77 corvette valve lifters

D

deweys77

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Joined
Jun 24, 2008
Messages
5
Location
Torrington CT
Hi, I have been a member for quite some time and this is my first post. My question is this. I have a 1977 corvette stock L-48 4 speed which I have been restoring. I had a popping thru the carb. I replaced all the plugs wires and replaced the dist. with a msd. But the popping still was there at 2500 rpm's. So last weekend I removed the intake and found that 3 of the ex. lifters were concave on the area that rides on the cam. I have decide to remove the heads and have them cleaned and gone thru. I am also going to remove the camshaft, lifters and pushrods and replace them. My question is, What would be a good cam (not stock), something with a little lope as an upgrade and also should I replace the rockers and nuts? In other words I want to rebuild the top half of the motor. Oh I have a rochester stock carb on the engine. If you guys can give me any help that would be greatly appreciated. Thank You Steven
 
Steven,
I am fond of what they call the GM #151 cam. It works well on an otherwise stock engine.
 
Unless there is a problem with the rockers or you want to spend your money, there is no reason I can see that you need to change them. Inspect them- make sure the ball seat and the area that contacts the valve stem are good, look at the rocker balls for signs of burning or galling. If they look good, no need to change them GM SBC rockers are good for many miles. Same with the nuts. Unless they've lost some retention torque, use them until they do.

Have a good shop do the heads- dont' just drop them off at your local auto parts store. Find a good reputable machine shop that does some race car work. Take the heads in there. Tell them what you're going to use them for and to have at it. They should check the guides, replace as needed and do the same for the valves. I'm a fan of matching the valve springs to the cam manufacturer's recommended springs too. And a good machine shop will setup the correct installed height for the springs and install good valve seals.
 
Welcome to the motley crew of the Flying Dutchmen....

and the above two guys are right.....

per usual..:bump:
 
Thanks for the replies. I researched that #151 cam and sounds like it would be what I am looking for. I will remove the heads this week and drop them off at the local speed shop. I will discuss the cam selection and make sure the valve springs will work with this cam. I am trying to keep everything stock. Hopefully these 882 heads. are fine and don't have any cracks. Thanks Again. Steven :bounce:
 
I dunno what years, or any numbers, but later 70's SBC heads were thin castings, and so prone to cracking....especially when really hot....

:gurney::shocking: so maybe check those numbers out good before blasting money....:ill:
 
Update

Well finished my vacation last week and went back to work monday and received a lay off slip. What a bummer!!! Finally was able to remove the cam today and what a shock, #1 ex and #6 ex perfectly round. The camshaft was a Kinetic Eng. # C1H272-S. Looks like this engine was worked on before.(Bubba and his mates) The new cam (the #151 you guys recommended) was order and the chevy dealer from IL. called yesterday and stated it was cracked in half so have to wait till next week for shipping. Will give me time to clean and paint everything. Anyone know the specs on that Kinetic cam or have heard of them? Thanks Steven
 
I'll bet that the Kinetic cam is actually "General Kinetics". IIRC, Bill "Grumpy" Jenkins used that brand back in his "King of the Pro Stock" days. No idea what the specs might be- you did an internet search?
 
Update: The 882 heads were no good so I picked up a set of 993 heads cheap. These are 72-73 75 chambers not the ones made in mexico. The 151 cam is in with new lifters and also installing new rockers, pushrods, and nuts. The heads were checked. Everything was perfect. Will be picking up the heads on Wed. This engine was worked on before because when the heads were removed , I noticed that the pistons are marked .060, so I have a 350 with 60 over. I have a few questions #1 With the 993 heads and a felpro 7733SH-1 head gasket(.016) and .060 over, what might be the compression ratio? #2 I removed all the plug brackets to set up for the headers but looking I noticed the the wires run thru the motor mount for the front 4 plugs. The AIM manual shows this also to me. Is this correct? I probably will have to reroute them anyways. Last question a rough guess on how much HP this engine will make?

Engine 350ci .060 over
Cam #151
Summit headers( cheap ones for now)
3998993 heads 1.94/1.5 valves
stock intake and street fire distributor
stock rochester carb
4 speed and 3.70 rearend
 
Sorry to hear about your lay-off.
My wife just got laid off 2 weeks ago so my little engine project is :gurney: for now.
The overbore is not going to do anything for your compression so that will be stock(ish).Don't remmeber what the stock gasket thickness is but the felpro may raise it a decimal point or so.
My best guess as far as HP is concerned, high 200's maybe 300 at the crank.
But that's all it is, a best guess, didn't run it through any simulation programs.
Others will chime in with a more educated guess.
 
Be sure to use oil that has an additive package designed for use with flat tapped cams. Many of the newer oils don't have the needed additives, like zinc, and using them will result in accelerated camshaft and lifter wear.

Many guys use Rotella. Valvoline VR1 Racing Oil is said to have an excellent additive package, too.

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!
 
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