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Old 08-12-2010, 08:55 PM
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350 Mild Thumper Cam Help!!!

I Currently Have A 89 Suburban Tht Im Getting Ready To Drop A 350 Outa 97 Tahoe Into It...Im Wanting A Mean Sounding Engine With Out All The Swapping Of Parts Right Now...Not Really Worried About Performace As Of Right Now....Jus Wondering Wat All Parts Would Be Needed For The Mild Thumper Cam Into This Engine
(this might help)
I Am Keeping My Same Setup So I Will Be Taking The TBI Intake Off An Putting It On This Motor Thanks For The Help


Last edited by 95wagdog; 08-12-2010 at 09:13 PM.
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Old 08-12-2010, 10:17 PM
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if i am wrong someone will correct me on here. but depending upon what valve springs you have and what kind of lift they will take and the lift of the cam you will need to get new springs. you will also need to get an intake that will flow the air needed to get the most out of the bigger lift. also you will need a set of headers since stock manifolds wont let enough air out. (have made the mistake of just putting in a bigger cam without changing anything and it actually made the motor run worse.) basically from what i have learned is everything in the engine and the drive train is all centered around the camshaft. when i build a motor i buy the camshaft first and then build the motor (and tranny) around it. (seems to work better that way). so i would think it to be a smarter move to just save up your money and buy all the parts to go along with the cam, it will work out better in the long run for you.
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Old 08-12-2010, 10:56 PM
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Thumpr cam + TBI + ECM = TURD. You are going to have a hard time making this work. Fuel injection and large duration/overlap cams don't get along well.
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Old 08-13-2010, 01:44 PM
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i was wanting to put a trottle body intake on it instead of the fuel inject. would tht help anything there or would i have to run a different setup
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Old 08-13-2010, 01:57 PM
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A throttle body engine is fuel injected. If you really want the thumpr cam then you have to get a torque converter and valve springs to match. Make sure your heads can handle the lift. Get some headers for it or it will ruin the concept of the thumpr cam. Run 2.5 true dual exhaust with thrush turbo mufflers (they sound mean with a big cam). Get a new intake that will fit your heads (I'm guessing vortecs) and a 650 carb.
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Old 08-13-2010, 02:50 PM
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I have just gone through the pains of installing the smallest Thumpr Cam in my Gen 6 Big Block zz502 (Hydraulic Roller) Chevelle. It needs a lot of TLC to get it running right.. Start with timing.. 25degrees initial.. Then recurve the distributor for 36 total. Must connect vacuum advance to full manifold vacuum not timed port.

All this timing causes, or at least amplifies hot starting issues. (See my previous post today about all the fun I had fixing the hot start issues)

Carburetor needs a power valve replacement because it runs so rich at idle it will burn your eyes (brand new street avenger out of the box not a junk used carb) I had 8in hg of vacuum at idle which means a 3.5 power valve. I have not yet done any additional tuning (jets etc) but fully expect to once I get it finished.

Power brakes do not work with 8in hg vacuum. Installed electric vacuum pump from SSBC ($225)

I have a manual trans and already had the edelbrock RPM aluminum heads and a 3.73 rear so I didnt need to do any upgrades to springs, gears etc. but I DID install summit roller rockers and tall valve covers to clear them.

Altogether the cam swap alone has cost me somewhere between $700 and $900 - not exactly a cheap price for a choppy idle..

Here is a vid of it running after the thumper swap
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Old 08-13-2010, 02:52 PM
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the truck wont want to run with that cam and a stock PCM, you would be lucky if it idled.
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Old 08-13-2010, 03:08 PM
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Contact Howell Fuel Injection for a custom programmed chip to make the truck run. I would contact them before you build the engine as they have programs for specific combinations which might suit you and save you the expense of having to try multiple programs and/or dyno tuning your specific combination.
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