PDA

View Full Version : billet comp cam



90blkbrd
09-18-2009, 06:49 PM
A local guy is having a engine built. He purchased a cam from SCP (stage 2) with 460 lift. The engine builder states that using stock springs won't work with this cam. So he didn't follow my recommendations and create an account here and well lets just say he is happy with the valve geometry but the valve covers will need an extra half an inch.

The heads have been ported but retain the stock valves.

What all is needed when installing a cam such as rockers, spring cups, springs, retainers etc?

Stupid Canuck
09-18-2009, 10:09 PM
Comp 942's will take .500 lift, and more, and are an easy swap with stock geometry. Good match for that cam.

There are some Crane (forget #) springs that require some machining of the seat.

90blkbrd
09-19-2009, 06:51 AM
942 helped me find the thread I couldn't find before, Thanks!!!

http://www.sccoa.com/forums/showthread.php?t=86684&highlight=942

If I read that thread correctly the retainers are available only through SCU.

Part numbers ???:
Valve springs - comp 942
Retainers -
Valve locks -
push rods -

90blkbrd
09-19-2009, 06:57 AM
This thread said this application should be using a crane spring that works for the lift of this cam.

http://www.sccoa.com/forums/showthread.php?t=104227&highlight=comp+942

rzimmerl
09-19-2009, 08:08 AM
Comp 942 springs will work with stock retainers and locks. I used them for a couple years with no problems.

90blkbrd
09-19-2009, 09:04 AM
Comp 942 springs will work with stock retainers and locks. I used them for a couple years with no problems.

Ryan what lift is your cam?
You are using Scorpion 1.73 ratio roller rockers along with them?

rzimmerl
09-19-2009, 09:33 AM
It was a stock cam, forgot to mention that. I used Scorpion 1.73 rockers, and also had to use longer pushrods.

90blkbrd
09-21-2009, 08:25 AM
It was a stock cam, forgot to mention that. I used Scorpion 1.73 rockers, and also had to use longer pushrods.

So you used a stock cam, comp 942 valve springs, stock Retainers, stock valve locks and different push rods?

When you say stock cam did you mean stock cam or a stock cam that has been reground? Thus the need for different push rods?

Would this be the same requirements for a aftermarket cam? Do you happen to have the part number for the push rods?

rzimmerl
09-21-2009, 08:54 AM
It was a stock cam not a regrind. I used 942 springs, stock retainers, stock locks, Scorpion rockers, and the pushrods are for a 95 Camaro Z28 (length I think is 7.192). The rockers required a .060 longer pushrod, because I could not get any preload with the stock length pushrods. Do a search for the Z28 pushrods, there are a few posts on them. As for what you would need for the regrind pushrods, best bet would be to use an adjustable pushrod and measure what you will need from it.

90blkbrd
09-21-2009, 09:16 AM
It was a stock cam not a regrind. I used 942 springs, stock retainers, stock locks, Scorpion rockers, and the pushrods are for a 95 Camaro Z28 (length I think is 7.192). The rockers required a .060 longer pushrod, because I could not get any preload with the stock length pushrods. Do a search for the Z28 pushrods, there are a few posts on them. As for what you would need for the regrind pushrods, best bet would be to use an adjustable pushrod and measure what you will need from it.

Sweet! Thanks Ryan.

fturner
09-21-2009, 09:18 AM
That .460 lift, is that with 1.73 rockers or is that for 1.60 rockers.

The stock springs are ok until about a .500 lift but I would not venture any higher than that. It never hurts to get new springs though.

Fraser

CMac89
09-21-2009, 09:22 AM
The 942 isn't the best spring. A double coil spring will have a bit longer life and it will be better at dampening. I would use the 987 springs, if you could. The problem is that it coil binds at 1.150 instead of 1.125 like the 942's, so it's .025" closer to coil bind than the 942's. The stock valves have a double groove lock, so I don't know where you could find +.050" valve locks at. If you can find some, then I would go that route.

**EDIT** With .460" lift, he won't need to worry about it. Just use the stock locks and retainers.

90blkbrd
09-21-2009, 09:34 AM
That .460 lift, is that with 1.73 rockers or is that for 1.60 rockers.

The stock springs are ok until about a .500 lift but I would not venture any higher than that. It never hurts to get new springs though.

Fraser

I haven't seen the cam card, but I'll ask when I call.

90blkbrd
09-21-2009, 09:35 AM
The 942 isn't the best spring. A double coil spring will have a bit longer life and it will be better at dampening. I would use the 987 springs, if you could. The problem is that it coil binds at 1.150 instead of 1.125 like the 942's, so it's .025" closer to coil bind than the 942's. The stock valves have a double groove lock, so I don't know where you could find +.050" valve locks at. If you can find some, then I would go that route.

**EDIT** With .460" lift, he won't need to worry about it. Just use the stock locks and retainers.

So use the 987 even if the 460 lift is figured with the 1.73 or 1.6 rockers?

CMac89
09-21-2009, 09:38 AM
Regardless, max lift will still be slightly under .500" lift. You'll be safe either way.

bigpoppa822
09-21-2009, 09:41 AM
I have a .480 lift cam from SCP with stock springs and have had no issues in 2 years.

90blkbrd
09-21-2009, 10:13 AM
1. rocker arm boss milled to remove tabs and changed from 8mm stud to 3/8ths. (to accommodate the roller rocker)
2. comp cams stainless roller rocker (listed for cam in comp cams book)
3. valve changed to a taller stem (stock Ford 289 valve)
4. 26120 spring (bee have spring listed for cam in comp cams book)

Currently everything fits under the valve cover with polylock not installed. They believe if they mill off some of the polylock it will fit under stock valve cover.

Does all of this make sense? It seems they are going overboard trying to use what is listed in comp cams book.

90blkbrd
09-21-2009, 10:28 AM
I have a .480 lift cam from SCP with stock springs and have had no issues in 2 years.

According to the engine builder the stock springs don't have enough seat pressure listed for the cam.

(If I am getting my terminology wrong, please correct me)

fturner
09-21-2009, 10:49 AM
If the stock springs are still good you should be fine at that low lift.... besides, its not like our motors are high rpm motor's.

It sounds like they are going way over board for a cam like that. The comp springs that the guys have mentioned would be perfect with stock rockers. I ran a set of those with my cam, and it has about a .490 lift on the intake and a .530 lift on the exhaust with the stock 1.73 rockers.

Fraser

90blkbrd
09-21-2009, 10:53 AM
If the stock springs are still good you should be fine at that low lift.... besides, its not like our motors are high rpm motor's.

It sounds like they are going way over board for a cam like that. The comp springs that the guys have mentioned would be perfect with stock rockers. I ran a set of those with my cam, and it has about a .490 lift on the intake and a .530 lift on the exhaust with the stock 1.73 rockers.

Fraser

I don't think stock is 1.73.

CMac89
09-21-2009, 10:57 AM
I don't think stock is 1.73.

Yes, sir, it really is. Same as a 351C and a 429/460.

90blkbrd
09-21-2009, 11:04 AM
Yes, sir, it really is. Same as a 351C and a 429/460.

No comments on what they are doing? I was expecting a 3 page thesis from you on whether it was right or wrong. Just kidding. :)

I'm confused. I thought the scorpion roller rocker changed the ratio to 1.73. So what does it change?

XR7 Dave
09-21-2009, 11:25 AM
Wow, talk about re-inventing the wheel. lol

First off, most of you guys are doing a certain amount of guessing here. I would probably not follow any advice you'll get here because of that reason. Haha, even me.

Seriously.

Anyway, the engine builder did go to a lot of extra effort for no real good reason but what is done is done.

First of all, Comp 942 springs have changed over the years. They used to coil bind at about 1.080 which meant they could be used with the .520 Dr. Fred cams (1.650-.520=1.130) leaving .050" to coil bind. That is absolute recommended minimum clearance and was hard on the springs but it worked. Well, kind of worked because a number of people dropped valves using that combination and more than one person bent valves when they floated at about 5700rpm.

But back to the part about Comp 942 valve spring changing over the years. The Comp book lists coil bind at 1.150 for that spring and the last set I got did exactly that meaning that they BIND before .520" lift and the max acceptable lift (1.650-1.150-.050=.450"). :eek: Now the springs are only any good for a totally stock cam. Don't try to use them on a higher lift cam or you WILL have problems.

There are other options (and Fraser your springs were not Comp 942's) which leads me to the next point which is that most SC people really don't know or understand what they have in their motors.

But that still doesn't tell us anything about the current question.

First of all, the SC does come stock with a 1.73 rocker arms. Not all V6 cams are spec'd using a 1.73 rocker arm. (!) Make sure you do the math by checking the lobe lift and applying the rocker ratio to make sure that you are seeing the correct final lift for the rocker arm you are using. Often times the cam cards are printed assuming a 1.6 rocker ratio because half the time the Comp (and other cam companies too) reps just assume that this is a 5.0. This motor is NOT like a 5.0 and assuming it is will get you in all sorts of trouble. More on that coming up.

In this case they are using an aftermarket valve. Unfortunately they chose to use one that is too long for the application which is why they are into the valve covers on this one. Using a stock length Chevy valve in a slightly larger diameter (say 1.840/1.550 for example) would have kept the valve tips lower (stock height if you are careful) and provided plenty of rocker clearance up top as well as enough clearance for .650" lift (with the right spring). Having a high valve tip can also screw with your valve tip to rocker arm geometry which, while it "looks ok" upon installation, can end up wearing out valve guides pre-maturely due to the side force generated by incorrect geometry. Whether or not this is the case here will only be known by the engine builder himself.

I agree with the engine builder that stock springs do not provide enough seat pressure for any aftermarket cam grind. Stock springs run about 75-80psi on the seats which when you put a more aggressive ramp profile, even at stock lift, will send the valves into bouncing gyrations above 5000rpm that will not only severely hurt power but also destroy valvetrain parts if left unchecked. That a motor might "run" with stock springs is like saying that the motor will "run" with transmission fluid instead of engine oil. Doesn't make it right. ;)

For all the work involved (and nothing the engine builder has done seems wrong, just a little overboard) I would hope that the cam has more than .460" lift. Typically on a motor with beehive springs and roller rockers I would run at least .550" lift, but that's just me. :)

90blkbrd
09-21-2009, 11:47 AM
David answering this might give away some of your secrets, but if someone were using stock valve sizes and were installing a less than a 550 lift cam. What would you use for valves, rockers, push rods?

90blkbrd
09-21-2009, 12:17 PM
Cam card was done with 1.6 rocker. So if he uses a 1.7 rocker lift would be .498.

The alteration to the poly lock worked and they now have clearance under the valve cover, he said it was hitting the baffle.

FYI Engine has stock rods and Wiseco OE replacement FORGED pistons (PT-113). I asked him to order them from SCU but he thought it was better to use his discount and wait for them (Wiseco was out of stock). Then he realized he needed different wrist pins and had to wait for those. These heads are supposed to be ported and it will be sporting a 89-93 ported supercharger.

XxSlowpokexX
09-22-2009, 02:20 PM
Valve covers neeed an extra 1/2"???

90blkbrd
09-22-2009, 02:59 PM
Valve covers neeed an extra 1/2"???

I guess they were exaggerating. Whatever it was they were able to mill down the poly lock to make it work.

The builder claims that by using what is stated in the book, if something goes wrong he can go back against the manufacturer. If he uses what we tell him and it goes wrong, he is liable.

I think they don't have enough work to do so they found ways to bill this kid form more shop time.