Robbie2734
Lambcharger
Did the builder degree the cam when he installed it?? That's really low vacuum for a static of 10.5
340 dog out of the hole/no low end torque??
- Thread starter 340Duster247
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340Duster247
Well-Known Member
I get asked this all the time and to be honest. I have no idea. He is so good at what he does that I can't see him not. But people do screw up. I don't know a lot about the cam degreeing stuff. And have no idea how to find out.
340Duster247
Well-Known Member
Thanks for the reply and I agree with you. My last cam was a shitty comp POS cam. When I got made fun on here for choosing that cam, I opened my ears or my eyes for suggestions from guys on here and mostly everyone said the lunati I chose would be perfect. I then asked lunati what cam out of there line up would match best with my combo. They also choose the one I had been looking at. Lastly I asked my engine builder and he said also the 60405 would be great.
Dave1967
Cuda crazy
I agree with Robbie. My first thought was cam timing. Sounds to be way retarded. If the timing set had several key always to choose from and the cam wasn't degreed to verify. This would also cause Vaccum loss. I'm running very similar cam ans I am pulling 15 pounds of vac. Degree the cam again to verify.
340Duster247
Well-Known Member
[ame]http://youtu.be/4wnGg8x8qL8[/ame]
Another bad launch. Need to lower launch rpm. I just set the 2step and went with it to see what it would do.
Another bad launch. Need to lower launch rpm. I just set the 2step and went with it to see what it would do.
340Duster247
Well-Known Member
Thanks. This comment keeps comming up and I will have to check this.
Did you get a build sheet for the engine. The ICL should be somewhere on the sheet.
Tbone416
Well-Known Member
I was hard to tell
ops:
340Duster247
Well-Known Member
Is there a way to check if it was degreed correctly
340Duster247
Well-Known Member
When you see my build sheet you would laugh. Hand written in the hardest to read chicken scratch. Says nothing about te degreeing. The lunati cam was put In After when I had to bring the engine back to him for some other details. (Long story). When I asked about the cam degreeing to him last summer he said they do it to the cam manafactur specs.
340Duster247
Well-Known Member
Once again thanks for the help guys.
Dave1967
Cuda crazy
You will have to put a degree wheel on the crankshaft. You will measure valve lift before and after tdc. The directions are in mopar book and on the degree wheel.Your cam specs say 106 centerline. Let's say your timiing gear had key marks in two degree increments. This is your you adjust cam centerline by moving the timing gear. So if you moved the timing gear the wrong way retard or advance and forgot to verify the cam again. You could be way off. This may or may not be the problem. But having the cam retarded in the motor would give you both symptoms you are describing.
bbrroowwnn
never re member
Based on that cam chart it says "the above centerline ( 106 degrees )will make this cam 4 degrees advanced"....So you want to check the cam and make sure it is degreed to 106 degrees.....Advancing the cam 4 degrees give you more low end torque which is what you are looking for.....I have an Erson Cam and mine is advanced 4-1/2 degrees to 105-1/2.....
gold66cuda
Well-Known Member
I would have to say as mentioned above I agree that the cam timing and ignition timing sound out and the obvious lack of gearing with that tire choice. One other thing you might want to look at that as dumb as it sounds, is it really getting wide open throttle. I think we have all seen this before and the reason I say that is once you do get the car rolling it just doesn't sound to me that it is ever really gaining any rpm, however you may not be covering enough ground in the video for the to tall of gear to catch up. By the way nice looking ride!
MopaR&D
Nerd Member
Troll alert: The Voodoo cam one step down would have run better lol...
crackedback makes a great point about the tire size 30" is huge and really affects the gearing. Like putting 33's on a stock Jeep... turns it into a total pig until you put in some 4.10s.
Taken from the Lunati website for your cam:
Hydraulic Flat Tappet. Designed for hot street/bracket race ap- plications, requires minimum 10.5:1 compression, 4.11 gearing and 3500 RPM stall converter. Works with up to 250 HP nitrous, pulls hard past 6500 RPM when coupled with the correct parts.
crackedback makes a great point about the tire size 30" is huge and really affects the gearing. Like putting 33's on a stock Jeep... turns it into a total pig until you put in some 4.10s.
Taken from the Lunati website for your cam:
Hydraulic Flat Tappet. Designed for hot street/bracket race ap- plications, requires minimum 10.5:1 compression, 4.11 gearing and 3500 RPM stall converter. Works with up to 250 HP nitrous, pulls hard past 6500 RPM when coupled with the correct parts.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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My 360 smokes the 295s at just off idle with 3.55s and a 3.09. Thats a 9.9 starter gear with a 26.6 inch tire. And a 230* cam.And 10.7 true cr. The Dcr is near 9/1
Doing the math my combo is 12/(26.6/2) X 3.55 X 3.09 =9.9; 9.9 X 400ftlbs crank =3959# max theoretical out the axles at 1 ft radius,to the road.
Your combo is 12/(30/2) X 4.3 X 2.45 X 1TC on brake = 8.42; 8.42 x 350ftlbs= 2947# max theoretical out the axles,to the road.Thats a difference of over 1000# theoretical. (guessing at the ftlbs;but the numbers are relative)
But, here it comes; The 360 at 9/1 Dcr and a small 230# cam makes a shxxload of torque right off idle. Your 340 With the extra 12* intake duration, and the less than optimum Dcr, and handicapped by the starter gear and a TC that wont play, is just plain struggling.
But wait Mine breaks traction at less than 2000rpm(pavement).Which is no where near max torque.And your Tc is letting the engine get closer to its torque band.So, your combo has more issues, than just gearing. And more issues than cam timing. And more issues than TC stall. Or timing or valve lash/lifter preload.
Your problem lies at the heart of the build.A mismatch of parts leading to a low Dcr. I am gonna preach this until I die or it becomes accepted.
The short stroke motors lose Dynamic pretty fast with cam selection.The only way to get it back is to bump up the Static cr. Low Dcrs make off-the-line slow engines. Now on the track,a low Dcr can be compensated for easily enough that its mostly a none issue. Up the gears, and up the stall, and you get through it in a heartbeat. But on the street it becomes paramount to have a decent Dcr.
If you want to keep that engine as built, and those 30 inchers,you will need some serious gears, and another one in the trans for cruising,and probably a new TC. That means 4.88s and an A-500.
The only other option is to Re-engineer your Dcr. That usually means giving up the 242* cam and building the static up. Well there is/are other avenues.One, hardly streetable is stall. Plenty of it. The engine needs to flash to where the torque is.The other is tires; little skinny 245/[email protected] tall. Should be able to light those up. Or maybe 275/50s@ 25.8
I really think you need to reexamine your Dcr.You may find a smaller cam, maybe around 220* will get you an acceptable Dcr. I had a 223*fast-rate a few years ago, in my 360.Dynomite street cam.
Sorry. I thing you mighta got greedy with the cam.
Now, getting back to your low idle vacuum.That cam should idle around 10 to 12 inches, at maybe 800rpm to 900max.I would get a second gauge. If it really is that low, it should be a bear to start.
And if it really is that low, you will have to find and fix the problem. I would be tempted to check the timing with a second light to prove the timing is correct and that all the systems are working. Then I would do a careful search for vacuum leaks. Followed by a compression test, a leakdown test,and determine the degree at which split overlap occurs. Next would be lifter preload. And dead last cam timing.I do the tests in order of ease, time and probability of results.(Split overlap usually occurs within 5 degrees of tdc on exhaust stroke and is a quick and easy cam timing check and doesnt care about lifter preload, so long as the lifter doesnt leak during the test. Test takes a couple of seconds, once access is gained and set-up is complete.)
The very last thing I would do is determine the exact point of intake closing. This number has to be known along with exact TOTAL chamber volume, to determine Dcr.
All the best to you in your search. No malice intended.
Doing the math my combo is 12/(26.6/2) X 3.55 X 3.09 =9.9; 9.9 X 400ftlbs crank =3959# max theoretical out the axles at 1 ft radius,to the road.
Your combo is 12/(30/2) X 4.3 X 2.45 X 1TC on brake = 8.42; 8.42 x 350ftlbs= 2947# max theoretical out the axles,to the road.Thats a difference of over 1000# theoretical. (guessing at the ftlbs;but the numbers are relative)
But, here it comes; The 360 at 9/1 Dcr and a small 230# cam makes a shxxload of torque right off idle. Your 340 With the extra 12* intake duration, and the less than optimum Dcr, and handicapped by the starter gear and a TC that wont play, is just plain struggling.
But wait Mine breaks traction at less than 2000rpm(pavement).Which is no where near max torque.And your Tc is letting the engine get closer to its torque band.So, your combo has more issues, than just gearing. And more issues than cam timing. And more issues than TC stall. Or timing or valve lash/lifter preload.
Your problem lies at the heart of the build.A mismatch of parts leading to a low Dcr. I am gonna preach this until I die or it becomes accepted.
The short stroke motors lose Dynamic pretty fast with cam selection.The only way to get it back is to bump up the Static cr. Low Dcrs make off-the-line slow engines. Now on the track,a low Dcr can be compensated for easily enough that its mostly a none issue. Up the gears, and up the stall, and you get through it in a heartbeat. But on the street it becomes paramount to have a decent Dcr.
If you want to keep that engine as built, and those 30 inchers,you will need some serious gears, and another one in the trans for cruising,and probably a new TC. That means 4.88s and an A-500.
The only other option is to Re-engineer your Dcr. That usually means giving up the 242* cam and building the static up. Well there is/are other avenues.One, hardly streetable is stall. Plenty of it. The engine needs to flash to where the torque is.The other is tires; little skinny 245/[email protected] tall. Should be able to light those up. Or maybe 275/50s@ 25.8
I really think you need to reexamine your Dcr.You may find a smaller cam, maybe around 220* will get you an acceptable Dcr. I had a 223*fast-rate a few years ago, in my 360.Dynomite street cam.
Sorry. I thing you mighta got greedy with the cam.
Now, getting back to your low idle vacuum.That cam should idle around 10 to 12 inches, at maybe 800rpm to 900max.I would get a second gauge. If it really is that low, it should be a bear to start.
And if it really is that low, you will have to find and fix the problem. I would be tempted to check the timing with a second light to prove the timing is correct and that all the systems are working. Then I would do a careful search for vacuum leaks. Followed by a compression test, a leakdown test,and determine the degree at which split overlap occurs. Next would be lifter preload. And dead last cam timing.I do the tests in order of ease, time and probability of results.(Split overlap usually occurs within 5 degrees of tdc on exhaust stroke and is a quick and easy cam timing check and doesnt care about lifter preload, so long as the lifter doesnt leak during the test. Test takes a couple of seconds, once access is gained and set-up is complete.)
The very last thing I would do is determine the exact point of intake closing. This number has to be known along with exact TOTAL chamber volume, to determine Dcr.
All the best to you in your search. No malice intended.
those cams correctly matched work great, and for the nos question I can tell you from experience if the heads have been worked good giving that lower compression 340 a lot of air flow it wll love nos mine picked up almost a second in the 1/4 on 150 if the heads are out of the box, that is a little of the prob, don't shoot me guys I have a set, my mildly worked j's were a lot faster, but after getting them worked they worked good, also the you loose a point of compression with aluminum heads through the heat dissipation process that why you can run higher compression with them, any way got mine to run 10.60,s spinning at 126 with 150 that nos takes care of the torque prob lol, good luck
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I agree with AJ/FormS,
The fact that your getting 4.5 inches a idle with that cam says more than anything else.
I would first start with the carb and idle settings to get your vacuum higher before doing anything else. It will cost you nothing if its a carb and timing issue.
Hysteric
The fact that your getting 4.5 inches a idle with that cam says more than anything else.
I would first start with the carb and idle settings to get your vacuum higher before doing anything else. It will cost you nothing if its a carb and timing issue.
Hysteric
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