opions and real world numbers needed

[ws6nighthawk]

ok, i've been doing a little research and i have been considering the GM847 cam and i wanna know whats some of the up and downs of this cam. I want this cam if the stock bottom end can hold it. If any of you guys are running it or have ran it your input is great :D.

thanks in advance

brian

[joelster]

ok, i've been doing a little research and i have been considering the GM847 cam and i wanna know whats some of the up and downs of this cam. I want this cam if the stock bottom end can hold it. If any of you guys are running it or have ran it your input is great :D.

thanks in advance

brian

I run the XFI468 cam 242/248 .584/.579 on a stock bottom end and it's fine. As long as the oil presure is good and the bearings are good, I don't see a problem with it. You have to spin the motor pretty high with the 847 or the XFI468. I shift around 67-6800rpm.

[ws6nighthawk]

I run the XFI468 cam 242/248 .584/.579 on a stock bottom end and it's fine. As long as the oil presure is good and the bearings are good, I don't see a problem with it. You have to spin the motor pretty high with the 847 or the XFI468. I shift around 67-6800rpm.
ok let me ask you this, when you upgraded to this cam, did you also do injectors and 255lph? if so what lbs injectors and did the 3.73 make up for the lack of low end since the power range is higher? what can make the oil pressure not good enough for the bottom end to spin that high? also what kind of number did you put down and finally do you have stock heads?

[Spartan7]

The stock pump should be enough for just a cam. The stock injectors will max out with that cam, some 30# or more should be enough for you.

[AChotrod]

I say get a LE custom cam!!!!

[Joker Z28]

Your revving your stock bottom end to 6800?

[Z28pr0jekt]

I have 30#'s for sale :) haha

[mrbadlt1]

Your revving your stock bottom end to 6800?

x2, if you have an automatic car the gm847 is too big for an auto car, i would not spin the stock bottom any more than 6400, like achotrod said get a custom LE cam

[ws6nighthawk]

I say get a LE custom cam!!!!
will they grind one up kinda to those specs but more forgiving?

Your revving your stock bottom end to 6800? nah i was actually asking a ?. i was reading and some do but the ones that has revved it that high on a stock bottom end continuosly have spun bearings.

I have 30#'s for sale :) haha
how much you asking for those 30#'s?

x2, if you have an automatic car the gm847 is too big for an auto car, i would not spin the stock bottom any more than 6400, like achotrod said get a custom LE cam
mines is an M6 and i was thinking of also putting 4.10's in the rear. do you know of a cam thats close to that GM847 that in the XFI series comps?

[gregrob]

XFI is more aggressive lobe profile so you can attain the same lift as the 847 with less duration.

LT1's love short duratio / high lift cams. Thats why I went with XFI lobes.

People wanting these huge donkey dick cams have no idea what theyre in for, and when they get them they have no idea what theyre missing, because theyve never ran anything else.

Big duration cams with tons of overlap sacrifice under the curve, bleed off cylinder pressure (read dynamic compression), drive like ass for a street car, etc.

You dont have to sacrifice all that to make power. Sure if you are doing a RACE ONLY setup then you can obviously live with all that stuff and you can GEAR and set up the car to run in that big cam's narrow power band, then the donkey dick is worth a few 10's over a smaller grind.

You need to focus on valve events, and not get caught up on the numbers when choosing a cam.

My car has proven this theory. I have what some would consider a TINY cam (duration-wise at least) and I have WALKED cars with way bigger cams and way more mods.

The low rpm powerband is explosive, its brutal on the street. I've driven bigger cammed cars and mine is waayyy more fun. And most of the time I will be in front of the donkey dick cammed car because my car is just nasty out of the hole and bangs through the gears and is GONE while theyre still waiting for their big donkey dick cam to spool up like a damn turbo lol.

I'm telling you dont jump on the bigger is better bandwagon. Pick a cam that has a controllable amt if overlap maintains or even increases DCR (mine did) and has enough lift to take advantage of the flow capabilities of you top end, and you'll be happy with it.

.02

Greg

[Z28pr0jekt]

how much you asking for those 30#'s?



140 shipped

http://ltxtech.com/forums/showthread.php?t=6336

[joelster]

Your revving your stock bottom end to 6800?


Yes.

My shortblock is out of a Caprice or Roadsmasher. It was disassembled, looked at, cleaned, and re-assembled with new bearings a light polish on the crank, and the stock oil pump. We had no idea of the mileage on it so we figured we had better put new bearings in it just to be safe. This bottom end was supposed to be just a "motor to tide me over" until I built a solid 383, but it has run for 3 1/2 years now without a hitch. I shift it at 67-6800 when i'm beating on it. The oil pressure is very good though, or I wouldn't do that sort of thing. On a cold start it will go up near 80lbs, at a hot idle it is at 20-25lbs.

[Joker Z28]

XFI is more aggressive lobe profile so you can attain the same lift as the 847 with less duration.

LT1's love short duratio / high lift cams. Thats why I went with XFI lobes.

People wanting these huge donkey dick cams have no idea what theyre in for, and when they get them they have no idea what theyre missing, because theyve never ran anything else.

Big duration cams with tons of overlap sacrifice under the curve, bleed off cylinder pressure (read dynamic compression), drive like ass for a street car, etc.

You dont have to sacrifice all that to make power. Sure if you are doing a RACE ONLY setup then you can obviously live with all that stuff and you can GEAR and set up the car to run in that big cam's narrow power band, then the donkey dick is worth a few 10's over a smaller grind.

You need to focus on valve events, and not get caught up on the numbers when choosing a cam.

My car has proven this theory. I have what some would consider a TINY cam (duration-wise at least) and I have WALKED cars with way bigger cams and way more mods.

The low rpm powerband is explosive, its brutal on the street. I've driven bigger cammed cars and mine is waayyy more fun. And most of the time I will be in front of the donkey dick cammed car because my car is just nasty out of the hole and bangs through the gears and is GONE while theyre still waiting for their big donkey dick cam to spool up like a damn turbo lol.

I'm telling you dont jump on the bigger is better bandwagon. Pick a cam that has a controllable amt if overlap maintains or even increases DCR (mine did) and has enough lift to take advantage of the flow capabilities of you top end, and you'll be happy with it.

.02

Greg

That's pretty good advice.
BTW how much you think would be safe to rev a stock bottom end for a DD/strip car?

[gregrob]

I'm admittedly not the best person to ask. With stock rod bolts I'm leary about anything over 6400. Thats where I'm shifting now.

I also think people make it more of an issue than it really is though. There are a lot of people on the 6500+ territory and have been for a long time.

I do know I'll be switching rod bolts whenever I get the chance, just for the added security.

[gregrob]

Yes.

My shortblock is out of a Caprice or Roadsmasher. It was disassembled, looked at, cleaned, and re-assembled.with new bearings a light polish on the crank, and the stock oil pump. We had no idea of the mileage on it so we figured we had better put new bearings in it just to be safe. This bottom end was supposed to be just a "motor to tide me over" until I built a solid 383, but it has run for 3 1/2 years now without a hitch. I shift it at 67-6800 when i'm beating on it. The oil pressure is very good though, or I wouldn't do that sort of thing. On a cold start it will go up near 80lbs, at a hot idle it is at 20-25lbs.

Did you guys do arp rod bolts or anything?

[joelster]

Did you guys do arp rod bolts or anything?

No. Just the stock stuff, rods, bolts, pistons, rings etc...all were reused. Just new bearings (not sure of the brand) and a light polish of the crank. Everything was torqued to factory specs. This motor was built just to get me back on the road in a hurry, no $$$$$ were thrown at it.