_Remi

Hi friends,

As some of you know, I had my stock heads replaced by edelbrock performer aluminium and I kept the original cam in it as well as my performer (non RPM) intake. I was unhappy with the changes, I had to rev a lot to get power and I had a lot of hesitations at low RPM. I was not able to floor it at 2k RPM for example, it would hesitate 2 seconds and then go.

I am back from the mechanic and I had the following done: New XE256 cam and Performer RPM Air-Gap intake

Here is my feedback:

- The sound is different, now I know what it means to have a somewhat aggresive idle (but nice). It definitely sounds meaner than before.

- Compared to before, I need to rev more to launch the car. Basically, I have to go at least to 1800/2000 RPM if I want to start correctly. In the past (stock heads and cam), I would be able to launch it with pretty much no acceleration. Now it is "rough" (as opposed to smooth) but when I change my driving habit I can manage to launch it properly.

- The car has become a race car When I go past 2500 RPM, it pulls really strong, the sound is great and it is a blast to drive! Best are highway entrances, I keep it around 3K in 3rd gear and hammer it down: broooooooar nobody can follow me I don't think I went past 5.5K, no need to.

- It took time to warm up, is it because of the air gap?

- If for some reason I shift too early (i.e. it goes around or under 2k in the shifted gear), it stumbles. I basically need to rev more than what I am used to.

That's my first impression of course, I will take it this week-end for a "cruise" and see how it goes. The problem now is that it seems obvious that my 2.79 stock rear end ratio is completely off.

(time to update my signature!)

fakesnakes

Excellent news! Yes, that cam needs 3.50 or better gears for the best performance.

boogerschnot

Yep, those gears explain why you have to rev so high to get going.. I feel that with mine now..

Adrenolin

Glad you like the new setup. I personally went with the 3.25 gears with a TrueTrac limited slip. Really thought about 3.50 but its gonna be a daily driver and I wanted the fuel mileage.. (yes.. I'm silently laughing here) ..really.. fuel mileage

kalli

seems you're having a lot of fun with it :-) glad to hear. again make sure you use oil with lotsa ZDDP to not grind down the lobes of your new cam.
I would have though that the cam would pull at lower revs as well but it'll be interesting to hear how your 'cruising experience' goes

Starfury

That cam should have better low-end than that. Even my Magnum 280 (albiet w/Rhoads lifters) with 3.25 gears still has some usable power down low. You should really get your carb retuned. I suspect your carb is running lean now at low-rpm's (low vacuum condition with the new cam). This condition might also exaggerate warmup time. What kind of carb do you have?

_Remi

Hi,

The carb is a Holley 600cfm and it has been retuned. Let me rephrase, I don't think I really have a problem at low RPM, I feel like I am starting the car in 2nd gear pretty much: I have to rev it higher than before to do it correctly.

@Starfury: when you say 280 with 3.25 gears, are you talking about a T5 transmission? That's what I have with my 2.79 and now I start to understand why I am the only one with this setup...

I am about to leave for a ride: San Francisco to Santa Cruz by the Cabrillo Highway (http://tiny.cc/qO9Ss). It is the kind of road I like where I would drive 3rd and 4th gear before with the stock head/cam.

I will keep you posted!

cprstreetmachines

Sounds like a tune problem

Starfury

No, I mean my cam is the Comp Cams Magnum 280, which is quite a bit more aggressive than your XE256H. My rear gears are 3.25's. Your XE256 should have plenty of low-end power, although the 2.79 gears are definitely holding you back.

I'm not a Holley tuning expert, so I'd recommend opening another thread and seeing if you can get that low-end sluggishness tuned out a little.

And save for gears

_Remi

Hi,

I am back from my day trip (160 miles, nice roads and highway on the way back). It was pretty useful, now I am convinced that I still have a problem!

1/ Starting it was difficult: I had to maintain a small acceleration or it would stall. This has never happen before, it seems that my choke is not working anymore. Even with my old carb with a broken choke it would start without any problem. The car is in a normal garage, probably 60 degrees.

2/ Driving in the City was just like yesterday, I needed to rev high to launch the car and because I was not doing strong acceleration I did not feel any hesitation issue.

3/ Highway entrance, going up, I did a nice and strong acceleration and it was great. There was a R32 Golf next to me, he is probably very sad now! I did not hammer it down with violence, I went slowly up to 3K and then went stronger.

4/ Rest of the trip was dissapointing: I have an obvious hesitation problem under 3K (and maybe higher). I even had an explosion in the carb when I really floored it at 2K in 4th. It is not smooth at all, I have power but very bad throttle response. I noticed that when I started the car on my way back I had white smoke coming out of the exhaust. I was only able to use my fifth after 70 MPH but that's a different problem.

It is better than before (probably because now everything matches) but it is not fixed at all!

Does it sound like a running lean issue? Any other symptoms that I can look at? I would be assuming that they tuned it correctly, that is suprising.

Thanks!

P.S: Pure random, on my way down there was a meeting with a couple of Mustangs: