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