I went to a race engine builder this morning and had him perform a leak down test to help figure out why I have a little gettty-up in idle that I have not been able to tune out; more on that possibly later. All cylinders showed 97% or more, so bottom end is like new tight and not contributing to any idle issues. Head was rebuilt 14,000 miles ago, and all valves are sealing.

I guess that leaves the camshaft’s condition, which must be showing its age, where I have to play with the lash to even out cylinder pressures. Because of this, and the nonstreet friendly attributes of this cam, it is time to select a more suitable camshaft for street use.

Recap:
Holley 390, oversized valves, Clifford headers & intake, 9.5:1 SCR with 44cc peanut head, 2200 rpm stall converter, 3.55:1 rear gear turning 24.5â€￾ tires (turns 3000 rpm @ 60 mph. Stock block, and piston depth 30 over. Current cam starts to run strong at 3800 rpm on up over 6000 rpm, making sweet spot too high for most street driving.

I would be looking for a cam that is capable of 6000 rpm to take full advantage of small 4V, develops good torque around 2000 rpm or less, makes a decent vacuum signal at idle in gear, and is suitable for high compression as I don’t want to replace head.

Any suggestions are welcome.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

I have had good success at that SCR range with the Comp Cam 252 to have a torqueband from idle to 6000 rpm in my original build...a similar grind (like Ted's would be a better substitute)...that would get you a very flat torqueband through all the gears....that being said you could also go with an Erson 270/270 which provides good low-mid range torque and will allow more top end if you are going to do more racing (it should also have less "lump than the 280/270" and make better use of the valves). 9.5:1 SCR isn't very high compression (10:1 with the right cam is about the limit for "street driven and performance with good mileage").

-D.Idiot

DI:
A Steel factory stock head gasket would yield a calculated 9.9:1. How the dynamic compression number sugars out with a smaller cam with less over lap needs to be examined.


I have to trust you guys that have similar builds or collection of parts as my car. I don't want to reinvent the wheel or discover fire; ain't nobody got time for that... What would be real nice would be able to drive a few cars with these different cams, but I'm on the wrong coast and too deep in the boondocks for any of those test drive. LOL


I do know I need more low end grunt. Even though the engine will put down twin black marks on dry pavement, I suspect the whole show could be a lot more aggressive.


Are there cam cards posted for any of these cams?

Is Ted's a Dutra highbred, or home grown?

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

wjajr,

My cam came from Delta Cams in Tacoma, WA just south of where I live. They reground my stock 74 cam. The cam is just a stock RV cam with .435 lift on both lobes and 254 duration. It has a nice sound, very perky and lots of low end torque. It is similar to Doc's RV10 and the Erson's E47031. Doc's has a little higher lift on the exhaust, .435 intake .446 exhaust with 254 duration. They feel quite different from the Chrysler P4120243 which is a stock cam. Maybe on paper they look similar but like you say. You need to drive the car. My experience is with a 2.76 ratio in a 8.75 rear with a Sure-Grip. I drive very aggressively but watch the vacuum gauge so it stays above 15". Once your at cruise it stays between 16" and 21" at 60 to 70 mph.

Ken at Delta Cams said the have (3) programmed grinds for the SL6. They are based on Comp Cams profiles.
The 254S which I have 212@.050 - .435 lift, the 264 which is 220@.050 - .440 lift and the E2 for racing 227@.050 - .430 lift. All are ground at 110 degree lobe centers.

He said the 254S will bleed of the compression the least of the three cams and will produce the most torque especially if you increase compression. He said to install it straight up which should be 106 degrees, but if you want more torque set at 108 degrees. No advance ground into the cams......

Prices are still cheap $44.50 if hand them a core. They will do a custom grind like one of Doc's if they the correct tooling. Price is $83.50. But like Doc, says it would be nice to see a copy of the program or profile plot.

Hope this helps you!

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Hi Ted,just curious,what is the idle quality of your cam like compared to stock? What vacuum do you pull at idle? Thanks!

Similar....very steady with a slight note. It is not like going to a high lift high overlap cam that sounds lopey with low vacuum. vacuum remains high and it just gets a little more mix in there at cruise for more power and better peddle feel. In fact, right off idle say 1200 rpm you can feel the torque on up through 2500 which is the real sweet spot when going over mountain passes loaded. That equates to 70 mph in my car. I run the high 2.76 ratio with 26" tall tires. It still shows good vacuum from 12" to 18" depending on how steep the climb. When the power valve kicks for passing @ 6" it is real punchy!

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Could you say a few more words to quantify how they are different? Having used the Chrysler P4120243 cam (which is slightly hotter than stock, especially compared to the early years), I was very pleased at how much it woke up a stock 64 170... of course we bumped up compression at the same time, so I can't say for sure what improvement the cam would have had by itself.

The stock engine (232* duration & 8.5:1 advertised) was a typical mild-mannered grandpa car. With the 244* duration and 9.5:1 (measured), keeping the 3.23 axle, it was perky and peppy at any reasonable street RPM. (No tach, but based on the sound of other cars I've driven, I doubt I ever took this one north of 3000.)

I like your approach of the RV grind, since I find it annoying to not have stump-pulling torque at idle.

Am very curious to know what's "different" compared to the P4120243, because I really like that one. It turned the car into a playful kitten.

- Erik

_________________
Lots of early Valiants and Barracudas have crossed my path.
Also a handful of other toys for variety now and then.

I would say consistent idle quality, and smoother and broader midrange power. It seems to run an average of 2" higher vacuum. That might be due to the wider lobe separation of 110 degrees verses 106 on the Chrysler P4120243 244 cam. My car is very heavy and changes in power are very noticeable. I have not been able to try one of Doc's cams, but would like to............

If I can get 25 mpg plus on trips heavily loaded (my wife shops till the trunk and where the back seat is suppose to be is full) over the mountain passes at 70 mph I am pretty happy.
With the tall tires and high gear ratio that is a must. You need that punch when your in traffic with fuel injected cars. It also helps with the mileage. When I was running the stock 74 cam 18 mpg was about it...with an occasional 19 mpg. With the Delta Grind 23 to 24 is more the average mpg and 25+ on trips depending on if I behave......... Running the 244 cam I get a stable 22 mpg but not as much spunk.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Ted

How would your cam live with 3.55 rear and 24.5" tires; that works out to 4000 rpm @ 80 mph, 3000 rpm @ 60 mph, 2000 rpm @ 40 mph. Dose that cam have any lungs to say 5000 rpm or 5500 rpm?

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

That cam with O/S valves and a bigger 2 or 4 barrel should wind all the way to the 6200 mark and still have torque to spare (you will run out of road before you drive it up to that level and the A904 will shift before you reach 4000 rpm unless manually shifted or specially prepped.

The 110 will make a shorter overlap keep the cylinder pressure from bleeding out and have a good idle if you don't over do the valve lash (i.e. tighten it more by .001 or .002)...I think going with a 109 LSA would still be OK as well here.

-D.Idiot

Bill,

I think it would be fine as DI says...I have reved it up many times at the track or coming down the pass but my speedo maxes at 110 on my car. That is about 4200, you just need more carb and valves to run it on up. I think it would be fun with your set up. It sure would be easy to tune and go like heck, and not burn your eyes like the cam you have now does...

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Lots of compression with the addition of an RV cam might introduce lots of detonation. Methanol might be in your future.

_________________
'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

I have to say I think that anything below 220 @ 0.050" duration will cause lots of detonation/pinging on pump gas. Probably you need 230 @ 0.050". I disagree that you will be able to run such short duration cams with 9.5:1 static comp.

Personally, I have run cams such as what is described above (RV, MP small grind) with 7.5 - 8.8:1 static comp, and they work well. For me, on 9.5-10:1 and pump premium, I would not run anything less than 220 @ 0.050", and 224-230 @ 0.050" sounds about right for what you are after.

The BEST way to get more "low end grunt" is to drop in a 2800 stall converter. It just transforms the car.

Remind us what cam is in there now, spec wise?

Lou

_________________
Home of Slant6-powered fun machines since 1988

I will argue back on this one since the Beater Valiant ran on 9.66:1 SCR and a Comp Xtreme short cam (256 advertised duration, 218 @ .050, .466 lift, 110 LSA) and I did not have any detonation using 87 from the local pump...this is where the DCR calc will be critical in selecting the right cam for the job (try to keep the DCR in the low 8's in your selection), on the short cam side LSA selection will also play a critical selection as a Comp Cam 252/264 with a 110 LSA would detonate in the 9.5-10:1 range but if setup with a 106-108 LSA it would work for the 9.5:1 area but nothing over that. If I were to pick a 270 to 280 advertised duration cam (about 225-230 @ .050) I would build the engine for 10:1 to make the most efficient use of the compression and cam (the longer duration is going to bleed down during the longer overlap event so more compression *up to a certain point* would be desired to make up for the bleed down, and the duration allows for use of the top end of the engine). So at 9.5:1 SCR I would want to err on the conservative side and not go over the 270 advertised duration mark (Erson 270/270 would be a perfect daily driver match), or I would pull a Lou and get the 280/270 and bump compression to 10:1 to get the most out of my mill low end and top end.

I would plug your motor into a DCR calculator and try some lobe grind combinations and see if you can land it at 8-8.11:1 for streetability.

Ultimately once you make the switch you'll have to recurve the distributor and requalify the carb to be the most out of it.

-D.Idiot

Lou,

I must have lucked out by advancing the my 254D .435 lift cam 4 degrees as DI noted (212@.050 - .435 lift on 110 lobe centers). It never pinged at 9.5 to 1 compression unless it got up over 220 degrees with 60 plus degrees of timing. Then it would talk to me......that is why I started running alcohol/water injection during the summer months.

The tops of my pistons and plugs look great, nice and smooth, clean with no pitting...

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG