1989GTATransAm

iTrader: (3)

Kevin91Z did the initial tune on the can last night so that I can drive it and break in the new motor. Mods in my signature.

Maybe it's Kevins excellent tune but I'm very happy with the drivability of the XFI268 cam. Better than I would have thought. Here are the advertised specs at .050". They are 218/224. However the cam doctor and our degree wheel check actually puts the cam at 220/225 degrees. A little bigger than advertised.

It idles very nicely at 750rpm. Best it has in years and with the biggest cam the car has seen. The throttle response is very crisp with no lag or sluggishness at all. I did not go over 4000rpm driving the car around for the intitial break in. The idle sounds almost stock with very little lope. So in my opinion if you want a cam with a lot of lope this is not the cam for you.

The vacuum is between 14 and 15 inches of mercury which is quite good to run all the accessories including the power brakes. After I get some miles on the car we will take it to the dyno for the WOT tuning. Got to see how close I can get to 400rwhp. Hahaha.

Mark 89Formula

This is a really encouraging start. The short seat duration and 113 deg LSA are helping out driveability and vacuum. Here's hoping the fast ramps and mega lift get you the dyno reading you're looking for. I have little doubt you're going to have one of the fastest naturally aspirated LTR style cars.

Mkos1980

iTrader: (8)

Good News!!. I hope to be swapping in the 280 XFI soon. BTW what was your P/V clearance with the 570ish lift?

1989GTATransAm

iTrader: (3)

I did not measure the P/V clearance as I was told it would not be an issue with the advertised 218 degree duration.

I found the cam doctor sheet last night. The cam actually measures 220.7 degrees on the intake and 225.6 on the exhaust.

I also have the 2.05 intake valves that will also help on the cylinder filling at all lift's. So far so good. I took it up to 5000rpm yesterday. No lack of power I can tell you that. Very responsive to the throttle. Just got to put some milage on it before I let it rip to 6000+rpm with some WOT runs.

thirdgen88

Hey guys!! Nice to see good results with the XFI 268... I just set my motor back in the car (will be putting the rest back together tomorrow).. I installed the very same XFI 268 cam in my E-Tec 200'd 355ci... I also installed the 26986 beehive springs.. Should make for some interesting fun... I've [obviously] got the SDPC TPI manifold along with Edelbrock runners, along with good exhaust... I've got the Ostrich ready to go, tuning sounds like it might not be too bad with this cam...

I'll let you know how mine runs!

1989GTATransAm, just curious, which springs did you go with??

Mkos1980

iTrader: (8)

I ended up going with 918 Springs with the 280.

1989GTATransAm

iTrader: (3)

I also went with the 918's and associated Comp Cams hardware. I have them shimmed from .050" to .060" of coil bind. That appears to be the hot ticket these days from what I'm told about beehive springs.

We made a nice first run with the motor to get it heat soaked. Then let it cool off. No high rpms. Rechecked the bolts on the runners and exhaust system and looked for leaks etc.

I went with the Comp Cams 1.6 Pro Magnum rockers, 7/16" studs and 3/8" pushrods. Went with the factory 2nd generation roller lifters. I want to keep the spring action from the valvetrain parts to a minimum.

Mkos1980

iTrader: (8)

What did you set the springs up at? I know stock was 1.8 per comp but when talking to bret baur about it, he said he likes to set these springs up at 1.75-1.77.

1989GTATransAm

iTrader: (3)

Bret is one among many that likes the tighter numbers from what I have read in some of his later posts. Mine came out around 1.750" with my .570" lift cam. I would have to run the numbers again but that number is close enough.

widarsson

Any more impressions with the new cam?
I am following this thread with great interest since I have that cam in my motor but the motor is still out of the car

EvilCartman

iTrader: (1)

Bah, let that new engine rip! hehe First time out with mine it saw 6000 rpm, the following week it burried the stock tach at 7000 rpm. Only mechanical problems with it have been 2 broken pushrods over the last 3+ years.

KZad

Will that cam fit in a motor (305 TBI) with stock heads and intake? Has full exhaust. If not, how about an '86 355 with stock intake and heads.

Dyno Don

iTrader: (7)

That cam will not fit any stock headed motor.

1989GTATransAm

iTrader: (3)

Hehehehe. I let her rip yesterday while doing some data logging. Feel I have enough miles on it. The tires are not up to the task. It wants to break loose anytime in first gear when I nail it most of 2nd gear.

As far as driving impression I'm still amazed at the idle. Drivability is great. I would say it is virtually like stock. I don't want to jinx it put there seems to be a nice power increase over the last motor. Old numbers in signature. I will have more info when I get it on the dyno. Then onto the 1/4 mile track.

One thing to remember is that this motor has all the supporting mods for horsepower. By that I mean a free flowing exhaust system with the latest metallic spun catalytic converters etc. The 3.5" cold air intake should have no restrictions along with the 58mm throttle body. The only restiction is the Edelbrock intake manifold which has been Extrude Honed. I will fix that with the First intake.

thirdgen88

Well, I'm still roughing in the tune... I've got the idle a little better, and the low/midranges the fueling seems decent (still need to do more logging/tuning sessions)... I've got a question for you 1989GTATransAm... What kind of kpa's are you getting at idle?? I'm at about 55 kpa... Idles well, but not quite stock on my end... I think I might need a bit more idle spark advance, but still working on it... Glad things are going well on your end... This cam doesn't suck, thats for sure!! I think these beehive springs aren't hurting anything either!

1989GTATransAm

iTrader: (3)

Yes the beehives are part of the combination along with the rockers. The cam was designed on the \Spintron with those combination of parts.

I will have to check my KPA on the computer for the latest. When Kevin was tuning he mentioned the KPA was around 52 at idle. Now that I have some milage I will look at the datalog and check it.

1989GTATransAm

iTrader: (3)

OK, fired up the laptop and looked at my data logging. I would say the average KPA is 51 at idle. It varies a tad. By the way I'm running around 10.75:1 compression so that may be a factor.

norcalz28

iTrader: (13)

I know this is an old thread, but where did you end up setting your timing? I have a new engine with the xfi268, and at 6BTDC it seems to be running hot. Stable temp at idle, but between 1500 and 2K it will start to climb. Just wondering where your timing is at to compare. Thanks

Will

1989GTATransAm

iTrader: (3)

6BTDC. By the way did you degree the cam when you installed it?

norcalz28

iTrader: (13)

I did not degree the cam. I lined up the marks on the sprockets. I've got get at 6btdc now and while it runs decent, I may have to play with it a bit. Thanks

NAITSIRHC

I'm running this cam with brodix ik180 heads and first intake. Think i could buy a chip from your tuner?