[Jay S]

This HFT cam is a little different than the vast majority of HFT cams for the way it is ground. Most HFT cams if you degree the ICL in from the intake opening @.050” off the base circle or from .050” from Max lift you will get the same ICL. On this particular cam it will produce a little different numbers on those two methods. Going of the base circle to .050” from the intake opening and closing will show the ICL is a couple degrees retarded versus off max lift. I can’t recall the exact difference but it seems like it is 1-2 degrees difference on this cam, checking from the base circle shows it is retarded. If you go off the base circle like I think Cliff usually does instead of the 103 ICL it will probably be closer to 105. What Cliff said about the 110 LSA cams not wanting more than 4 advance to make max power on a dyno I think is generally very accurate, but it only holds true on this cam if you degree the cam in from the base circle to .050”. The cams that have gentler profiles on the exhaust often respond to less advance also, this cam isn’t one of those.


The only down side for some to advance the cam a little more is it will likely idle a little rougher. I like the choppy idle on my cars. Not a bad idea to start with a little extra advance with the double rollers, the better made ones seem like they tend to stretch early in there life. The cheap ones just keep stretching. Lol

[TransAm 474]

Originally Posted by Formulajones

I'd leave it at 103. The intake lifter rise is right in the money spot and that's the most important thing. Where the ICL ends up to get it there is less important. The ICL that Harold recommends with each camshaft is a number that should get you right in the ball park for the lifter rise that he likes to see with his camshafts, but as you found out, you may have to fudge that number a pinch one way or the other to get the lifter rise you want.

Yep, we have decided to leave it at 103. All of your help is much appreciated

[slowbird]

Just curious what is the lsa of this cam?

[1968GTO421]

Originally Posted by slowbird

Just curious what is the lsa of this cam?

According to Lunati, the LSA is 110*.

https://www.lunatipower.com/voodoo-h...8-276-284.html

[TransAm 474]

Yep, LSA is 110 on the shelf 704, although I believe you can order it ground on a 112 for no extra charge from Lunati

[1968GTO421]

Thanks for the info ^ as I did not know I could order it ground on a 112* for no extra charge from Lunati.

[Jay S]

Originally Posted by TransAm 474

Yep, LSA is 110 on the shelf 704, although I believe you can order it ground on a 112 for no extra charge from Lunati

That has changed, they now charge it as a custom cam now. Last I knew to widen it to 112 was 179 + shipping and handling. Probably gone up more, that was last year. $230+

[Formulajones]

Just a little piece of info to keep in mind. The wider the LSA is, the harder it is to accomplish the intake lobe scenario that was talked about here. In other words it would need more advance to get it there, and sometimes you just can't get it there with a reasonable amount of advance.

[Stan Weiss]

I really don't care about how much I have to advance the cam. I care about ICL. If I have a 704 with 112 LSA installed @ 103 ICL and I have a 704 with 110 LSA installed @ 103 ICL. The 112 LSA cam will have a great difference between the intake lifter raise and exhaust lifter raise ATDC than the 110 LSA cam.

Stan

[pastry_chef]

Originally Posted by Stan Weiss

I really don't care about how much I have to advance the cam. I care about ICL. If I have a 704 with 112 LSA installed @ 103 ICL and I have a 704 with 110 LSA installed @ 103 ICL. The 112 LSA cam will have a great difference between the intake lifter raise and exhaust lifter raise ATDC than the 110 LSA cam.

Stan

Exactly.
110 LSA would have exhaust center at 117
112 LSA would have exhaust center at 121

For kicks found Comp lobes that closest match the 704 specs.

Comp intake lobe 5446
Comp exhaust lobe 5107
----------------

103 intake / 117 exhaust centers (110 LSA).

2.5 mm lift TDC intake
1.6 mm lift TDC exhaust

.9 mm difference @ TDC or about .035 inch

Very close to what TransAm 474 measured on that 704 Voodoo.
----------------------

with exhaust centerline at 121 (112 LSA).

1.3 mm lift TDC exhaust

1.2 mm difference @ TDC or about .047 inch

[Formulajones]

Originally Posted by Stan Weiss

I really don't care about how much I have to advance the cam. I care about ICL. If I have a 704 with 112 LSA installed @ 103 ICL and I have a 704 with 110 LSA installed @ 103 ICL. The 112 LSA cam will have a great difference between the intake lifter raise and exhaust lifter raise ATDC than the 110 LSA cam.

Stan

Yes that was the point. The further you spread out the LSA, then the more advance (or less ICL) is needed to get the intake lifter rise in the sweet spot that Harold and others that test these cams are looking for.