tunnel ram

I've got a 78 350 out of a C10 pickup to put into a 29 Ford. I'm porting and polishing the heads (how to from Utube). I'll be getting a cam, already got 30 over Mahle pistons. I'm looking for the best combination of cam, rear end, intake and carbs to have an engine that sounds good with the cam thump and runs dependably for long runs. It has an S10 rear end (stock). I have tunnel ram for it and was wondering if there's any combination of engine components to be able to run the tunnel ram without goin to a 383 stroker. I really love the way that it looks but if it's just impossible to use dependably, I reckon I'll have to get rid of it. Right now I have 2 Holley 650's to put on top. I've heard that's way too much for a mild or moderate performance engine but was hoping the experts here could let me know of a good combo of components, or do I just trash the tunnel ram idea.

You can run a tunnel ram with pretty good results.
The 650's are way too big for a 350 small block.
That's 1300 cfm and you only need 650 to 750.
Two 390's would be a better choice. imho
Comp Cams h268ex would be the cam of my choice.
I wouldn't get too carried away with the port job being as you're running it on the street.
S10 rear will stay for awhile but, I'd change it out before romping it too hard.

Thanks old iron

Thanks a lot old iron. I'll certainly make note of your suggestions. Now I just gotta get rid of these 2 650's and try to find 2 390's.

what ya gonna want for one or both of them? I might be interested.[S

For the street most tunnel rams are more for looks. Run your 650s and unhook the secondarys. I'm not sure if that comp # is for their thumper cam but they have one that's designed for that rumpy sound. Also if you like noise, a gear drive for the cam is pretty cheap. Don't forget about the convertor, nothing worse than having a mismatch there.

Old Iron said:

You can run a tunnel ram with pretty good results.
The 650's are way too big for a 350 small block.
That's 1300 cfm and you only need 650 to 750.
Two 390's would be a better choice. imho
Comp Cams h268ex would be the cam of my choice.
I wouldn't get too carried away with the port job being as you're running it on the street.
S10 rear will stay for awhile but, I'd change it out before romping it too hard.

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S-10 rear ends are actually quite resilient. I've got on behind my '455 Buick and my dad has one behind his 454, for a combined 40,000 KM's. If you want to run a locker or something it might hold up better, but I know lots of guys running them with nitrous or big power with no problems.

Willowbilly3 said:

For the street most tunnel rams are more for looks. Run your 650s and unhook the secondarys. I'm not sure if that comp # is for their thumper cam but they have one that's designed for that rumpy sound. Also if you like noise, a gear drive for the cam is pretty cheap. Don't forget about the convertor, nothing worse than having a mismatch there.

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From what I've heard about the Thumpr's (never used one), they just make your engine sound gnarly but actually lose power. You're better off with one of their high energy cams, I think.

you could get away with two 600 cfm list #1850's vac sec but as said two 390 vac sec will be better on the street try not to us 1 to 1 carbs. them truck heads will have to go too, most are 1.72 intake valve size. a single carb is best on the street and a 650 would be nice on a 350.

2 new 390s is going to eat up close to a grand, about the cost of my average car,lol.
Like I stated, a tunnel ram on a street engine is just a decoration. But it will get the job done with everything else breathing ok. Local lezzy has one on her basically stock 350 engined T-bucket, secondarys blocked off, only gets cruised on warm summer days but behaves ok.

26Troadster said:

you could get away with two 600 cfm list #1850's vac sec but as said two 390 vac sec will be better on the street try not to us 1 to 1 carbs. them truck heads will have to go too, most are 1.72 intake valve size. a single carb is best on the street and a 650 would be nice on a 350.

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If that. A 350 with a decent cam will run really well with a 570 Street avenger, as well.

The thing about a tunnel ram is they are designed for high RPM use, idling around town they are usually dogs. The long path from the carb to the valves makes for an off the line stumble when you mash on it. One way around that is to install the largest squirters and the large 50cc accel pump. I wouldn't use vacuum secondary carbs, the vacuum signal will be weak and the secondaries may never open. And if you do have vacuum secondaries, don't put a bolt or something in the linkage to make them mechanical. A true mechanical seconary carb will have a accel pump on both the primaries and the secondaries,a vacuum secondary carb doesn't. All you are doing is adding extra air when you convert the linkage like that, and the gas comes in after the airflow gets started, creating a instant lean condition. Mechanical secondaries put the gas in before the air flow starts, then it all mixes on the way down.

A friend had a wicked 383 stroker, he listened to the bench racers and pulled off the 750 Holley that ran great and replaced it with a tunnel ram and dual 650 vacuum secondary carbs. It actually slowed the car down, and made it a dog to drive. It either was starving or flooding, there was no happy medium. Went back to the single carb/ dual plane intake, car ran fine.

Thanks for all the info yall. I did get 2 new Holley 390's and for only about $600.00 bucks for the pair. I'll be askin about that much for the 2 650's I have just to cover that expense. I'll have em both on Ebay soon. I'll be listing them there for $350.00 each or 6 for the both of em. They're Holley/Carter never used completely rebuilt by the professionals at "Carburetors and More". Like new.
You all have been a ton of help and I really appreciate it. Thanks. I'll be lookin at cams next. Now with all that, will I have to use a new crank?
I'll post a pic of what I've done to the heads. I've been porting and polishing them thinkin that would make a difference. I may have over done it as the ports and combustion chambers shine like chrome.

Bamamav said:

A friend had a wicked 383 stroker, he listened to the bench racers and pulled off the 750 Holley that ran great and replaced it with a tunnel ram and dual 650 vacuum secondary carbs. It actually slowed the car down, and made it a dog to drive. It either was starving or flooding, there was no happy medium. Went back to the single carb/ dual plane intake, car ran fine.

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I also know somebody that did that recently. He's running a completely stock Pontiac 350 in a 67 Firebird, and wanted dual carbs. I told him not to do it, but he liked the look. So, after buying another 650 to put with the one he had, and a small-cap distributor, coil, and other stuff, it would barely run. He asked me to come over and tune it up. Well, I worked it as much as I could. He drove it around the block, then took it all off.

I told him, I have a 489 stroker big block that dynoed at 490 hp and 566 lb-ft of torque, and it runs a 770 cfm carb. (It's also a 2 bolt main block. ) It takes quite an engine to run over 1000 cfm.

05snopro440 said:

S-10 rear ends are actually quite resilient. I've got on behind my '455 Buick and my dad has one behind his 454, for a combined 40,000 KM's. If you want to run a locker or something it might hold up better, but I know lots of guys running them with nitrous or big power with no problems.

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I have to disagree. 7.5" ten bolts are very week and that's why they are used in s10 trucks. You hook much of any power to the ground with them and you will be snapping axles. I've saw stock 80s camaros snap them when they put a good tire on them at the strip.

Heads

Here are some pictures of the heads I've been working on. Like I said, I may have gone too far or even wasted (a lot) of time. Of course they're not professionally done, but I'm a rookie at this kinda stuff and got my info online (Utube) on how to. You guys let me know if I messed up and need to get another set of heads.

21willys said:

I have to disagree. 7.5" ten bolts are very week and that's why they are used in s10 trucks. You hook much of any power to the ground with them and you will be snapping axles. I've saw stock 80s camaros snap them when they put a good tire on them at the strip.

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There's a big difference between something holding together on the street and putting sticky tires and running it on the strip. If you're racing with slicks on a prepped track there's a lot that won't hold together. For a street vehicle with moderate power and torque (as this thread started), I have seen a lot of S-10 diffs stand up to a lot of abuse without any issues.

S-10 rear ends and frames get a bad rap from people who have never used the stuff and know nothing about them other than they're "light duty" (not saying that's you, but I've heard this time after time). If you abuse anything enough it will break. That doesn't mean they're not resilient and reliable in a lot of situations. There are thousands of rods using S-10 rear ends, reliably.

The 14,000 KM's on mine with a 455 Buick really show how weak it is.

carbs

If I rejet the 390's down, will they work sufficiently?? I realize this tunnel ram set up is mostly for looks and I really do like the way they look however, not bein a mechanic, I don't wanna compromise reliability and performance just cause they look cool.....but I really do like they way it looks......Oh...did I say that already??
I do have an Edelbrock Performer intake (Single carb) that I can use and will if it really will make that much more of a difference. If I do go back to a single carb, using a mild thmpr cam, what size would be good for performance and reliability?

mdlahotrod said:

Here are some pictures of the heads I've been working on. Like I said, I may have gone too far or even wasted (a lot) of time. Of course they're not professionally done, but I'm a rookie at this kinda stuff and got my info online (Utube) on how to. You guys let me know if I messed up and need to get another set of heads.

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What's your compression ratio with those heads and pistons?

Just a couple more of my opinions. From what I understand about porting, you don't want mirror smooth on the intake side, at least on the 2 stroke nikes we used to port.
And not to be a dick but it takes a pretty good mechanic just to tune one Holley for optimum performance, let alone 2. It's about a lot more than just jetting. There are power valves, secondary spring and cam, squirters, ect. and all need to be tuned as a package. I've been wrenching my whole life and I wouldn't know where to start.

I wouldn't worry with the jets until you get it running. I would try to get the 50cc accelerator pump put on though. It will help any off the line stumble it might have.