need some help selecting the right cam
Thread Starter
Pro
Joined: Jun 2006
Posts: 508
Likes: 1
From: Miami Florida
need some help selecting the right cam
I know this is asked a bazzillion times, so please forgive the repetition, but I need the advice from those who know cams far better than I do. The cam in my motor is just not working well and I would really appreciate some suggestions for a performance cam I can use that will actually idle as well as give me solid bottom and mid range up to 5000 rpms.
Here's what is in it now:
230/230 -480-500 108* cam. (this is my problem! it won't idle! It surges between 600 and 1400 rpms and stalls at a light if left in gear. I would like performance but drivable too. It pulls good once it gets rolling, but sitting at a light requires me to shift up to neutral and give it a little gas to keep it from stalling. Vacuum is very low.
1.6.1 crane roller rockers
This what I have built so far:
383 stroker with 9.5 compression
Headman long tube headers
beefed up 700R-4 auto trans with BM shift kit - 2500 stall converter
.308 posi. (may go up to 3.73 soon)
First Injection complete intake system with larger runners, plenum and throttle body.
Nitto street radials.
Pul-eez! somebody give me some suggestions for a better cam!
ThanX!
Steve
Here's what is in it now:
230/230 -480-500 108* cam. (this is my problem! it won't idle! It surges between 600 and 1400 rpms and stalls at a light if left in gear. I would like performance but drivable too. It pulls good once it gets rolling, but sitting at a light requires me to shift up to neutral and give it a little gas to keep it from stalling. Vacuum is very low.
1.6.1 crane roller rockers
This what I have built so far:
383 stroker with 9.5 compression
Headman long tube headers
beefed up 700R-4 auto trans with BM shift kit - 2500 stall converter
.308 posi. (may go up to 3.73 soon)
First Injection complete intake system with larger runners, plenum and throttle body.
Nitto street radials.
Pul-eez! somebody give me some suggestions for a better cam!
ThanX!
Steve
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
You can tune it out but a 108 lsa is a little tight for F.I.
Id drop the intake duration 8-10 deg, LSA of 112-114 or so thats a start.
3.07 gear/2500 converter and that cam arent happy together btdt
3.73 and 2800
Id drop the intake duration 8-10 deg, LSA of 112-114 or so thats a start.
3.07 gear/2500 converter and that cam arent happy together btdt
3.73 and 2800
Thread Starter
Pro
Joined: Jun 2006
Posts: 508
Likes: 1
From: Miami Florida
I forgot to add that I also changed over to a Dynamic EFI system with a different ECU that is now programable and got rid of the MAF sensor, now using a MAP sensor system which actually helped a bit, but I'm still stuck with the idle problem that two different tuners haven't been able to solve. I also added a vacuum canister to hopefully get more vacuum for the brakes, but it didn't help much, if at all. Both tuners think the cam is the problem because of excessive overlap and a 110 or 112 degree cam would cure the problem. I have been looking at Comp Cams and also the 22-409 TPI's cam. any opinions for lift and duration with what I have now?
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
Try a cam with less than 215 degrees intake duration and 220/225 exhaust duration on a 112 LC installed at a 108 ICL, also shoot for .525 to .550 lift. I do not know what heads you are using if they have good exhaust flow exhaust to intake ratio of 80% then reduce the exhaust duration to the lower number. The first intake system is a long runner design and it will not work as well as it should with a 230/230 duration but it should idle ok with tuning. Your idle surge issue is a tuning problem, it is too lean at idle would be my guess.
Last edited by bjankuski; May 3, 2010 at 10:35 AM.
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
[QUOTE=cuisinartvette;1573950435]You can tune it out but a 108 lsa is a little tight for F.I.
Id drop the intake duration 8-10 deg, LSA of 112-114 or so thats a start.
I ran my 383 with a 222 230, LSA 112 Crane cam and it was a great all around cam.
Id drop the intake duration 8-10 deg, LSA of 112-114 or so thats a start.
I ran my 383 with a 222 230, LSA 112 Crane cam and it was a great all around cam.
Thread Starter
Pro
Joined: Jun 2006
Posts: 508
Likes: 1
From: Miami Florida
I forgot to add that the heads are stock aluminum. I just pulled the plugs and they were black and covered in soot indicating a too rich mixture. The vacuum pressure is very low as well, as I notice it when braking. Can anyone suggest a tuner in the Miami Florida area familiar with the C-4 and has the tuning programs?
Steve
Steve
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Thread Starter
Pro
Joined: Jun 2006
Posts: 508
Likes: 1
From: Miami Florida
383: The Dynamic EFI system gave me a flashable chip and the ability to plug a laptop directly into the ECU via a pigtail connector so I don't have to pull the ECU out from under the dash every time I need to flash the chip. Unfortunately, I can't do it myself due to lack of knowledge, and must rely on local tuners who have the correct software for the C-4 and the obd-1 system. Most tuners around here are C-5 and up.
I have a guy who is working on tuning it and has managed to pull some good power on the dyno. ( 363 rwhp and 427 torque). That was with the original ecu and the MAF sensor. Now that I have changed to a MAP sensor and a different ECU, I haven't had it on the dyno. I do know that I lost a bit of HP and the car is now a little hesitant off the line, but pulls strong through midrange to about 5200 rpms.
We have been trying to get the tune right, and the wot is just fine. It's the idle and surging that has me in fits.
It's my opinion that I would be better off with a friendlier cam than trying to make this one work in a less than great application, considering what I have to work with.
I'd like to get some input from those who may be running something similar in a 383 and see what has been successful for them.
Steve
I have a guy who is working on tuning it and has managed to pull some good power on the dyno. ( 363 rwhp and 427 torque). That was with the original ecu and the MAF sensor. Now that I have changed to a MAP sensor and a different ECU, I haven't had it on the dyno. I do know that I lost a bit of HP and the car is now a little hesitant off the line, but pulls strong through midrange to about 5200 rpms.
We have been trying to get the tune right, and the wot is just fine. It's the idle and surging that has me in fits.
It's my opinion that I would be better off with a friendlier cam than trying to make this one work in a less than great application, considering what I have to work with.
I'd like to get some input from those who may be running something similar in a 383 and see what has been successful for them.
Steve
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
Steve, with the cam I mentioned above, my car was running low 11's and was very streetable; idled at 700 rpm and had great torque. Close up your LSA to 112 or so and you'll be running a lot better. I was also running 10.4 compression with that cam which helps somewhat.
Le Mans Master
Joined: Dec 2002
Posts: 5,270
Likes: 3
From: Seattle Area WA
I agree on changing from 108 to 112 or 114 but I think you should still be able to pull decent vacuum with that cam in a 383. What exactly is "low" vacuum?
Are you sure you don't have a vacuum leak? That could cause the idle surge? Is your IAC working like crazy trying to stabilize it (datalogging would show this)?
Before pulling the cam I would verify there is no vac leak by using a smoke test or similar. Then maybe it is the cam, but right now sounds more like a problem with leaks/tune.
Are you sure you don't have a vacuum leak? That could cause the idle surge? Is your IAC working like crazy trying to stabilize it (datalogging would show this)?
Before pulling the cam I would verify there is no vac leak by using a smoke test or similar. Then maybe it is the cam, but right now sounds more like a problem with leaks/tune.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
If someone is really good...I had a cam similar to that in a 350 and it pulled maybe 10 lbs ona good day, guessing you may get 12 tops which really isnt enough to make the brakes work real well, your on the edge there. Maybe a cam change is the way to go for you. EFI likes different things than a carb motor