500 stall converter.

If you think i need a biger cam that wont be a problem i can get a biger one for the tunnel ram.

My heads are the stock .202 Camel hump heads, And i have flow tech headers with a 350 trans. I think i have stock gears, but i might not because the 1970 Camaro i have should have a 12 bolt posi but its only a one leger.:mwink:
 
#5 ·
<--------- well like poncho said, if you dont have the right stuff i wouldnt do it. ,but if you have the money to spend on it,i say --GO for it.. Im running a tunnelram on my 350sb, It was a big headack at first..You will need good flowing heads,good cam..
The 2500 stall wont work.. I have a 3500 in mine... I had a 2600-2800 stall in mine and it wasent enoufe stall, you need to make sure your cam rpm range,your intake rpm range,and stall, all comes in close together.. because if you dont,it will sound good running,but once you hit the gas ,you will be so mad .. believe me ,been there ,done that... so do your home work on it..

Robbie
<-------check mine out
 
#6 ·
A tunnel ram can work better then a single 4 barrel even on a mild motor,but you need the right tunnel ram.With the combo you have,I would run a stret type tunnel ram,with no porting,and run the smallest carbs you can find.If you could fin a pair of those little 390cfm carbs,they would do well.A pair of 450 tunnel ram carbs ius as big as you can go.You will need to set the carbs up right or it will idel dead rich and foul the plugs.Choose the tallest tunnel ram possible and run the smallest carbs possible and you will make more low end torque and top end horsepower in a 2500 to 5500rpm range then any single 4 barrel on the market.In a 3500# camaro with the engine you describe you should be able to get into the 13's with a good combo,but I would plan on at least 3.73 gears with 27" tall tires and a th350 with 2500rpm stall.
I did a totally kickazz tunnel ram a few years back for a 406 that ran from 3000 to 6000 rpm,and it was worth a solid 50 hp and 40# of torque over a strip dominator and 850 carb.I took and old Edelbrock tunnel ram{TR1yx I think},that had a single 4 barrel "fishtank" plaenum on top,and I sawed off the plenum to make it about 2" high,and epoxied a flat aluminum plate on top and bolted 2,1" carb spacers to the top and added a pair of 600 double pumpers,and the combo was rediculously more repsonsive then the single 4 barrel setup.The only port work I did was a match to the heads I had.So while a single 4 barrel is easier to tune then a tunnel ram,a well tuned tunnel ram still has an edge perfromace wise.Tuning it will be tough,but if you really want it,it will be worth the effort.Good luck.
 
#7 ·
I did my homework, the tunnel ram comes with two 450 hollys and the Manifold can come with these specs:

They mount either single or dual square-mount carbs and, depending on the application, have power bands that run from 2,500 rpm to as high as 9,000 rpm. Separate tops and runners are available for some manifolds.

I figure if i get one with a 2500 starting powerband that will match my cam and my stall right?

And my heads are good flowing, my cam is respectable So im hopeing it will run right, unless anyone else thinks that my set up needs more parts i would like to hear there thoughts on this, thanks.
 
#8 ·
Your car will end up slower with the tunnel ram. With stock heads etc., a single 4 bbl. carb will make more power. If you were to buy all the parts necessary to make the tunnel ram work, two fours requires constant retuning. The guys that say they don't, are the guys that have cars that are never quite in tune anyway. You will be working on your car more than you drive it.
 
#9 ·
lluciano77 said:
Your car will end up slower with the tunnel ram. With stock heads etc., a single 4 bbl. carb will make more power. If you were to buy all the parts necessary to make the tunnel ram work, two fours requires constant retuning. The guys that say they don't, are the guys that have cars that are never quite in tune anyway. You will be working on your car more than you drive it.
[

lluciano77, have you ever owned a tunnelram setup????.I do,and no you dont have to tune them all of the time..and what do you mean it will be slower?? I had a 750 holly,on a edelbrock rpm air gap intake, and what i have now will blow my old set up away..
I have built different types of engines,and at first ,you have to tune the carb,or carbs, to what the engines likes..
And plus 1970camaro is asking for help on putting his setup together,trying to get advise,not to have someone try to talk him out of it.. Pull up my old treads on tunnelram, I had guys like you tell me it would never work,and it want run good on the street, and i would be tunning it all the time,well guess what??
They was wrong.,I drive mine all over town.. Its how you build it.. Yes at first it requries more tuning then others. but its worth it...
 
#10 ·
Wow Robbie

I could kiss you if i wasnt gay. i seen your 350 sb thats a dam good looking Ram you got there, i went to hotrod.com and they tested the summit combo that im going to get and said it was the overall best one to get for the money its worth. so sunday or monday ill be geting it and ill let you guys know how it turns out.
 
#11 ·
Robbie said:
[

lluciano77, have you ever owned a tunnelram setup????.I do,and no you dont have to tune them all of the time..and what do you mean it will be slower?? I had a 750 holly,on a edelbrock rpm air gap intake, and what i have now will blow my old set up away..
I have built different types of engines,and at first ,you have to tune the carb,or carbs, to what the engines likes..
And plus 1970camaro is asking for help on putting his setup together,trying to get advise,not to have someone try to talk him out of it.. Pull up my old treads on tunnelram, I had guys like you tell me it would never work,and it want run good on the street, and i would be tunning it all the time,well guess what??
They was wrong.,I drive mine all over town.. Its how you build it.. Yes at first it requries more tuning then others. but its worth it...
Yes, I have. I have owned many different carbureted setups.

If your tunnel ram will blow away your single carb setup, you didn't have it tuned right or you had the wrong carb.

I know 1970Camaro is asking for help with his tunnel ram. How do you know he doesn't want to hear if a tunnel ram would be a bad idea?

I didn't say a tunnel ram wouldn't work. I said tunnel rams won't work as well as a single carb on the street.

Did you know that you feel the most seat of your pants pull when there is a slight hesitation just before it? I bet that is what you are feeling with your tunnel ram. I bet it feels like it pulls harder.

If you want to argue that tunnel rams are more streetable than single carb setups, well you can be as ignorant as you like. Here is my theory on advice. It is better to give no advice than to give bad advice.

Running a tunnel ram with stock heads and a mild cam is bad advice!
 
#13 ·
I agree ,like i wrote before,he will need good heads and a good cam to run a tunnelram setup.. With stock heads and a mild cam the tunnelram want work..I never said he could use that set up on what he had.. And as far as my last engine i had with the 750 holly,the plugs color was kinda brownish color so i know i was close to it being tuned right,maybe not perfect ,but close.. and yes,a single carb set up would be a better choise..
when i first built mine,it drove me crazy at first tuning it,and i was so close in taking it off,but i stuck with it ,and it drives,and runs great...The only bad thing about running 2 carbs is,is having to take the front carb off to get to the other one when youre tuning it..
 
#14 · (Edited)
tunnel-rams

I say go for it and find out for your self . I think every hot-rodder should experience the power , feel and look of the two filters sticking up through the hood . At least when we used to drive our 55s with 2 velocity stacks poking through we got the looks and dont let someone tell you a single set-up is going to out do a tunnel ram. You are going to get more power , that is why they are made . It cost more to set up ; but power cost ., it is more trouble to set up ; thats why more people dont run them . Ive run them on nearly stock engines and on highly modified engines ; you could tell a big difference on everyone . Mine were all 4 speeds and steep gears and had no trouble driving around town at all . I never had them with automatic but if you have a standard and good gears youll be amazed ; try it youll like it !

Also ; your 327 350 horse should work well if you use small carbs . You dont need to run a wild cam . Just get some more research from some of the experts and some of the drag racers to tell you what combinations to use for the track or if its mostly street . I think with your set -up the 390 Holleys would be great but the 450 might work out good too! You just have to get the right combination .

oh another thing ; I ran mostly 600 Holleys because it was all I had in those days and a weird thing I just remembered : on an Offenhauser polished aluminum intake there would be ice on the manifold ; I just thought that was kind of funny .
 
#16 ·
The 390s are going to run too lean. 450s just barely cut it on my 5.0 that I had the tunnel ram on. The idle circuits are just too lean on the 390s.

Musky2,
There was ice on your Offy because you had a fuel leak in one or both of your carbs. Fuel is a coolant. With a tunnel ram, the cooling effect is greatly increased. You were running rich.

If you want show without go, then run a tunnel ram on the street. I think it is cooler to have a faster car than it is to have a poser car.
 
#17 · (Edited)
390 vacuum sec carbs will work on a tunnelram setup . After i had built my set up ,I was in the process of tuning my carbs,and i asked if any one on here had experience with a tunnelram set up,with tuning the carbs.. One of the moderaters on here(Willys36} helped me tune my set up along with camaroman,and 1bad80.. but at first Willys36 told me i would be better of running a set of 390 vac-sec carbs,cause the sec-plates wouldnt come into play until they was needed..NOW his advice was only for street use driving,not drag racing. But i already had what i had,so they helped me tune them.. I went to a local car show and there was a truck that was running a set of 390 carbs on his 350.. so yes i know they will work.

lluciano77 said:
The 390s are going to run too lean. 450s just barely cut it on my 5.0 that I had the tunnel ram on. The idle circuits are just too lean on the 390s.

Musky2,
There was ice on your Offy because you had a fuel leak in one or both of your carbs. Fuel is a coolant. With a tunnel ram, the cooling effect is greatly increased. You were running rich.

If you want show without go, then run a tunnel ram on the street. I think it is cooler to have a faster car than it is to have a poser car.


Just because your 5.0 was slow ,doesnt mean everyones else's is.. I have a fast car,and believe me,its not a poser..To bad you dont live close to silverdollar raceway here in georgia,cause I would show you.
He** i would even let you drive it,:thumbup: and feel the power.
Im not saying a tunnelram setup is better then a single carb setup,but what i have now is badddddddddddddd. period..
 
#18 ·
I'll stick by my two vac secondary 390's recommendation for a street engine. After all, that gives a healthy 780cfm potential which will serve a small V8 very well thank you! Just take your time and tune them properly. Any carb is a good carb, problems come when someone who doesn't know what they are doing tunes them improperly. Holleys, Carters, Edelbrocks can be dreams or nightmares, just depends on if you know what you are doing. Avoid the siren's song of bigger is better for carbs. Sure you can run two 1000cfm Dominators on the street but why? If for looks then by all means go ahead. I run a Holley 950cfm 3-bbl on my 354 for the look but I modified it so it runs more like a 650cfm @ part throttle (see inserts I made for the primary throttle bores in photo). Yes it is a racing carb but notice that Holley designed it w/ vacuum secondary. Wonder what they knew? However if you are after performance and economy (a well designed hot rod engine), then go with a properly sized vacuum secondary carb setup.
 
#19 · (Edited)
CFMs are one thing. Metering is another.

Changing airflow ratings without changing the air bleeds and fuel restrictions is lame. You end up with a carb that never quite works right. Like I said you need a flow bench and a dyno to properly adjust thes parameters. Experience helps too.

Again, the 390s are to lean. The airflow totals may be good, but the metering is way too lean. Take a look at your exhaust valves. They either are or will be white as a ghost.

A sleeved 950? Did you adjust anything to compensate? Did you enlarge the air bleeds, PVCR restrictions, idle restrictions, change jetting, anything? If not, I can tell you right now for sure your carb isn't metering right.

Vacuum secondaries? I know what they knew. They knew if people had a carb that was too big, it would be a lot more forgiving with a vac. secondary. You get better customer response, and can sell a lot more carbs that way. I'm not saying they don't have their place. I have one on my SBC 400 right now.

A 1 barrel carb might "work" for your engine, but would it work best? A tunnel ram and two fours might work for your engine. Show or go that is the question.

Oh yeah, and was my 5.0 fast?

The front wheels came off the ground.

It beat my friends GTO by a few car lengths. The next day his car ran low 12s all day long.
 
#20 ·
Small carbs tuned for small engines can and do work well on 2X4 applications. The 390's being discussed are such carbs. When you double them up on a tunnel ram you're also doubling the fuel area. That's why they work. Holley recommends them for that particular usage because of the fuel curve.

When any carb builder specs a part number for a 2X4 application the air bleeds, emulsion circuits and supplied jets are downsized considerably.

The whole reason behind using multiple strombergs in the old days wasn't for the extra airflow, it was for the fuel curve. One or two of them wasn't enough for a 327, it ran too lean no matter what. Four or six of them was just right, together they would allow anough fuel to pass to keep it from running lean.

Take a pro stock engine in a fine state of tune and remove the tunnel ram, use one of the carbs by itself, with no changes, on a 1X4 intake and it will be too lean to work because you just cut the fuel in half.

The 390's in question will work on a tunnel ram because one of them would be too lean to use by itself.


I disagree with you on Musky2's icy manifold. Fuel may cool to a degree but only fuel changing from liquid to a gaseous state could form ice on an intake. If anything the carbs were slightly lean and only fuel that was atomizing well enough to cause a temp drop of that magnitude.

Not try to insult or bust anyones chops here. Please don't get mad.

Larry
 
#21 ·
That is true, you are doubling the fuel area. But the flow isn't exactly double for each carb.

Holley most definetly does not recommend using two 390s on a V8. The 390 is recommended for single carb applications on small dispalcement V8s and performance 6 cylinder engines with aftermarket intakes.

If you ever get the chance, take the powervalve gasket out of one carb on a dual carb setup. Let the engine run for a little bit. There will be dew and ice forming. It is because of the over rich condition. The excess fuel does evaporate inside the tunnel ram plenum.

Running lean will not cool things down. Think about it.
 
#23 ·
A well thought out tunnel ram intake and corresponding two four barrel carbs will out perform a single four barrel system hands down. The trick on the street is to keep runner size long and narrow, to help with low speed operation. Tuning for driveability is the issue and requires some work. However, you cannot beat a tunnel ram for high speed operation.

I will say this, however. I do, however feel it's a waste of time to use one for performance if you don't intend to twist it over 6500 RPM. If your intended RPM range is under this, I would probably stick with a single four barrel.

On drag engines that I have dyno'd, I have seen as much as 75 or more horsepower increases with a tunnel ram vs. a single four barrel system. They just work that much better over 7000 RPM, and even though they seem "old school" they are still the ultimate carburetion system. I firmly believe that the atomization capability produced by the large plenum of a tunnel ram offers better top end horsepower over injection.
 
#24 ·
coldknock said:
http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSC/0-8007.html

Third line down under Features.

A lean burn most definately causes higher combustion temp. A liquid converting to a gas will reduce ambient temps in the immediate area, hence the ice on the intake.

Larry
That is a new description they added recently. I have a few older Holley books in my bookshelf and none of them recommend 390s for 2x4s.

I have used two 450s, two 600s, and two 750s. The 600s were about right for my 5.0.. The 750s were a bit too much. When I used the 450s, the mixture was lean all around. The idle circuit was insufficient, and the top end (PVCR area) was inadequate.
 
#25 ·
tunnel ram

LLuciano 77 ; you might be right about the carbs were running rich or leaking on my old Offenhauser because : that was the first tunnel ram I ever tried out , I brought it from Calif. around 1972 in the back of my 64 327 , 365 horse Jeep . I was young and dreamed of running this polished ram , especially in L A my original home . I sold the 327 and replaced it with a stock 327 in the jeep and believe it or not it ran pretty good , but yes it was well over carbureted with two 600 Holleys ; so you were right about that point . Now I dont understand what you are saying about show and no go ! Seems to me if I am running the well set up tunnel ram on my highly modified 350 Chevy 55 that I would be show and go not just one or the other . Do you really believe that the same two cars with the same engines but one with a single 4 barrel and the other with the tunnel and two 4 s that the single 4 car would win ? Im not brilliant but ! Ill leave it to the experts so youll carry on so I can learn . never too late they say !
 
#26 ·
lluciano77 said:
That is a new description they added recently. I have a few older Holley books in my bookshelf and none of them recommend 390s for 2x4s.

I have used two 450s, two 600s, and two 750s. The 600s were about right for my 5.0.. The 750s were a bit too much. When I used the 450s, the mixture was lean all around. The idle circuit was insufficient, and the top end (PVCR area) was inadequate.
That's the very reason my next carb purchase will be a Race Demon RS. Adjustable everything. No tiny drills or impossibly small chunks of brass needed. One carb does it all.

This was all so simple when I didn't give a hoot about the last hundredth of a second.

Larry
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top