loneroad

iTrader: (3)

i guess im looking for some advice

what have you guys done when youve just went a little to radical with a cam choice?

yank it,sell it. or try to work around it.

I had a comp cam xr270hr in my old setup. my new setup has a comp cams nx 288hr.

im thinking i might of went to radical for a all around fun car.(drag, autcross, road course and DD)

AlkyIROC

The XR270HR is for the street. It says it's the largest you can still use with a stock converter.

The NX288HR is a nitrous cam. It's probably a little too much for a daily driver. You need at least a 2500 stall converter and deeper gears to make it work. It only has an rpm limit of 6500 so I wouldn't consider it too radical.

If you don't want to build a car around a cam grind then pull it out and install a cam grind more suited for what you've done to the car.

Without knowing exactly how your car is built, it's hard to say which cam is better.

gtpro700

Depends what you have for a motor but doesnt look like that radical of a cam in my eyes. My cam is around the same duration but I have a ton more lift and I drive it all around. I guess its just what your looking for. Let us know what your motor combo is and what you might be worried about...

loneroad

iTrader: (3)

the old set up was,
383
pro comp heads
1-5/8 shorty headers
holley 770 sa
75 shot
xr270 hr cam
ran 11.8x consistently .

Great street setup. I wanted a little more..

new set up.
383
afr 1095
nx288hr
quick fuel q750
1-3/4 long tube into 4in ex
175 shot
1.6 ultra magnum rr
afr rev kit


i have a 2800 stall in it. and 370 gears waiting to be put in.


i researched the cam for awhile. i didnt think it was very radical myself.i even called C>Cams and talked with tech for awhile.

To keep it in the rpm range 2400-6500, i was looking to swap the 700r4 for a th350.and swap in the 370 gears.

ill be the first to admit all this could be me. Its been 2 yrs since actually driving the car. But its the mannerism of the powerband that im not really liking at the moment.

//<86TA>\\

iTrader: (14)

i have the xr288hr, very similar to yours, in my 408, its far from what i would call radical. I would DD my car if i had too. Drove it to carlisle a couple weeks back (almost 3 hours with traffic), it was a pleasant drive.

its a little doggish under 2300 rpm or so, but its a 5 speed car with 3:70 gears, so its easy enough to keep in its powerband.

AlkyIROC

Biggest mistake anyone can make. They want a car that runs around town with a fuel economy low rpm yet install a cam that starts to make power above the rpm they'll usually drive.

I'd ditch the 1.6 rockers and put some 1.5's back on it. That should tame it down slightly. You already bought a high lift cam then decided you wanted more by switching the rocker ratio. The increased lift might only be worth 5HP but you also changed how the cam performs especially at the lower rpms.

Your single 4" exhaust is a little overkill. A single 3" or 3-1/2" would have been more than enough. The large tube is killing the low end torque. Same with the 1-3/4" headers with such a small engine and such low rpms. 1-5/8" would have worked better. If it was a 400+ CID then the larger diameters would have been better suited.

You're not spinning the engine high enough to need a rev kit.

loneroad

iTrader: (3)

it was my undersatanding hyd rollers would start floating the valves at 6k. id be spinning close to 68k.

AlkyIROC

With the camshaft only making power to 6500, I doubt you would get it to 6800.

I have no idea what a hydraulic roller would do at that rpm. I run solid rollers and spin my engine to 7600 without a rev kit.

brandoz28

iTrader: (1)

my buddy daily drove an xr288hr in his car with a 350 and vortec heads, drove great IMO. had a 3000 stall in a built 700r4, and 3.73's in the rear

loneroad

iTrader: (3)

the headers are 1-3/4 into a 2.5 collector. into a 3in y. and then into the 4in.

i talked to a few people about doin a stepped up exhaust. i understand about losing some bottom end with bigger headers.

the general ides is to keep the pulses tight together until they pass the y., and utilize the scavenging effect. after that . out as fast as possible.

usaully there is some debating, head scratching. but noone has ever told me it wont work. so i did.

loneroad

iTrader: (3)

2400-6500 will be the rpm range ill be driving in once the gears and trans go in. fuel economy isnt an issue.

Shagwell

full cam specs for those of us who are lazy? lol

Compression will make or break a camshaft; the larger the cam, the more critical of a roll it plays.

My street motor was a 355 sbc, topline 200cc alum heads; hyd roller 242/248@ .050, .567/.585 lift with 1.5's, 110ls. It ran well with the Team-G intake and 750 holley, though likley would have made better all-around power with an RPM air-gap style intake. That motor spec'd out at 10.989:1 compression, I ran 34-36* total timing on 93 pump gas. - With the 5-speed and 3.73 gears I could(meaning if I wasn't pounding on it) average 15-16 around town and 20-21 on the highway at 75mph; the car ran high 11's at considerably more weight than most.

loneroad

iTrader: (3)

im not explaining myself very well so i got up this mornng and drove out to a industrial complex thats in foreclosure. so i can make some mental notes. the i/d park has roughly 1/8 th mile straight aways and big sweeping curves.

on the drive over. it is like 86ta said. doggish under 2300. manually shifting the car i can keep it where i want. not an issue.

straight line.. 1st is useless w street tires......rolling in 2nd and hammering it is awesome. gobs of torque. the car screams thru third. i ran out of road. i cant wait to get it to a prepped track with some slicks, not to mention actually spraying it. again not an issue.

now going into corners and dwn shifting isnt a prob. its coming out of the corners that is. it tends to want to come in a little to hard to fast.
im having to really feather the throttle and drive the car. the best way i can describe it is instead of a power curve, its more like a power spike.
i did bring my timing light with me, to pull a little timing out while running in the curves and lay it back a little. but left dist wrench laying on tailgate of my truck. at the moment thats still up in the air.

loneroad

iTrader: (3)

comp cams 08-303-8

236-248@50
520-540 lift
113 lsa

11.1 comp
20 init 18 centr
93 oct
im running the rpm air gap.

the last time i weighed the car it was at 3725. alot has changed since then

Shagwell

Sounds like it could use a little more converter, but otherwise not horrible.

pancherj

I have a similar cam in my 355, but it is on a 109LSA. I recently switched from a miniram to an Air Gap with a 750 annular Mighty Demon. Night and day difference! The new setup pulls more vacuum at idle (don't need a pump anymore) and the power curve is much better. There is definitely morre down low than before. I have the same heads and compression as you too. Do you have vacuum advance with that distributor? I have mine set at 18* initial, 20 mechanical and the vacuum takes it up to about 52* at cruise RPM. I would like to go to 25* initial and only 10-12* mechanical, but that will require some mods to the HEI. Also, is the 11:1 measured compression? If the timing is well sorted, I would be looking for more converter (3600 minimum) and also gears (probably 4.10's).