[RA462]

I'm wanting to change the camshaft in my 433. Since I originally built it I have changed from a Performer RPM intake/750 Holley to a Barry Grant Six shooter with a FiTech Go EFI Tri-Power system. I had to weld the intake runners up just like has been done to get the aluminum Tri-Power intakes to fit larger heads. Probably the main thing driving this change is the FiTech wants to idle at 1200 RPM and FiTech says it is because of the 108 lobe separation angle my current camshaft has.

What I'm thinking is a new Comp hydraulic roller with 236/236 duration @ .050, .380 lobe lift give me .608 lift with 1.6 rockers, and a 112 lobe separation angle. This is the same lobe that OLDER versions of the "old faithful" used on the intake and the "stump puller" uses on the exhaust (3122B). I'm thinking that with cylinder heads that have an intake/exhaust flow ratio of 79% I don't need a dual pattern camshaft? Yes I know this is an odd combination but it is what I have. See below for the injun specs.

What are your thoughts on the camshaft I am thinking of having Comp grind up for me?

THANKS GUYS!

4.15 Bore AutoTech Pistons
4.00 Scat Forged Crankshaft
6.700 Forged Rods
KRE High Port Heads with just a gasket match
Barry Grant Six Shooter Intake
FiTech Go EFI Tri-Power
Comp 232/236 @.050 Hydraulic Roller Camshaft .560/.544 Lift 108 Lobe Sep. Angle
1.60 roller rockers
200-4R transmission with about a 3400 stall (long term plan is to go 5-6 speed manual)
3.75 gears
1-7/8 header - 3" exhaust
99% fun street car that I might take to the track if my other car is down

http://forums.maxperformanceinc.com/...d.php?t=793958

Stock High Port Head Flow
.100 85 71
.200 170 129
.300 234 179
.400 284 221
.500 316 248
.600 322 263
.700 331 270

[steve25]

You don't need the duel pattern Cam even without factoring in the added 4 to 8 percent more flow above your 79 percent that a 1 7/8" tube put on the end of a Exh port adds in above ..400" lift as seen on my flow bench.

[Scott65]

I don't have any experience with FItech. That being said, using FAST ezefi, which must be similar... I was able to maintain decent idle(900 rpm) with a cam with a 106 lsa, 248/254@.050 duration. Bypass air, and timing are key. You can probably get where you need without changing cams. Do you use the fitech with timing control? Hopefully some of the fitech users will be along to offer specific guidance.

[Speargun]

I think this a tuning issue and not a cam issue.
I had a high idle / hang idle issue with my Fitech and was able to dial it down to 760rpm after making some adjustments. iirc, I adjusted the DFCO & disabled another setting having to do with idle. It's been a while so I don't remember exactly what I did.

I'd start with setting your target idle rpm, then dialing in the throttle plates & IAC. If the IAC # is high (20+), open throttle plates a hair. If the IAC is low (<3-5), close the plates a bit. Then shut off engine and let controller screen go black, start again & check.
Also make sure that the TPS is at 0, or very close to 0, at idle.
If you can get the IAC set to 3-5 like Fitech recommends, great! If not, 12-18 will still work. If you hear a high pitched whistle driving down the road, re-adjust the IAC to a lower setting.

[JLMounce]

Agreed, this is likely a tuning issue, not a cam issue.

I don't have experience with the tri-power system, but I would be looking for a few throttle plates that might be slightly out of alignment. I'd also be looking at the IAC. What are your counts at warm idle in park? What are they at warm idle in gear?

[Lee]

EFI does not care about the LSA. Lots of overlap and cause the MAP signal to bounce around, and THAT can cause problems with an EFI system that is trying to "learn". The cure, if using a lot of overlap, is using an EFI system that can be tuned to stay in open-loop while at idle.

[JLMounce]

The FiTech software itself without doing any "tricks" will successfully run an engine down to about 5" of vacuum at idle. There are people running them on combinations making as little as 2" but you have to really mess with the VE tables and deal with the overlap issues.

Based on the combination the OP is running, that's likely not the case. That engine is probably making 9-10" of vacuum at idle, if not more. This information from the OP would be helpful.

In idle operation, if you can't get the idle to come up to target, or down to target it's either not receiving enough air, or receiving too much. That's controlled by a small amount of leakage past the throttle blades and then fine-tuned by the IAC valve.

There is a sequence of steps required to set that valve and the IAC counts properly so that it has enough adjustment, closed and open to keep the idle at target. This is not to say it's going to create a smooth idle, overlap, timing etc. will all work for or against keeping the idle stable.

If he hasn't already done so, what the OP needs to do is start the car and bring it up to operating temp and bring up the IAC counts on the controller. If there is an issue with how the throttle blades are set and are too far open, causing a high idle, this will present as showing an IAC count that is very low, if not zero. That means the IAC valve is completely closed and the system can not move the idle downward any further.

The fix is to start closing the throttle blades so there is less air leakage past them. This will allow the IAC valve to start controlling total airflow to obtain target idle speed and you'll see this as the IAC counts rising on the handheld.

With the engine warm, the OP should adjust the idle screw until his idle comes down to target and the IAC counts are between 10-20 while in park. Shut down the engine, let the FiTech cycle off, then turn the key, but don't start the engine so that the TPS can reset. Verify on the handheld that TPS is 0, then restart the car and verify the vehicle maintains target idle speed with IAC counts in the 10-20 range at warm idle in park. Repeat this process, until that is maintained.

This will then produce a sweet spot for cold start idle and warm idle in gear. You'll see counts typically in the 150 range at cold idle down to about 20-40 at warm idle in gear. This gives the system the widest possible range to control idle properly with the IAC valve.

[Scott65]

Good written instructions from Jason. The OP will, with some patience and perseverance be able to get a good idle with that. Or use the same procedure to get it correct after changing a cam.

[KEN CROCIE]

What cam now? I have a feeling you are going to ADD more overlap in spite of using 4 more deg. LSA

[RA462]

Sorry for the delay getting back here. I have been busy with some family things I have been dealing with.

The current cam is a Comp 232/236 @.050 Hydraulic Roller Camshaft .560/.544 Lift 108 Lobe Sep. Angle.

I did some tuning last spring when I installed the FiTech and I was never able to get it right. I have the idle set at 800 but it runs at 1200. I'm currently installing a A/C radiator support and Cold Case radiator to help with the car overheating in traffic. I does fine rolling down the highway. I thought while I have the radiator and the grill off it might be a good time to see if a different camshaft will fix the 1200 rpm idle issue. I want to say the idle vacuum was 14" but again that was at 1200 rpm. I know I messed with closing the throttle blades a little back in the spring but I honestly don't remember what all I did. Maybe I should just get the radiator/fans installed a wait until spring to do some adjustments? I would think getting more valve lift would help make some more power with the heads I have.

[Scott65]

Nothing wrong with wanting a different cam. I think the point was being made that you dont HAVE to, to get it to idle. The process Jason laid out will get your idle down. Make sure that the only source of air is the throttle blades and the IAC valve. No vacuum leaks letting unaccounted for air in.

[RA462]

Well in another thread another member mentioned a couple hydraulic roller camshafts that peaked my interest. After doing some searching around I found out these cams were made by Howard's. I ended up ordering a part number 4144495-12. It looks like Howard's version of the Old Faithful but with a 4/7 lobe swap. Cost less too. The bad news is I will have to wait a couple of months to test it out due to the weather.

[AG]

Is it a billet steel core or cast?

[RA462]

Originally Posted by AG

Is it a billet steel core or cast?

I didn't ask. I think billet. 10-14 days for them to grind it since it was not in stock,