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Old 06-20-2005, 04:56 PM
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Duration @ .050" is 26 degrees more on exhaust. . .

will this cam work on a 540 CID BBC with 10 to 1 compression and set of 188 heads that have been ported? No NOS

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Old 06-20-2005, 05:39 PM
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What are the specs? A little more duration on the exhaust is good, but that is alot especially for an N/A motor. That is alot even if you were going to be running a supercharger. Personally, I would find another cam that was a little more conventional.

Adam
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Old 06-20-2005, 07:17 PM
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Mmmmmmmmmm, no. Unless the intake flows 350 and the exhaust flows 178.
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Old 06-20-2005, 08:00 PM
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Here's the scoop. This engine belongs to friend of one of my vendors. It made 534HP at 6200 rpm when it was built. Nothing to right home about but still a legit 500HP engine. It ran about 2 hours between the fenders of the '66 Chevelle it resides in before it started knocking. Long story short it had taken the bearings out do to some oiling issues. So my vendor had called me to get a good oil pan for his buddy and in typical BS session style the dyno numbers came up and he asked me about the camshaft.

Someone had stuck a 268/268 duration single pattern cam in it for an engine that was going to see mostly street driving and a few 6200 rpm shifts. Being is was OEM headed I told him I had seen very few BBC with OEM heads that ran good with single patterns. He asked if I would do the cam and I said yes if you get me the flow figures.

Rick, youre about right. E/I ratio was 52%. The intake runners flowed okay and the exhaust had been butcherd. So I came up with a cam with duration of 246/272 @ .050". Lift was in the mid 600 range on the intake and high 500's on the exhaust. I told him I had done 2 others like this over the years because of E/I ratio and they both ran real well. So he said grind it.

I e-mailed the specs to one of the cam company's I use and about 2 hours later I got a call from the owner of the cam company, "Chris, are you sure this is what you want." "Yep", was my answer.

So this BBC went back together and back to the dyno. On dyno day the shop owner that was doing the testing asked him a few questions, the owner, and typical guesses of 560HP, 600HP were the estimates. Then the engine owner mentioned the camshaft. Looks of *** came over a few of the "shop groupies" he said as he stated the spec's at .050". I guy said it might not start.

Engine with oil pan change, cam change, and 0 decked instead of .015" in the hole made 668HP at 6400 rpm and has over 600#/ft of torque from 2800 to 5400 rpm. It idles, its throttle responsive, and it absolutely hauls the mail in the '66.

I posted this to reinforce my point that camshaft selection is the most critical decision in the engine building process and if the cam is designed for the engine combination, then it will make power.

Chris
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Old 06-20-2005, 08:24 PM
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Do you think there is a chance that there was something else wrong with the motor before? 534 hp is less than 1 hp/ci. That doesn' sound right with ported heads and 10:1 compression. I had an as cast vortec headded 355 with a 268 duration hydraulic flat tappet cam with 9.9:1 compression that made over 1 hp/ci. Although I agree that a dual pattern cam is a better choice for that motor, It just seems that to gain that kind of hp, while going with a cam with less duration on the intake that their could have been something robbing hp besides the cam in the motor originally. I am not saying you are wrong, I just want to understand this better, it is really interesting.

Adam
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Old 06-20-2005, 09:50 PM
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Quote:
Originally Posted by Cstraub

I posted this to reinforce my point that camshaft selection is the most critical decision in the engine building process and if the cam is designed for the engine combination, then it will make power.

Chris
You hit it right on the head Chris. It isn't uncommon for engines with weak intake or exhaust ports to have a camshaft that is designed to accommodate the flow characteristics of the weaker flowing side. This has been the key to having engines, restricted by sanctioning body rules or the availability of better flowing cylinder heads, to run in certain classes and make enough power to be competitive.
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Old 06-20-2005, 10:18 PM
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Butchered porting, not uncommon. Never tried to cmpensate for that poor of an exhaust before. Usually we either try to fix the port or junk the heads. No matter what though each head is flowed for all the engines built in the shop prior to specing a camshaft, even the hallowed AFR's. Sounds like that head was pretty fooked up.

Sounds like things worked out for you though.
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Old 06-20-2005, 10:56 PM
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What is the charge for flowing a couple of intake and exhaust ports for evaluation on a basic home ported set of BBC 2.19/1.88 049's? Bob
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Old 06-21-2005, 12:01 AM
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It takes about a half hour to hour start to finish to flow a head. So anywhere from $60 to $100 bucks. The variables though that can add time is if you start to play with different valves. They can make a huge difference and usually it is worth the time if the builder has a nice selection on the bench. We keep quite a few in the room to play with on heads.
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Old 06-21-2005, 06:06 AM
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cam

Man Chris you had me worried for a minute..... I thought you fell and bumped your head????? or the new wife was using the frying pan for more then cooking?????

I am gald you went Paul Harvey on us and told the rest of the story!!!!

How are you doing anyway????

There is always a reason why some guys are fast and others are not and it always comes down to the correct parts for each engine.....But i'll admit i never thought it would take that much cam to wake up the exhaust side of a big block head???? Now you need to design the same cam with intake lobes that help the 4 bad ports???????L.O.L.

I need to talk to you about a pan for that 427 sb going to denmark. I'll PM you....

Keith
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Old 06-21-2005, 09:05 AM
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Adam,
I thought I posted it but this was a new Merlin block and the pistons were .015" in the hole. So the engine did get a zero deck. This is a 4.250" stroke engine and the pan that was on the engine was not condusive to a BBC with stroke. So I am sure the Zero deck to bump compression a little an a good oil pan helped in the power gain.


Topfuel,
Eactly. I love the 2 barrel stuff I do because you are limited to what you have to work with and therefore for me, makes it more fun to make power. I just want people to realize that the cam is the "Brain of the engine" and buying one cam is cheaper then trying 3 or 4.

Keith,
Doing real good. It has been a good year. The Pro stuff for NASCAR has been exceptional. We have several pans in process for the Engine Masters and we have added a couple large WD's, Liberty in fact just put in their first stock order yesterday.

Your comment about "crutching" the 4 bad intake ports on a BBC. It is done, that is old Pro Stock technology but in some Truck Pull Classes that I do camshafts for that have to use OEM heads, the camshaft has 2 intake lobes on it; one is designed to maximize the short runner and the other to maximize the long runner. These engines have a unique sound.

Yeah, just let me know about that 421. I just did one for a Rodeck going to the Middle East.
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