I'm looking at the Thumpr cam from Comp Cams...how hard is it to install camshafts, and I would only need to buy one, correct?

 

Don't take this the wrong way, but if you are asking how many cams you need for a SBC, you're probably in a bit over your head doing a cam swap now. You'll definitely want someone with more experience to help you install a new cam in your car, as it is a pretty involved job. Yes, you only need one camshaft.

(Hey, I've been there... everyone has to start somewhere right? )

Now... What engine do you have in your car now? What mods have been done? Do you have a part number for the specific cam you were looking at?

If you do decide to change the camshaft, you'll also need a new set of lifters if its not a roller cam, new valve springs, a timing cover gasket set, water pump gasket set, and intake gasket set (intake has to come off to get to the lifters). Now is also a good time to replace the timing chain & gears.

You'll need a timing light handy too, as the distributor has to be taken out.

 

Sorry...I've only owned two V8s. The rest before that were single and dual overhead 4 bangers, that's why I asked.

As far as the cam swap, I wasn't planning on doing it myself, but was wondering if it was easy enough for a DIY or if I should just go to a shop.

The car is an 87 Z28 / Iroc carbureted...305 I believe. Seems to be stock everything, single snorkel air intake. I think it is the LG4 motor, automatic transmission. I heard that it is a roller cam...?

I haven't done anything to the car yet, but I was planning on doing headers, Y pipe, high flow cat, 3" catback with a Flowmaster Super 40 or Super 44 muffler. I kinda wanted to run open headers so I get a really loud sound from a cam, but I think it will be noticable enough with a whole exhaust. Plus, it is only a 305.

Part number is 08-600-8 and it is a Thumpr cam made by Comp Cams. Here is a link http://www.compperformancegroupstore...ry_Code=Thumpr

Would I need to change out the valves and everything, or can I just run the cam?

 

you'll need new taller springs like the comp 981's or manley 22410 (better choice)

then get .050 offset locks and .050" of shims... i think they only make .015 .030 and .06 shims so .045 is close enough if you add those two smaller ones.

that will give you .530 lift margin which is enough to run on that cam.

that cam tho is a pretty large cam for a 305...it will have a very rough idle and need alot of time tuning... probly best that you have a carb motor

 

Where would I get the shims and everything? I have a carbureted motor, so I'm sure they could tune it up. I'm looking for a rough idle...choppy and all. How much do you think it would run for the shims and the springs and locks?

 

Unless this is a Canadian car, it has a computer controlled carburetor. Rough idle and computer controlled anything don't play well together - tuning isn't the answer, because you can't tune around that.

Rough idle and stock stall torque converter aren't very fun to drive.

'87 would be a roller lifter cam if it is the original engine.

Valve springs are a must with an aftermarket cam, but they aren't sufficient. Most factory heads can't handle more than about .480" lift without some sort of machining work. That means removing the heads. The head work after they are off the engine is stuff best left to a machine shop.

Your plans for exhaust are the right place to start. Open headers are a very bad idea unless the car is trailered to the track.

 

locks, shims, and springs can be had from summit racing for under 150 bucks.

but yes, i wouldnt do the cam unless you have exhaust work done, rear gear upgrade and new torque converter if your automatic

 

So that brings me to a new question....would it be more favorable money wise, time wise, economically, etc. to just buy a built 350 and upgrade the rear gears, along with a TH700 tranny and 2500 stall converter?

*What do you think of an engine like this? http://cgi.ebay.com/ebaymotors/350-3...spagenameZWDVW

 

well considering the amount of money that is involved in going with a cammed 305 setup, i think its more economical to go crate motor

a cam swap for your motor, to do it right and with all the tools and machine work needed is probly gonna run you 1000-1200 dollars, depending. you may need to get a new manifold/carb too just to handle the new cam's characteristics and added power. it all depends on what you do.

Now if you go crate your getting a new motor, with more cubes and depends on what crates you get, a better set of cylinder heads on them. a GM 330HP crate comes with vortec heads and is pretty cheap at 3300 bucks. just buy your thumper cam or something for another 300 bucks and add that to the motor and sell off the cam you take out. This motor will make more power than that cammed 305 and you get a much newer/fresher motor. seems worth it to me just to ditch the 306 and get a new rebuilt motor

 

Not much.

A 330 HP 350 HO from GM makes more sense.

 

THey make a big deal about the horsepower rating and then in little bitty text at the bottom state that it is a desktop dyno program rating.

It isn't fired before shipping either... that scares me.

 

I posted the wrong link, sorry. It is this engine http://cgi.ebay.com/ebaymotors/350-4...spagenameZWDVW

408hp, 406 ft lb. But if it's not that great, where could I find that rebuilt 330hp crate motor?

 

those engines on ebay are a scam... i believe the cylinder head casting "accidentally" shown at the bottom of the page is a TBI head

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you will notice that in almost every pic of their engines the front of the heads are cast in shadow...all except one

 

Where would I get a good, built, reliable engine?

 

before you start spending the cash with it man let me tell you when I was 16 I got my first thirdgen 86 sc stock 305 lg4 and I wanted to go fast to I had a big cam carb and intake package put in along with someheaders and some other bolt on goodies but little did I know after dishing out almost 3k when it comes to high performance you cant just modify the parts you want and expect it to make a big difference so needless to say I had spent 3k on a 305 that ran like crap becuase all the other stock parts needed mods to go along with it .. so my advice slap a nice 350 you can even start by checking your local junk yard.

 

Find the parts you like, take them to a reputable machine shop, hand over a cheque and ask when you should come back for it. Or find the parts you like and assemble them yourself.

Of course, theres the crate motor route.... but I would only buy one from GM myself; too many shifty builders out there. At least the dealer will be in the same place I left it when I go back to bitch and complain when it doesn't work.