Hey guys, just got a question for you about LT1s and cams.

I've got a basically stock '97 LT1 engine w/6-spd to play with the 561 (?) casting heads on it.

What I'm wondering is this - I've been told by many LT1 guys that the GM #847 cam (is this the LT4 hot cam?) is a good cam to use on a stock-ish 6-spd LT1 engine. Now, what I want to know, is what is needed to make a cam like this work in my LT1? I looked at the specs for this cam at Summit, and its something like .540/.560 lift with a 1.5 rocker - can stock LT1 heads handle that much lift? Or would they need removed and have the valve guides cut down? I realize I would need to change the valve springs of course - LT4 hotcam springs?

Also, would a cam this big need ECM tuning chages? Or should it work fairly well with the factory tune? I'm pretty new to EFI, so I don't really know this stuff yet. It came with an OBD2 ECM, for what its worth.

 

847 is not the hotcam. The 847 is going to be a bit much for a mostly stock lt1. If your going to go with an off the shelf cam I would recommend the cc 305 or 503. Check out eportworks.com for good heads and cam package.

Might want to look into switching to an obd1 comp. Easier to work with when adding mods. As with most upgrades only way to see the full potential is to get a good tune. Hope this helps some.

 

Any of the aftermarket cams that are for the LT1 you will need to swap out the valve springs to be safe, It would be best to swap over to OBDI for ease of tuning (not to mention a tad cheaper) but for the cams, look at the XFI series that Comp makes, even though the 305 and 503 are made for the LT1, the XFI are exclusive LT1 cams that can be bought at a reasonable price, make good power with little tuning done on stock heads (with valve springs of course)

 

if you look on ls1tech.com you can find a cam guide that someone has created....heres the link http://ls1tech.com/forums/showthread.php?t=826333

 

Tuning isn't an issue... I know a few local guys with software for the '96/97 OBD2 LT1 F-bodies, so me or maybe one of them should be able to handle it as far as tuning goes.

How much lift can a stock aluminum LT1 head handle? I know the older small blocks are usually limitted to around .460 or so....?

I know I'd have to change valve springs, I'd get a set to match whatever cam I used in the engine.

 

oh the stock heads can handle about .580 or so, you'll just have to maybe change pushrods to keep the geometry in line. As far as swapping to OBDI, they handle the tuning better, and aren't as finickey as the OBDII setups.

 

.580? Really - that much?? Wow...

So can a stock rocker also handle that kind of lift, or will they bind up at a lower lift number?

I'm just trying to find out what the mechanical limits are for a cam swap w/o removing the heads from this engine.

 

Would be worth putting full self aligning roller rockers on to be safe.

 

the 847 is definitely not the lt4 and it might be a bit much but can be done i think you might be happier buying the lt4 hot cam kit that comes with rockers, springs, cam,ect... I've been running it in my 97 TA for years now and tuning isn't bad at all. in-fact you can run it on the stock tune you just wont get the full potential out of it or you can go bigger but it great for a dd

link to lt4 hot cam kit

http://www.sdparts.com/product/12480...mshaftKit.aspx

 

So the real hotcam (not the 847 I mentioned) would be just fine without any tuning? Will it cause any issues with the computer - engine lights etc? Or is it tame enough that the computer can deal with it as-is?

 

It will cause the ses light to come on as it is just a little erattic and makes the ecm think theres a misfire, but no big deal that can be tuned out and a tune will help take full addvantage of the cam. If you don't care, for a bit you can run it w the ses light on, but if you live in an emmissions county like i do the light has to be off to pass. I have been running it in my 97 ta for about ten years now. If the cars 95 or older it wont matter about the emissions so long as the tail pipe smells good.

 

is the same as the 93-96 f-body cams....even the same as the y-body

 

It will run half way decent. When I did the HOT cam in my 96 WS6 back in 97, I would get the SES light for random misfire. Mine also ran incredibly lean at WOT. So much so that it would buck. Even on a dyno, you could see the car bucking. Nobody tuned OBDII back then so I had to switch to a 95 computer. Now its no problem to tune OBDII.

Mine also passed the tread mill for emissions quite easily. I had SLP headers and stock dual cats. It was a great running little cam. I was able to run 12.4 with it, got great gas mileage even with 4.10 gears.

 

just a questionfor the above post are your running 4.10s in a 6 spd car? i have a 94 formula and for some reason it has 2.76 gears dont ask me why it doesnt have 3.42s but o well i want to put either 3.73 or 4.10 in it what rpm do you get in 6th down the highway? and what all mods do you have when you went 12.4? my car is bone stock except exhaust. and one thing to mention on camshaft choice comp and crane cams......not so good. i have done research and compared many camshafts in my day on the dyno developement. the materials used for their cmashafts are unreliable and low grade. so far the best camshaft i have come across has been lunati cams their 122 cam for lt1's is a bad dude on the strip and street

 

IMO, i wouldn't even bother with the hot cam kit. Do the job right the first time so you don't end up doing it twice. IMO one of the better off the shelf cams is the cc306. Its a pretty big cam but will drive just fine on the street with a t56.

However, I would save up and do heads and the same time, then have a custom cam done to match the heads. This will get you the best performance but will cost a good deal more.