I recently purchased a 427/390hp car that had the engine rebuilt a couple of years ago and a Crane hydraulic roller cam kit was installed. The kit included the cam,rockers,lifters,springs and push rods. The car has a noticeable lope in the idle and it runs very strong. What are the advantages of a roller cam and is there a real performance and power increase or just a false perception?
-
-
Re: Hydraulic Roller Cam Kits
Rob-----
There are lots of advantages to a roller hydraulic cam. The biggest advantage is that, due to the roller lifters, cam profiles can be used which would not be possible with a flat tappet. Flowing from that advantage are greater HP potential while maintaining good driveability.
Additional advantages include somewhat greater fuel economy due to lower friction and virtual elimination of the problems of cam break-in. The primary down-side is cost---hydraulic roller cam set-ups are a lot more expensive than any other sort of cam set-up.
Virtually all modern pushrod engines use hydraulic roller cams. A big part of the reason is the fuel economy advantage, but there are also the other advantages I described. I'm a BIG fan of hydraulic roller cams. I consider them the ultimate for a street engine and I'm using one in my "ZL-1".In Appreciation of John Hinckley -
Re: Hydraulic Roller Cam Kits
Joe
Thanks for the insight. I just love this car. It runs like no other vintage 427/390 I have ever driven. The former owner said it was a bit pricey when he did it but it was well worth it in his mind for all the reasons you stated.Comment
-
Re: Hydraulic Roller Cam Kits
Rob-----
The Crane retrofit hydraulic roller kits are among the most expensive on the market. They're probably the best, too. However, I like the Federal Mogul/Speed Pro, too. They are lower priced but just about as good. Plus, they have certain advantages like an austempered ductile iron core. Federal Mogul/Speed Pro was the very first to have a retrofit hydraulic roller cam kit on the aftermarket. It took Crane about a year more to get their first kit on the market.
The first kits from Crane and the others when they finally got them out used a cam with a steel core, including distributor drive gear. These cams required the use of a bronze distributor driven gear. Bronze distributor drive gears are absolutely no good for street use---they have very poor durability and I'd never use one. Later, I believe most of the cam makers have gone to a pressed-on, nodular iron gear which means you can use a stock distributor driven gear. The Speed-Pro cams, being manufactured of autempered ductile iron cores were completely compatible with stock distributor driven gears from the get-go.
GM hydraulic roller cams use a special steel alloy for the cam cores. This alloy is compatible with a special distributor driven gear which has received a melonized treatment. These distributor driven gears MUST be used with all GM hydraulic roller cams or the gear will be "wiped out" very rapidly.
GM does not offer any RETROFIT hydraulic roller cams and/or kits, though. This means that they offer no such cams or kits for pre-1987 small blocks or pre-1992 big blocks, all of which were originally equipped with flat tappet cams.In Appreciation of John HinckleyComment
-
Re: Hydraulic Roller Cam Kits
Joe,
What do you anticipate the idle characteristics to be from your ZL-1 roller
cam? I guess a better question would be why you chose a roller cam vs. the
solid lifter setup ( original ). Is it the maintenance of the solid lifter
valvetrain? Will your roller cam idle anything like the ZL-1 did? Or, did
that not even enter into your equation? Will you be able to use the stock
chrome valve covers with the roller cam? Lastly, what cam will you be using?
I often bounce back and forth about this on the L-88 project I hope to build
soon.
SteveComment
-
Re: Hydraulic Roller Cam Kits
Steve-----
I have ABSOLUTELY no desire, at all, to use a cam with the idle characteristics of the original ZL-1 cam or the L-88 cam. If I had to build the engine with a cam with those idle characteristics, I would not have done it, at all. DRIVEABILITY and CIVILITY is the absolute most important thing to me. With a modern hydraulic roller grind I hope to achieve more than enough power and torque while still maintaining a reasonable idle quality. It won't be smooth like a passenger car engine, but I expect it to be APPROXIMATELY similar to an L-72/L-71/LS-6 cam and, hopefully, smoother. If it turns out ANY worse than that, I'll immediately change the cam. I don't think I'll have to, though.
The stock chrome valve covers will work perfectly with this cam even though I'm using roller rocker arms, too. I've already tested that.
As far as what cam I'm using, I'll report on that after everything proves out. No sense in leading folks down a "primrose path" until I see how it works and conforms to my expectations.In Appreciation of John HinckleyComment
-
Stock type valve covers with roller rockers
I have owned multiple engines with either Comp Cams or Crower steel roller rockers. Using these rockers and cams up to .600 lift has been compatible with the repro valve covers WITHOUT drippers. I have never tried with the drippers. The worst I have had to do was to use the Fel Pro thick valve cover gasket (about 1/4" thick cork gasket). Don't go crazy with your valve spring pressures for street use!
Good luck,
MarkComment
-
L-88 cam, lower compression
Joe-
I have seen some things for sale recently that I have wanted to ask about. One was an L-88 motor on eBay, the other a ZL-1 'recreation' Camaro. Both reported to be using the stock mechanical cam, but pistons to achieve a much lower-than-stock compression (both 11:1 I think). Besides the poor street manners of the cam, wouldn't this combination perform poorly?
Also, I think I speak for many people in asking for an update on the 'ZL-1'. The picture of the motor you posted a while back had many of us drooling on our keyboards.
Thanks
ChrisComment
-
Re: L-88 cam, lower compression
Chris------
If the only changes to the engine involved the reduction in compression from 12.5:1 to 11:1, I would not expect the engines to run very much different from stock. I doubt that ayone would notice the difference except, perhaps, for 1/4 mile ET's.In Appreciation of John HinckleyComment
-
The L88 cam does not perform well with mufflers
The stock L88 cam performs REALLY poorly with the stock exhaust system (open headers is a totally different story). You would have a MUCH better combination going with the stock L89 specs and cam.
MarkComment
Comment