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

 

[dsmgsx98]

How hard is it to degree cans when the motor is in the car

 

[Sandman817]

you degree the cams with them installed the car with a set of adjustable timing gears. well that is the easiest way atleast, with the new timing gears.

 

[dsmgsx98]

, I know that! I was wondering how to set up the degree wheel and all that stuff with the frame in the way

 

[JusMX141]

That may be a difficult task- you may do better on your own just by retarding the exhaust cam a little or advancing the intake...or both.

Overlap is used on racing applications to use the intake pressure to help evacuate the exhaust from the cylinder. As you can see, with a lot of overlap at high RPM the engine makes a lot of power, but your torque curve is ruined when you're not making boost because the engine no longer has vacuum.

On vacuum, the overlap is now working the opposite way- the exhaust is drawing the pressure out of the intake manifold, and you're left with a much lower vacuum number at the manifold.

I'd suggest getting in touch with Delta direct and ask them these questions- DSM Graveyard is not going to be able to answer questions for you regarding cams that they did not grind.

 

[dsmarmy777gst]

I'd suggest getting in touch with Delta direct and ask them these questions- DSM Graveyard is not going to be able to answer questions for you regarding cams that they did not grind.[/QUOTE]

+1

I have a set of adjustable cam gears. I adjusted them with the 272 cams but have not yet with the 274s. that would explain a lot as far as idling and drive-ability issues go.

 

[dsmgsx98]

Thanks Justin, ill call Delta today. What would you suggest starting out on the adjustment of the cams

 

[95gst16g]

Just curious...I have Delta 272 cams and i lost a little bottom but oh well.Anyways if they are a stock regrind how can they have more lift then a stock cam? I get how they can have longer duration and overlap etc but if they just grind stock cams how would the lobes get taller?

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[Boomdeeze]

Just got off the phone with delta:

He said to try and advance your intake came 2* and retard your exhaust cam 2*. If this doesn't work to call back and they will try and solve this problem. He also said that if we can't get this figured out, he will be willing to regrind our cams back to 272's for free. Don't know if he meant everyone who has 274's but Said he will regrind them to cams that are proven to work.

 

[dsmgsx98]

So when are you going to adjust them? Ill let you first because you already have gears. .. and I am willing to send them back for some 272.

 

[Boomdeeze]

My motor is being dropped in this weekend Call and talk to them, they will tell you everything.

 

[dsmgsx98]

OK ill call thanks bro

 

[RT-AWD]

With my Kelford 272s I see -10.

 

[dsmarmy777gst]

I'll make an attempt to adjust my gears. I'll let you guys know what happens

I'm gonna try to do it before i work tonight.

 

[Boomdeeze]

^^^ Thanks

 

[empie1]

That may be a difficult task- you may do better on your own just by retarding the exhaust cam a little or advancing the intake...or both.

Overlap is used on racing applications to use the intake pressure to help evacuate the exhaust from the cylinder. As you can see, with a lot of overlap at high RPM the engine makes a lot of power, but your torque curve is ruined when you're not making boost because the engine no longer has vacuum.

On vacuum, the overlap is now working the opposite way- the exhaust is drawing the pressure out of the intake manifold, and you're left with a much lower vacuum number at the manifold.

I'd suggest getting in touch with Delta direct and ask them these questions- DSM Graveyard is not going to be able to answer questions for you regarding cams that they did not grind.

I find it amusing dsm graveyard labels these delta cams as their own.... Wtf

 

[dsmgsx98]

I'll make an attempt to adjust my gears. I'll let you guys know what happens

I'm gonna try to do it before i work tonight. ]

Please do cause if it doesnt help he said 50$ and he would regrind to hks 272 spec and i would have these cams out and to him by tomorrow,

I find it amusing dsm graveyard labels these delta cams as their own.... Wtf

He said they came to him with the specs and he regrinds them and then dsm grave yard puts there mark up on them and sells them as there own cams, pretty funny

 

[aba60620]

Just curious...I have Delta 272 cams and i lost a little bottom but oh well.Anyways if they are a stock regrind how can they have more lift then a stock cam? I get how they can have longer duration and overlap etc but if they just grind stock cams how would the lobes get taller?

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The lobes don't actually get taller on a re-grind cam, they get smaller because you're taking material off. So to compensate, shims are used to effectively gain lift. Thats why on re-grind camshafts you have to use the recommended shims for that particular cam.

 

[RadDsm]

FFWD does the same thing as DSMGraveyard with Delta cams... it's not an uncommon thing.

 

[empie1]

FFWD does the same thing as DSMGraveyard with Delta cams... it's not an uncommon thing.

Uncommon? No...but stupid...yes. Why have a middle man when you can deal with delta directly?

 

[RadDsm]

Uncommon? No...but stupid...yes. Why have a middle man when you can deal with delta directly?

I agree.

 

[cantgo2fast]

Ya keep us informed, Hopefully ill have mine going in next week over spring break. I think with cams this big you really need adjustable gears. I was going to start with -3* exhaust +3* intake.

 

[dsmarmy777gst]

retarded the exhaust 2 degrees and and advanced the intake 2 degrees. my vacuum is almost 15 now so i assume if I went another degree or so it might drop a bit more? Any ideas? I dont know, my gears could of been out of whack in the first place. When i swapped in a 4g64 I used my 4g63 adjustable cam gears and just matched them to stock 64 gears, so i dont know if that makes a difference or not.

 

[dsmgsx98]

How does it pull wot and how does it drive

 

[Boomdeeze]

retarded the exhaust 2 degrees and and advanced the intake 2 degrees. my vacuum is almost 15 now so i assume if I went another degree or so it might drop a bit more? Any ideas? I dont know, my gears could of been out of whack in the first place. When i swapped in a 4g64 I used my 4g63 adjustable cam gears and just matched them to stock 64 gears, so i dont know if that makes a difference or not.

Dam 15!!! Thats pretty good for 274 cams, how does it feel at WOT?

 

[ilco187]

i pull 16 with stock is that bad?