Cam help for sb350

[baddawgcustoms]

After building the frame for my T modified I decided to tweak a few dimensions, so I'm giving RPM my dimensions and having him do a new frame for me. It will be a couple months finishing it up so I'm going to rebuild my engine and have it ready. Let me tell you what I have and get some help with what I need. The engine is a 89 model 4 bolt block with 193 casting heads. From what I've read these heads aren't much at high rpm but have good low end torque. (Not running high rpm anyway so no biggie). Best my research can tell the engine specs show factory 9.3-1 compression. Heads are supose to be 1.95 Intake 1.50 exhaust. I have a s10 rear 3.73 gears and using 29.6 tall rubber on the back, th350 transmission. I have a 80457-7 Holley which is Basicly a 4160 with non adjusting float bowls, 600 cfm vac sec. I'm using an old points distributor that has a HEI upgrade. (Trying to give all info I can). The intake I'm using is a weiand 3984 single top tunnel ram. I'm using the single top because I love the look, NOT because I'm running quarter miles! This engine will probably never see north of 5000, or 80+mph.

(Mike I read your comment about the guys that ask for the biggest cam for stock heads so I'm trying NOT to be that guy).

What I'm looking for is recommendations on cam specs for what I'm running. I Basicly want the mildest cam that will work. (Yes I will talk to the cam reps but i know some guys here may know better than them, but I will get both). I don't care if it has the big cam sound, I just want to optimize the setup for around town cruising and highway speeds the best I can with an intake I know wasn't designed for everyday street use. (But they look good).

Also with this setup what's the general concencous about stall rpm for the converter.

Open to all input. Thanks.

 

[baddawgcustoms]

Let me change one part of my post. The weiand intake is what I plan to use. If a different single top is a better choice for what I'm looking for please advise on that as well. I will wait till the weekend before I order the parts.

 

[choppedtop]

For fairly good economy and good low and mid torque, I have always been happy with a RV type cam.
Lee

 

[Hotrod46]

If that 89 block is set up for a factory style roller cam, I would take advantage of it. No oil or break in issues.

 

[baddawgcustoms]

If that 89 block is set up for a factory style roller cam, I would take advantage of it. No oil or break in issues.

Would have loved that but no such luck. Got lucky with the 4 bolt tho! And it's a 84,000 mile engine fleet maintained. Still looks new inside. It doesn't even need a bore job.

 

[Screaming Metal]

Yes, go with a good RV cam. Another alternative is the factory Hi-Perf. cams. Theres alot of folks that run way more cam than what they need. They think if it doesn't idle like at top fueler it isn't making power.
On any given day a half assed all out race motor will be beat by a good prepped mildly build motor that has all of its components selected to work with one another....
A good RV cam is plenty good, will work with your stock springs and heads, etc. Some of the Factory stuff can be pretty hot, so if you go that route, just get something that'll idle that way you want it to.
Some of the RV's have a nice lumpty idle to them. Another thing....you can get a Thumpr Cam. You can get those just a little warmed up, and they'll grind it to give you that nice wicked idle, while using a low lift and a mild duration, the same as a RV cam.
To answer your question, a RV cam will be plenty, YOU have to be happy.

 

[Screaming Metal]

Yes, go with a good RV cam. Another alternative is the factory Hi-Perf. cams. Theres alot of folks that run way more cam than what they need. They think if it doesn't idle like at top fueler it isn't making power.
On any given day a half assed all out race motor will be beat by a good prepped mildly build motor that has all of its components selected to work with one another....
A good RV cam is plenty good, will work with your stock springs and heads, etc. Some of the Factory stuff can be pretty hot, so if you go that route, just get something that'll idle that way you want it to.
Some of the RV's have a nice lumpty idle to them. Another thing....you can get a Thumpr Cam. You can get those just a little warmed up, and they'll grind it to give you that nice wicked idle, while using a low lift and a mild duration, the same as a RV cam.
To answer your question, a RV cam will be plenty, YOU have to be happy.

That mild cam will work great the single top TR. I've always had to fight the vaccum secondaries on a single carb tunnel, you usually have a bog when accelerating. A doublepumper works better for that, since you won't be hanging your foot off in it, it'll get decent fuel mileage. Doublepumpers never get great mileage, except for blown apps.

 

[RPM]

I used to like to use the 327-350hp cams and the 350-350hp cams. They work well with a stock valve train, saving $$$$ on special springs, retainers, locks, rockers and all the other stuff that an aftermarket cam might need. Then there are the factory solid lift cams also if like adjusting the valves.

 

[Mike]

Call your local speed shop and tell them you are wanting to buy a Comp Cams 12-211-2.

Duration @ .050" - 224° I / 224° E
Advertised Duration - 270° I / 270° E
Lobe Lift - .313" I / .313" E
Valve Lift (w/ 1.5 rockers) - .470" I / .470" E
Lobe Separation Angle - 110°
Power Band - 1800 - 5800 RPM

Let's face it, you want this thing to make a pile of torque, but you are also wanting that lumpy idle, so just order this one and be finished with it. Buy a decent set of rocker arms, like 1212-1 Comp Cams, which will get you verified ratios, long slots and grooved pivot balls. Pull the springs off your heads and measure installed heights and coil bind heights. Verify the springs will have adequate coil bind clearance (Installed height - valve lift - coil bind height = clearance). See this page if you cannot wrap your head around the math. Verify the springs will have adequate loads. Use a quality timing set and don't fret about chasing the trick of the week, just put the cam in, straight-up.

Personally, I wouldn't use that intake, but if that is the look you are after, then bolt it on and go for it.

I see RPM just posted about the Chevy performance cams, which are also good choices.

 

[TriodeLuvr]

Tough decision considering the tunnel ram. I suspect much of the usual gain in low end torque and fuel efficiency from an RV cam will be lost due to fuel fallout. I'd go with something a little hotter, maybe a grind like the old 327-350HP cam. Also, cams with a lift below .450 will be kinder to your stock valve train. Ask the folks at Crower Cam what you can get away with using a stock converter.

Jack

 

[Screaming Metal]

I love the cam Ron Suggested, the 350 Horse 327 cam. It works great with your stock springs and retainers, doesn't beat your valvetrain to death, and doesn't cause alot of pushrod flex or stud wobble from violent, wild ramp acceleration.
Comp Cams, Lunati, all have budget roller rockers, and that eases the load on your valves as the tip rolls and doesn't scuff across the valve tip. That can cause wear on your guides and seals.
And as Mike said, set all your springs up the same and at the correct height....
Proform and Scorpion have good rockers that don't break the bank. Whatever you do, get the roller tips that actually have a bearing in them instead of a bushing. A lot less resistance...less heat buildup going to the rocker.
If you go with the slotted rockers, check to make sure you won't bind in the slots, and run grooved balls, as per Mike...

 

[RPM]

Tough decision considering the tunnel ram. I suspect much of the usual gain in low end torque and fuel efficiency from an RV cam will be lost due to fuel fallout. I'd go with something a little hotter, maybe a grind like the old 327-350HP cam. Also, cams with a lift below .450 will be kinder to your stock valve train. Ask the folks at Crower Cam what you can get away with using a stock converter.

Jack

I don't think anyone will be happy with a stock converter in a lite weight T Bucket.

 

[baddawgcustoms]

I don't think anyone will be happy with a stock converter in a lite weight T Bucket.

Definitely doing a stall. Was looking at about a 2400. That sound about right for this setup? The cam I'm leaning toward says minimum 2000 recommended. Even tho I'm not going to use a real tall cam I am going to do the heads right with all new stuff. (Now where the heck is my slide hammer? I got some studs to yank out....)

 

[TriodeLuvr]

I don't think anyone will be happy with a stock converter in a lite weight T Bucket.

This is probably one of those things that depends a lot on how the car is built and how the owner uses it. I have a stock converter, and if anything, I'd like to have a lower stall. In fact, when I had the transmission replaced (TH350 to TH400), I asked for a truck converter for that reason. I drive my car almost every day, and for me, it's all about low end torque and fuel efficiency. Even with the stock stall and 2.79 rear, the driven tire goes up in smoke whenever I want. The only thing I would accomplish with a higher stall would be more smoke and poorer gas mileage.

Jack

 

[Screaming Metal]

I suspect much of the usual gain in low end torque and fuel efficiency from an RV cam will be lost due to fuel fallout.
--------------------------------------------------------------------------------------------------------------------------------------------------------------
Not really, the single tunnelram tops were designed for midrange HP and torque, mostly for boats and certain classes at the drags, as well as for street apps back in the day.

The mixture only has to spread out once in the plenum, then at even low rpms in dumped straight down on top of the intake valve in each individual runner. As rpm picks up, further atomization occurs as mixture velocity picks up.
What kills the low rpm in the tunnels with dual quads is the cross pulses coming across that open plenum just below the carbs before the mixture enters the runners. That 'reversion' at lower rpms screws up the stable mixture falling straight down into the runners, as rpms increase, addition velocity is increased as the volume in the plenum is squeezed down and ramed into the runners.
If you get a liquid ( this is very over simplified), drop it from high above, after a short distance, that liquid enters a funnel than necks it down some more, increasing speed and density, falling more increasing speed and density. Thats the reason why a tunnelrams runners will ice up....that and heatsoak from those heated heads is slowed.
In laymans language, this is whats happening inside the tunnelram with the atomized mixture that is falling, but is also being pulled in by a vaccum, via, the intake stroke. At low rpms, that mixture is being disrupted by the intake suction of each cylinder, 1-8-4-3-6-5-7-2, across that plenum.

But a single 4 tunnel negates that, to a extent....offering more midrange torque....

 

[Swampdog]

I suspect much of the usual gain in low end torque and fuel efficiency from an RV cam will be lost due to fuel fallout.
--------------------------------------------------------------------------------------------------------------------------------------------------------------
Not really, the single tunnelram tops were designed for midrange HP and torque, mostly for boats and certain classes at the drags, as well as for street apps back in the day.

The mixture only has to spread out once in the plenum, then at even low rpms in dumped straight down on top of the intake valve in each individual runner. As rpm picks up, further atomization occurs as mixture velocity picks up.
What kills the low rpm in the tunnels with dual quads is the cross pulses coming across that open plenum just below the carbs before the mixture enters the runners. That 'reversion' at lower rpms screws up the stable mixture falling straight down into the runners, as rpms increase, addition velocity is increased as the volume in the plenum is squeezed down and ramed into the runners.
If you get a liquid ( this is very over simplified), drop it from high above, after a short distance, that liquid enters a funnel than necks it down some more, increasing speed and density, falling more increasing speed and density. Thats the reason why a tunnelrams runners will ice up....that and heatsoak from those heated heads is slowed.
In laymans language, this is whats happening inside the tunnelram with the atomized mixture that is falling, but is also being pulled in by a vaccum, via, the intake stroke. At low rpms, that mixture is being disrupted by the intake suction of each cylinder, 1-8-4-3-6-5-7-2, across that plenum.

But a single 4 tunnel negates that, to a extent....offering more midrange torque....

Yea, What he said

Swampdog

 

[TriodeLuvr]

I suspect much of the usual gain in low end torque and fuel efficiency from an RV cam will be lost due to fuel fallout.
--------------------------------------------------------------------------------------------------------------------------------------------------------------
Not really, the single tunnelram tops were designed for midrange HP and torque

That was my point; it's designed for midrange. Why not get a cam that complements that performance, rather than a low-RPM grind that operates best in a different window?

The mixture only has to spread out once in the plenum,

At low RPM, that's all it takes to lose enough velocity to encourage fallout and degrade combustion. I understand your point about dilution, but I don't agree that the tunnel itself will otherwise maintain the conditions necessary for good low end torque. I still say the correct cam for best performance under these conditions will be a street performance cam like those mentioned earlier in this thread, not a low-RPM RV cam. That's especially true if he will be using a higher stall converter.

Jack

 

[smokeyco75]

Remember the old Crane Fireball 2 cams? I had a Camaro once that had one in it and it was a decent cam with headers and such.

 

[Golly]

It seems if you ask 3 different engine builders , what cam to buy, you'll get 3 different answers!. It's my understanding that the old 350HP cams have a little more lift and a lot of duration, because in the 60's, the factory had to deal with stock OEM style springs. Those profiles are what the economy SSI series from P.A.W. and the cheaper Jegs camshafts use today. Manufacturers today like Comp , and Crane use more lift and push the valves open quicker, and close it quicker, with alittle more lift, which makes more power , but doesn't give the rough idling lope that we all like. That also helps keeps vacuum levels where power brakes etc aren't adversly affected too much. Personally I would use a mild late model style grind from a reputable manufacturer, and add a decent set of medium performance springs, retainers and locks, from Jegs. for an extra $150.

 

[baddawgcustoms]

Thanks everyone for the advice. I've spent hours reading about cams and carbs this week. (You can do about anything if you read the right books). I ran the 350hp 350/327 cams a lot back in the days of pissing away tons of money on dirt track cars where "stock" cams had to be used, and they worked great. I keep getting conflicting opinions on the heads I have. Some say they are junk, some say they are great. I talked to a couple cam reps yesterday and they recommended about the same exact cam that Mike recommended with the same upgrades. The comp rep suggested the thumpr cam,but I've read lots of conflicting pissing matches on line about it as well. The weiand rep recommended at LEAST a grind as big as the thumpr. (Nice folks at weiand). He said anything smaller would actually hurt fuel efficiency and would not perform nearly as well. Bottom line I'm having the heads worked with studs and guide plates, and changing out the springs retainers, pushrods, and rockers. A little more than what I wanted to spend, but in pondering the matter I'm not going to spend 2 or 3 years building a car with thousands of dollars spent and scrimp on a few hundred bucks, even if it takes a little longer to get on the road. Thanks for all the input. Your advice, and this website is always appreciated.
RPM is setting up my frame with the engine and trans just above the bottom of the frame rails so the engine will sit pretty high, and that intake ought to look great sticking up in the way so I can't see around it!