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 S.O.P said that id get a free before/after dyno, so the results will be documented!!

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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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's 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.

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's, cause he's not blown.

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.

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?

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.

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's been done. Not to say there's 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.

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.

Thanks DrJay for chiming in for me, I've been at work all day and not able to defend myself! :lol:

Ok lets get started.... Changing my heads to the later style wont help me any, as far as I know, unless I got them ported because i'd be going to the 1.72 rockers anyway. Porting the heads is definately an option later down the road but not right now.

With .473 lift im not at all concerned about a valve hitting a piston. Granted I dont know what lift it would take to hit a piston, im sure its more than that especially with the dishes we have in the pistons.

Valve springs, lifters, pushrods, etc. and all other supporting mods will be done.

Im not concerned with the mileage of my engine because most of the parts that will see the added stress, will be replaced, except the bottom end and tranny (for now). :) And the bottom ends of these engines are bullit proof as my engine proves (I drive it very hard!!)

I realize that untill or if I port my heads, I will not unlock the full potential of the cam and rockers, but I still feel it will help quite a bit. Supercharging may be an option later down the road too.

As far as getting into series 2 territory, it should be close. With a CAI, cam, rockers, computer re-tune (maybe), high flow cat, and 80 series, compared to a stock L36, it should be close. Obviously this depends on how much the cam and rockers give me with stock heads. On a side note, I raced my buddie's 2000 something impala with an L36, and beat him by about 6 inches in the 1/4 mile. I think its because he had a full tank and I only race with a 1/4 tank, and he himself is not heavy either. Thats the only reason I can come up with because we both got about the same reaction time too.

Alll in all, the way I see it, if the parts are there, why not try them to see what works and what doesnt. And who else can say they have a cammed L27??

Defend? You HAVE been talking to DrJay quite a bit. :lol:


Won't help you any? You're going to have everything out of the heads anyway, why WOULDN'T you go to the more common top end? Porting later will be much easier because the 93-95 L67 heads are much easier to come by.

They are quite tough. Wasting your money on the bottom end won't be a good idea for quite some time.

Heads? Try the LIM bud. That's the restriction. At least it's MORE of a restriction than the heads. Supercharger may be an option later, but it's quite costly. You've obviously been listening to DrJay on that subject too. NOBODY has converted an L27 to an L67 for some very good reasons, and you should ask yourself why DrJay is the only person that pushes the idea, when he himself has never done it. Possible? You bet. Practical? FAR from it. Ask any Gearhead on this Forum. An absolute shameless waste of money and time to accomplish something you can do MUCH easier and cheaper by other methods.

Something is seriously wrong with your friend or his car. You MAYBE would have been close at the 1/8, but an L36 would have killed you by at least a second on the 1/4, particularly the lighter car.

Bill's got a point about the heads. Something to think about... the rockers won't swap between the different heads, because of the stud difference. There is a work around for that, but I don't know all the details about the stud swap. If you're gonna take the heads off anyway, I'd personally get 93+ series I heads, in fact, I already have. Not on yet, I'm waiting to see how some other things work out.

Not really actually, just a couple of e-mails.

I was under the impression the only differences are the rocker arms. What are the others?

I know its quite hard and not worth it on a series 2, but I thought it was much easier and possible on series 1, mostly cause of the compression. I know theses a LOT more to it than compression, but that is one thing going for me. If its really that hard to do, I wont do it.

The stud size is different, and maybe the pedestal?

For the heads, there aren't too many of the 92 heads as compared to the 93-95(L27) heads... The 95 heads have Roller fulcrum rockers stock as opposed to the Pivots which was a known friction point in the 88-92 Bonneville valvetrain...

Then if you were to SC an L27 you need to understand that there are diffrenced between the piston and the wrist pin... They are not the same between the two.. And then when you look at the L27 engines you have to understand that there have been 2 diffrent compression ratios stated for the engine... 8.5 to 1 for some and 9.0 to 1 for others and no one is sure when the change was made..

You could use the 1.72 rockers, but that alone isn't worth the $$$ for the increase in power you may gain.. Adding a cam may help as well but for the headache you will need to go through to replace the cam bearings you might just as well rip the motor down and replace the cam bearings and do the rest while you are there...

Your are more than welcome to do what you will but it may be a waste of time and $$$ unless its done right..

Also as mentioned, the lower intake is a restriction... And every series I I have ever seen could have used help with the ports in the lower intake..

Even my series II could have been cleaned up for better or smoother flow... Sadly I had to have the car back together in a hurry.. Next time it will get ported..

Best of luck to you and I hope you will achieve the best of results

;)

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Reversion. Do you know what it is? The L27 in stock form is more susceptible to it than the L67, as the Boost pressure of the L67 combats it to a point.

So you're going to an increased lift and duration on a Stock LIM and Stock heads? You are going to increase reversion. This robs power and efficiency. 2 steps forward, one step back.

Now let's look at what's involved in this cam and rocker idea:

1. Cam AND rockers? Why not have a cam custom ground for the lift and duration you want instead of doing BOTH at 3x the cost?

2. Why NOT go to the 4x more common heads and valvetrain components if you're even considering head work in the future?

3. You're going to have the top end torn down, so why wouldn't you go after the single biggest restriction in the L27/L67 Series 1? It's the LIM. And porting it can greatly reduce, if no totally prevent reversion. It can also increase port velocity. This benefits efficiency and performance.

The Aussie Holdens are envied here. Why? They're not RESTRICTED. They have more options. Why? Government. Emissions. And Holden was willing to GO FOR IT. But this makes them totally different in hp and tq curves, potential gearing, intake design, top end flow, and many other things.

The Crow Cams are designed for the AUSSIE setups. And for the L27/L36 that THEY have.

If you don't go after the OTHER issues we have when you're in there anyway, you will only gain PART of what the Aussies would gain from the same work. If you want to save a little money AND increase performance, let's keep this topic going.

Bolting on parts from another application isn't the answer. At least not all of it.

And I haven't even talked about your exhaust manifolds yet, or the fact that you are likely to be EGR-less, and suffer from higher cylinder combustion temperatures than the years before you or after you to begin with.

Next time you remove the throttle body, the SC and LIM take a quick look at all the dark sooth: it is called reversion. The reason why many of us preach the port of the LIM, exhaust and cylinder heads is because they will r\either reduce and/or do away with reversion. That is also the reason why I have so concerned about velocity and fuel distribution on the LIM. Due to the increase in overlap, putting a high performance camshaft may enhance the problem and the reason why many cars loose bottom end/torque at low RPM's. In layman term, is like going out and running hard and then trying to exhale your breath through a straw instead an open mouth.

Some of that soot will be from the PCV/EGR mess, but if you look near the ports themselves, and wipe your finger in it, you'll be able to tell that there is a distinct fuel smell to it. That's from reversion, not the EGR or PCV. You WILL make it worse rather than better if you don't do other work to your car.

It's like buying 75% of a cam. When a little elbow grease might get you the other 25% for free.

waste of time and money....
 

interesting work there i wish you well...however since most highly modified head engines have an aftermarket camshaft to maximize VE/Power I am going the route of using the superior large valve/symetrical port, SII heads with the SI tall deck block, but i digress...
do you have a link to your thread that i may bookmark it? thanks.



good thoughts...a set of rockers is just a bandaid instead of getting a camshaft made for your specific requirements...your kinda putting the carriage before the horse...

i REALLY dont think a camshaft/rockers is gonna do what you want...your best option right now is to spend that money on getting the (OEM) Roller rocker heads and LIM etc from a 95ish L27/L67 and do your porting work/intake work to them and spend on some gaskets and swap all of that over...i bet you would feel the same power increase that a mild cam with your stock components would give. as the engine would remain stock you couldnt go with a cam that would be optimal in the future...and you will lose performance in the short term (not to mention tuning fer a cam...)

if there in ANY Tenant in the engine building world it's "what power and in what RPM band do i want it" you build the base engine to achieve these goals AND THEN you have a camshaft ground to take full advantage of the engine's performance specs

you may be getting in over your head here...and its this community's goals to spread mod knowledge and experience as well as to relieve headaches before they become...headaches...

then again you may be the guy who spends the coin to throw an SI L67 top end on an L27 factory shortblock (with your stock cam) and tune it from there...then once you find what you want from that, get a camshaft ground to maximize a blower/high compression combination (which with the smaller displacment M62 may be a good thing)
that would be able to be worked into a low RPM Tq monster...

but then the other mantra of all this is..."how fast doya wanna go?...how thick is yer wallet?"

then again you could always throw another engine/trans in the back...where one engine is good, two.... :lol:

Regards, James

James, you are right on track. Except that crazy twin-engine crap. :lol: Don't put nutty ideas in EVERYONE'S heads. :shock: ;)

The idea that your heads and LIM can be refined in order to achieve as much power as a mild cam is a very valid point. These engines weren't flow optimized from the factory (or at least the factory castings didn't really get 'there' even if the designs were originally right). The cam in our engines is actually quite good, the flow/passages/porting is not.

So make sure you get the horse first, then the cart. Fix what's not right before you change anything. You'll FEEL just the LIM porting alone. I speak from a point of experience on it from the L67 side, and I'm quite sure the same will hold true for your L27.

These are some captions of the different valves and chamber design for the 94-95 L27, Series 1 cylinder heads:
https://i26.photobucket.com/albums/c...7/Valves_4.jpg
This caption shows the comparison of the OEM valve versus the aftermarket oversize valves.
https://i26.photobucket.com/albums/c...nChamber_2.jpg
This caption shows the aftermarket 1.71" Intake and the 1.51" exhaust versus the OEM. The combustion chamber is well designed with a quench pad and spark plug is located at an optimum location just like many racing heads:towards the exhaust valve. Anyone with Chevy high performance experience will recall the "angle plug" well sought cylinder heads.
https://i26.photobucket.com/albums/c...nChamber_1.jpg
This caption shows the 1.77" Intake and the 1.55" exhaust. they do touch each other; however, I have machined the intake to 1.75" and the exhaust to 1.54" and they fit perfectly.
https://i26.photobucket.com/albums/c...Chamber_01.jpg
This caption shows a closer look of the 1.71" intake and 1.51" exhaust.

Ryfly05. you have a PM waiting for you. ;)

Just so no one gets confused:
Attachment 68553

I really like these pics. They are much more specific than jeffery10x2's old pics.

Those pics are sitting on the coffee table at ssei1995's house. You do the math. ;)

Methinks I know what your PM is about. WCBF would be a good place to explain and perhaps do a show 'n tell on porting. I may have a spare ported manifold by then, and Joe may also.

Boy, you guys just dont like this cam idea do you? :lol:

Thanks for pointing out the need for LIM porting/cleaning up. I had no clue these were that bad. Since the LIM is coming off anyways, this will DEFINATELY be done. However, I have NO porting experience. Is this something I can do myself? What are the things I should look for to clean up? Does anyone have an extra one layin around that they could port for me for a reasonable price?

The reason I dont go with the more "popular" heads is mainly because I dont have the time, or the money (hard to beleive huh?) to buy new heads, find someone who knows what there doing with them, have them ported, put bigger and better valves in them, then take the whole weekend and at least a day off of work to put them on. I plan on doing this cam in a weekend, as I cant afford to have any down time. I realize this would probably give me the same gain as a cam and rockers and LIM porting, but it would still cost about the same, and it would be more work.

Again, these are just my opinions, and if someone can prove to me the time/effort/money of head porting is worth it, I may go that way. I'm still just curious to see exactly what a cam will do, since no one knows for sure. I know you guys know what you're talking about, thats why I asked for your opinions in the first place, but all we can really do is speculate until someone tries it. Like me. :lol:

You don't have to change to '93-'95 heads to use '93-'95 rockers.

- 1992 rockers have a friction trunion in the rocker arm and are retained by a 3/8” bolt. A steel guide plate is used under the rocker to keep them inline.

- 1993-1995 rockers have a roller trunion in the rocker arm and are retained by a 5/16” bolt. The rockers sit in an aluminum pedestal plate to keep the rockers inline.

- To get 1993-1995 rockers to work on 1992 heads:
Re-drill the trunions from a 5/16” hole to 3/8” hole. The pedestal plates also need to be re-drilled to a 3/8” hole. 12 2” x 3/8” grade 8 allen socket bolts are then needed to retain the modified rocker.

I'd upgrade to a plastic upper intake manifold if your going to keep it N/A. Supercharger and N02 would help you see the benifits of a cam.

Upgrade the heads from a wrecker even if you're not having the heads worked over.

No, I'm not a fan of that cam idea, particularly with rockers. That's an ENORMOUS amount to spend for greater duration and higher lift, when you could just get the cam itself ground to those specs.

And doing the cam itself without the LIM porting (and the manifold upgrade Blazin' mentioned) would be pointless.

You have the bastard-child of the 92-99 generation. The 92 L27 was rather odd for most of that model year.

Your ignition is severely lacking as well, so consider upgrading to the 93-current Delco ignition and retire the old Magnavox setup you have.

The point here is that those rockers and cam on your current setup would be like putting a Turbo on a Ford Fiesta with no other changes. You'll gain a little more power, but cause a bunch of problems, too. And it'll never see it's fullest potential.

Keep bouncing ideas off these guys. You'll get some good experienced solid advice.

PROJECT CALLED OFF!!!

Someone broke into my car last night at the movie theater, they broke the back window thing that is behind the roll down window. They stole my deck and all my cds and destroyed the backseat trying to get into the trunk for my subs :x

Luckily they didnt get my subs or anything else in the trunk but im soooo pissed right now!

Anyways, now i think im gonna go for a GTP, as this has always been one of my favorite cars, and my car is just too hard to make fast.

Does anyone have or know of someone looking to sell a 98-00 GTP for arond 10K?

Thanks for all the help anyways guys!

Ryan

GAH!

Damn thieves and vandals. I hope the radio blows up on them! Just glad you're ok!

Get an Eclipse radio... free replacement for 2 years and the thief can't use it if it is stolen. 8)