The Long (Over)Haul
Part IV: Tearing into the top end of our engine
Dave Verna - April 18, 2013 10:00 AM
1 Pictured is the custom COMP cam, with an Edelbrock head ported by Modern Cylinder Head, and a Edelbrock Super Victor single plane intake.
2 Valve timing is critical. We will be verifying the profile is correct and the valve timing matches the cam card provided with the cam.
3 The 828s (left) are good lifters, but the time it takes to fit them to a block renders them outdated in our eyes. 16 Take time to make sure the outer and inner diameters of the springs are in the correct locations in relation to the retainer as well as making sure the rocker sweep is good. The rocker should always cross over the center of the valve in the middle of its travel.
4 You can see the added room the new 8043 provides by moving the link bar to the inside of the lifter.
5 These are COMP’s Ultra Pro-Magnum series rockers. Made from chrome-moly steel they can be a lot smaller than the aluminum versions.
6 The “914” spring (left) features a double spring and the custom cam’s necessary “954” version (right) features a double spring with damper.
7 Even though the box-stock heads were never run, the keepers still distort the valves. Neal McGory is taking the edge off the valve stems. He spins the valve head and takes a honing stone and lightly files the peak that the keepers create.
8 Opening the guides is an easy process that involves a honing stone and some light oil. Neal always stresses the importance of a little too loose is better than a little too tight.
9 All head bolt openings were given a slight chamfer to take the edge off. The head bolts can strike the edge of the holes, causing a piece of aluminum to flake off and distort your measurements.
10 We needed to open the spring seats up to accommodate the 954 COMP springs. They have an outer diameter of 1.525 inches. The stock set of heads did not require this.
11 We had all the exhaust valves measure +/- .0005-inch, which is well within spec. The intake valves all came in great except two of them. The two in question were .0015-inch (one and a half thousandths of an inch).
12 Neal proceeds to grind the valves back into shape. Getting the intake valves back in spec only requires a few swipes of the valve grinder.
13 Now that the castings are bare and the parts are loose, we can now proceed to visually inspect everything to make sure that there are no obvious flaws.
14 Checker springs are now assembled on the valves – also notice the lack of a valve guide seal. They are a one-time use item, as the valve tip will cut the seal upon removal.
15 We also checked for the proper pushrod length, which came in at 7.595 inches so we needed to order 7.600-inch long pushrods.
16 Take time to make sure the outer and inner diameters of the springs are in the correct locations in relation to the retainer as well as making sure the rocker sweep is good. The rocker should always cross over the center of the valve in the middle of its travel.
17 The clay is checked for the valve face distance to the piston notches in several directions. The depth, as well as the outer diameter of the valves, is compared to the diameter of the piston reliefs.
18 The next step is to measure the volume of the intake and exhaust runners as well as the volume of the chambers. These volumes will be needed to accurately calculate things like flow and compression as we continue.
19 All three heads came with flow sheets, but to get a true comparison, you really need to test them all out on the same bench, on the same day if you can.
20 Shims are added under the springs to get the correct installed height of the springs. We measured the new retainers, keepers, and shims to get us where we needed.
21 As we cleaned the springs, we checked them one by one – we had all of them within spec – mostly within a pound or two of each other.
22 The COMP seals which replaced the original rubber ones are made of a Viton material. There is a plastic guide that covers the valve stem that prevents any damage from the grooves.
23 One last double check to make sure we do not have any coil binding issues and we are cleared for final assembly. It’s a lot easier to find a problem and correct it now before you cause any damage.
24 Terry stated that his .120-inch wall pushrods come in three sizes for our application: 5/16-inch (right), 11/32-inch (center) and 3/8-inch (left).
With The sheer amount of parts that are being slung around the top of an overhead valve V-8, it’s amazing it all stays together as it sings at 7 grand!
The top end of an overhead valve V-8 controls power production while torque is derived from the bottom end, more specifically, the displacement of the engine.
Getting the top end nailed down took some homework, but we managed to get three sets of heads, two cams and three different intakes to try out. We’ll be testing different sets of Edelbrock-based heads, a stock casting, a hand-ported set and a CNC-ported set. The latter two versions have enlarged the intake valves to 2.055 inches, up from the stocker’s 2.02 inches.
Since we had a variety of heads and cams, we needed more than one length pushrod. We elected to get the stockers from COMP and enlisted the help of Terry Manton of Manton Pushrods for the ported heads. He took into account the spring pressure, length and intended usage. Pushrods are all Terry does and he suggested we use one of his 11/32-inch pushrods. Terry stated that his .120-inch wall pushrods come in three sizes for our application: 5/16, 11/32 and 3/8-inch.
Terry began to describe that the solid roller we were using would be a bit much for any 5/16-inch pushrod, but that the 11/32-inch pushrods are 50 percent stronger than the 5/16-inch and the 3/8-inch are 50 percent stronger than the 11/32-inch. Sadly, Terry passed away shortly after supplying us with these pushrods, but his legacy continues through his family business.
Edelbrock’s stock heads are marketed as ready to run, but if you want to have the peace of mind that your engine is built correctly, you need to blueprint every part. The stock heads will be disassembled and checked thoroughly. Neal also feels the guides to check to see if they are too tight or too loose while the valves are being removed. Only two guides were on the tight side and will be opened up later during re-assembly. Before the valves are removed we etched the number of the cylinder they will be going in. After the valves are removed, the valve face run-out was checked on all the valves.
With everything getting the OK, we can proceed to clean everything. There is a multi-step process just like the block, including the parts cleaner with brushes, jet wash, power wash, and finally a compressed air session to remove any leftovers. The castings are then ready to be mocked up on the top of the block. Care must be taken with the deck as well, as you don’t want any scratches or any dirt left over as you bolt these to the block. You could ruin your work by cranking down on something and messing up the deck. That’s why we ran these through a cleaning process prior to mock-up.
We’re going to combine these heads with three different intakes. One is an Edelbrock Super Victor single-plane intake and while the typical rpm range for this type of intake is 3,500 to 8,000, we are not bolting this on a stock stroke bottom end. The rpm range should come down considerably with the amount of stroke we are adding to the mix.
We are also going to run two camshafts, a custom COMP solid roller cam and a COMP XR280R, also a solid roller. The ease of break-in on a roller cam is worth the effort. If you add up the costs to get a flat tappet cam nitrided along with an EDM lifter we are getting real close to solid cam territory. The specs on the XR280R cam are: lift (with 1.5 rocker) .570-inch (intake) / .576-inch (exhaust), 110 degrees lobe separation with a duration of 242 (intake) / 248 (exhaust) at .050-inches. The COMP custom we ordered has .639-inch (intake) / .645-inch (exhaust) lift (with 1.5 rocker), 108 degrees lobe separation and 258 (intake) / 262 (exhaust) duration at .050-inches.
The custom COMP roller will offer a little more top end power, but we are still going for a 3,000 to 6,500 rpm range engine, something that will work for a street/strip set-up that will be plenty of fun. The new COMP lifters made that decision a lot easier as well. COMP’s new 8043 lifter features an EDM oiling hole to lube the roller as well as locating the link bar in front of the lifter. This enables the lifter to drop in and requires no clearancing of the block to get them to fit. The new version also has a taller body to keep the lifter from exposing the oil gallery and subsequent loss of oil pressure that can occur.
COMP also got the nod for the rockers. We chose COMP’s Ultra Pro-Magnum series. They are now available in a bushed version that contains a proprietary bushing insert that is pretty slippery. Made from chrome-moly steel that has been heat treated, these rockers are not as cool looking as the aluminum versions sold but they are actually lighter (143.6 grams bare) and can handle the 550-lbs of open seat pressure we are going to be using. There is not a lot of room when you start throwing a big spring in the small-block Mopar head. The COMP rockers eliminate the fight for space, since the 8620 chrome-moly steel can be a lot smaller than the aluminum versions.
COMP supplied the valve retainers, keepers and springs for both cams. The retainers are tool steel that offer strength, performance, and value while being lightweight in construction and are held with a 10-degree lock. Edelbrock ships the stock heads out with a seven-degree lock that is rolled and cut to be formed. There is nothing wrong with these for most applications, but with a lot more spring pressure added to the mix we elected to go with COMP’s 10-degree locks. The super locks are machined from hardened steel that are stronger and able to keep up with higher spring pressures we are running with a solid roller. There are some debates regarding the seven versus 10-degree locks, but we will stay far away from that. The locks we chose are a needed upgrade and will perform in more rigorous combinations.
COMP’s “914” springs were used for the 280R cam and feature a double spring while the custom grind requires their “954”, featuring a double spring with damper. Double springs are required for most solid rollers due to the added spring pressure they require. The larger 954 spring has a 1.525-inch outer diameter, which will require the heads to be opened up to accommodate the larger outside diameter as compared to the 1.489-inch for the 914 springs.
The springs are checked at the opening and closing heights that the valves will be used. Our closed height is 1.800 inches and we would add the .570-inch intake lift minus the .016-inch valve lash, to get .554-inch lift. We checked the 1.800-inch installed height and it came right in at 165 lbs. We add in the .554-inch lift to get the open height of 1.246 inches which came in at 380 lbs open pressure. We did the same thing with the 954 springs at opened and closed heights.
The head(s) can now be bolted down to the block and checked with clay for piston to valve clearances. We threw the small cam in and checked it against the stock head. While we are only showing the process of one head, we have to do the exact same thing to the other two sets of heads. Stay tuned because we are getting closer to firing this engine up and testing out all these combinations!