TedH

In 1999, with the help of a master mechanic-turned hotel manager neighbor, I rebuilt the L48 in my '80 Corvette in my garage in Tampa, FL. I engaged a local machine shop to bore the block .020 over, turn the driveshaft .020 under and generally prep/clean the block and hang new pistons on the stock rods after ensuring they were true. The pistons/rings are Sealed Power Federal Mogul H345NP hypereutectic pistons and Hastings Moly rings.

The valvetrain is a combination of Cloyes true-roller timing set, Crane Energizer Cam (272H10 grind), Crane hydraulic flat tappet lifters, stock length moly pushrods, Summit stamped steel rockers/grooved pivot ***** and DART Iron Eagle 180cc intake cylinder heads with guide plates, screw-in studs, 2.02/1.60 valves, and springs that will support up to .525 max lift.

Induction is a recondition corvette ram air system, Lars-rebuilt q-jet and Edelbrock #3701 dual plane intake breathing through a paper-element air filter.

Ignition is an Accel Performance HEI with a performance recurve, 8mm Taylor Spiro Pro spark plug wires and AC R45TS spark plugs with stock gap.

Exhaust is Jet-Hot Hedman 1 5/8 headers, 2.5" duals with h-pipe and Dynomax super turbo mufflers (no cats).

The engine lights the P255/60R15s from a stand-still and barks the tires in the 1st-2nd gear change. The car is a blast to drive except for...

My problem is my engine sounds like a sewing machine; the valvetrain has had loud mechanical tick that has (to me) persisted since about the 2nd year after the rebuild. I've had it checked by a mechanic and have verified it is NOT an exhaust leak.

The valvetrain noise is most noticeable off idle and until I engage the overdrive in the Bow-Tie 700R4 transmission. I converted from my tired, slipping TH350C transmission in the summer of 2000 in my garage. Along with the transmission conversion, I included a 2000 rpm stall converter, fresh DANA 44 assembly blueprinted with 3.54 Spicer gears, Van Steel rebuilt half-shafts, rear trailing arm assemblies and brakes.

13 years later and employed for nearly 9 months after a 2-year layoff, I have some spare $$$ and am thinking of refreshing the top end of the engine. I don't want a crate engine; I want to tear this engine down, in-car, and refresh the top end. I have all of the needed tools and relish the thought of finding something that I need so I can take a trip to the local Sears to add to my collection of tools and perhaps justify the purchase of a new (Craftsman) toolbox stack to replace a cheaper/smaller stack. In 2007, I purchased a fresh Energizer cam/lifters thinking I had a wiped cam lobe or failed lifter but I never got into the engine and they are still, in-box, on the shelf.

At a minimum, I intend to tear the top end down to see if I can visually determine where the issue lies. If it IS a cam/lifter failure then I have the needed items and just need to get the gasket/seals, maybe a set of new ARP fasteners for the cylinder heads (I get a little smoke at start-up and am considering having them cleaned/recon'd) and whatever else I find I need to complete/augment the project.

However... I am also seriously considering IMPROVING on the 50's vintage valvetrain with:

Retro hydraulic roller cam/lifters, cam button and bronze gear for distributor (Howard's CL110235-12)
matching moly push rods (Comp)
Pro magnum rocker arms (Comp), 1.5 ratio

It isn't as if I can justify the swap to the updated valvetrain. However, I would like to not have to worry about the (lack of) additives in the engine oils AND I want to eliminate the engine noise.

I'd be happy with a little HP/Torque boost from the roller drivetrain as I'll pick up some lift without sacrificing LSA and idle quality.

One nagging question I have is how to ensure all of the parts 'fit'? Since the roller lifters are taller, I've read I have to go with shorter pushrod length. Is there a pushrod length that is suitable for ALL retro roller camshaft kits on standard deck, gen 1 small blocks?

Don't even try to sell me on converting to an LS platform. I like the vintage nature of my engine and would buy a gen 1 crate engine before I went that route. When I pop the hood, I like the fact that it says 1980 yet has the performance of the late 80's.

Thoughts and advice are welcome!

cardo0

After u locate the tic source area u can just pull the intake and inspect the lifters (one at a time) for wear. Also cut open and inspect the oil filter for metal and u can have your oil samples analyzed for wear products if suspicious.

The sewing machine sound is what your using for exhaust system - not the engine. If u what more noise go bigger. My experience recommends a professional performance exhaust shop - someone in the business over 5 years or more. Most exhuast shops can build you and install a custom system for the same money as pre-made tubing and usually for less and it won't leak either. For Ex my stock LT1 350" in my camaro sounds bad azz just using a single 4" pipe through preformance a cat and muffler - no engine mods.

If u have any specific questions on heads and cam let me know and i will try too answer. Just too much prior posts for this.
cardo0

TedH

Good points all. The tick is my 'sewing machine noise'. I'll pull the intake and valve covers and inspect the lifters/cam. May be just a lifter that is bleeding down (bad lifter valve). If I can get away with just that, I'll have less than $200 in the repair including the cam/lifters I already bought, seals/gaskets, new mix of water/coolant, oil/filter and some ZDDP additive. Sure would increase my fun time in the vette

63mako

A roller valvetrain would be my choice if your tearing it down. You will need new springs but your reconditioning the heads anyway so now is the time. This is a better cam for your build. It has almost the same intake closing point as your existing cam and more duration @ .50, more lift and wants an 1800 RPM stall convertor. It will do what your looking for and no more sewing machine sounds 2 years after the swap.
http://www.summitracing.com/parts/HRS-CL111145-10/
These springs are the same OD as yours but correct for hydraulic roller. The beehives will get you better valvetrain stability and increase RPM capability
http://www.compperformancegroupstore...egory_Code=BEE
You will also need new retainers. The retainer numbers are listed in the link.

TedH

What about push rod length to match the roller cam and lifters?

63mako

You will want to assemble everything and use a pushrod checker ($20) to establish correct length. Valvetrain geometry will vary with differing heads, valve length, rocker arms, lifter manufacturer and cam lift so no carved in stone pushrod length.

TedH

Good idea on the $20 tool. However, I think I'll stick with the cam grind I am considering as I'd rather the safety margin of the .50x lift (the rockers I am eying are 1.52 ratio). I'm sure my current stamped rockers are not 1.5 ratio; probably more like 1:43. So, with a bit more lift with the Howard's cam I've identified, I think I'll be at the limits of my 180cc cyl heads and #3701 dual-plane intake manifold.

What's the deal with the need for new springs and retainers? With the .525 max lift in my DART's, aren't they sufficient? I would guess I've put all of 20K miles on the cylinder heads as I first installed 882's from Advance Auto parts (with the 1999 rebuild). They are smoking at start more from lack of driving than use. I'm probably not even fouling my spark plugs yet... I could probably get by not rebuilding the cyl heads this time.

cardo0

Try a compression and leakdown test and verify cylinders are leak tight. U can replace vlv seals while on the car. PC seals i believe fit right over the guide boss.
Use your experience guide u in your cam choice - no one knows how you like to you want your car to run and drive more than u do. And too much spring pressure only shortens the life of the cam while producing no additional benifits.

Great way to gain experience is replacing the cam as long as u pay attention to the results. And concider if u do have a wiped cam lobe u are leaving power behind a good cam of same size.

Good luck,
cardo0

Little Mouse

Your talking about a bronze dist gear on your street car

TedH

Isn't the aluminum/bronze distributor gear required for most hydraulic roller camshafts? I think I have cast iron on my distributor today.

63mako

If the spring pressure is right on the dart heads for the hydraulic roller you chose your good. Best bet is find out the recommended spring pressure for your cam and compare the recommended open and closed pressure to what is on the heads at their installed height open and closed .

I don't think anyone told him to put springs on that had to much spring pressure for his cam????