Cam & rockers in series1---think im gonna try it!!! - Page 3 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Performance, Brainstorming & Tuning Talk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

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Old 03-09-2006, 01:42 PM   #21
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James, you are right on track. Except that crazy twin-engine crap. Don't put nutty ideas in EVERYONE'* heads.

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'* 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.
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Old 03-09-2006, 03:23 PM   #22
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These are some captions of the different valves and chamber design for the 94-95 L27, Series 1 cylinder heads:

This caption shows the comparison of the OEM valve versus the aftermarket oversize valves.

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.

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.

This caption shows a closer look of the 1.71" intake and 1.51" exhaust.
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Old 03-09-2006, 11:36 PM   #23
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Ryfly05. you have a PM waiting for you.
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Old 03-10-2006, 12:20 AM   #24
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Just so no one gets confused:
Name:  CombustionChamber_2.jpg
Views: 1
Size:  21.1 KB

I really like these pics. They are much more specific than jeffery10x2'* old pics.
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Old 03-10-2006, 12:23 AM   #25
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Those pics are sitting on the coffee table at ssei1995'* house. You do the math.
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Old 03-10-2006, 09:06 AM   #26
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Quote:
Originally Posted by driverjohn2005
Ryfly05. you have a PM waiting for you.
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.
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Old 03-10-2006, 07:05 PM   #27
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Boy, you guys just dont like this cam idea do you?

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.
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Old 03-10-2006, 07:23 PM   #28
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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.
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Old 03-10-2006, 10:43 PM   #29
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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'* 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'* fullest potential.

Keep bouncing ideas off these guys. You'll get some good experienced solid advice.
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Old 03-13-2006, 12:31 PM   #30
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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

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
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