BBC heads question (Tunnel ram??)

Hey Guys,
Im was lucky enough to find a 396 BBC in a Chevy truck that does not need rebuilding. I was wanting to go with a Tunnel Ram on this engine, but do not want to break the engine apart since it runs so well. I want to know if the TR will operate fine on just a basic 396.
The heads are the Oval port 3933148 (122cc, open champer heads)...Not looking to build a huge power house, but a good driver.

A few questions.... Can reg. port tunnel rams be made to work on oval heads? Or do you have to have a tunnel ram with oval ports (they are hard to find)?
Are there any good tricks to make the tunnel ram work its best on the 396 with these heads?

I know I should just find other heads, but for cash sake, I would like to just use what I have since it runs good.

Crazy question I know, but I am new to engine work, and just getting this project started on limited knowledge.

 

It'll run, probably ok, you might want to use small carbs and a manual transmission (or high stall converter in an automatic), and kinda steep rear gears

 

Outside of a high Bubba factor why run a tunnel ram on a stock truck engine?

 

Not what he asked, but a very good question....

 

It will work fine as long as you are willing to work with it. A light car, or like was said above with gear and converter. Might as well throw a small cam in it while your at it. Just a few more bolts a 3 extra gaskets.

 

Oval port heads and a rectangular port tr will work fine. I run tunnelrams on all of my cars that aren't injected from the factory. Open the hood of any new car and one way or another they all prety much have tunnelrams on them. Old school thought was they aren't any good on the street. The factory has changed that. I run three twos on mine. Both 454 and a 350 chevy and they love it.

 

I think I still have a 396 high ram cam from sig erson brand new in the package. small by todays standerds, but good for a older 396 motor setup.

 

Any disadvantage to running square port tunnel ram on oval port heads?

 

Tunnel rams have carbs on top of them, tuned port efi systems have injectors at the bottom. Big difference in how they work. But yeah, you can make a tunnel ram work on the street if you want to.

 

I ran a rectangular port intake on oval ports heads on a 396 using a Sig Erson Hi Flow I cam. The carb was a Holley 800 double pumper. Maybe the turbulence at the mismatched ports atomized the fuel better, but for some reason, the car ran hard. It was a '65 Chevelle with a 4 speed and 4:88 gears.

 

Those heads are off of a big truck.
Sure you don't have a 366?
Those are tall deck motors and a regular manifold won't fit without spacers.
And as for an oval port manifold http://www.jegs.com/i/Weiand/925/1981/10002/-1?parentProductId=746533

 

Im not sure really (newbee)? Is there anyway of telling by ways other than engine block numbers? Maybe something different about the engine look? I have the engine number from the front of the engine (10920JT/ 19D007946), but the ones on the back of the block are impossible to read, or see good enough to get numbers. I can barely see something that looks like "GM8".....The guy who had this truck said it came out of a 1969 Impala. He "jammed" it into a 63 Chevy truck and this is where it sits now. I can barely get my hand behind the distributor and coil. Some of the firewall had to even be beat inward, for him to make this engine fit.
I would love to know what this engine maybe, but I was not counting on it being a 366....any thoughts?

 

Correction....I went back and checked the numbers again and made some mistakes...The engine code # is T0920JQ....(not 10920JT...I was way off!!!)
This is a 396 engine from 1969 (396/265h.p.)

 

Thanks for all the good advice guys!!

 

The partial VIN of 19**x... means Chevrolet car, 1969 or 1979 model year. The two digit JQ suffix means it's from the 60s (they went to 3 letters starting 1970), and JQ is indeed the rare 1969-big-car-only 2bbl 396 engine, rated 265 horsepower. Those 148 heads are the same type used on the late 60s pickup truck 396 and the early 70s 402, they have an open chamber with a bit more open than the later open chamber heads, and they have the normal oval ports and 2.06/1.72 valves.

I had some of the 366 type heads from a bigger truck, they use smaller intake valves and have closed chambers. You don't have them, don't worry.

You probably want a bigger cam, headers, steeper rearend gears, etc but it should work ok if you take the effort to set it all up properly. I wouldn't bother with the tunnel ram, but hey, it's your truck

 

Thanks for the info and help. Always good to know that I can get answers here at the HAMB. Im not much of a motor guy, so I am just getting started on that end.
I would like to get a nice chop to the engine, but not work against the stock 396. Again this is going to be more of a car show cruize-in ride, and not as much a daily driver. Going more for looks and sound, and not as much performance to "twist an axle in half" . Thoughts on a good cam for this?

 

The cam needs to work with the gearing, and you want to think carefully about what rpm band you want the engine to run well in. Stock is usually around 1000-4000 rpm roughly. A healthy street cam will have about 230 degrees duration at .050 lift, and will work from about 2500 to 5500. You'll want at least 3.73 gears, which the truck probably has already if it has the original rearend. But if it has an automatic transmission in it, like the one that was originally behind the engine in the Impala or Caprice it came from, then you'll need to get a converter with higher stall speed. With the tunnel ram, you want to set the drivetrain up so you can get the engine revved up right away, to get the air moving thru the carbs, so it won't bog.

 

That iron 396 2-bbl intake is pretty rare... I seen one once and couldn't believe my eyes.. Had to do a double take and scope it out some more... It was in a '68-'69 Chevelle or Malibu wagon... Wish I had a picture of it...

 

yeah I guess so. took these pics just for you, just now

 

The only disadvantage is if you are trying to make maximum horsepower there is turbulance caused by the mismnatched ports. I would bet that most of the cars running tunnelrams on the street are running the same combination. I ran 9.90's with the same setup on my super gas car in the mid 80's. I am running a tunnelram right now on a stock 350 in my 48 suburban. 3x2 set up running only on the center carb, a 2G rochester and it runs great. No lean condition but It is a street rod. not looking for max rpm's. 80 MPH at 2500 rpm so I am not complaining. 350/700R4/ 3.42 rear and 28" tires.

 

Thanks for all the info guys, and forgive me if I sound too much like a newbee to engine and set-ups...because I am.
I bought this Chevy truck for the motor, so I could stick it in a '36 2 door Sedan I am working on. So I have been getting parts together, as I can.
Which brings me to the rear axle.....It is a Ford 9" rear and the ratio is 3.25..........Is this a bad choice on gear ratio with a stock 396/ Tunnel ram? Again, the car will be mostly show and weekend, not a daily driver. I understand that this is a good rear size for all around highway use, but to show power under the tunnel ram, do I need to look into another gear.
I believe Squirrel said 3.75 on gear choice (being it was a Chevy truck and I didnt mention my Ford rear)....Any thoughts pros/cons on the 3.25???

 

You can give it a try. If it doesn't work out, you can add more gear.

 

Very true.....The rear in the truck was a duelly rear (guy used it for pulling), so it looks like my choice for right now will be the 3.25's.

 

a guy in the cl***ifieds has an Oval port tunnel ram for sale. seen it yesterday.

I went thru this same thing for months... After talking with a few machine shops an such i came to this conclusion. It will work, But your going to look at about an 5-8% power reduction *Quoted by 2 machine shops both very good guys.

For me it came down to power was more important that being cool, just for cool sakes.

But by all means, if you already have one then run it, you can always swap it out later. gaskets are cheap.

Good luck man

 

Thanks bud!!

 

I run a TR on a stock 454 w large ovalport stock heads and a mild cam, 3500 stall and a 3.55 and 4.11 ratio rear (car has had both) it runs just fine maybe not to full potential but enough to give a pucker factor, You'll be alright with that setup

 

This deal just cries out for a Comp Cams Thumpr.

 

Theres that satire again....yeah or sit and do the math and figure something out that will work well with it...
It might not be the most optimal combo but it draws attention,is cheaper than a blower or hilborn(I have one I know),and fills an engine bay up nicely! could I run a few tenths faster with a RPM Air gap yes probably but why not run a tunnel ram? guys were putting them on cars in the late sixties so why not? tell me they aren't traditional(I've heard it) grumpy ran one in '68 on the camaro and if its good for grumpy its good for me!

 

Well said!.....I have half the stuff to put together a small block 350/671 blower combo, but do to both lack of engine knowledge and funds, I s****ped the idea for now. I love the look of the Tunnel Rams and think that they do make a great hood stuffer. A guy with a budget like mine, and still be able to have a killer look, and not have to "break the bank"...The tunnel ram is perfect! If I was going racing every night, then I would look into more performance and "inside the block" goodies. But I think this will be a great look..... Also, with all the great advice and info on here (Thanks Guys!!), I will be very happy!
I still have a long way to go and a lot to learn! Thanks for all the great advice and I am always looking for more
P.S...Even picked up the tunnel ram today, for one of the earlier posting member! (Thanks MIke)

 

Never seen a tunnel ram with a top for 3x2, got pics?