Really low vac with 274 cams

[dsmgsx98]

So I installed some Dsm graveyard 274 reground cams strait up and trying to figure out why the my vacuum is at -8 at 900rpm. I thought they would still have a vac of around -12 to -14 can someone that has these cams help me out

 

[Guzman08]

can u post up a video ?? i just want to see how they sound

 

[LiquidX]

274 doesn't mean anything. Need the lift and duration of the cam lobes to figure it out. Kelford claims their 272s are better than the other 272s. In a sence that's right. The reason is there 272 profile is the profile of most 280s+ in their specs.

 

[Guzman08]

the only 274s i know are gsc's

 

[Sandman817]

i have the same cams but haven't built my motor yet so i can't help you with that.

I did go on their website and found the duration and valve lift at .050"

200 duration @ .050 .408 lift

 

[Boomdeeze]

I have these cams too and my vac is really low. I need my idle to be at 1k or my brakes are hard. I tried to degree them but I still have not got it right. I only tried once

 

[dsmgsx98]

Yeah they sound pretty mean at idle, and drivablity sucks cause anything below 1500rpm and the car wants to Buck or lunge back an forth, boom are you have this problem too?

And if you degrees the cams what did You adjust the can gears to?

P.s.- these bad boys pull like a beast from 3500 to 7500 and that's on my Lil old. E3 16g. Lost all bottom end though


And here are the specs sorry for not posting.
valve lift at .050" 200 duration @ .050 .408 lift

 

[Boomdeeze]

Ya my car bucks bad under 2k when trying to idle cruise. I am going to call Graveyard tomorrow and see what they recommend for degreeing their cams. A buddy of mine had these cams in his car and he had no problems with the bucking back and forth at low rpms.

 

[dsmgsx98]

Ya my car bucks bad under 2k when trying to idle cruise. I am going to call Graveyard tomorrow and see what they recommend for degreeing their cams. A buddy of mine had these cams in his car and he had no problems with the bucking back and forth at low rpms.

Ill try calling too. Did your friend install them straight up or did he adjust them?

And have you done any WOT pulls with yours

 

[Boomdeeze]

Ya I did a lot of wide open pulls when I had a G50 on and it pulled hard al the way to 8k. We should actually try and call delta too because they might have some good insight on the cams.

 

[beihl304]

Interesting, I recently installed 272 in my car and it bucks like crazy. Is that a possible sign of needing degreed?

And to the op, I dont think that the vacuum should be that low. Since that is the only thing u did that could potentially change vacuum I would definitely try and get them degreed.

 

[2GFWDbeast]

i have hks 272's and my idle vac is at 12-13 in/hg

 

[dsmgsx98]

I will for sure be calling dsm graveyard today, hope they answer some questions

ill check my timing marks again but boomdeeze said his was the same, so i am leaning to them having so much lift its .408 and hks 280s have .403 and HKS 272 only have .399. So maybe it has some thing to do with that

 

[dsmgsx98]

So i contacted DSM graveyard. Not sure who i talked to, but a really nice guy, he said that he has had no complaints untill now, he also stated that these cams where designed with the 2.4 stroker motor in mind thats why we have no low end power on are 2.0s. he said that the lunging is normal so he is suppose to call me back with more info and a cam card because i didnt recieve one from the other owner. I really believe these cams are going to be way to big for what my set up

 

[Boomdeeze]

The lunging is not normal. A buddy runs 275's and his car doesn't buck at all at low rpms until you reach really low rpms. Bucking at 2k is not normal.

 

[dsmgsx98]

yeah it sucks i have to feather the clutch down the road to get out of my drive way!! well i really think these cams are going to be to big for my setup anyway so i might try to trade them or something cause its no fun to dd this car with these big ass cams

 

[giammojoe]

The problem comes with the lift and duration of the camshaft. If you close the cylinders and all four valves are closed you build vacuum. When the cam opens the valves, you lose the overlap of the closed cylinder and the vacuum is less/lost. You can get a vacuum canister to help relieve the vacuum issue, but it sounds as if the duration of the camshaft is keeping your valves open way too long.

 

[dsmarmy777gst]

This is crazy. I have the DSM graveyard 274 cams and ALL the same problems. Vac is -8 at idle. I have to tap the gas pedal before I brake because my brakes get hard. It also dies on start up. I am running a 2.4 so no problems with low end power loss. The cams do sound pretty beastly thats for sure!

 

[giammojoe]

The problem is figuring out whether you are daily driving or trying to get in to higher RPM's. Most long duration, high lift camshafts require an adjustment to raise the idle RPM's. The cams will start making decent horsepower at low to mid range, but really come on at the mid to high end of the RPM band. You have to decide which cam is best for your application and then tune accordingly.

 

[dsmgsx98]

This is crazy. I have the DSM graveyard 274 cams and ALL the same problems. Vac is -8 at idle. I have to tap the gas pedal before I brake because my brakes get hard. It also dies on start up. I am running a 2.4 so no problems with low end power loss. The cams do sound pretty beastly thats for sure!

I am not having the brake problem like you and boomdeeze are because i have my computer set at 850 and i have my idle adjust screw set to where when i let off the gas it goes to 1200 then falls to 950 so i never get the hard brake but it still is sucking for a dd even tuned it has no power before 3500 but after that it pulls all the way to 7500 will no problem!

 

[dsmarmy777gst]

oh nice, i didnt think about that. im gonna change my target idle and go flash it now and mine pulls really hard as well! I still dont get the whole low vac thing. My vac was around 20 when i had my bc 272s in!

 

[dsmgsx98]

it's because they are based on kelford 272 cams and hks 272 and hks 280s so they have a . 408 lift and a little longer duration than a hks 272

 

[JusMX141]

You need to get some adjustable gears and degree those cams- sounds to me like the overlap is off.

Did the cams come with shims? If so, did you install the shims?

 

[cantgo2fast]

Degreeing should help driveablity. I also have a set of DSMgraveyard 274's going in here over spring break. Did you shim them properly?

 

[dsmgsx98]

Yep 1 #10 SS washer per lash adjuster