Detroit Rockers SC cams with heavy springs and VCT

[wht67]

I am getting very close to starting my engine build and I need to make a decision. I have a set of ported big valve heads that I purchased used and had Modular Head Shop check out for me. They said that the springs on the heads were Pacaloy set up at 95# on the seat. I currently have a brand new set of Detroit Rocker cams for supercharged applications that I had planned to use but I am worried about VCT. Will VCT be able to reliably handle retarding cams with the heavy springs I have with the Detroit Rockers?

Would bigger (more lift) cams be easier for VCT to control with the heavy springs?

info on build:
JDM 302 forged stroker short block stock compression
ported big valve heads with Pacaloy springs
IW 10% OD balancer
oil pump with TSS billet gears
ID1000 injectors
Detroit Rocker SC cams (or???)

 

[BruceH]

Do you have the cam card and if so can you post it up? I'm mostly wondering what the intake centerline is. That info will help to determine what to do about vct.

Most people don't have good results with heavier springs and vct. There are some exceptions.

I am getting very close to starting my engine build and I need to make a decision. I have a set of ported big valve heads that I purchased used and had Modular Head Shop check out for me. They said that the springs on the heads were Pacaloy set up at 95# on the seat. I currently have a brand new set of Detroit Rocker cams for supercharged applications that I had planned to use but I am worried about VCT. Will VCT be able to reliably handle retarding cams with the heavy springs I have with the Detroit Rockers?

Would bigger (more lift) cams be easier for VCT to control with the heavy springs?

info on build:
JDM 302 forged stroker short block stock compression
ported big valve heads with Pacaloy springs
IW 10% OD balancer
oil pump with TSS billet gears
ID1000 injectors
Detroit Rocker SC cams (or???)

 

[RocketcarX]

Wouldn't the spring pressure over power (if it was going to) the VCT regardless of the cam grind?

 

[wht67]

My scanner is not communication so I had to take a picture. Not a lot of info on the cam card


Here is the info I got when Modular Head Shop worked my heads:

 

[BruceH]

If I was in your shoes I'd just get comp 127550 and call it a day.

On a side note how in the world does a company expect anyone to properly tune without knowing cam timing events? The fuel injectors have to be told when to start spraying in the tune. It's dependent upon when the valves open. Valve opening also helps to guesstimate how much if any to retard the cams at higher rpms. Depending on the cam sometimes you can just lock them out at a certain intake centerline and still be ok. Especially with a positive displacement blower where a small loss at lower rpms won't be noticed.

Do you have the ability to degree your cams to find out the icl (intake center line)?

 

[wht67]

If I was in your shoes I'd just get comp 127550 and call it a day.

On a side note how in the world does a company expect anyone to properly tune without knowing cam timing events? The fuel injectors have to be told when to start spraying in the tune. It's dependent upon when the valves open. Valve opening also helps to guesstimate how much if any to retard the cams at higher rpms. Depending on the cam sometimes you can just lock them out at a certain intake centerline and still be ok. Especially with a positive displacement blower where a small loss at lower rpms won't be noticed.

Do you have the ability to degree your cams to find out the icl (intake center line)?

I don't currently have the tools to degree my cams. I have followed your posts in other threads and that was what got me thinking about not using the DR cams. I am wondering if I should look into having some custom cams ground like the 127550 profile but with 108 intake centerline like you have in your big bore then locking the VCT out.

 

[BruceH]

I don't currently have the tools to degree my cams. I have followed your posts in other threads and that was what got me thinking about not using the DR cams. I am wondering if I should look into having some custom cams ground like the 127550 profile but with 108 intake centerline like you have in your big bore then locking the VCT out.

You don't need special grind cams. Just get a set of shelf 550 cams and install them retarded with the tfs crank gear set. The DR cams might be fine for your application, it's hard to tell without any specs though. I don't understand the "secret" aspect of the cam specs. IMO it's more for marketing than for protecting a big "secret". I can't see any shop recommending a cam that doesn't come with a card but that's me. All it does is make it harder to get the best power out of them which is counterproductive imo.

 

[05stroker]

You don't need special grind cams. Just get a set of shelf 550 cams and install them retarded with the tfs crank gear set. The DR cams might be fine for your application, it's hard to tell without any specs though. I don't understand the "secret" aspect of the cam specs. IMO it's more for marketing than for protecting a big "secret". I can't see any shop recommending a cam that doesn't come with a card but that's me. All it does is make it harder to get the best power out of them which is counterproductive imo.

Unless they install it and tune it for you...

 

[wht67]

You don't need special grind cams. Just get a set of shelf 550 cams and install them retarded with the tfs crank gear set. The DR cams might be fine for your application, it's hard to tell without any specs though. I don't understand the "secret" aspect of the cam specs. IMO it's more for marketing than for protecting a big "secret". I can't see any shop recommending a cam that doesn't come with a card but that's me. All it does is make it harder to get the best power out of them which is counterproductive imo.

I like this, it is kind of what I was leaning towards when I started thinking about moving away from the DR cams. The DR cams are also NSR and since I have the ported heads with springs to handle the lift, I would leave quite a bit of power on the table for just a little more $ and not much extra work. I am going to order a set of 127550 cams, TFS adjustable crank gears, and lockouts from Livernois. Then retard the cams 6 degrees to get the intake centerline to 108.

I think Billy was on point with "Unless they install it and tune it for you... "

 

[RED09GT]

From the part #'s the lobes are:
234/239 @0.050"
273/282 @0.006"
.450"/.450" Lift
I can't find anything that tips off as to what the LSA angle is and I am really shocked they don't have any info as to what the ICL should be on the cards. If there are problems, there is no way to verify that the cams have been properly installed-I hate that.

 

[wht67]

It's settled, I have ordered 127550 cams, Livernois lockouts and TFS adjustable crank gears. My DR cams are for sale. Time to go big or go home!