Please help me decide on camshaft

[Nascar fan]

I have a 1994 Chevy Silverado P/U with 5.7L, 350 cu (L31) engine. I recently purchased new GMPP cast iron Vortec heads, an aluminum Vortec intake manifold, shorty headers, Holley 670 Street Avenger carb, and 1.52 roller rocker arms +timing chain, +HEI dist, racing wires etc., etc.

I am looking for more power and low end torque.

My intention was to install a used ZZ4 roller camshaft and roller lifters. But, after dissassembling the engine (still in vehicle) I found that I would have to drill and tap the three bolt holes intended for mounting the roller lifter retainer tray. I am concerned about getting metal filings in the engine cylinders and crankcase.

My second choice cam is a Howard Cams, CL112031, hydraulic flat tappet cam that I recently ordered from KMJ Enterprises. It is recommended for 4X4 and heavy vehicles.

My question is: Should I drill and tap the block and install the ZZ4 cam, roller lifters and pushrods, or should I just go ahead and install the new flat tappet Howard hydraulic cam, with new lifters?

Any comments on risk, horsepower and torque are welcome.

ZZ4 cam specs. -- .474/.510 lift, 208/221 @ .050, 112 separation (LSA)
CL112031 cam specs. -- .475/.475 lift, 232/232 @ .050, 108 separation

Note: While writting this note I came across another vendor with two additional Howard cams that make "good"/"strong" low to mid-range torque.

Can anyone provide advise? I am nearly at my limit financially, and the parts I've purchased will soon exceed the value of my truck.

[mountie]

Originally Posted by Nascar fan

I have a 1994 Chevy Silverado P/U with 5.7L, 350 cu (L31) engine. I recently purchased new GMPP cast iron Vortec heads, an aluminum Vortec intake manifold, shorty headers, Holley 670 Street Avenger carb, and 1.52 roller rocker arms +timing chain, +HEI dist, racing wires etc., etc.

I am looking for more power and low end torque.

My intention was to install a used ZZ4 roller camshaft and roller lifters. But, after dissassembling the engine (still in vehicle) I found that I would have to drill and tap the three bolt holes intended for mounting the roller lifter retainer tray. I am concerned about getting metal filings in the engine cylinders and crankcase.

My second choice cam is a Howard Cams, CL112031, hydraulic flat tappet cam that I recently ordered from KMJ Enterprises. It is recommended for 4X4 and heavy vehicles.

My question is: Should I drill and tap the block and install the ZZ4 cam, roller lifters and pushrods, or should I just go ahead and install the new flat tappet Howard hydraulic cam, with new lifters?

Any comments on risk, horsepower and torque are welcome.

ZZ4 cam specs. -- .474/.510 lift, 208/221 @ .050, 112 separation (LSA)
CL112031 cam specs. -- .475/.475 lift, 232/232 @ .050, 108 separation

Note: While writting this note I came across another vendor with two additional Howard cams that make "good"/"strong" low to mid-range torque.

Can anyone provide advise? I am nearly at my limit financially, and the parts I've purchased will soon exceed the value of my truck.

It looks like you are in conversation with some knowledgeable venders. They could have your answer...

My friend who builds remarkable 350's, doesn't usually use rollers. 350's don't have a history of lifter's failing, anyway...... when engine oil quality is maintained. ...What RPM's do you expect to run the truck, anyway? If you're revving the crap out of it all the time, then maybe rollers?

( If I built my own engine, and had the time, I'd consider roller rockers due to the lesser oil, way up at the top of the engine) My engine was purchased built stock but with a 4-bold main caps.

Schuebeck (sp?) Out of Vegas manufactures COMPOSITE lifters that have nearly zero wear to themselves and the cam. If you are that concerned.

I believe Petty Ent. uses them in NASCAR engines.

[Nascar fan]

Hi Mountie, I'm an old gezzer (67). My hot rod days are over, but I enjoy having a little punch left in the gas peddal. I might make a few jack rabbit starts, but I've outgrown burning rubber at every light. I'm after the feeling of a strong engine, and the throaty exhaust sound that comes with it.

My delema is trying to match the cam with the heads, manifold and vehicle weight. Thanks for your reply.

[Nascar fan]

It's me again. That silly ZZ4 cam is what got me started on this project. I got it, with the roller lifters and pushrods, for $75. I also bought the ZZ4 heads, but found them too costly to repair. After seeing the flow rates of the new cast iron bowtie heads, GM #25534421, I couldn't resist taking the plunge.

One thing has led to another and now I am at the point of no return. WHAT WAS I THINKING?

[mountie]

Originally Posted by Nascar fan

Hi Mountie, I'm an old gezzer (67). My hot rod days are over, but I enjoy having a little punch left in the gas peddal. I might make a few jack rabbit starts, but I've outgrown burning rubber at every light. I'm after the feeling of a strong engine, and the throaty exhaust sound that comes with it.

My delema is trying to match the cam with the heads, manifold and vehicle weight. Thanks for your reply.

Add the the "match" with the rear end gears / wheels ( final ratio) that ends up contacting the asphalt.

I know there is a formula for what you are wanting. Try talking to Art Carr of California Performance Transmissions. He sold the Art Carr name to Torco. But He's a good guy to discuss set-up, because his famous Auto Transmissions, required the whole package to make a car haul-ass. Uh, also Paul Pfaff ( engine builder / dyno genius) .. They are both in Huntington Beach, Ca.

Call Ken Black w/ Keith Black Engines ( South Gate, Ca.)..... He'll have his guy talk to you.

These guys are 'old school' smart. And old school friendly. Catching one of these guys will give you a fast answer with little delay.

( I've worked with all of them for racing stuff.)

(Today, I'll be watching a guy I used to crew for.... driving in Kentucky... Casey Mears... A good driver without a good carchief... again)

[b454rat]

I've had good luck with Comp Cams Xtreme cams. I had the 268 in a TBI 406 in a 90 1/2t 2wd short box that would flat out fly. The tranny was getting weak, so I had to be careful, but would annihilate the tires off the line, still pin you back in the seat at 60-70 mph. Had a sweet lumpy idle that was just heaven to listen to!!!

Had a thrown together 355 in a 2wd S-10 Blazer, that had the high energy 262 I think, nice idle, and ran real good.

[Captainfab]

I would go with the ZZ4 roller cam. There is power to be gained not only from less resistance of the roller lifters, but also in the more agressive design of the roller cam lobe.

You can drill and tap those holes if you are very careful. Lay a bunch of rags/shop towels in the lifter valley, covering escape routes for metal chips. Then coat your drill bit and tap with bearing grease, and drill/tap slowly. The grease will contain most of the metal chips. Then carefully use a magnet to pick up any stray chips on the rags. Then once again carefully pick up the rags/towels. If you are still concerned, use a shop vac or maybe wash the valley with solvent really well and then drain it out the bottom.

[Nascar fan]

Thanks for the reply. I had thought about plugging all holes and using rags and a magnet, but the bearing grease had not occurred to me. That's a very good idea.

I'm still not comfortable with my choice of cams. I read that alot of guys are replacing their ZZ4 cam. I'd like a roller cam, but is it worth the effort?

Any advice on the flat tappet cam I purchased?? I chose it because the ad said it is for heavier vehicles and has a wide power range. But then, after I ordered it I saw that the best performance is between 3000 - 6000 RPM. I am looking for low end torque, a lumpy idle and more power. For a 350, my truck feels pretty sluggish.

I am not a mechanic, and I value everybody's advice. I have two cams to choose from. I will probably take mountie's advice and call an expert.

[fleetsidelarry]

I would certainly agree about using the roller cam especially since you have it already. in addition to their primary advantages, particulary the lobe profile, as mentioned, you also don't have to worry about break-in.

[fleetsidelarry]

for the roller cam, you will also need to install the lifter retainer tray which requires drilling/tapping 3 holes in the lifter valley.

[Nascar fan]

OK guys. I'm gonna drill and tap the block. If I don't get any more suggestions, I'll go with the ZZ4 cam.

Thanks for the advice.

[mountie]

Originally Posted by Nascar fan

OK guys. I'm gonna drill and tap the block. If I don't get any more suggestions, I'll go with the ZZ4 cam.

Thanks for the advice.

It is always your call..... If I am not sure.... I ask around.....

I always consider the cost/time versus the result. I was going to get custom built headers. But the minimal performance gain wasn't worth the bragging about having headers. (In my stock application)

My crate engine choice was for adding a Pro Charger someday. ( I just want a mild enhancement & still keep reasonable mileage)

[fleetsidelarry]

Originally Posted by fleetsidelarry

for the roller cam, you will also need to install the lifter retainer tray which requires drilling/tapping 3 holes in the lifter valley.

Duh. Sorry, don't know why I said that, was thinking the previous discussion was about the cam retainer.

what about the GM HT383 cam. too mild?

[Captainfab]

I didn't suggest a different cam as the OP stated that he was about at his financal limit. If the cost could be managed, I would suggest either the Ram Jet 350/HT383 factory cam, or one of the aftermarket 4x4 cams for increased lowend torque. A few years ago, we built a 355 for my son using the Vortec heads and the Ram Jet350/HT383 cam. It produces nice low end torque and pulls good to about 5000. And this is with the 1.5 rockers. When used in the Ram Jet 350, 1.6 rockers are used. Another engine we built for my son was a 404 (SB400 +.020) with the Vortec heads and a Comp XE4262 FT cam. It pulled hard from just above idle to about 5000.

[BigDan3131]

That Howard cam with the .475 lift is ok but since its a truck a cam with split duration will bump up your bottom end a little more. The zz4 cam will seem very mild due to the duration at .050 while the Howard cams duration at .050 will give your motor a little rumble and with that tighter lobe separation angle too. If Howards was contacted directly and they said that cam was right for you I'd stick with it.

[donut]

Are the new GMPP cast iron Vortec heads lift limited like the old 062's?

Sorry if I'm off topic a little, but if they are, it could affect his decision some.
(that and Google on dial-up....)

[Nascar fan]

The small port cast iron bowtie head (GM #25534421) has a max lift of .530 in. See link below

http://www.summitracing.com/parts/NAL-25534421/

The best price I've seen is $494.70 at http://www.gmpartsdirect.com/results...umber=25534421

[donut]

Thanks Nascar fan, guess I missed the "Bowtie" part (now that I scroll up I see it. That's what I get for reading at almost midnight)

[Nascar fan]

Big Dan was right. I contacted Howard Cams and they said the cam that I purchased would work well in my truck.

I had already drilled and tapped the block for the roller lifters, but I found that my new Cloyes double roller timing set would not fit the ZZ4 roller cam.
Also, after I read that the ZZ4 cam would seem mild, and that the Howard cam would have a rumble, I was leaning toward that cam anyway. I had also ordered heavy duty push rods and an HEI distributor for the flat tapet cam.
The new cam arrived late this afternoon, but unfortunately I was on my way to our cottage for the weekend.

Get this: I haven't done any real engine work in nearly thirty years. I'm trying to work in a small single car garage in a condo association. I have accumulated plenty of tools over the years, but I'm having trouble reading the socket sizes, and I have lost the ability of just grabbing the particular wrench size I need. Also, my truck has a mix of both metric and regular sizes. I have been cursing every GM engineer alive for designing an engine that is so complicated to disassemble. Every part I want to remove has two or three other parts that must be removed first. I fear I'll never get all the wires and vacuum lines right.

I should have done more homework I guess, When I tried to drop the oil pan, I couldn't get it past the front differential. Tell me, should I have pulled the engine to do this job? I spent several hours just trying to unbolt the oil pan.

Now I know why two mechanics had no interest in taking this job on.
You can call me Bob

[mountie]

I chose a GMC back in 1990.. My '88 Sierra. I opened the hood and it looked just like my 1973 Chevy Malibu, sitting in the driveway ( Man,, I wish I kept it)

Anyway, I looked at a same year Ford..... All the crap... I couldn't see the engine, where as, I could put luggage in the '88!!

My complaint is also the stupid idiots using metric along side the American bolts. ( GMC made in Canada?)

Also.... TAKE DIGITAL PHOTOS OF YOUR ENGINE AREAS FOR MEMORY.... ( edit).. One of us members could take photos of a similar engine set-up and post them for you to see?

(Oil pan removal)..... What year is your truck? My '88 manual says to remove transmission converter cover & slide oil pan back. (350 / 5.7 ltr.)

[Nascar fan]

Hi mountie, It's a '94. I did take the converter cover off. I want to change the leaky oil pan gasket while I'm at it. I'm also curious to see if I have a four bolt main engine.

[BigDan3131]

I don't even like bending over my engine compartment and I'm only 43. A full size truck plus cramped working area = aching back for weeks. Pull the motor so the chiro doesn't have to pull on you.

[mountie]

Originally Posted by BigDan3131

I don't even like bending over my engine compartment and I'm only 43. A full size truck plus cramped working area = aching back for weeks. Pull the motor so the chiro doesn't have to pull on you.

I agree... that "1/2 way lean forward" ..is a lower back killer!!

Get some old patio chair pillows. & a short step ladder.

Get up & inside the engine area, and have a seat.

Caution..... Don't do what I did once..... sit on the radiator top hose outlet. They break.

Or, get a couple seat cushions, and lay them on the fender edge, & lean against them. (Watch your belt buckle!!)

[Nascar fan]

UPDATE: Hi guys, I've made some progress. I installed the flat tappet cam and the engine is back together. I was not able to use the standard +.100 pushrods I purchased because the valves were contacting the pistons. I used a pushrod length checker and it appeared to be okay, but when I hand-turned the engine to adjust the first valve, I thought I felt something when the valve opened. It didn't want to turn after I adjusted the second valve. YIKES! All the major parts are on and it looks good. I had to make modifications to the heater and air conditioning hoses to clear my new valve covers.

My problem now is trying to find longer cables for the throttle and automatic transmission linkage. Also, ...trying to determine how much of the computerized stuff (vacuum hoses and electronics) I can remove.

I connected a wire directly from the battery to the HEI distributor to see if the engine would run. It fired once, just one or two quick pops. I tried turning the distributor and cranking it over again, but it didn't start. My time is limited to just one or two days a week because we have a cottage at a lake. I can't wait to get back home.

This turned out to be a much bigger project then I expected. I'd be going nuts if a mechanic had my truck for more than a week.

I appoligize for stretching the topic of this thread; but thought mountie, BigDan and others might still be following.

Please submit any information you think I could use. By the way, I never did change the oil pan gasket. I cleaned as much as I could, removed the timing cover rubber gasket and applied silicone rtv, but will tackle that problem later if it leaks.

[Marv D]

A quick note you may have already considered. The original TBI in-tank fuel pump puts out somethinglike 12-14psi. Your carb isn't going to like that. You need 6psi for a carb. I have heard using a pressure regulator onthe TBI pump just causes a early failure. I do not know of a 'in-tank' low pressure pump, but modifications IN the tank, and a standard low pressure fuel pump (electric or mechanical) are in order here.

If you had valve to piston contact with the longer pushrods, you will STILL have the same issue with the stock length pushrods. The length of the pushrods does not alter lift, it just corrects the geometry of the rocker slipping / rolling over the top of the valve stem. Youmight want to investigate that issue further.