camarors2399

So I'm thinking about doing a cam swap. What all is required? Can I just put in a bigger cam and continue to use the push rods and stuff in it or do I need to replace all that two?

Night rider327

iTrader: (13)

Well it would help to know the year and engine size..

But yeah for a cam swap all you need is cam, lifters, and gaskets for valve covers, intake, timing cover, water pump, and front oil pan lip seal..

You can reuse your rocker arms, pushrods, etc. (depending on cam lift, the slot in bottom of rockers will only allow for X kift before the slot binds on stud, at that point you would need aftermarket rockers with longer slots... Same with pushrods they can only handle X amount of spring pressure)

Now depending on size of cam you get, you may need to change the valve springs to handle the lift.. Might even need to have heads machined to handle the extra lift or use valve locks that gives you a taller spring installed height.

If cam is real big, you could also get into piston to valve clearance where pistons have to be fly cut or replaced...

Also being timing chain has to be removed, its a good time to put a new one on.

You also need to match parts up.. Sticking a 290 adv. duration, 240@.050, .530" lift cam in a stock engine is gonna leave you with a gutless wonder that's slower than it was stock.

If it's an EFI engine then again you have to match cam to work with the computer and or get a tune for the computer so it will work with cam

camarors2399

Its a budy of mines 1988 z28 350 l98 i think and he is looking at a zz4 cam if that helps any.

2005Impalla

You could reuse your push rods and lifters but valves, springs, retainers will have to be replaced and valve guide to retainer clearance should be checked on the exhaust side with that cam. I would also replace the timing chain as I think some of the factory Chevy timing chains for the roller motors install with the cam in a retarded position and the cam is already ground with a 112 ICL. At least Edelbrock claims the timing chain installs retarded. I was going to run there rolling thunder cam, the smaller one with the idle to 5,500 RPM power band and in the instructions it stated this^ Honestly if it was me I would install that cam + 4* so it has a 108 ICL. You don't want a cam that wants to make peak torque at 4,000 RPM when your intake is going to start to run out of steam at 4,500 RPM

camarors2399

OK thanks for the help.

2005Impalla

O dam no no you don't have to replace valves LOL just springs, retainers and locks. SRY I responded before going to bed after a 12 hour shift and was way tired. I meant Valve springs not Valves, springs!

2005Impalla

you might be able to just replace springs if your on a tight budget but it is a good idea to replace the retainers and locks too. And check retainer to valve seal clearance on any thing with lift over .500 Best bet if your friend can afford would be to get a set of comp cams beehive springs with there 787 retainers. The retainer is thinner and has more clearance than stock retainer and will allow quiet a bit of lift with out machining of the head for clearance. I am installing these springs on my vortec 350 and comp cams claims I can run .525 lift and still have quiet a bit of clearance between the retainer and valve stem seal there not cheep though. If your friend is going to carb the motor I would pic a different cam though. If he is keeping the TPI than the ZZ4 would be great. If its carb I would pic a single pattern cam like the comp cams magnum 270.

Night rider327

iTrader: (13)

Ok, now have more info to go on.

The ZZ4 cam may not be the best option. Its a high lift, lazy ramp, mild duration cam.

It specs as...
275/280 adv. duration
208/221 @ .050" duration
.474"/.510" lift

You will need to change the valve springs for sure, you may run into retainer to seal and guide clearance with springs installed at stock 1.7" installed height. So I would use +.050" valve locks to be sure you have the needed clearance.

You will need around 110-120 # valve springs.

I recommend howards 98212 springs http://www.competitionproducts.com/H.../#.VIqIKtLF_bM

VTO 4134 7* +.050" locks http://www.competitionproducts.com/V.../#.VIqJQ9LF_bM

And at .510" lift I would worry some about the pressed in rocker stud.. You may end up pulling a stock and trashing alot of parts. I would recommend pinning the studs at the very least but going to screw in studs would be a much better idea.

Heads needs to come off for that though and took to machine shop. You will also need to buy screw in rocker arm studs..

Then you have two options.. Go with the shoulder-less screw in studs, or go with a shouldered stud and have heads also machined for guide plates then buy and install guide plates..

If you go with guide plates you also need to change out the pushrods for hardened ones as the stock ones are too soft and the guide plates will cut through them. Also if you go with guide plates, you will need to change your rocker arm style. Yours now is self aligning rocker arms, where the rocker has two little "ears" on the pushrod side of rocker that guides the pushrod in right place. You can not double guide the push rods, it will bind up. The guide plates, guides the push rods so you will need non self aligning rockers.

Also at .510" lift your stock rocker arm slots (in bottom, where rocker fits onto stud) may be too short and bind on the rocker stud and break rocker or stud.. You can use a die grinder to elongate the slot some, or buy aftermarket long slot rockers

If the car does not have headers on it, the cam swap will be a waste.. No point in holding the valves open longer and wider for more air to flow through engine if it can't get out of the engine.

So it needs headers as a supporting mod.

The zz4 cam will work with stock chip, but a custom burnt chip will make it all work better

Night rider327

iTrader: (13)

Why would you run a single pattern cam?

I tend to run dual pattern cams in most builds due to the common weak exhaust port in most SBC heads. The extra duration and lift can "push" more air through the weaker port overcoming the port's weaker flow.

I don't start running single pattern cams until I get into great flowing heads that have almost as strong exhaust port as intake port.

Even with my Brodix IK200 heads on carb'ed engine I still use a dual pattern. Not a real wide spread though.. 249/252@.050" .570"/.579" lift.

You mentioned vortec heads. On all the builds I have done vortec heads seems to really like a wider split dual pattern.. Like 10-12* min more on exhaust side than intake with .020"-.030" more lift on exhaust side

2005Impalla

Ya the vortecs are the only head I would run duel pattern on unless I was running NOS or building a truck motor I planned on towing with. My cam for my vortec is 214/224 @ 0.050 but I think the single pattern on the L98 heads will make more torque and if I was using L98 heads I would have used a cam with 224/224 and a 108 LSA instead of my 110 LSA and I might spray this motor some day with a 100 HP shot of NOS. Usually duel patters sacrifice a little torque for a wider power band by increasing exhaust scavenging at high rpm to help the intake when it runs out of flow.