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Old 02-27-2012, 04:43 PM   #1
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Default cam swap on my 92 gmc tbi

I see everyone doing engine swaps I can't afford it plus it's my daily driver so I was looking for some feed back on any good cams
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Old 02-27-2012, 06:28 PM   #2
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A tbi motor needs some head work and tuning to really benefit from a cam. They really are a low output engine and every component is pretty well matched to their power rating so improving Just one component really won't be an improvement honestly.
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Old 02-27-2012, 07:09 PM   #3
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Not true..... at all. The stock TBI cam is not well matched to anything other than making as little power as possible.

Op, you need more than a cam, period. Even with the stock heads you should get long tubes on it and go with a carb style intake with a TBI adapter plate. The stock manifold is a POS as are the exhaust manifolds and factory Y pipe.

I recommend something mild for this application, and torque oriented. I personally would see if your engine is roller compatible and go that route. Something like an XR258 Comp at the max. The XR 252 is probably a better choice.

Now even staying flat tappet you need a timing chain, lifters, the cam, valve springs and all your gaskets.

Plus you should mod the throttle body itself by shaving the throttle shaft down, taking off the rings around the top of the bores and radiusing them as well. Then add an adjustable fuel pressure regulator.

Next you need to tune the truck so you need to get a competent PCM tuner to burn you a chip that accomodates for the changes.

You honestly can't just stuff a cam in the otherwise bone stock engine and expect it to perform....... So you can add all that stuff up yourself....... And realize a $500 junkyard 5.3 really isn't all that expensive to get in there afterall.....

Or even better honestly, just look at it this way. If you can't afford the mods, and can't afford the downtime, leave the engine alone!!!!!!!!
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Last edited by 1994Vmax; 02-27-2012 at 07:21 PM.
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Old 02-27-2012, 09:24 PM   #4
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A good cam for the 5.7L TBI is a single pattern camshaft such as a 206/206 or 212/212 would be a good choice. Obviously, get any type of header on that engine whether it is a shorty or long tube and tune it and also get an Edelbrock TBI intake manifold while you took the old one off and have fun.
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Old 02-27-2012, 10:18 PM   #5
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Edelbrock's TBI manifold is hardly any better than the stock GM TBI intake that is on the truck and a huge waste of money. Even the standard Performer manifold is a better piece than that thing. Not to mention you are dollars ahead for a superior setup with a standard square bore manifold and a TBI adapter plate you could honestly make yourself.....

And a dual pattern cam is still a better choice than a single even on a TBI 193 head. The exhaust port is still a lot weaker than the intake, even with the stupid big swirl ramp in it.

Roller cam is the way to go hands down, especially if the block is provisioned for it. The lifters, spider, link bars and retainer can be found in any car engine or Vortec truck engine in a junk yard and had for next to nothing.
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Old 02-27-2012, 11:11 PM   #6
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Thanks for the input I will look into everything.my truck has a hypertec chip in it so would I still need a custom one or will that work
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Old 03-18-2012, 12:26 PM   #7
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I have a roller cam, headers, tb spacer, ported heads, port matched intake, chip. You can get a flat tappet from summit for cheap. The one i had in my 1990 TBI was a .510/52x. Shorty header with timing advanced about 3 degrees. A cam and headers wake those motors up but in the long run there is only so much you can due with TBI. I did how ever gain mpg after headers cam.
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Old 03-18-2012, 04:46 PM   #8
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Hes right ^^^ i had a 91 5.7 comp cam (cant remember which but it didnt require tuning), edelbrock performer tbi intake, hypertech chip, tbi and injector spacer, electric fans, headers full exhaust. I sounded great but was slow. If i had it to do all over again id just go full exhaust, electric fans and spend the rest of the money making it look good.
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Old 03-18-2012, 06:02 PM   #9
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The stock 76cc swirl port heads are what are going to hold you back... With a decent cam swap and a vortec head swap with a nice intake manifold along with headers and the "Ultimate TBI mods" will really wake up that truck. Those stock swirl ports are junk...
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Old 03-18-2012, 06:58 PM   #10
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Quote:
Originally Posted by N20zuki View Post
The stock 76cc swirl port heads are what are going to hold you back... With a decent cam swap and a vortec head swap with a nice intake manifold along with headers and the "Ultimate TBI mods" will really wake up that truck. Those stock swirl ports are junk...
193's are 64 cc's, just like 062 or 906 Vortecs..... The only swirl ports with larger chambers are found on some 1 ton trucks with a casting number like 14102191. Those have 76 cc chambers. A half ton's LO5 will be 9.3:1 compression with 64 cc chambered 193's.

They are a terrible head for top end power, but for low end torque they actually do okay. That said Vortecs will do better than the TBI's across the board...

But then a junkyard LQ4 will skulldrag all above combos so who really cares.....
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2013 F150 FX4 SCrew. 6.2/3.73's. AFE/3.5" MBRP SCT but soon to be HP tuners tuned by me.
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Old 03-18-2012, 06:58 PM
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