re cam question 3849346

[Wayne P.]

I currently have a comp cam 12-107-3 replacement for 3849346 solid lifter. It was mentioned that it might be a better idea to go to a hydraulic lifter less maintenance. I will also be replacing my intake from a torker 2 to Edelbrock 350-2101 . Would their be any suggestions ? I don't plan on racing the car . I do enjoy the low end torque . 327 300 plus 10 :1 compression . 4 speed

[Duke W.]

Re: re cam question 3849346

If you really want low end torque, put the OE 300HP cam back in it - NAPA CS274 - about 50 bucks. Plus you'll need a new set of hydraulic lifters.

If you want more top end power with OE 300HP low end torque, massage the heads and install a McCagh Special camshaft. See the Fall 2010 Corvette Restorer for all the details

Duke

[Wayne P.]

Re: re cam question 3849346

Thanks Duke. I will look into the CS274 cam. I asked the engine builder to replace my existing cam with the same one used on the 365 hp. I guess he didn't.

[Duke W.]

Re: re cam question 3849346

The "365 HP" cam aka 3849346, "30-30" cam is WAAAAY too big for sensible road operation. The 300 HP engine has the best torque characteristics for the way most of us drive our cars, today, and you can retune a 300 HP engine to make as much top end power as SHP engines while maintaining all the low end torque and idle behavior of the 300HP engine.

Most aftermarket cams are even worse than the big OE cams because they have even more overlap, which is what kills the low end torque while adding little, if any, top end power.

Duke

[Wayne P.]

Re: re cam question 3849346

Thanks Duke.
Would the stock hydraulic lifters from napa also be the best option . I guess I didn't do my homework and let the engine rebuilder ( speed shop ) Make the decissions. Live and learn .

[Duke W.]

Re: re cam question 3849346

Yes, there is just one hydraulic lifter for all vintage Chevy V-8 applications. You should also look into the valve springs. Chances are they are WAAAAAAAY to stiff - typical "engine builder" nonsense. The OE replacements are NAPA VS677 and this same spring was used for all SBs including including the big mechanical lifter cam versions.

Duke

[Wayne P.]

Re: re cam question 3849346

I talked to the Napa guys. They don't believe the cam CS274 is a roller cam. I will check with comp cam and see if they have the same specs .
I prefer my roller rocker arms if possible. Push rods are also for roller cam I believe. I might replace intake and adjust valves for this year and see if that makes the difference first. I am still looking for the Fall 2010 Corvette Restorer for all the details Thanks

[Duke W.]

Re: re cam question 3849346

The Comp Cams 12-107-3 is advertised as a duplicate of the OE 30-30 cam, so it has mechanical flat tappets. My recommedation is that you replace it with a Sealed Power CS179R which is the L-79 cam if you want to give the engine an "SHP flavor" or the CS274, which is a duplicate of the "300 HP" cam if you want a smooth 500 RPM idle and stump pulling low end torque.

Roller rockers are a complete waste of money.

Duke

[Wayne P.]

Re: re cam question 3849346

Well I wasted my money on rollers . So I am not going to get rid of them. Thanks I will look at a roller cam in-between the 30-30 cam and the cs247 . I like a little rock Regards

[Duke W.]

Re: re cam question 3849346

You appear to be confusing "roller lifter" and "roller rocker".

According to what you say your engine has a flat tappet (lifter) camshaft, and any replacement you choose should be designed for mechanical or hydraulic flat tappets (lifters) - not a "roller (lifter) camshaft" designed for use with roller lifters.

As I stated previously either the Sealed Power replacements for the L-79 or 300 HP cams from NAPA will be good choices depending on whether you want the original 300 HP characteristics or SHP engine characteristics.

"Roller rockers" can be used independent of the type of lifter, but like I say - they are a waste of money. You can always sell them on ebay and you will probably be able to get more than the price of a new set of OE equivalent rockers from NAPA, but be aware that they will be of the later "slotted" design, and they are not compatible with mechanical flat tappet camshafts - just hydraulic flat tappet camshafts.

Duke

[Patrick B.]

Re: re cam question 3849346

Duke-- Are you saying that the newer OE rocker arms with alignment bumps cannot be used with a mechanical cam even if you use narrow feeler gauges and set the clearances statically?

[Wayne P.]

Re: re cam question 3849346

You are correct sir. Comp cam 12-238-2 looks like a fit as well. thanks

[Duke W.]

Re: re cam question 3849346

Duke-- Are you saying that the newer OE rocker arms with alignment bumps cannot be used with a mechanical cam even if you use narrow feeler gauges and set the clearances statically?

That's correct. These rockers came into being long after the last mechanical lifter cams were OE. They were never tested with mechanical lifter cams that I know of, and I wouldn't want to risk my engine testing them.

I believe you can still buy conventional OE design rocker arms from the aftermarket. Crane comes to mind, but I'm not sure. You can check their Web catalog.

A decent set from a junkyard engine will also work. As long as you keep the balls and rockers matched and the wear surfaces show no signs of galling, they should provide good service.

Duke

[Duke W.]

Re: re cam question 3849346

You are correct sir. Comp cam 12-238-2 looks like a fit as well. thanks

I don't know why you keep bring up Comp Cams, but would never personnally buy a cam from them and never recommend them to anyone else. Their cams have a high lobe failure rate - especially the XE series. They are not Parkerized, which is the OE process that prevented lobe failures early in the engines' life, and OE engines did not get a "cam breakin". Plus, for a given duration they have too much overlap, which kills low end torque and fuel economy.

The EX series have aggressive flanks and require a stiffer than OE valve spring. This loads up the lifter-lobe interface and greatly increases the risk of lobe failure. Their purported improvement in performance, even if it's actually true, is not worth the risk.

All Federal Mogul OE replacement cams are Parkerized, and so are Crane's OE replacements, so they are my second choice.You can't go wrong with a Sealed Power or Speed Pro (Federal Mogul's two brands) OE replacement, and they are easy to order through any NAPA dealer.

When it comes to both performance and reliability, you cannot beat the OE valve train including OE cam lobes, although sometimes combining lobes from different cams (which is what Chrevrolet did to make the LT-1 cam) to achieve maximum across the range performance without altering OE idle behavior can work out very well.

Duke