Cam & rockers in series1---think im gonna try it!!! - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 03-08-2006, 03:13 AM   #1
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Default Cam & rockers in series1---think im gonna try it!!!

Hi all, just let me say that i've been considering this for quite some time now, and it seems that there is now more info on this subject than ever.

The reason for wanting to do this is because I cant afford a series 2 L67 like I want, (im 19 with 5 tickets!!!) so ill just do the next best thing, work with what I've already got.

Anyways, some people seem to think that it will/could be a waste of time and money because of some differences between the aussie cars and ours. I feel that doing these mods could only help, considering the stock cam and not-roller rocker arms on my car are very conservative setups. Yes, the aussies may have different intakes, and different flow rates, but our intakes, from what I understand, are actually better than the aussies, so this should help a bit also. Granted, one of "their" cams may not give the absolute best possible gains with my specific car, I think it would still be much better than stock.

The rockers I will go with are the 1.7 from seriesoneperformance.com and still dont know about the cam, either the street or the street/strip. I dont wanna go too wild because like some of you said in the other thread, it could be hard to tune for.

Anyways, just thougth i'd let you all know, prolly wont be for a few months at least, but what do you guys think???

Also DrJay from *.O.P said that id get a free before/after dyno, so the results will be documented!!
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Old 03-08-2006, 08:44 AM   #2
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What kind of lift are you looking for? Say you got a cam with a tad more duration, and a bit more lift... Say the lift was .300 intake and .305 exahust( these are just example , so lets not make a war out of this )

With the stock rockers 1.6 your intake lift would be .480 and you exahust would be .488 ..

Now with a 1.72 rocker, that would be .516 intake and .525 exahust... Remember these are just examples..

Bone stock your cam has a lift of .250 intake and iirc .255 exahust ... with the 1.6 rockers that equates to .400 intake and .408 exahust.. 1.7 rockers would make that .430 intake and .434 exahust...

It would seem to me that if you were going to go with both the cam and the rockers you'll want to know the totall lift you are exerting on the valvetrain... As well at this point you will need better valve springs too...

What are the Specs on the cam? I'm more concerned with the amount of lift as compared to the duration... But there are a couple here that can explain what changes in duration can do for you...

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Old 03-08-2006, 09:31 AM   #3
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I think the valve lift is a good question to ask. Other options available are to convert your heads to the 93-95 style with the roller fulcrum rockers to begin with. If you're going that deep anyway, it makes sense.

Another question to ask when going that high assuming valves kissing pistions is a possibility is to see if anyone has run that cam and rocker ratio before.

I can tell you that cam and rockers isn't going to get you into Series 2 territory, but by the time you've spent the money for the Cam, Rockers, and other stuff, you MIGHT be able to get into a Series 2. There'* alot of support for that in the Seattle area. Alot of members to help you find the car you want, or locate better heads for your 92.
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Old 03-08-2006, 10:47 AM   #4
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With that many miles on your car, my first choice would be to convert to the later model cylinder heads with some oversize valves and mild porting on the heads, LIM, exhaust and SC. You will not benefit or exploit the true potential of a cam or rockers until you do so.
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Old 03-08-2006, 10:51 AM   #5
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Quote:
Originally Posted by ssei1995
With that many miles on your car, my first choice would be to convert to the later model cylinder heads with some oversize valves and mild porting on the heads, LIM, exhaust and SC. You will not benefit or exploit the true potential of a cam or rockers until you do so.
Minus the cam, this sounds like my plan. Not quite Ryfly'*, cause he'* not blown.
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Old 03-08-2006, 11:06 AM   #6
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How effective the rockers would be is based on the specifications on the camshaft. The only problem that I have with the Crow cams is their cam specs appear to be generic for both the NA and SC engines. In comparison, when you look at the L67 cams developed by both Intense, ZZP and Comp cams, they all are for specific applications and not a "one-size-fits-all" spec.
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Old 03-08-2006, 03:54 PM   #7
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I personally would stray away from the cam myself, and stick with just rockers. Isn't there also a possible issue with the valve cover clearances?
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Old 03-08-2006, 04:11 PM   #8
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I wouldn't do a cam on an engine with that many miles. Rockers maybe... but for a cam too many things need to be replaced. Drill and tap the intake manifold and run a direct port N20 setup. You will be faster then a cam'd N/A 3800 and then when something goes rebuild the engine and then throw in a cam.
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Old 03-08-2006, 04:31 PM   #9
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The street and street/strip cam both have .440" lift at 1.6:1 which comes to .473" with the 1.72 rockers. The difference is in the duration. How about this, if your "valve kisses a piston" I'll buy you a new engine.

Honestly, I can't say if that'll get you into SII territory because I haven't see the dyno, maybe someone else has. You're looking at a 35hp difference between a NA SI and NA SII.

I wouldn't really bother with oversized valves very much. I've seen it done and there are two ways to go about it. If you've actually seen the combustion chamber you'll see that the valves are extremely close together so one way is to go just slightly oversized and plug them in with the required machining. From what I've seen on the high end you're looking at about 0.01" larger. The other way I've seen is to have extensive welding and cutting done to separate the valves and go from there. Last I saw it was around $2,300 but it'* been done. Not to say there'* no benefit, but I would use the spare-change pile on that.

The rockers come with the required spacer and there are no clearance issues.
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Old 03-08-2006, 05:15 PM   #10
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I have used two different combinations of oversize valve on the Seires 1 engine cylinder heads, and exploring which combination is the most effective. Every bit you can use is worth since the valves I am using, are also undercut and swirl polished, which enhances velocity and flow.
Whomever plugged the guides and rewelded the heads, just went too extreme and would not be required. If I wanted to move the valves, which I do not see the need for when you have a street/strip application, all is required is to use offset bronze guides, change the seats and machine a new location location for the seat. The only modification I have done to the chamber is to grind the intake valve side of the chamber to un-shroud the valve for additional gains. When I am done with all the R&D, I will be making templates available for all the mods to the intake and exhaust ports and also for thecombustion chamber modification. With the exception of a good hand grinder and patience, anyone should be able to replicate the same porting and mods to the chamber.
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