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HELP!!!!Need help with cam

 
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jgrant
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Joined: 04 Feb 2006
Posts: 2

214.98 points



PostPosted: Sat Feb 04, 2006 4:56 pm    Post subject: HELP!!!!Need help with cam Reply with quote

I bought a core engine from my nefew's dealership, story was engine had 30000 miles on it,he took it to Wal-Mart to have his oil changed and they forgot to tighten his oil filter....they replaced his engine.

I think Wal-Mart got scammed, anyway.... this is what I have 1998 vortec heads 12558062, I have put 9.1:1 Flat top pistons with the longer skirt on 5.7 connection rods, the block is 10243880 Gen 1 Crate ZZ4 roller cam.

I took it to the machine shop the cylinder walls were fine so it is still a std. 4.0 , no cracks, they put the valve springs back in and shimmed them.

Now for my problem, the camshaft. The lobes are worn, and do not mic out, I took it to the GM dealership, they did not have a clue what cam it was thought it too hot for the engine??? There is a number stamped in black ink on the end, but was told it was a meaningless number. My opinion, and only mine is that the engine had probs they replaced the heads didn't fix the prob, so hello Wal-Mart....or they did not have everything configured, its really a who the hell knows, now I have to deal with I have...

I need to know what cam I need, I am putting this in a 1997 C/K2500, it has the 3.73 rear axel. I have looked at so many different cam specs I am now totally confused, they are either for carb engines, require a computer reprogram, etc....

I do not want to make any mods, this is going to be my daily driver, I will be towing a trailer with concrete statuary occasionally, I think I want just a step up from stock. Also, since I have this engine totally apart besides changing the pushrods what else do I need to check?? This is my first experience with a roller rocker cam, fuel injected, SBC 350. I have called the specialist and no rel advise, I don't want to spend $$$$$ and turn 12's nor do I want to change my work P/U into a Geo Metro. I would appreciate advise as to what cam I need. Thanx!
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clay
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Joined: 24 Nov 2002
Posts: 3209
Location: South Carolina
318129.23 points


1972 Chevrolet Nova

PostPosted: Sat Feb 04, 2006 8:05 pm    Post subject: Reply with quote

96capriceMGR would probably be a better one to ask about this particular setup than me since the heads are LT1 based, but I would probalby put in a stock cam and run some 1.6 rockers, headers and maybe throw in a K & N. This would bump you up around 30ish h.p. and torque I would guess. Clay
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96capriceMGR
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Joined: 23 Aug 2003
Posts: 814
Location: New London Wisconsin
20327.88 points


1996 Chevrolet Caprice

PostPosted: Sun Feb 05, 2006 8:58 am    Post subject: Reply with quote

Yeah those heads are based pretty strongly on the iron LT1 heads from the Caprice/Impala and other b-d-bodies and that is what I have. Difference is the LT1 had different cooling that allowed more compression, mine is 10.0 stock, and I happen to run a ZZ4 cam in it, it did fine with stock gears and converter even with some light towing and stock gears for me were 2.93s. Understand I am talking from having it in a car that is every bit of 4300lbs with me in it, is 350ci displacement, heck has the same tranny and axle as your truck even. I actually have my stock cam leftover from when I did my cam swap it is 191/195 .41x/.42x(lift I am ballpark) and the ZZ3 cam will be coming out soon. If you really wanted to keep it on a budget.

For a new GM grind I would look at P/N 14097395 196 / 206 @ 0.050", .431 / .451 lift with a 1.5:1 rocker arm, on a 109 CL. This is probably pretty similar to the stock cam. Might have to do something with your springs though, ask the machine shop if they are suitable for this much lift after the shimming they did.
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jgrant
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Joined: 04 Feb 2006
Posts: 2

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PostPosted: Sun Feb 05, 2006 3:16 pm    Post subject: Reply with quote

I appreciate the advice, I have a couple of more questions. In the Chilton book in regards to the cam it says stock on the intake is .276 Exhaust .285? Also I am concerened about the CL or lobe seperation of a 109. Isn't that going to give it a fairly rough idle? I haven't given to much thought yet to the exhaust, I am concerned that I am way out of my league trying to put this project together Exclamation As it is I would have been better off buying a remanufactered as far as $$$'s, but too late for that now, besides I have the advantage of knowing exactly what I have for componets, that's what I keep telling myself anyway:-) They have a couple of Air intake kits I looked at, Autobacs1 has one and a company called Bomz which I haven't heard of. Please let me know what you think about the specs in Chiltons. Also, exactly what is the diff between the 1.5 & 1.6 rockers and how do I measure what came with this cam I have? That's approaching total moron status, but I have never even seen a roller cam prior to this, Thanx
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96capriceMGR
Member


Joined: 23 Aug 2003
Posts: 814
Location: New London Wisconsin
20327.88 points


1996 Chevrolet Caprice

PostPosted: Sun Feb 05, 2006 4:20 pm    Post subject: Reply with quote

Overlap is what causes a rough idle not LSA. A small cam can have a tight LSA but still have little overlap since the lobes are so small and you end up with a good idle. To get valve lift multiply the numbers in your manual by 1.5 the stock rocker ratio you get .414/.428. Switching to 1.6 rockers is a popular upgrade because it is an easy way to in crease valve lift, it would push your stock cam to .442/.456. Most cam specs you see are listed at the valve lift with stock 1.5 ratio rockers so you can divide by 15 and then multiply by 16 to get the new lift you would have with 1.6s.

I would guess whatever rockers you got are stamped 1.5s there should be a groove in the one end for the valve tip to ride in. Many people switch to roller rockers which use bearings both at the center pivot point where those use like half a ball and they use a roller on the end at the valve. These provide a truer ratio less friction and honestly some noise probably overkill for you. You could look at 1.6 ratio stamped SELF ALIGNING rockers. The self aligning thing is the way those stock rockers have a groove to retain the valve tip, older smallblockes used another method of keeping the rocker on the valve tip.

I can point you towards some GM parts suppliers MUCH cheaper than the local dealer. Dealer markup is often as much as 100%, but there are companies who will sell at 10-15%. GMpartsdirect is one that comes to mind but they often charge outragous shipping, so they are best for looking up part numbers and getting an idea of cost.
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