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Built 304 RPM air gap or Torker

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sc/1967 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sc/1967 Quote  Post ReplyReply Direct Link To This Post Topic: Built 304 RPM air gap or Torker
    Posted: Sep/05/2014 at 8:32pm
   Hi it's been awhile since I've posted on here. To catch everyone up I have a 1967 rogue with a 304 that I was in the process of building. I now have the engine back together, broke it in, and the car is running and driving again. The engine has been bored .030 over, has TRW forged flat top pistons, factory 304 heads with 2.025/1.680 valves, with some bowl work ( they were that way when I got the motor ), block was notched to accept the larger valves ( also done before I got it ), I had a fresh valve job done, converted the heads to screw in studs with guide plates, Scorpion full roller rockers, comp 280H cam kit ( .490 lift 280* duration ) with matching springs, lifters, double roller timing chain, etc. I think compression should be in the range of 9.75:1 to 10:1. I am currently running 2-1/4" factory free flows and and a Edlebrock R4B with a vacume secondary Holley 600, I am planning on getting a set of hooker super comps and either a RPM air gap or a Torker intake. The car has a 727 trans with a B&M stage II shift kit, and will soon have a 3000 stall converter. I also have a ford 9" rear end that I am going to set up with 3.73 gears and a posi. The car is going to be a street/strip car. Will see mostly street use, but I'm 23 and don't mind a little harshness on the street for an improved track time. Let me know where you think my combo could be improved and if you think my motor would like the Air Gap or Torker better? Also what size carb do you think 650 or 750? Thanks.
1967 Rogue 304ci,727
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Ken_Parkman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Sep/07/2014 at 9:40am
For the track the torker is better, even on a small engine, as in track use the rpm band is not where the air gap has an advantage. But with the mild converter and cam (for track use) there will be very little difference between the intakes. The air gap with it's small runners will definitely make a better torque curve for the street. Depends on what you are looking for. Also true there will probably be little difference with the R4B - it's a good intake; I would like to back to back it against the air gap. I actually think the r4b might make more power, but I expect the air gap again would be petter on the street. Regardless none of these will be a significant difference power wise.

But put a solid cam in there and an 8" converter biased more for track use go with the torker.

Hooker 7105 for the small body cars are the one that fits, and that is a very good header. It is 1 3/4", and even on a 304 it will make 10-15 more hp than a 1 5/8", and that is on a 6000 rpm engine.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wantajav Quote  Post ReplyReply Direct Link To This Post Posted: Sep/07/2014 at 7:31pm
Hello:

Ken: Why the solid cam recommendation versus a hotter hydraulic cam? (getting ready to buy a cam...)

Question 1: Any duration /lift preferences

Question 2 : are solids less resistant to "low zinc" tappet flat spotting

Final Question : any thoughts on stall speed and stall/torque ratio for his combo? I have one about the same weight

Thanks
Mike


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Sep/08/2014 at 9:52am
The problem with a hydraulic is the lifters start to give up at high rpm and my experience is once you get above 6000 rpm it's time to start thinking about a solid. Of course you can do it with a hydraulic, but you start needing to making sacrifices to make it work, and why bother? Run a solid designed for the purpose.
 
I do prefer a hydraulic on the street.
 
For duration it must match the intended use and the rest of the combination. When comparing solid and hydraulic add 8-10 degrees to the duration (intake at .050") due to the way the take up ramp works. It's not that simple, but that's a good ballpark to start. Also as a ballpark above 230 degrees start thinking about a solid, and above 235 it's a good idea and at that point jump to 245-250 degrees. Again it's not that simple, but a good start.
 
Besides at that point you already are into good springs and valvetrain stuff, so you already have the ability to set lash.
 
High rpm big hydraulics never make as much effective power as some catalogs would have you think - at that rpm a solid will make more power. The only reason to go above 235 degrees in a hydraulic is if the race rules specifically require it, and you start looking at fancy lifters to make it effective.
 
For lift - really not that important - more is better for a given duration, as long as the cam design is right. Lift is a very poor thing to compare on cams as it can be very misleading.
 
If you need the springs for high rpm you start needing to worry more about cams going flat. But at that point just buy a proper race oil (Joe Gibbs etc) formulated for a flat tappet. Don`t go overboard on springs - go with the cam manufacturer recomendations.
 
For converters that`s the most important part of the combination. Don`t be afraid of stall if it`s a quality piece. If it`s a race car throw out street mentality and get a race converter from a top notch supplier with a good reputation. For a race car you should be looking at an 8" with a stall of 5000 rpm or more. I've run an ATI 8" behind a basic mild 9 1/2 compression 401 with a 236 degree hydraulic cam that the lifters would give up at 6000 rpm and the power fell like a rock above that. So it had a 5400 rpm stall and a 6000 rpm shift and went 10.70's in a 2900 lb Hornet. The engine was built from left over junk parts, but with a good converter it worked well.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Traveller Quote  Post ReplyReply Direct Link To This Post Posted: Sep/08/2014 at 12:00pm
What Ken said.   The hydraulic setups are basically done much over 6000, so if you get a cam that needs to spin that kind of RPM you're giving up low end power for the big cam, with a valvetrain that won't let the motor use the larger cam up top.   It's a big loss in average power to sound cool.   

The cam you have should have about a 2800-3000 converter to go with it for street use.   With the 3.73 rear gear, you'll be turning 3K+ over 60MPH, so the converter won't be slipping driving down the road.   For a more track oriented car with that cam, probably 3500-4000 and figure you'll be giving up drivability for a decent gain on the track.   For all out track use, a modern converter that "stalls" lower on the street for drivability at low power input, then flashes all the way to the real stall RPM under high load is the way to go.   They cost more, but they work neat.

The solid cam setups can use EDM holes drilled in the lifter face the same way the hydraulics can, so you can help keep lifters from spalling.  For an increase in RPM, making valvetrain components lighter is key to keeping spring pressures down, but you will have to run more spring pressure as the RPM comes up.  Balancing act between longevity and performance.   It won't be a 100K mile motor, but that's not why you're building it right?

I prefer a hydraulic cam for the street also.   Get the heads set up properly to flow air, use a conservative cam that will give great throttle response and great average power in the useable RPM range, then let the head airflow carry the power in the upper RPM range.   By that I mean, if the heads move air, Cam "X" might have a 1500-5200 RPM range in the catalog (typical 350 inch engine).   If the heads work, add 500 RPM to that, which means that you can run a milder cam and make more power on the street.   The engine will pull a lot longer (which means more power due to the HP/TQ math equation).  The cam won't be as radical which means the power brakes work better and the car doesn't idle very rough (stealth) and it's drivable from low RPM all the way to the shift point.   Motors like that are fun to drive, because there aren't as many compromises.    

I'm kind of a fan of the stock appearing, factory tire cars for that reason.   Go 10's and 11's with a stock appearing, mostly stock sounding, stock width tire car.    Beware of older guys in grocery getter looking cars!  :)


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