Hello

New to Moparts

Could anyone suggest a replacement cam for a 1974 Roadrunner 400 "P" code motor? I don't want to change the factory rockers or pushrod length if I don't have to? I see Sealed power CS-661 or kit KC661 with lifters, or Yearone MP31, Comp Cams 21-212-4. Cannot seem to find the exact specs of the original. Heck, what would Worman use? Also anyone use the Sealed power rockers or arms (vintage)

Thanks

Welcome welcome. You might checkout the Summitt house brand cams. they're cheap & have a good rep for what they are. the specs would be listed there. I have one (not installed yet tho).

You can actually go with quite a bit of cam before you have to change rockers or pushrods. I don't have my factory service manual in front of me, however I think the factory cam was roughly 210* @050 and .430 lift. The lunati voodoo 10230700 would be a good approximation with a little extra lift.

welcome to the jungle ! now you know where to spend all your free time !

If you find out what the specs are on the cam for your 74 RoadRunner with 400 motor, most major cam companies will grind you one to those specs for just a few dollars extra. They may even have the stock specs for that cam on record. Just give one of them a call. Crane, Comp Cams, Lunati, etc, etc.

I agreee Summits brand cams work great and are reasonable.for close to stock use the smaller one.Ive run all their Mopar cams and a few Checvy ones.No problems.The big cam is a bit lumpy but not radical.smaller one is just a bit over stock and all OE parts work great and idles almost like stock with a bit more power.Rocky

http://howardscams.com/i-24079963-howard...lifter-kit.html

a little hotter...

http://howardscams.com/i-24079922-howard...lifter-kit.html

Comp Factory Muscle cam for bigblocks, it's like a revamped 440HP camshaft, should slot in with no other substitutions.
http://www.jegs.com/i/COMP-Cams/249/CL21-305-4/10002/-1

It's a little hotter than the Crane 680101 Factory Blueprint camshaft, the Crane has lift and duration very close to stock but the lobe profile has been smoothed out using computers.

Lunati's Voodoo series the 10230700 is actually smaller than the factory HP cam, the 10230701 is nearly identical to the factory HP cam but with modern lobes that will get more airflow.

Last but not least I'd suggest the Crower 267 HDP. It is a tiny bit bigger than the other three. It seems to be a very satisfactory camshaft, we have gotten good reviews on it.

The 271 HDP and the Summit larger cam are too big, the summit smaller cam is too small. The four cams listed above should meet your needs and not make your car undriveable with stock drivetrain.

Good Luck!

R.

Thank you all

This is all great info.

Just got home so will research the above.

Thanks again for all of your help.

Still searching for original specs. Found this. Very interesting. Only gives part of the specs. though.

http://www.allpar.com/mopar/V8/400.html

Still want to know what Worman would use LOL

Another piece of the puzzle.

www.dodgecharger.com/forum/index.php?topic=62851.0

Your SCR might be fairly low so I would stay conservative

Your right

How about Howard's 727511-13 or CL727511-13

Looks like very similar to original and I assume I can use all stock valvetrain.

We just got the milder Howards .434 lift cam for a 383.It will be a while for results as it turned into a complete engine rebuild...
RT

Welcome to Moparts!
You have my reply on FBO.
Someone here might know the valve spring specs that come with the AeroHead cylinder heads?

I found it. Original cam is 3512907

https://www.scribd.com/doc/24470110/B-RB-ENGINE

Unfortunately the exact specs for the factory cams seems to be unavailable, at least to the average guy. I'm sure there are guys that have been doing this forever that know the specs or have measured factory originals. The problems with any of the published factory specs (service manual, DC manual etc.) is that they don't specify at what lift the duration numbers that they list are at. And without that info your guessing. From what i have seen that is available, the crane 'blueprint' cam is pretty darn close to factory specs. But that's for the HP cam. You'll probably be able to find max lift and LSA specs, but the duration specs are going to be a chore to find. Good luck and keep us posted.

Are you looking to "replace" the original cam, or are you wanting to "upgrade" the original cam?

If your motor has the "2bbl" cam, it probably doesn't have the hp springs either, which would hinder the options unless changing them was part of the plan.

Before spending money on a new cam I'll suggest first buying a copy of the Mopar engine manual to have as a guide.
Check this site for the Mopar Engine Manual, 8th edition, P5249010, it is a give-away price if still available:
http://www.2040-parts.com/mopar-performa...gines-i2187928/

Although the 'usual' cam companies have excellent products, using a cam designed by the same people that designed the engine isn't a bad idea.

With that said, as noted above, the Crower 267HDP is one of my favorite profiles and have used it on many EarlyHemi projects.

Fast 68

I needed to pull the heads as I had a bent valve. Then I checked the lifters an found a couple slightly con caved. It is believed to be the original cam and lifters. I was initially thinking of bumping up a notch but do want to keep the original valve train so that limits my selections. Right now I am leaning toward Crane 3512907 (680101) which is a blueprinted cam. It is in a 1974 true Road Runner with the numbers matching "P' code motor.

Oh

Crane originally made the 3512907 (680101) with the one bolt. According to the latest document they have changed to 3 bolt only. Can you suggest a good 3 bolt timing set?

Dogdays

Good call on the 680101

That's the same one I found here as 3512907 which is now 680101 only three bolt. I didn't know it at the time.

www.scribd.com/doc/24470110/B-RB-ENGINE

I believe this is the same question posted on "For B-Bodies Only"?

PSH, let me know if this info is correct?
Engine is a stock 74 400
Cylinder heads are stock and sent to AeroHead to be rebuilt with the larger 2.14"/1.81" valves, and hardened seats. (No porting or bowl work.)
Car is the '74 Road Runner (likely 3,900+ lbs), stock converter, 3.23:1 rear gear.
I don't think tire size was listed, assuming about a 26-27" tall tire?
Assuming a 235x60x15 tire of 26.1" height, 3.23:1 gear, no converter slipage, then RPM at 60 MPH = 2494.7 RPM, at 80 MPH = 3326.2 RPM, 100 = 4157.8 RPM

The Sealed Power stock 2-bbl replacement cam #KC327 specs are 206/209@ 0.050" duration, 0.434"/0.431" lift, 113 LSA.
From the '71 Factory Service Manual, the 2-bbl cams is 260/268 advertised duration, 0.425"/0.435" lift, 113 LSA, Intake open 18 BTDC, Intake Close 62 ABDC, Exhaust Open 68 BBDC, Exhaust Close 20 ATDC, 38 degrees overlap.
To get those valve events, the cam would need to be installed 112 centerline.

Engine numbers:
Bore = 4.340" Stroke = 3.380", Rod Length = 6.358", Block Height = 9.980", Piston compression height should be 1.812", flat top, no valve relief volume.
This puts the piston 0.120" below deck at TDC. Displacement is 400.01 CID.
Assuming a 0.020" head gasket of 5cc volume (4.410" diameter), and an 84cc cylinder head volume, then compression is 7.94:1
Using the FSM advertised duration numbers to calculate dynamic (effective) compression = 6.31:1 This should be about 119 PSI cranking pressure at sea-level? Using the sealed Power KC327 cams 0.050" numbers = 7.40:1 Dynamic compression ratio. I don't have a pressure conversion for 0.050" dynamic numbers?

I recommended the Hughes Engines SEH1620BL-12 cam, 216/220 duration @ 0.050", 0.495"/0.503" lift, 112 LSA.
Hughes shows installing on a 108 centerline, but installed at 107 cl will give the exact same intake closing point @ 0.050" as the KC327 cam installed at the stock 112 cl. This means the dynamic compression calculated at the 0.050" lift numbers would be the same.
In theory (based on effective/dynamic compression, but not accounting for overlap) the larger cam should not give up any low end power to the smaller cam, and then make way more power through the RPM range.
Here are the numbers side-by-side:
CAM KC327 SEH1620BL-12
Intake Duration @ 0.050" 206 216
Exhaust Duration @ 0.050" 209 220
Lobe Seperation angle 113 112
Intake install Center Line 112 107
Intake Opens (BTDC) -9 1
Intake Closes (ABDC) 35 35
Exhaust Opens (BBDC) 38.5 47
Exhaust Closes (ATDC) -9.5 -7
Overlap (0.050 duration) -18.5 -6

Yes same on B-Bodies. looking for all the suggestions i can get. These forums are a wealth on knowledge.

This is my first teardown. It's hard to find the time working full time so it's a slow process working on the bird weekends only.

After getting into the changing the cam idea while she's open I cannot believe all of the endless choices.

Why did you list the 2bbl KC327 and not CS661 4bbl cam?

I do like the SE1620BL but now the .503 and .536 valve lift have me a little concerned. I would prefer to put in a known cam with no issues but that info is hard to find for a particular motor. I have a new single bolt timing set installed. Should I go to thee bolt?

I probably wont research any more till Saturday but I think I have narrowed it down to these albeit conservative cams.
Melling SPD-31, Crane 680101 (supposed to be like stock 74 road runner), Elgin Pro Stock E-1094-P, Hughes SEH16020BL

Much appreciated input.

Getting the valve job done, I wouldn't replace the stock cam with another stock cam.

On specs I like the crower 267HDP... INITIALLY suggested the 271 at FBBO ( although gave the 267 option later ), but is true, it could be a bit big with stock CR, unless you bump out the CR cutting heads and using metallic headgaskets..

Although I WOULD STILL cut the heads ( light 0.020" cut or so ) and use metallic headgasket with any cam you choose.

I used the KC327 because it is likely the specs are very close to what the stock camshaft is, so we have a starting point for comparison.

The CS661 was the stock HP 4-bbl cam, and the engines that used it had over 9:1 compression.

The Hughes cam is going to cost more, and I think you would need to use their valve springs too. But it should also make more power.

If you are trying to keep costs down, the single bolt timing set is likely less expensive than the 3-bolt setup.
The question is what single bolt timing set is it? You do not want the one with the slot for the cam pin. I would at least get one with the 3 crank keyways, usually 0, 4 advance, and 4 retard.
The 9 way adjustable billet units from 440 source are nice, but cost $99. They have a 3 way adjustable for $60. These multi-keyway crank gears are easier to use to degree the cam in than drilling out the cam pin hole and using the offset bushings.

If I get time tonight, I can plug some of the other cam specs into the calculations spreadsheet and see how they look for dynamic compression.

I realize this will probably come off as some Internet guru who just likes to complain, but I'll let the numbers speak for themselves.

One set of numbers is from a clean, used 452 head with the OE valves and OE valve job, the other is from a 452 head than was done at Aerohead like what the op is getting done...... Big valve install, no porting:

Lift--------A/B
.100---61.4/ 67.8
.200--123.6/118.3
.300--184.8/169.5
.400--205.7/198.4
.450--215.0/207.9
.500--222.5/219.9
.550--226.2/224.9
.600--225.1/224.9

The much better option, especially for these milder applications is to retain the std valve sizes and do some mild bowl porting, which not only increases flow but also has much higher discharge coefficient rates(more flow, smaller valve = higher air speed around the valve).

902(1974 head) head with 3 angle seat(stones), back cut OE valve, and very minor bowl blend:

Lift-------flow
.100---67.2
.200--139.0
.300--202.5
.400--230.5
.450--237.0
.500--240.7
.550--243.8
.600--245.7

The big valve install without some accompanying porting is a step backwards for most applications, IMO.
Even if the flow was the same, or slightly higher, the speed of the air around the valve as it leaves the port and enters the cylinder is slower(same amount of air flowing through a bigger hole), which results in more reversion and less efficient cylinder filling.

Fast68, you are on a roll today!

Thank you for a real life example on how installing larger valves can actually reduce flow. I'm sure you have other examples on homemade porting jobs that actually reduced flow.

R.

I do...... But the worst part is....... I have several examples where it wasn't done at "home", but was what someone paid a shop to do......like the example above.

Those Aerohead 452's, after recutting the seats, back cutting the valves, blending the bowls, and opening up the pinch slightly, flowed 261cfm.

Fast68plymouth, do you know what valve springs are used on the AeroHeads?
I called yesterday and Russ was busy, but the lady on the phone said Pioneer G911? I looked and pioneer does not have a G911, but maybe it is the Pioneer S-1050? That is a 1.525"OD spring, lists 117-132@1.875", 341-369@1.375"
That would be similar to a comp 911 spring, but with a higher spring rate?
Or maybe they just use the Comp 911 spring and they told me the wrong vendor?

The G911 is an Indy number afaik, and I have seen at least 4 different springs from them where the invoice listed them as "G911".

What I've been getting recently, listed as the G911, is about 150@1.900/350@1.300/CB@1.200.

Prior to that they were very similar to what would come on RPM heads, and I had a few sets of heads years ago where they were even softer than the RPM style.... Two different versions of those.
They were too soft to use on anything(IMO), so I ended up adding an inner to make them useable.

I just got some heads two days ago with the "G911" springs..... I'll have to see where they stack up.
It's always a mystery.

Lunati 10210241LK cam (single bolt timing set) that is 216/228@ 0.050", 0.454"/0.480" lift, 112 LSA , $208 price for cam and lifter kit looks good for the price.

The Summit K6400 214/222@0.050", 0.444"/0.466", 112 lsa specs look OK too (the advertised duration looks pretty big, but might be rated at 0.002"?) and is really inexpensive $118 cam/lifter kit. I never used one of these so I don't know about their quality?

I also noticed the Howards CL720031-12 cam 215/223@ 0.050", 0.446"/0.465, 112 LSA $220, or $249 for the "Max Certified" version MC720031-12
I had to look at their web page to find out what the "Max Certified" was, it looks like it includes a bottle of break-in oil additive and a 5-year insurance policy on the cam/lifters (if you add their oil additive at each oil change.)

the oil additive is about $8, so what do you think about paying an extra $21 for a 5-year warranty?

I have a small Summit cam in my 440 pickup and the bigger Summit cam in my 440 Valiant. Quality is excellent. I have been running both cams for 2 years now without a problem. The 440 in my pickup is a late model low compression engine and the small cam idles smooth and creates lot's of torque. The 440 in my Valiant has 9.25 compression and the larger cam pulls hard. I can't say anything bad about them and would gladly use them again.

The small Summit cam would certainly be on my short list for the OP's combo.

fast 68

Those summit cams are very economical.

Does anyone know the max valve lift for this engine. Don't want to play with clay.

Lift has nothing to do with clearance.

It's duration that uses up clearance(amount of lift at TDC).

On a stock 400 that has the pistons down the hole .080+, and heads that havent been cut a bunch, pretty much any cam with less than mid-230's @.050 should fit okay.
So, anything that's "appropriate" for the rest of the combo shouldn't be a problem.

The only place where lift might be a concern with that build and stock heads is retainer to seal clearance.

Thank you

You should not have any problem with piston to valve clearance, you piston is 1/8" (0.120") below the deck at TDC, and as mentioned, duration is what reduces P-V clearance. The maximum lift will occur around 108 degrees after TDC (depending on where you degree in the cam centerline), so the piston will be more than 1/2 way down the bore (well over 1-1/2") at that point.
The two places that lift might be an issue is valve spring coil bind and retainer the valve guide seal clearance. With these small cams (under 0.550" lift) neither of these clearances should be a problem.

If this helps you any, my 1974 FSM lists the following:

400 2bbl/440 std cam
260* intake duration .434 lift/268* exhaust duration .430 lift
intake opens (BTC)18
intake closes (ABC) 62
exhaust opens (BBC) 68
exhaust closes (ATC) 20
Valve overlap 38

400 4bbl/440-HP
268* intake duration .450 lift/284* exhaust duration .464 lift
intake opens (BTC)21
intake closes (ABC) 67
exhaust opens (BBC) 79
exhaust closes (ATC) 25
Valve overlap 46

Thanks Daytona

That does help.

I know this is totally different than what i was looking for but has anyone tried this cam? Would it work with stock springs/valve train? SMC2942BL Hues. Hues says it is specifically made for low compression motors. Don't know how the vacuum would be for the power brakes?

Like I said this is my first time doing this. It seems the options are endless.

Dave Hughes has a good rep. & a cam for low compression would for sure have enough vac for PB, no worries there.

That is the Whiplash cam. It installs at 102 intake centerline (closes the intake early for good dynamic compression) and has a narrow lobe seperation angle which gives it alot of overlap (rough idle, low vacuum.)


It will work with your compression. The Dynamic compression is almost the same. Remember the stock cam 206duration @ 0.050" installed at 112 intake centerline = 7.40:1
The 216 duration @ 0.050 cam installed at 107 ICL = 7.40:1 (108 ICL = 7.37:1)
The whiplish cam 229 duration @ 0.050" installed at 102 ICL = 7.35:1 dynamic compression.

Call Hughes up and tell them what you are doing and see what they recommend.

FWIW I would send it all to FAST 68 and let him do it for you as well as pick a cam.Probably be the best end result for you.

If you use the Hughes Whiplash cam it would be fine with a 4speed, but if you have an automatic, you are going to want a higher stall convertor. I found this out the hard way in a 383 w/727. I have to swap convertors next weekend, because when I put it in gear it lugs the motor down and stalls. Definitely needs a looser convertor.

so one of those cams intended for low comp actually has low vac? I never would of guessed & I woulda thought just the opposite.

You're surprised a cam that specs out as 232/245-107(as per the Hughes site)would have low vacuum?

I would absolutely expect low vac out of that cam...... Especially in a low cr motor.

It's designed to idle rough...... Which is done by dirtying up the idle with lots of overlap.

I didn't see it mentioned anywhere...... But if the "plan" is to retain the OE carb(TQ), intake, and exhaust manifolds, then IMO........ That really narrows down what I would feel are the "appropriate" cam choices.

And if that is how it's going to be run, then I def feel the big valves are a step in the wrong direction.

and then avoid it at all costs ...

Well I ain't a cam guy & I had assumed that a cam that is specifically designed to build/trap compression would have a good vac #. Obviously not & I learned something today.

psh you said the cam had flat lobes , safe to assume you are taking this engine further down ... like completely apart ... than just a bad choice head rebuild?

If you are stuck on stock iron junk then fast68plymouth is the person to see , it's only a 2.5 to 3 hour ride up to his shop.

I still vote for the Crower 267HDP

I know some of you wont like this but I purchased the KC661 kit. I Know I know. It mimic's the original.

Cam Lift Exhaust (Inch) 0.3090
Cam Lift Intake (Inch) 0.2990
Cam Series Pro-3000
Cam Type Hydraulic
Duration @ .006 Lift 292/309
Duration @ .050 Lift 214/225
Engine Family Big Block
Exhaust Duration 225
Exhaust Lift (Inch) 0.4640
Exhaust Lift (MM) 7.849
Exhaust Valve Lift 1 (MM) 11.786
Footnote Code (050) Duration at .050 Lobe Lift
Intake Duration 214
Intake Lift (Inch) 0.4490
Intake Lift (MM) 7.595
Intake Lobe Center 110
Intake Valve Lift 1 (MM) 11.405
Lobe Separation 115
Manufacturer Chrysler
Overlap 46

Thanks again for all of your input.

Nah we're good with that! post how it acts when the time comes.

I have the same car

35000 mile 74 Roadrunner with a 400/auto.

My car is stock except for a 3" TTI exhaust and 3.91 gears.

The no. 5 intake lobe went bad and I had to replace the cam.

The cam that's free is right for me, so I wound up with a 274 comp.

This is not a great selection, rough idle noticeably less low end torque. I'm not happy with it.

I was going to make the same post, so this is what I need to know.

I look forward to seeing how it works out for you.