Camshaft help

What looks awesome ( tunnel ram, 2 4s and velocity stacks through the hood ), and what sounds good ( exhaust note while standing beside the car ) is rarely so great inside the car. One of your posts mentioned a 2 hour drive. Add a tall gear and she may come to hate this car.
The round town hotrod and the highway cruiser have always been 2 separate vehicles. Only recently have mfgrs added mode buttons to make the one vehicle seem like both.

Lugnutz said:

I also found a little information that broke down the duration by groups for anybody searching in the future.

• Class I (200° - 215°)
Good idle quality. Low rpm torque and mid range performance.Will work with
stock or slightly modified engine. Manual or auto transmission. Good vacuum.

• Class II (215° - 230°)
Fair idle quality. Good low to mid range torque and horsepower. Will work with
stock or modified engine. For use with manual or automatic transmission with mild stall converter. Lower vacuum than stock.

• Class III (230° - 245°)
Rough idle quality. Good mid to high rpm torque and horsepower. For use with manual transmission or high stall automatic. Requires improved induction, exhaust system, and ignition system. Good street/strip cam, but has low vacuum.

• Class IV (245° - UP)
Rough idle quality. Good high rpm torque and horsepower. For serious racing.
Need proper selection of rear axle ratio and improvements in carburetion and exhaust systems. For use with manual transmission or automatic with very high
stall converter. Will not have enough vacuum for power accessories.

Click to expand...

I'm not sure where you found this, or what engine size it's referring to but it's so vague, subjective and outdated it's pretty much BS.

LSA has a huge impact on idle quality. HUGE... This makes no mention of it, only duration, which is only half the story. It also doesn't mention compression, heads, carburation, timing, etc.

"high stall convertor"? What's high? To me its 4500 and up. The last 2 convertors I've run have been a 3500 and a 4000. You'd never know they were anything other than a stock convertor under normal driving conditions.

Axle ratio, if you want the best of both world's here get her a GVOD unit. You won't regret it. I run the interstate with 4:56 gears without issue.

RedFish said:

What looks awesome ( tunnel ram, 2 4s and velocity stacks through the hood ), and what sounds good ( exhaust note while standing beside the car ) is rarely so great inside the car. One of your posts mentioned a 2 hour drive. Add a tall gear and she may come to hate this car.
The round town hotrod and the highway cruiser have always been 2 separate vehicles. Only recently have mfgrs added mode buttons to make the one vehicle seem like both.

Click to expand...

Hey guys, I never said anything about a tunnel ram or anything poking through the hood. As most know, the D series or STR-12 Edelbrock's are a low rise manifold and fit under the hood. I am just trying to build a fun little cruiser for the girlfriend with a hint of cam at idle. I'm not looking for a loud exhaust, and all out max horsepower was never the main goal.

As I mentioned in the beginning, drivability and fun factor are more important than max cubic inches or max horsepower. Twin carbs on an under 6000k rpm engine street car is very doable, and if I give up 75 horse power in favor of vacuum for power brakes for the girlfriend, I’m okay with that. If I was building a street car for myself it would be entirely different.

FWIW, the vacuum information I found was the results from using google and most of it was from Chevrolet forums and people complaining about no vacuum with lumpy cams. :cheers:

Twin carbs is 1000+ CFM. We aren't talking about power. No one here has been talking about power. We're talking about Streetability and user friendliness.

I suppose the second carb could have a block-off plate under it, and a disabled throttle link.Nawwww, that won't work
Or you could disable all the secondaries.I would be up for trying the disabled secondaries and a staged, progressive linkage, but I imagine it would have distribution issues.
Or best of all a couple of really tiny 4bbls, like 390s.Yeah, you get the cool look, and driveability .
One of the problems I see with too much primary throttle area opening at once is that the car is very hard to drive smoothly at slow speeds. It gets real sensitive to gas pedal inputs.This is especially noticeable on a small-cammed, torquey V8. Maybe a 318 with a little lazy compression might be ok. I think it's certainly worth a try, especially since you already have the set-up,and since it's important to you. Still with a manual trans, it may be tricky.

I think with low engine speeds (low velocity) you are going to have tuning issues with that intake. It wasn't made for cruising.

AJ/FormS said:

Or best of all a couple of really tiny 4bbls, like 390s.Yeah, you get the cool look, and driveability .
.

Click to expand...

780cfm. That might work. I'd have a 600 eddy or holley hp style on it. but the 2 390's might work.

The intake sure looks great only car I've seen it on was a race car that spent most of the time 5500 rpm up , but I suppose with the right carbs and tune it could run well with a 4 speed . Will sure look great at the drive in or shows , don't see them often .

Basically a stock 318 with a little bump in the exhaust, this may work for you.

http://www.lunatipower.com/Product.aspx?id=2341&gid=287

justinp61 said:

I think with low engine speeds (low velocity) you are going to have tuning issues with that intake. It wasn't made for cruising.

Click to expand...

That's fair enough. But with a small cam, the vacuum will be way up, and with some small primaries, I imagine it will work. Might take some pumpshot to get her moving tho.If I already had that manifold, I would certainly give it a go.The cool-factor alone would be worth a few hours of tuning time.
What's the worst that could happen? a do-over; no biggie.
Hey, I wonder what the smallest spreadbore ever made flows? IIRC, the Q-jets had triple boosters.I wonder... Hmmm, if a guy staged those just right,on the secondary side....Can you hear it roar?

Don't know why so many guys are hammering you on your dual quad idea. Here's a guy on the forum using your setup: http://www.forabodiesonly.com/mopar/showthread.php?t=105196 Check out comment #7. Using 500 cfm carbs with straight linkage would give you two 200cfm carbs when you were cruising on primaries and an extra 600cfm when wide open. The rear counterweights wouldn't even open all the way giving you exactly what the engine needed. Hardly problematic.

Chrysler used factory inline dual quads on 383's, 361's and the one year 350. Also, there were three years of poly 318's with dual quads. None of those engines used cams with more than .430 lift and virtually no duration. Of course, they didn't have lope which is why they worked so reasonable with automatic transmissions in the family turnpike cruiser. Your choice of 500's is excellent. The only thing better would be the ultra rare Carter 400's or a matched pair of 273 carbs since they are said to be in the 435-485cfm range. Since you say you aren't building a powerhouse engine, you'll gain midrange over top end, which sounds like what you are looking for.

Your only real challenge is getting lope and vacuum. They are directly contradictory. If you can live with a mild lope, you could achieve your goals. Duration up to 230 degrees would work if you kept the lsa on the wider side. The issue is overlap. You really need at least 14-16inches of idle vacuum to be comfortable for your girlfriend to be safe in stop and go traffic. Your best bet is to get off the forum and get on the phone. A few calls or emails with your intentions to five different camgrinders would give you more insight than a thousand comments from people like me. They grind cams for a living and know the why's of what they recommend. If you must have significant lope, consider a hydraboost braking system. Here are a couple of links: http://www.hydratechbraking.com/ and http://www.thehollisterroadcompany.com/hydroboost.html You can use factory equipment if you would consider some GM pickandpull stuff.

For sound, consider a dual mode muffler which gives you muffled exhaust when driving four hours to mamma's house and open exhaust when cruising the circuit. You might even get the rumble you are looking for. Another idea is a cutout with one side muffled and the other side open with resonator for sound. I'd keep the exhaust on the muffled side smaller to keep the torque at the bottom and bigger on the cutout side for top end power. Then use matching tips out the back. Be a little unconventional, it's your rig. From your description it sounds like your girlfriend wouldn't turn over 5500rpm anyway. I don't get the impression she's a racer with this build. Good luck, but call the experts.