z28tommy

Hello fellow lt1 owners I'm in the process of rebuilding my motor due to a spun bearing.I'm gonna do I cam swap since the motor is out and completely apart.I currently have long tubes,373 gears,k&n intake, and a 58mm throttle body the car is a six speed.I'm getting the stock heads ported as well as the intake I will be upgrading top bigger injectors and Walbro 255 fuel pump.I called up comp cams and was told to go with the 280 XFI cam.is this a good enough cam or is there better for my setup? Any advice would be greatly appreciated

96capricemgr

iTrader: (1)

I would call it too much duration for a CA emissions driver, with the 6 speed and a cam like this I would say 4.10s too.

Comp claims an rpm range of 2000-6000 with this cam but reality is you will be turning this solidly over 6500.

I get the feeling this is a local machineshop port job, if so save the money on the intake porting, an average port job and an emissions cam on a mild 355 aren't going to really see a lot of gain from it.

If you want to go with a shelf Comp cam the 503 is probably about as big as you should consider.

Mystery Bird

iTrader: (7)

I ran the XFI 280 for a few years and liked it, took it into the mid-upper 11's with stock internals and home ported heads. 96capricemgr is correct, you really need to spin it pretty high for maximum performance. I was running an auto most of the time. I did put a six speed in my car for a few months with 3.73 gears and it was OK. It would drive out of the hole but then around 5k RPM's power would come on strong and it would blow the tires off then would have to short shift.

z28tommy

Is the 503 the best I can do I really don't care about emissions since the car doesn't pass anyway the intake porting I will be doing myself what valve springs would be best?

supermaro

iTrader: (64)

280xfi does pass emissions in cali. It's not Carb approved but it will pass the sniffer.

96capricemgr

iTrader: (1)

and it is still bigger than necessary especially with 3.73 gears.
If you think bottom of the catalog page is important just go all out and do the 292.

Could you do better than everything discussed sofar, hell yeah, but maybe not by ordering shelf Comp grinds.

The fact you are asking about springs when the cam is still up in the air suggests you need to slow down and do some learning before you get this too screwed up.

nitrous2fast

iTrader: (2)

In your situation i would lean more towards the comp 268xfi aka the 466 part number wise.
It's smaller than the 280, and will also shift power lower in the rpm band. The 13* lsa will keep it emissions friendly too.

z28tommy

Thanks for the info I'll do some research on my own

96z28_lt1

iTrader: (3)

i just did a cam swap to the 280xfi cam as well, i love it but at thee same time it is the first cam ive ever had thats aftermarket, no track times, or dyno numbers, but i will tell you i have cam surge with stock m6 rear gears, and have some kinks that need to be worked out with split fuel trims but it sounds good with the 113lsa its not excessivley choppy and you can hardly tell its cammed just sounds like i have loud exhaust, and these cams do like the higher rpms pulls reall hard up top... as far as springs go they recommend beehives, but ive got patriot gold extreme springs and they see to be doing just fine


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BALLSS

+1^^

I run it in my 383, smog legal but frankly that is due to the tune. Mild idle and great low end TQ which for my 4200lb car works great

there are other options like custom grinds from AI or LE that perform very well especially when matched with their heads

if the 268 aka 466 XFI cam COMP 918 springs. the 280, IMHO, is to large for your application