Brent,

Do you think that he is referring to potential damage to the valve train via valve loft, or potential power loss? If his complaint is due to potential damage to the valve train, that does on the short term provide an increase in power, I can see why NHRA racers would go with that trade off. The engine is rebuilt more often and the damaged parts are then replaced, as opposed to a street performance car in which the person hopes to not have to build the engine.

Jim

Not sure on that one. It certainly makes more power when it's "engineered loft". On a stock eliminator, you're limited to factory valve lifts. Some of those back in the 60's were .450-.490". You can open the valve a lot further than that with some carefully designed parts, but when measured at inspection, it looks stock. :cool:

The thing about camshafts is that cam companies spit them out and most guys are happy with them because they have never tried anything else.

I've been testing and dyno'ing camshafts in Fords for quite a while, back-to-back, many times doing cam swaps the same day on the dyno.

Here's a couple of scenarios, tell me how much hp you think is different between the two camshafts, given that all other engine specs are exactly the same:

Scenario 1, 445 ci Ford FE:

Camshaft 1: 286/294, 231/239 @ .050", 114 LSA, 108 ICL, .630"

Camshaft 2: 286/290, 231/235 @ .050", 113 LSA, 108 ICL, .630"

(If you'll notice, the overlap is exactly the same on these two cams)

Scenario 2, 354 ci Ford Cleveland

Camshaft 1: 289/297, 259/267 @ .050", 108 LSA, 106 ICL, .700"/.660"

Camshaft 2: 287/315, 257/277 @ .050", 112 LSA, 108 ICL, .700"/.700"

(Overlap the same on these two cams as well)

This article? https://elgincams.com/camshafts/

Brian,

That is it! Thanks. The guy does seem to know his stuff.

Jim

I believe the FE exhaust ports are decent, so I would guess Camshaft 2 gave 25 Hp more. I would have said less but that big of an engine is likely above 500 Hp.

If the Cleveland has the factory 4 V heads with too big on the intake and a constipated exhaust port, then I'm thinking Camshaft 1 will make more Hp because it needs the overlap, but I think it could use more duration on the exhaust. Therefore I'm not certain, as Camshaft 2 may do better. It should give much better low end torque. I only expect 20 Hp difference.

As you said, this is hard to do not knowing what the heads are.

Yes, a nice article.

I don't see any mention of 17 arc versus 3 arc.

Gary

I am just going to test the waters with the first scenario. I am guessing the second cam is going to make more power, it's a large engine so maybe in the 15-20 HP range because the intake is opening a little sooner to let more fuel in and the exhaust is closing just prior to TDC. It's a tough one to figure without knowing a lot of other information, but given what we have that would be my guess. This situation may produce more vacuum to suck the next flow of fuel mixture into the cylinder.

Jim

Ok Gary,

Educate the uneducated; what is 17 arc versus 3 arc?

Jim

Now I need to find where I read about this. :rolleyes:

Very clever!;)

I know less than most of you about this stuff, but this is the way I would have generally guessed, as well... emphasis on guessed! I would not be able to predict a value for the difference, though... no way.

That's kind of the point.

A cam grinder who doesn't work with engine builders on specific applications, or doesn't do dyno testing, won't have competitive products. Even then, unless you do back-to-back testing with the same engine, you won't learn much and it could be that you won't have the upper hand.

My first scenario with the 445 was a test that I did because practically every shelf cam is either a single pattern (intake and exhaust durations the same) or a split pattern with a 6° split. I can basically show with dyno testing that neither one of those are optimal for practically every FE engine out there. Would they work? Sure. Is there more to be had without losing anything? Absolutely.

Most FE head exhaust ports stink, putting out about 65-69% of the intake side's flow. There are exceptions to that, but all of your factory heads will stink and even the newer Trick Flow heads are less than desirable in that respect.

The difference in horsepower between the two was 11 hp and 13 lb-ft of torque, keeping the manifold vacuum exactly the same, street manners the same, etc. The winner was camshaft #1 there.

When hydraulic rollers first came out for the FE engine, we were reaching "walls" of about 6000 rpm where the engine just simply couldn't pull any higher. FE valvetrain is much heavier than most other engines, with some having 3/8" stem valves, large valves, heavy adjusters on the rear of the rocker arms, etc. The shelf cams from one of the biggest cam manufacturers used aggressive lobes because they were used to grinding cams for SBC's and other engines with lighter valvetrain. When we started experimenting with custom cams, the lightbulbs came on and we figured a bunch of stuff out. As of now, I have taken FE's with hydraulic rollers up to 7500 rpm.

The second scenario that I posted was a result from a custom cam grinder who wanted me to do business with him. He emailed me and asked me if there was an engine that I was working on that he could me a custom cam to use. If it worked, I could pay him for it. If it didn't work, I could send it back.

I told him that I had a 351C bracket race engine that I was building and already had a cam that I spec'd for it, but he was welcome to send one. He proceeded to ask all the engine specs and I gave him all the data that he asked for, and even sent him the specs for the cam that I had ground.

I degreed both cams in at build time and even ordered pushrods to favor *his* cam as the base circle was slightly different. On dyno day, I tried both cams within a couple hours of each other because I had a two piece timing cover and was able lift the lifters up out of the bores with some clothes hanger wire so that I didn't have to pull the intake.

The cam that Straub Technologies spec'd made 587 hp @ 7750. The cam I spec'd (camshaft #1) made 615 hp @ 8000. That's a difference of 28 hp at peak and there was a 10 *average* hp as well.

I don't understand. Looking at the FE cams specs, I would have thought the second cam would need a LSA of 112 to make the overlap identical.

regarding the 351 cams, I would have thought the 2nd cam would need either a LSA of 116 or 112 (depending if took gross lift duration or at .050) to have the same overlap.

I calculate overlap with advertised durations.

Yes. I did that as well.

Maybe try with a cam calculator.

OK. Yes, that made the difference. I understand now.

We have traveled off topic for quite a while, so, to get us back on track I will note that some of the original magazine articles, specifically Sports Car Graphic, August 1962, Sports Car Specials, 1964, and perhaps others reference a "300 cubic inch" engine option for 289 cars. This seems like the 302 engine, though it was several years before Ford released the 302. I have never heard of any street cars that had this as an option. Was there any truth to that?

I doubt it ever happened.

Many typos exist, and surprise, many reporters IQ test would have gotten them placed as a sewer worker in the USSR.