help hitting 11's

[allkiller]

Hi im new on here
Im posting from the UK
I have a an all steel Cuda, 383ci 12.5 trw old school pistons, xe290 cams 1.5 roller, Holley 800 dp, rockers, MSD, timing set at 38 degrees, 906 O/C heads 2.14 1.81 w/ mild porting, 727 JW 3800 stall, 4.10, frame connectors
car has gone 12.00 @118 with 150 shot of gas using a Crower stage 5 cam but I was told the cam was wrong and to get 11's I needed a different cam.

Comp cams suggested the XE290S cam with .540 .558 lift, dual pattern cam ??
But this weekend this combo could only muster 12.9 no gas,
where as before with the 310 Crower cam lift 574 /585/ it would hit 12.5's easy no gas.

Have I got the wrong cam or what do you think I could do to sort this

Any thoughts and knowledge greatly received
thanks in advance

And here she is only 24,000 on the clock from new:icon_super:

 

[Adrian Worman]

Hiya mate, good to see you on here, plenty of knowledge in this forum

 

[allkiller]

Hi Ade Great weekend don't ya think :happy5:

 

[Adrian Worman]

I'm still buzzin now mate

 

[Cudafever]

Did you degree the cam when you put it in?

Did your 60 foot times go up or down with the new cam?

 

[383man]

I wonder why it went only 12.0's @ 118 ! At 118 mph you should go almost 11.0's. Waht was your mph on the 12.50 and 12.90 runs ? Ron

 

[allkiller]

I wonder why it went only 12.0's @ 118 ! At 118 mph you should go almost 11.0's. Waht was your mph on the 12.50 and 12.90 runs ? Ron

12.50 @ 112
12.90 @ 107/ 109

 

[Mopar Dan]

I agree that with that small of a lift change there should not be 4 tenths difference . I would double check cam timing . What are the lobe centers ? If you went to a wider lobe center it will affect an all motor run

 

[Rob C]

Welcome aboard guys. I see a number of new posters here.

What intake? Single plane right?
What suspension upgrades?
How well are the heads ported? Flow number wise? Would you know the numbers? No big deal really. It's just not all described porting is the same from machinist to machinist.

MP suggests there own P4120661 mechanical cam and 4.56 gears.with 10.5 X 30.5 tires. (inch, sorry)
Has the car been lightened any? 3200lbs.max weight. The 383's do not make a lot of torque but a good amount of HP being a short stroke engine. They do like to rev up high.

 

[Steve Case]

Hi Steve, Just found this site too!

 

[Rob C]

All killer still around?

 

[burntorange70]

Not for over a month but it is that time of year when people go on vacation or just get busy.

 

[allkiller]

Yeah still here guys...sorry work/travel got busy
Hi Steve good to see you found this place.

Car is not lightened suspension is stock but with lightet Viper front brakes only and 90/10 up front snd SS rear springs.4.10 gears 28 tyres

 

[Tig]

Specific Nitrous cams usually have a wider lobe separation angle (110 - 114), this will bleed off some cylinder pressure as the intake closing event is later. On the other hand they usually have more duration on the exhaust and this would help with stock / ported iron heads when naturally aspirated. I don't think you should have lost that much in ET or MPH with that cam swap. Does the car Idle better, feel softer? as has been mentioned cam timing may be advanced a little.
Having just looked at the specs of both cams I'd definitely say the Crower would be best N/A (108 LSA). The comp cams isn't much of a nitrous cam either (110LSA) and about as good as they have to offer off the shelf if you want to stick to a solid. There's a lot better choices if you were to go to a roller but it gets expensive.
Edit. You're not getting the most from your nitrous system, I would expect up to 1 sec reduction in et with a 150hp shot, in off the line, fuel pressure, ign timing all ok?

 

[70bigblockdodge]

Shouldn't the timing be backed down a bit with spray?

 

[Tig]

Shouldn't the timing be backed down a bit with spray?

I'll say yes, but not always, though I'm no expert. Some answers that may help are here:- http://www.holley.com/TechService/FAQ.asp?category=NOS