cam question
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cam question Can one of you cam gurus explain what this cam will do for me, as in
where will the power be, is it a pretty hot cam, will it be optimal
for the mast 305 heads, or should I use the mast 285 heads?
244/248 608/608 113+4
going in a 445 ci ls2 with T56 trans 3300# car
I know with the intake I have it will choke it down over
7000rpm, cant do much for that right now.
Thanks for any knowledgeable answers
where will the power be, is it a pretty hot cam, will it be optimal
for the mast 305 heads, or should I use the mast 285 heads?
244/248 608/608 113+4
going in a 445 ci ls2 with T56 trans 3300# car
I know with the intake I have it will choke it down over
7000rpm, cant do much for that right now.
Thanks for any knowledgeable answers
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Going to use mast cathederal
Ports with there ls7 ss cam, pretty sure that's a hot cam, looks like over .700 .697 lift and .246 260 duration something like that, but have to figure out how to get vacuum to fuel pressure regulator, just realized that will be issue for the fast 2.0 controller, maybe have to use
Something other than that fast
Unit, don't know yet.
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Use an external vacuum pump. Helps with crankcase windage and ring seal.
And why, pray tell, are you using cathedral port heads with an ls7 (think: rectangle ports) cam? That cam has 14° of exhaust bias, and that just cannot be optimal for those heads.
With a build of this caliber, why settle for an off the shelf cam? Especially one designed for different heads than you are using.
And why, pray tell, are you using cathedral port heads with an ls7 (think: rectangle ports) cam? That cam has 14° of exhaust bias, and that just cannot be optimal for those heads.
With a build of this caliber, why settle for an off the shelf cam? Especially one designed for different heads than you are using.
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I asked if a vacuum pump would work, fast said no, that would be
constant vacuum, need to know difference when engine is at idle.
I called MAST MOTORSPORTS and told them what I want, said 700chp
and a driver, he said the cathederals will have more down low than
the square ports, and the top end will be about the same, said cathederal ports will have better velocity than the square ports, and the cam is pretty much set up for those heads,cubic inches and my power goal. I asked about custom cam
he said no reason to. He said, those heads set up for that cam with my cubic inches will get me around 710 or 720 chp
And I sure hope so, I just made the order to mast.
And There web site is wrong when it says for 1.7 rocker on the description
it is for the 1.8 rocker, so lift is not what I said earlier,
lift is .658 .666 duration @ .050 is 246 260
http://mastmotorsports.myshopify.com...ant=1317709251
constant vacuum, need to know difference when engine is at idle.
I called MAST MOTORSPORTS and told them what I want, said 700chp
and a driver, he said the cathederals will have more down low than
the square ports, and the top end will be about the same, said cathederal ports will have better velocity than the square ports, and the cam is pretty much set up for those heads,cubic inches and my power goal. I asked about custom cam
he said no reason to. He said, those heads set up for that cam with my cubic inches will get me around 710 or 720 chp
And I sure hope so, I just made the order to mast.
And There web site is wrong when it says for 1.7 rocker on the description
it is for the 1.8 rocker, so lift is not what I said earlier,
lift is .658 .666 duration @ .050 is 246 260
http://mastmotorsports.myshopify.com...ant=1317709251
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Oh, I fully understand why you want to use cathedral port heads. I have just never seen a cathedral port spec'ed cam with that much exhaust bias. Granted, it's for custom heads that have gigantic intake valves, and relatively small exhaust valves, in comparison. So maybe that explains the extra exhaust duration. At the end of the day, I don't know ****.
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Use an external vacuum pump. Helps with crankcase windage and ring seal.
And why, pray tell, are you using cathedral port heads with an ls7 (think: rectangle ports) cam? That cam has 14° of exhaust bias, and that just cannot be optimal for those heads.
With a build of this caliber, why settle for an off the shelf cam? Especially one designed for different heads than you are using.
And why, pray tell, are you using cathedral port heads with an ls7 (think: rectangle ports) cam? That cam has 14° of exhaust bias, and that just cannot be optimal for those heads.
With a build of this caliber, why settle for an off the shelf cam? Especially one designed for different heads than you are using.
Before I tried that cam, I would have agreed with you. I'm not saying this should be a standard, but the results were interesting to see.
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It's because of the difference between the intake and exhaust valves on the large bore cathedral port heads.
On the bores under 4", like the cathedral port heads were designed for, the intake valve never really got that much larger than the exhaust valve.
On the large bore cathedral port heads, they haven't increased the exhaust valve size nearly as much in relation to the intake valve.
This has changed the relationship between the two. On sub-4"-bore ls1's the relationship was very closely matched. Allowing for almost no need for exhaust bias built into the cam. A couple extra degrees, like 4-ish, and you were golden.
Now the big bore heads have increased the intake valve size more so than the exhaust, and so you have to add more bias to the exhaust on these bigger bore cathedral port heads.
Or at least that's my guess.
On the bores under 4", like the cathedral port heads were designed for, the intake valve never really got that much larger than the exhaust valve.
On the large bore cathedral port heads, they haven't increased the exhaust valve size nearly as much in relation to the intake valve.
This has changed the relationship between the two. On sub-4"-bore ls1's the relationship was very closely matched. Allowing for almost no need for exhaust bias built into the cam. A couple extra degrees, like 4-ish, and you were golden.
Now the big bore heads have increased the intake valve size more so than the exhaust, and so you have to add more bias to the exhaust on these bigger bore cathedral port heads.
Or at least that's my guess.
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It's because of the difference between the intake and exhaust valves on the large bore cathedral port heads.
On the bores under 4", like the cathedral port heads were designed for, the intake valve never really got that much larger than the exhaust valve.
On the large bore cathedral port heads, they haven't increased the exhaust valve size nearly as much in relation to the intake valve.
This has changed the relationship between the two. On sub-4"-bore ls1's the relationship was very closely matched. Allowing for almost no need for exhaust bias built into the cam. A couple extra degrees, like 4-ish, and you were golden.
Now the big bore heads have increased the intake valve size more so than the exhaust, and so you have to add more bias to the exhaust on these bigger bore cathedral port heads.
Or at least that's my guess.
On the bores under 4", like the cathedral port heads were designed for, the intake valve never really got that much larger than the exhaust valve.
On the large bore cathedral port heads, they haven't increased the exhaust valve size nearly as much in relation to the intake valve.
This has changed the relationship between the two. On sub-4"-bore ls1's the relationship was very closely matched. Allowing for almost no need for exhaust bias built into the cam. A couple extra degrees, like 4-ish, and you were golden.
Now the big bore heads have increased the intake valve size more so than the exhaust, and so you have to add more bias to the exhaust on these bigger bore cathedral port heads.
Or at least that's my guess.
I am going to agree with you, seems like I have read something like that somewhere.
And by no means am I saying I have a clue about valve events, I asked
around till I talked to someone whose answers I liked the best, and went with his recommendations, I guess I will find out around the first of the year.
I just sent the block to ERL after work today, they said 8 week turn around
for the superdeck 1 6 bolt. And it will be about a month for the heads and
cam, the waiting is the hardest part.
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From: athens, ga
idk man.. ive never heard of cathedral being better heads than square port... thats why gm switched to the square port and put them on every high performance car they make now... cathedral went the way of the dinosaur imo
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I have heard the cathedral head port velocity thing before. More than once, from more than one source. But I don't have anything empirical to support this.
You are clearly correct, though, in that the general sent the cathedral port heads to sleep with the dinosaurs.
You are clearly correct, though, in that the general sent the cathedral port heads to sleep with the dinosaurs.
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Honestly I don't have a clue, I have read that head to head story, and read
some threads with the good head porting guys on here, some was for them and some wasn't.
So when I called Mast, the person I talked with had nothing to gain either way,square ports and cathedral ports cost the same.
He said he preferred the
cathedral ports because they had a little better power down low, so that is all
I am going on.
I sure hope he was right, I have already purchased the fast 102 intake, fuel rails, throttle body (which I can still use) for ls7, so hopefully I can
sell those and then get the 102 truck version for cathedral ports
And again his recommendation on the truck intake.
David, Yes superchevy, popular hot rodding, Hot rod and a few more have
really good comparisons with cams, heads and other that I enjoy
reading