I do not think the stock springs could take the .517” lift of that cam without going into coil bind, but even if they could cranking a well used spring up a good bunch higher in lift is surly not a good idea! I would also want to check out what I had for retainer to guide / seal clearance.
Thanks. I'm just looking for a performance idea. How it runs. I have the proper springs, retainers, guides, etc.
that cam has a 15* spread between int and exh plus it's on a 116 LSA. would never use that cam no low end power. would have a lot of exhaust reversion too.
That cam is very similar to the lunati version of the hemi killer but its on a 112 ls 280/290, 230/240, 507/538. 112ls/108 icl I ran low 12 in a stk bottom end 70 block, ported stage1 heads 3500 stall and 4.10gear. For me it ran great......idled rough. I have manual brakes. But I feel if you didn't have a big gear and good stall it would be different.
Yes with that lobe separation it should drastically reduce overlap. Alot of marine cams run more duration than their street counter parts and they run ls up around those number specifically to help prevent water reversion of the wet exhaust system. The lower the number in lobe separation. Ls, the choppier it becomes.......take the 107 window rattler.......crazy overlap because the lobe centers were so tight together
It might not run power brakes, but with some mild gears and conveter should be good. Make sure you check piston to valve clearance........with that wider ls it most likely will run the exhaust valve closer. But my hemi killer ran with stk piston undecked blocked .040 gaskets and head clean up cut
Are you wanting to run that cam purely on availability,or you already own it? This is an old stubborn mule engine that I had in 3 different cars. It’s a mid-70’s 455 that was freshened up with rings & bearings,new chain,valve job on the heads,no porting. The cam is one of the Thumper cams. Basically,the largest one that I could run with the stock rockers. B4B intake,Holley 830,a good HEI,and headers. All 3 cars were between 3800-4000lbs and it ran 11:80’s-12:00’s. I had it just to use in those cars while their engines were being built. I would choose a different cam for your application. Are you looking for just something better than stock,or is this more of a max-power sleeper thing?
I can tell your from plenty of experience that the lift of this cam will stress both rocker shafts and rocker arms. I think I broke 3 of each b4 I swapped to older 430/400 setup.....after that no more issues. Most ppl that I've talked start running into these issues at or near .525 lift. Just food for thought
I wrote an article on picking a camshaft for the NE GS/GN club newsletter. I think there are alot of guys who really don't understand the effects of bigger camshafts and what the trade offs are. I'll cut and paste it here. Hope it helps. What cam should I choose for my engine? It's a common question you hear from someone planning on rebuilding their muscle car engine. The next question is how much horsepower can I expect to gain. Why do cams make more horsepower? An accepted fact is that the higher RPM you can spin an engine to, the more horsepower it will make, but the caveat is that the engine must be able to breathe at that higher RPM. As engine RPM increases, there is less and less time for air to move in and out of the cylinder. At some point, the engine reaches a point where it can no longer take in enough air to run at a higher RPM, and power starts to flat line or decrease. Increasing duration, the period in crankshaft degrees when a valve is open provides more time for air to move in and out of each cylinder. A camshaft that holds the valves open longer, allows the engine to breathe at higher RPMs where it can make more horsepower. Holding the valves open longer, increases overlap, the period in which both valves are open. More overlap increases cylinder scavenging at higher RPM, but it also decreases engine vacuum at idle which results in decreased idle quality. As you increase valve duration, the effective power range of the engine moves up the RPM scale. You sacrifice low RPM power and idle quality to make more power at higher RPM. That is the trade off. Modern high performance engines now incorporate variable valve timing to get the best of both worlds. We don't have that kind of technology for our engines, so our best bet is to be realistic about our goals when choosing a high performance camshaft. As mentioned, we are modifying valve duration so that we can make more horsepower, but to get that power, we need to operate the engine at higher RPM. We also need to get the engine into it's power range as quickly as possible. The biggest mistake made when planning an engine is selecting too big of a cam. The result is an engine that makes the car a dog until the RPM increases enough to get into the cam's power range. Bigger cams can require larger numerical rear gearing, and a higher stall torque converter to get the best performance from the car. Gearing and converter have no drawbacks for a race only vehicle that doesn't get driven on the street, but larger numerical rear gearing decreases fuel economy, and higher stall torque converters slip more, heating transmission fluid up more in a street driven car. Matching the torque converter to the cam is very important if you want the car to be enjoyable to drive in normal traffic. The best way of choosing a converter is to have it purpose built for your combination. It costs more, but in this case, you get what you pay for. With the current state of converter technology, it is possible to get a converter that feels like a stock converter until you punch it. A discussion of camshaft selection would not be complete without discussing cylinder head air flow. Head porting can increase air flow in and out of the engine so the engine breathes easier. Superior head flow lets you use a smaller cam to reach your power goals. The smaller cam has better street manners, and may not require more radical gearing and converter changes. Porting iron heads is time consuming and expensive. With the advent of aluminum heads, it is more economical to buy a set with entry level porting. Out of the box, they will out flow the best iron heads. They need to be used with higher static compression because aluminum conducts heat much faster than iron. Because of this fact, aluminum heads are much more pump gas tolerant, and they will not blister paint you apply to them. Speaking of static compression, if you have ever looked through a camshaft catalog, you'll notice included in the camshaft description is a static compression recommendation. The reason for this is Dynamic or running compression. Longer duration cams can bleed off cylinder pressure. Have you ever read that? Figuring out static compression is easy. Cylinder volume with the piston at the bottom of it's travel (BDC) divided by cylinder volume with the piston at the top of it's travel (TDC) equals the static compression ratio. What happens with any engine is that the intake valve is always open at BDC, and it closes as the piston moves up the cylinder on the compression stroke. Since no compression can occur with an open valve, the running compression differs from the static compression. If you figure the compression ratio with the stroke remaining after the intake valve closes, you calculate the Dynamic or running compression. Dynamic Compression (DCR) is an important consideration when you want to run pump gas. The target DCR range for pump gas is 7.5-8.4, but to be safe, it is best to stay at 8.0 or below. Since different cams close the intake valve, earlier or later, DCR is an important consideration when planning an engine. Matching the static compression and camshaft can be very important. If you don't you can end up with an engine that doesn't perform up to expectation, or one that detonates on pump gas. For more on DCR, type this address into your browser and read more. http://cochise.uia.net/pkelley2/DynamicCR.html At the end of the article is a calculator that you can download. With it, you can input your engine measurements and camshaft numbers. You can calculate Static, and Dynamic compression. I keep the calculator on my desktop. Several guys on V8 Buick have said that they cannot get the calculator downloaded or they cannot make it work. I had no problem doing so, but I can offer an alternative. One of the things the calculator does is figure out the intake valve closing angle. That determines Dynamic Stroke Length (DSL), the amount of stroke left after intake valve closing. Using the DSL in place of stock stroke results in the DCR. An alternative way to figure out intake closing angle is to use the following. Divide the Advertised Duration in half and subtract the Intake Center Line from the remainder. That will give you the opening event. Intake Opens Before Top Dead Center (BTDC) For the closing event subtract 180 from the duration and then subtract the opening number from that sum. That will give you the closing event. Intake Closes After Bottom dead center (ABDC) Using the TA 118 cam as an example. The numbers for the TA118 are advertised intake duration of 276*. The intake centerline is 114* (4* advanced from the Lobe Separation angle of 118*). You MUST use ADVERTISED duration. Using the math to figure intake valve opening, 276/2 = 138 138-114 = 24. The intake valve opens at 24* BTDC Now to figure out the intake valve closing angle. 276-180 =96 96-24 = 72* The intake valve closes 72* ABDC. Below is the internet address of a static and dynamic compression ratio calculator, so all you need to do is input your numbers. If you don't know the exact measurements of your engine, you can substitute values to get to your targeted static compression. Then input your intake closing number, and calculate the DCR. https://www.uempistons.com/index.php?main_page=calculators&type=comp Here's what the calculator looks like using our numbers for a 455 with 10.2:1 SCR
