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The specs on these two seem like what I want, with the second one favoring the exhaust with slightly longer duration and lift. I wonder if I need that with the AFR heads, or is it the more the better?
Of course, these specs don't say anything about other features that Dave mentioned, like ramp rates, or anything else that would provide a clue on how they will actually run.
The price is certainly right on those cams. I charge $200 to regrind a roller camshaft and in this case you're getting the grind AND the camshaft core. It is tough to say what the lobe design might be but to get .496 lift with a 1.6 rocker ratio takes .310 lobe lift. That and the 220 degrees of duration at .050 along with the 276 @ .006 is right at what the E303 lobe checks. Not sure on the dual pattern version what they might have used for the exhaust side.
As far as the quality goes who knows about the grind but it is probably fine. You can be sure that the OEM Ford core quality is about as good as you can get.
What usually happens with cams is that a single pattern cam tends to make the most peak torque and a dual pattern cam tends to sacrifice some of that torque at and below the peak to make more torque past the peak and therefore make more peak horsepower. In an application where you're running with an exhaust system that is less than ideal, tight fitting headers, mufflers and pipes is that the extra duration on the exhaust side isn't always helpful. Sometimes what tends to happen is the dual pattern design sacrifices torque down low and at peak yet ends up running about the same past the peak which tends to defeat the purpose.
Thanks again Dave, that's good information on the dual pattern behavior. I'm sure the 1.5" shorty headers I have are far from ideal, but getting bigger long tubes opens another dimension of complications.
Getting one of these cams also saves me the work of pulling the core from my local scrap yard.
Probably the way it works is the guy selling the cams has a friend who grinds them for him. They've got a box with a bunch of used core cams and when an order comes in they pull one out, check the gear and the journals, clean it up, check it for straightness, grind it and send it out.
As of right now this is the way it is soon going to work for the foreseeable future when it comes to flat tappet cams once all of the new unground lobe cast cores are used up.
What would scare me about going this route would be one of the seller's comments. "If you are building a high dollar build or applying a power adder, or you feel you are the second coming of Smokey Yunick or Dyno Don you need to find another source for your project." You have put a $2000 set of heads on your engine. Why are you trying to go cheap on the cam? I've become a firm believer in finding a good cam grinder that you can trust and sticking with them. A good grinder should be able to give you a cam that passes emissions and gives you good power.
I assume that's the seller's idea of a boilerplate EULA.
If the cam is ground correctly and it gives the engine the events that it needs for the intended application then it'll work as well as a cam from any other supplier.
I have not looked but I wonder what other cams they offer via E-Bay. Do they also have them for other engines or do they only have them for the small block Fords?
Dave, if I could have found a good stock Ford cam as a core, I would have sent it to you for your regrinding service. The offer from this place seems to be very good. But the note from their listing says the owner will be out until tomorrow. I've sent them some questions, and I'll see what their response is.
First off, didn't realize the services you provide Dave, and by no means wish to step on your toes, only to share my personal experience:
I went through the murky cam waters this winter on my 408 upgrades, and was refered to Sam Vincent of Vincent racing. After a good phone call I filled out the cam form and submitted payment. Your paying him a small fee (~$100) to spec a custom grind from Bullet cams. Cam came in a week or two, and not only upped the performance as expected, but kept other qualities I spaced out (power band, idle quality, idle vacuum).
And for anyone installing a Bullet cam, the intake lobes are not symmetrical, so id recommend calling the helpful guys at bullet to time the cam fyi.
That's no problem at all. I don't know Sam Vincent but I have heard of him before. Bullet grinds a nice cam and they have a ton of masters. They have their own designs but also a lot of the old Ultradyne, Lazer and I think some Cam Dynamics masters.
As far as the non symmetrical lobes go, most of the more recent designs are done that way at least a little bit when it comes to having a slightly different opening vs closing ramp. With that said I have some designs right now that were done for me by Mike Ingram that are significantly asymmetrical. They are intended to replace a couple of flat tappet lobes that I have used for many years in circle track two barrel engines. Flat tappet cores are not going to be manufactured for the foreseeable future so a lot of these classes that require flat tappet are going to have to allow rollers. The idea of these lobes is to be able to replace the flat tappets without a whole lot of trouble.
At first it would seem like it would be easy to just copy the lift table from the flat tappet but that isn't possible due to the limitations of the roller design. It can't accelerate the valvetrain as quickly as the flat tappet so the design has to be different. Once it gets it moving it can go much faster but it takes a bit to get there with the roller.
If I plot the cam it appears that the top portion of the lobe is about 3 degrees advanced when compared to the bottom portion of the lobe. If I put the lobes into the engine in the same centerlines that I've used with the old nearly symmetrical lobes the top of the lobe is in the same spot based on the max lift point BUT the bottom portion is now retarded about 3 degrees. Which centerline will the engine see? Will it be correct as it is or will the new lobes have to be advanced 3 degrees? Or will the ideal setting be somewhere in the middle? I don't know. I have a short block together with a belt drive that's going to be used to find out. Once I get time to finish up a set of heads.
Your informative post furthers my point; most of us don't understand enough to make the BEST decision on cams (not yourself in included), so for me at least moving forward, best left to a professional or specialist.
The extra I've spent on a custom grind prescribed by Sam V is worth it for having the confidence that come from realizing I probably have the perfect cam for my particular application.
I got the cam yesterday, and took some pictures and tried to take some measurements. Overall, I do not see any anomalies, but I'm not en experienced cam maker. I'll note something I did see.
In the close-up, you might see streaks on the side of the lobe. They just catch my fingernails.
Closer view of cam
I tried to measure the lobes with my digital caliper, but I'm not sure if that's the right way. I was trying to measure the base circle by measuring across the narrowest width of the lobes. I found that they varied by as much as .04". But trying to measure the lift as best as I could, I find that each lobe peak is about 0.3" more than the base, which translates to 0.48" lift with a 1.6:1 rocker. Overall view of cam
I will be getting my engine back from the shop on Thursday, and I will plug in the cam and try to measure with my dial gauge.
It it hard to tell from pictures but from what I can see that grind looks fine. I can't really tell about the streaks. When the cam is ground it can get a sharp edge/burr along the edge of the lobe. I like to knock off that sharp edge by using some Scotchbrite.
The base circle/overall size of the lobe will vary slightly depending on what's been done to the cam. The amount that the lobe has been changed in the grind has an effect on the finished overall size of the lobe. The cam started out as a dual pattern grind with an intake lobe that had less duration(and probably less lift) than the exhaust lobe. Assuming that it is now a single pattern grind with more lift and duration than before the intake lobe will measure slightly smaller than the exhaust lobe because they were changed more when reground. If gains lift and duration by changing the shape of the lobe in two ways, the base circle is reduced to gain lift and the base circle and the nose height are both reduced to gain duration(make the lobe get "fatter"). These changes are subtle and usually only involve removing a small amount of material.
It will be interesting to see what you find when you put it in the block.
Do you ever feel that the odds are just stacked against you?
The engine shop called yesterday to tell me that after they assembled the parts, the pistons stuck out of the deck by over 1mm. I go over and verified that it was over 0.05" above the block deck.
After a little bit of discussion with someone at Scat, he told me to check the parts. And damned if they didn't send the wrong crankshaft in the kit. I ordered part 1-94055, a rotating assembly for a 331 stroker kit, which is supposed to have a crank with 3.25" stroke. But based on my measurements, the actual crank is closer to the 3.4" stroke of their 347 kit. But that kit comes with pistons that have shorter pin height. I'm not familiar with the part numbers for their crank, but the box that it came in had the part number 9-302-3400. I looked at their catalog, and saw that was indeed the 3.4" stroke crank, and the 3.25" stroke crank should be 9-302-3250.
Scat claims to have been in business for decades, so you would think you can trust them to deliver the correct parts in a matched kit that they put together. I did, and I handed the whole box to the shop. Should they have looked closer at the parts? They're familiar with Scat, so they trusted them implicitly as well.
By the time I tried calling Scat again, they were closed. I sent them an email, and I'll see how they respond.
You've got the mechanics blues my friend. It sucks, we've all been there. There is a light at the. End of that tunnel, and some day soon you'll mash the throttle, he thrown back into the seat, and this moment now will be lost in time. You came this far, and you'll make it.
Sorry to hear about the setback, but you will get there.
