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350 tunnel ram question?

27K views 25 replies 8 participants last post by  DoubleVision 
#1 ·
Hey all, I just picked up an s10 with a Chevy 350. It has a mild build currently but I am looking to get more out of it. I have access to a dirt cheap high rise tunnel ram with dual 450 cfm carbs. Which brings me to my question. What kind of supporting mods would I need to run this setup? Could I run this on stock heads and bottom end? Or would I have to run its so lean it isn't worth it?

thanks, John
 
#2 ·
Do you have enough compression and cam to support that much fuel delivery? Tell us more about what your mild build consists of. Tunnel rams can be run on the street, but tricky to tune. If you run this setup, only tune or make adjustments when the intake is at operating temp.
 
G
#3 ·
to answer your question accurately we will need more information.

tunnel rams arent that expensive and unless your getting a super deal it might not be worth it because you will have to change things in the engine so it works in harmony or else it will suffer performance wise.

what is your goals?
What has been done to the engine?
what cam are you currently running?
have the heads had any work done to them?

the answers can help us help you so fill us in and we will do our best to help if we can.
 
#4 ·
It is a stock block and heads with performer intake and 650cfm carb. The P.O told me a mild cam and that's all, I am guessing its what ever size Schucks/ Oriellys' carries judging by the rest of what is on there. I can pick up the tunnel ram and carbs for $300. Right now I am just looking for more power without any head work or tearing into the bottom end at the moment. I have another major project at the moment and don't want this to become one.... yet.


thanks for your help, John
 
G
#5 · (Edited)
for 300 thats not a bad deal!

listen to me when i tell you that you dont need a tunnelram to make big power from a 350

all that needs to be done to a 350 is 3 things

cam swap
intake and carb swap
ignition system msd distributor,ignition box and a blaster coil.

you can get over 400 hp by just changing the above mentioned parts

i have built over 30 small block chevys in the last 20 years and some of them i have made 700 hp with a stock block


i built a 450 hp chevy engine for a 69 chevelle for 1200 bucks and its all chrome you can see it on youtube type in bigchevyftw and youll see the car i also used the cam everyone on the internet says isnt a good performance cam yea the comp mutha thumpr cam you tell me if you think it dont perform
http://www.youtube.com/watch?v=03YfbbBTExo
 
#6 ·
jlang said:
It is a stock block and heads with performer intake and 650cfm carb. The P.O told me a mild cam and that's all, I am guessing its what ever size Schucks/ Oriellys' carries judging by the rest of what is on there. I can pick up the tunnel ram and carbs for $300. Right now I am just looking for more power without any head work or tearing into the bottom end at the moment. I have another major project at the moment and don't want this to become one.... yet.


thanks for your help, John
Offer the guy $250 for the TR, settle somewhere between that and his asking price. Put it away for a trade, or to use yourself, but I'd suggest you not use it w/a stock cam- there's just no need, although it could be made to run w/a stock cam.

The best money you can spend right now would be on better heads. Production Vortec heads would be worth a good amount of power, but the TR or the intake you now have won't fit on them because the bolt patterns are different. But there are relatively inexpensive aftermarket heads available that (along w/a cam change) would really wake that 350 up.

I'm guessing you have some sort of headers on this, but if not you need to get them.
 
#7 ·
I'd snatch that tunnel ram and carbs up quickly, even though I wouldn't use it on your fairly stock engine! It's an easy money maker, or to use when you've got the itch to build your engine further.
I've had a few tunnel rammed engines (mostly SBC, one BBC) and they for the most part were not a huge deal to tune. The first one taught me patience though, and from there I've learned and it made susequent engines and TR's easier to tune.
I warned my friend about tunnel rams when he asked me to help with the 350 in his '56 Chevy, but he insisted on wanting it for looks. I was shocked when we installed the Weiand tunnel ram and twin 500 Edelbrocks on a failry mild 350, with a middle sized Thumpr cam and it purred like a kitten! I was even a little irritated knowing what I've gone through on some to get them running as well.
My present car is a Holley Pro Dominator tunnel ram with twin 450's on a .040" 327. It's not super radical, but well built, and I had a little tuning to get things responding well. Changed accelerator pumps/cams, squirters, jets, power valves, and fooled with the timing. It starts and runs excellent now, but it did take some tinkering.
 
#8 ·
BigChevyFTW said:
for 300 thats not a bad deal!

listen to me when i tell you that you dont need a tunnelram to make big power from a 350

all that needs to be done to a 350 is 3 things

cam swap
intake and carb swap
ignition system msd distributor,ignition box and a blaster coil.

you can get over 400 hp by just changing the above mentioned parts

QUOTE]

Presumably the OP has smog heads (with the terrible rectangular combustion chamber) and 8.5:1 compression (maybe 8:1 depending on deck & head gasket thickness). How can you make >400HP with that compression and those heads? I would expect to get no more than about 320HP.

Also, are you saying you can get there without headers, or just left it off the list?
 
#9 ·
jlang said:
Hey all, I just picked up an s10 with a Chevy 350. It has a mild build currently but I am looking to get more out of it. I have access to a dirt cheap high rise tunnel ram with dual 450 cfm carbs. Which brings me to my question. What kind of supporting mods would I need to run this setup? Could I run this on stock heads and bottom end? Or would I have to run its so lean it isn't worth it?

thanks, John
You can run it on the stocker. Is this an automatic? Stock stall? What rear end gears?

While you can run the TR on the basically stock motor, you will lose torque down low compared to a dual plane. I have been running them on the dyno at lower RPM as part of a project, and they are down on torque and have crummy response and really lousy fuel economy due to bad fuel distribution when running on the primaries. Once you get up to 3000RPM, they are better than anything else and just keep climbing.

If you have a stock stall and highway-friendly gears, you are not going to like the TR.
 
#10 ·
Thanks for all the help everyone. I think I will pick it up to hold onto for when I do a big build but for now I wont be using it. Bigchevy if you don't mind me asking what intake manifold, carb and cam were you using to make 400hp?

Thanks again, John
 
#11 ·
I run a TR on my 350 in my Vette. I have two 390 Holley carbs.
It looks great, sounds great but anything under 3000 RPM is just noise out the exhaust. It doesn't start making power till around 2800 RPM

Now its isn't exactly anemic at low RPMs but if you want to impress anyone you are going to want to do it above 3000 RPM, for that you need to have a cam and heads that will breath enough to support the intake.

My 350 has a nice street/strip cam and roller rockers. It has had a nice port and polished job on the heads.
Headers and side pipes. It breaths pretty good.

I love the car and the TR works ok for around town driving but the MPG sucks.

 
#13 ·
jlang said:
Do camel hump heads flow enough for a tunnel ram? I don't know anything about them I've just heard they are really good.
Here's a picture of my setup, complete with cc'd camel hump 2.02 heads:


With 3.73 gears and a TH350 with 2000 stall it yanks the wheels off the ground if I hit it hard taking off. A tunnel ram can and does make good low end power if tuned correctly, and the right cam/pistons used. My cam is an Isky 270 mega cam, with flat top 9.5:1 pistons. The car is about 2500 lbs., and M&H drag radials on the rear.
 
#14 ·
Alright, I just bought a 327. I want to run the Tunnel Ram since these have high compression from what I've been able to find 10.5:1. If Im wrong please tell me. I've heard these had really good heads but I don't remember the name. Would it be better to use the stock heads or change to Camelhumps? I'm still very new to engine building, would someone please explain how to calculate what camshaft to use for my application. Thanks again for helping me with all my questions, I'm just getting into small block chevy's and appreciate the help.

, John
 
#15 · (Edited)
First of all, a motor's c.r. is relative to the sum of it's internal parts, piston type, dish, dome, and they're volume, cylinder hear chamber volume, etc., just because it's a 327 doesn't necessarily mean it has high compression. Do you have any history on this motor? Numbers off the front block pad, what GM heads, and so on? Has it ever been rebuilt?

BTW, camel hump heads are a stock GM head for some motors.

Here's another TR example on my T-Bucket with two 600's, it's a BB, with lots of cam and makes big power right off idle.
 

Attachments

#18 ·
I got the codes off of the block, 3789817 (327 62-64 truck or passenger car) c2662 (march 26 1962) and the suffix code is T0417D, I have looked through the link you gave me and I found and there is no T0 listed. Does anyone know what this code is?

, John
 
#19 · (Edited)
The suffix (i.e. LAST of the code) is "D". From here:

D '56 265 Truck 205hp RPO 410 Manual 4-Brl
D '58 283 Impala 185hp Base Powerglide 2-Brl
D '59 283 Impala 185hp Base Powerglide 2-Brl
D '60 283 Impala 170hp Base Powerglide 2-Brl Hyd Cam
D '61 283 Impala 170hp Base Powerglide 2-Brl Hyd Cam
D '62 283 Impala 170hp Base Powerglide 2-Brl Hyd Cam
D '63 283 Impala 195hp Base Powerglide 2-Brl Hyd Cam
D '64 283 Impala 195hp Base Powerglide 2-Brl Hyd Cam

Given your March 1962 date code, the likely engine is in bold above. The c/n 817 block was used for both the 327 and 283.


3789817....283...'62-'64
3789817....327...'62-'67
 
#20 ·
Is there any difference between this motor and the high performance ones other than heads and compression? I intend to change intake carb and cam anyways. If I switched to flat top pistons and better heads would this be worth it?

Thanks, John
 
#22 ·
In all honesty, a 283 is not going to give you the kind of performance per dollar spent that a 350 will.

You will be much better off using a later model 5.7L (aka "350") SBC engine as a foundation. The 283 is small, and it is old school (2 piece rear main seal, no factory provisions to use a hydraulic roller cam). If it were a 327 (meaning it had a 4" bore from the start) it could be an OK block to work with, but it's not. The 283 block can be bored to 4" about 1/2 the time, but will fail the other 1/2. And even then the cylinder walls will be paper thin and there's no more rebuilding it. Plus it's a small journal block, meaning there are no factory cranks any larger than 3-1/4" stroke that will fit it- meaning the max you can get is 327 cid w/o using some sort of custom crank.

If you do a search here or elsewhere for a "vortec 350" or similar terms you can read up on the best engine IMO to use as a starting point.
 
G
#21 · (Edited)
look pal im going to be honest with you here.
if you want a street/strip car thats great! but, your opening a whole can of worms if you start with a TR intake swap.

"the 327 is a good engine"
"it all has to function in harmony"
alot of guys on this site build cars to run at WOT!
you want to build it to Run great at part throttle and drive it at full throttle im not here to get into a pissing match but i can tell you from experience you can get 400hp from a small block chevy with minimal parts but once again it has to work in harmony with the rest of the cars drivetrain to give you the seat of the pants performance your after.

L79 vette im sure he has headders already because he is considering a TR.
 
#25 ·
Code Year CID Vehicle HP RPO Trans Carb Comments
D 56 265 Truck 205 410 Manual 4-Brl
D 58 283 Impala 185 Base Power glide 2-Brl
D 59 283 Impala 185 Base Power glide 2-Brl
D 60 283 Impala 170 Base Power glide 2-Brl Hyd Cam
D 61 283 Impala 170 Base Power glide 2-Brl Hyd Cam
D 62 283 Impala 170 Base Power glide 2-Brl Hyd Cam
D 63 283 Impala 195 Base Power glide 2-Brl Hyd Cam
D 64 283 Impala 195 Base Power glide 2-Brl Hyd Cam
 
#26 ·
I agree, find a 880 casting Vortec 350 as a start. These come with factory roller cams and Vortec heads. With the correct pieces it's easy to get this engine to produce nice power figures. However, I wouldn't waste my time on a 283. While they were excellant engines, the small journal rods these engines came with are not very strong. Especially when you consider if they are stock they are over 40 years old.
The next thing I recommend is learning more about how to hot rod a small block. When you believe things you hear such as all 327's had high compression it shows you have a lot to learn. Next thing I can tell you also is
Lets say we have a stock, 8:1 compression 350 engine. We remove the stock heads and install a set of stock 305 heads with 58cc chambers. Now the compression shot up to 10:1 thanks to the smaller chamber. However when we drive it, we notice it seems to be more throttle responsive, and seems to have better low end torque than it did, but when it reaches 4000 RPM it falls flat on it's face just like the stock heads we removed did. Why? because the small valves in the 305 heads and the stock ports aren't designed to breathe any higher. The ports on the heads we removed aren't any better even so they used a larger valve. What am I getting at here? FLOW IS POWER. Many believe high compression is the ticket to big power, and it is, as long as the flow is there to support it. Many a novice rodder you can ask this question. Which would you rather have, a high compression engine that doesn't flow very well, or a low compression engine with good flowing heads? And the majority will say the high compression with low flow. But in reality, the low compression good flowing engine will eat the other alive. A Good book to get is David Vizards hot rodding small blocks on a budget.
Don't waste your money on camel back heads. Those are now things of the past and they aren't worth investing any money into. Especially when you can get Vortec heads on the cheap and make 30 more horses with them.
If you get a set of camel backs that are stock and need a complete rebuild, your looking at around $700 as they will need valves, hardended valve seats installed, new bronze guides, skim milled to assure flatness, new springs, locks and retainers plus worked. When Vortec heads were readily avalible me and my best friend quickly sold all the camel back heads we had.
You can get a set of Vortec heads for around $600 and still be power over the camel backs. Another thing to remember is if you have poor flowing heads you can't count on the intake to improve it any so sticking a tunnel ram on a stock set of heads won't do it any good.
 
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