So for Dcr should I be looking for something around like 8.2 and dynamic cranking pressure of 165ish for premium pump gas 92 octane? That would be at and intake closing of 57*Abdc according to Wallace racing's calc @ 500 feet altitude. I suppose a tight quench should hedge against detonation too if I get too close to the line. I just dont want to build a borderline detonator.
Cam for torque question
- Thread starter lomchivok
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yellow rose
Overnight Sensation
If you order a custom cam, you don't have to dick with all the math.
I never worry about DCR and all that bullshit. Buy the right cam and be done.
I never worry about DCR and all that bullshit. Buy the right cam and be done.
Hehehe I was thinking the same thing...and I will.
If nothing else I may just learn something. the calculators and cam quest stuff are certainly marginal at best.
Got a response from Bullet cams...here is their recommendation...
CRA 288/296 H110+4 Grind number
Has 231/239 at .050 duration
.485/.507 Valve lift with 1.5 rockers
110 lobe separation with 106 intake centerline
Should be big enough to blow down some pressure and work with combo very
Well!
Thanks Tim Goolsby
Here are the engine specs
Cam Type Interest: Hydraulic
Cam Used For: Street/Strip
Track Length: 1/4 mile
Class: under 14.00 second grudge
Engine Make: chrysler
Year: 3/8/1979
Cubic Inch: 408
Bore: 4.030
Stroke: 4.000 Scat forged
Block: 1979 LA360 decked @ 9.595
Cam Bearing Diameter: Std
Connecting Rod Length: 6.123
Connecting Rod Material: Scat I beam forged Steel
Cylinder Head Make: IMM/Indy LA X
Cylinder Head Material: Steel
Intake Valve Size: 2.02
Exhaust Valve Size: 1.60
Rocker Ratio Intake: 1.5
Rocker Ratio Exhaust: 1.5
Intake Runner Volume CC: 179/CC
Porting: Mild
Compression Ratio:9.8
Carbureted Or Injected: Carbureted for now
Carbureted CFM: 650
Number Of Carburetors: 1
Fuel: Gasoline
Injected CFM:900
Headers: Yes
Headers Tube Size: 1 5/8
Headers Collector Size: 3"
Vehicle Weight: 3500
Vehicle Make & Model: 1968 Plymouth Barracuda
Transmission Type: Automatic
Transmission Number Of Gears: 3
If Automatic: FootBrake
Stall Speed: 2300
Rear Axle Ratio: 3.23:1
Tire Height: 27.05
Tire Width: 10.04
Is This A New Combination: Yes
Idle Quality Desired: Lope to slight chop
DesiredChange:
The 1979 360 will be stroked to 408 it will be a nice day driver with more than occasional grudge matches at the track.
The heads are IMM indy LA X from Brian at IMM here
IMMENGINES.COM
My built 318 in this car runs 12.93's at 104 mph. The 408 needs to do much better than that... I will not putting a roll bar in it. I'm not opposed to a choppy idle and I will be running 92 octane at the pump and 98 at the track.
I will be installing a FiTech Go EFI 600hp power adder throttle body injection shortly after break in. The power adder part of the EFI is not for forced induction. I got that model for timing control and Idle step up at A/C compressor engage.
Edelbrock torker 2 single plane 4bbl intake.
Rotating assembly is forged Scat crank and I beams.
Pistons are forged 2618 Mahle.
Compression ratio will be 9.8:1 with a .041 quench. Piston sits .012 in the hole with 28cc valve reliefs.
CRA 288/296 H110+4 Grind number
Has 231/239 at .050 duration
.485/.507 Valve lift with 1.5 rockers
110 lobe separation with 106 intake centerline
Should be big enough to blow down some pressure and work with combo very
Well!
Thanks Tim Goolsby
Here are the engine specs
Cam Type Interest: Hydraulic
Cam Used For: Street/Strip
Track Length: 1/4 mile
Class: under 14.00 second grudge
Engine Make: chrysler
Year: 3/8/1979
Cubic Inch: 408
Bore: 4.030
Stroke: 4.000 Scat forged
Block: 1979 LA360 decked @ 9.595
Cam Bearing Diameter: Std
Connecting Rod Length: 6.123
Connecting Rod Material: Scat I beam forged Steel
Cylinder Head Make: IMM/Indy LA X
Cylinder Head Material: Steel
Intake Valve Size: 2.02
Exhaust Valve Size: 1.60
Rocker Ratio Intake: 1.5
Rocker Ratio Exhaust: 1.5
Intake Runner Volume CC: 179/CC
Porting: Mild
Compression Ratio:9.8
Carbureted Or Injected: Carbureted for now
Carbureted CFM: 650
Number Of Carburetors: 1
Fuel: Gasoline
Injected CFM:900
Headers: Yes
Headers Tube Size: 1 5/8
Headers Collector Size: 3"
Vehicle Weight: 3500
Vehicle Make & Model: 1968 Plymouth Barracuda
Transmission Type: Automatic
Transmission Number Of Gears: 3
If Automatic: FootBrake
Stall Speed: 2300
Rear Axle Ratio: 3.23:1
Tire Height: 27.05
Tire Width: 10.04
Is This A New Combination: Yes
Idle Quality Desired: Lope to slight chop
DesiredChange:
The 1979 360 will be stroked to 408 it will be a nice day driver with more than occasional grudge matches at the track.
The heads are IMM indy LA X from Brian at IMM here
IMMENGINES.COM
My built 318 in this car runs 12.93's at 104 mph. The 408 needs to do much better than that... I will not putting a roll bar in it. I'm not opposed to a choppy idle and I will be running 92 octane at the pump and 98 at the track.
I will be installing a FiTech Go EFI 600hp power adder throttle body injection shortly after break in. The power adder part of the EFI is not for forced induction. I got that model for timing control and Idle step up at A/C compressor engage.
Edelbrock torker 2 single plane 4bbl intake.
Rotating assembly is forged Scat crank and I beams.
Pistons are forged 2618 Mahle.
Compression ratio will be 9.8:1 with a .041 quench. Piston sits .012 in the hole with 28cc valve reliefs.
yellow rose
Overnight Sensation
Well there you go. It was easy wasn't it? Lol!!!
Once you do it, you'll never go back...............to off the shelf.
Once you do it, you'll never go back...............to off the shelf.
LOL...Yup
mopowers
Well-Known Member
I'm surprised the lift is so short.
yellow rose
Overnight Sensation
I was too, but he's got pretty tall gears and not a lot of converter.
And, off the top of my head, I can't remember what he has for valve gear. He may be using stock rockers.
That cam will work and do what the OP wants. I'm sure that Bullet has this one by the short and curlies.
The rockers will be Hughes rollers HUG15023. Talking with Brian at IMM now to determine if the retainers he uses will work with the Hughes gear without any bind on on the rocker. I know they are machined to clear a 1.5" spring...
yellow rose
Overnight Sensation
If your geometry is correct they won't hit. Look at the thread on push rod clearance. That's what correct geometry looks like.
so in conversation with Tim @ Bullet, here are the valve timing numbers.
CRA288/296H110+4 gives 38 open 70 close on intake
82open 34 closing on exhaust at seat to seat with cam in the motor at 106 intake centerline
If we went to a 296 /296 H110+4 would be the largest cam for 323rear gear it would open
42/74 closing with same exhaust events. It really needs more gear but sometimes we must put
More in just for compression.
Thanks Tim
That's a Dcr of 7.4ish "calculated" which leaves out a bunch of variables and only considers an average, I know.... I for sure am lacking in fully understanding cams and what the effects of valve timing events actually do to performance. I asked the question of an estimate of peak hp and torque at what rpm but didn't get that one answered. I want this thing to perform at the track and am not too concerned about fuel economy...I aint buildin this thing to pass gas stations...
I need shorter gears and more converter...?? I should have mentioned to him that I will be getting another case with 355's and a gear vendors.
CRA288/296H110+4 gives 38 open 70 close on intake
82open 34 closing on exhaust at seat to seat with cam in the motor at 106 intake centerline
If we went to a 296 /296 H110+4 would be the largest cam for 323rear gear it would open
42/74 closing with same exhaust events. It really needs more gear but sometimes we must put
More in just for compression.
Thanks Tim
That's a Dcr of 7.4ish "calculated" which leaves out a bunch of variables and only considers an average, I know.... I for sure am lacking in fully understanding cams and what the effects of valve timing events actually do to performance. I asked the question of an estimate of peak hp and torque at what rpm but didn't get that one answered. I want this thing to perform at the track and am not too concerned about fuel economy...I aint buildin this thing to pass gas stations...
I need shorter gears and more converter...?? I should have mentioned to him that I will be getting another case with 355's and a gear vendors.
yellow rose
Overnight Sensation
Yes, you need to tell him your getting deeper gears. And if you loosen up the converter he needs to know that too, preferably at the same time.
Not knocking getting expert advice and custom cams. But is there more to that cam spec then shown cause you'd think 230/240 .500 110 cam probably would be around the cam that would of been chosen anyway ??
yellow rose
Overnight Sensation
It's hard to "see" the lobe with just those numbers.
Lots of different lobes have the same specs. I have said for decades th cam grinders SHOULD post at .050/.100/.200/.300 numbers of the lobe. And then they should be checked in the block, because variations in lifter bore location will change the timing a bit.
Went up to Abbottsford B.C last weekend and picked up that 3.55 dropout. The gear set looks good and backlash felt okay...didn't bring my dial indicator...I checked the patch with paste on the gears and the wipe was right on. Said it was rebuilt...looked and felt it too. We'll see about the clutch pack. Gonna take it to the shop and check backlash and run out tomorrow.
Talked with Tim again to let him know of the 355's and if he could recommend a converter to match the cam and gear.... Ordered the heads from IMM Friday, 2 weeks out. saving up now for the Hughes rockers. This thing should be pretty stout.
Setting Lifter Preload.
One thing I ran in to on my 318 was with the 9.6 deck and the taller indy heads, I had to order longer push rods. i didn't have an adjustable lifter but I did have an adjustable push rod. I took an old lifter apart and machined a brass slug to fit into the lifter that allowed the cup and spring clip to be located in their original unloaded position. With the adjustable push rod and checking springs I brought the push rod length up to zero lash on the oem stamped rockers and added .040 to that length for preload. Worked fine.
Now that I'm getting the Hughes adjustable roller rockers, I'm not sure where The adjusting screw should be at initial setup. I guess, find a starting point on the screw...centered in it's travel??... then adjust the push rod to zero lash add .040 and check the wipe pattern...doesn't sound right. Would I be better off making a new slug for the checking lifter that allows the cup to sit .040 deeper that its uncompressed position, bring the push rod up to zero lash and then check the wipe? If needed adjust the length of the push rod and adjuster to get the proper geometry???? I would bet the instructions with the hughes setup would tell me...just curious if I'm on the right track....
Talked with Tim again to let him know of the 355's and if he could recommend a converter to match the cam and gear.... Ordered the heads from IMM Friday, 2 weeks out. saving up now for the Hughes rockers. This thing should be pretty stout.
Setting Lifter Preload.
One thing I ran in to on my 318 was with the 9.6 deck and the taller indy heads, I had to order longer push rods. i didn't have an adjustable lifter but I did have an adjustable push rod. I took an old lifter apart and machined a brass slug to fit into the lifter that allowed the cup and spring clip to be located in their original unloaded position. With the adjustable push rod and checking springs I brought the push rod length up to zero lash on the oem stamped rockers and added .040 to that length for preload. Worked fine.
Now that I'm getting the Hughes adjustable roller rockers, I'm not sure where The adjusting screw should be at initial setup. I guess, find a starting point on the screw...centered in it's travel??... then adjust the push rod to zero lash add .040 and check the wipe pattern...doesn't sound right. Would I be better off making a new slug for the checking lifter that allows the cup to sit .040 deeper that its uncompressed position, bring the push rod up to zero lash and then check the wipe? If needed adjust the length of the push rod and adjuster to get the proper geometry???? I would bet the instructions with the hughes setup would tell me...just curious if I'm on the right track....
yellow rose
Overnight Sensation
It depends on the rocker. If it's a ball adjuster the ball should be out of the rocker 9/32 of an inch. If it is a cup adjuster, you run it up into the rocker until it stops (lightly) and turn it 1-2 turns down.
And that's the starting point? I see now that Hughes sells an adjustable lifter. So use that to set the preload then just adjust the push rod and adjuster length to get the correct wipe? I suppose rocker shaft height comes into the equation as well. I've only done pedestal roller rockers...first time at shaft mount rollers.
yellow rose
Overnight Sensation
No, that's where they run. So you have to get the geometry corrected, and the pushrods the right length with the adjuster as said above. Make sure you go to b3racingengines.com and read his tech pages. There is no such thing as rockers that won't need some correcting. Brand don't matter.
yellow rose
Overnight Sensation
Yup, it's a bit to grasp. But it's a very good read. FABO should see if it's ok to post his tech pages HERE as a sticky. Of course, that might be bad because it might not drive business to his web site.
Just thinking out loud.
That's how i felt the first time i read it. have read it several more times. Very good article if you want to get in deep with valve geometry.
Then, once you get why the rocker need to move from it present place.......a new learning curve starts. how far and how much and what material......while the new parts lube right........ My pushrod are not gaulding, my guides are not bad, and i'm not breaking rocker arms. So, i think i will wait on the "Hands On" of them articles.
If i had read them article before or during my eng rebuild.......I think i might have dipped my toe in that there pool. LOL
yellow rose
Overnight Sensation
It won't change the oiling if you make the pushrods longer. I think my shafts had to go up .250 and back .080 or something like that. I'm sure Mike could look it up as I'm not sure if it calls out the changes on the receipt.
If your sweep is wider than it should be, you need to fix it.
wow, up .250 and back .080 too...did you need to machine the saddles to get the back set??
so with the 296/296 bullet cam and IMM heads, what guesseth thouest as to the power and Tq. And with 355's, what, a 3000 stall?
so with the 296/296 bullet cam and IMM heads, what guesseth thouest as to the power and Tq. And with 355's, what, a 3000 stall?
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My rocker arms on the pushrod did is only showing one thread(custom pushrods) and my sweep isn't that wide it's just not center on valve, but it's not trying to roll off the valve tip either.
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