HP500 Piston to valve clearance
01-19-2005, 12:19 PM
#11
Guest
Posts: n/a
Re: HP500 Piston to valve clearance
Originally Posted by jdnca1
Chris;
I gotta tell you though, I know several people who run that cam on blown 502's with great success, not only on the dyno but in their boats.
I gotta tell you though, I know several people who run that cam on blown 502's with great success, not only on the dyno but in their boats.
Compared to what other cams. I get this response alot and I ask the same question, "What other cam profiles were tried in the combination and how much more power did this cam make over the others tried?" The response is almost always nothing else was tried. So as far as runs good, runs good compared to what. Please I am not picking on you I just like people to think out of the box.
Cam, I have no idea. Depends on what the heads are flowing, boost, static compression, and on and on. I don't guess.
Chris
01-19-2005, 01:11 PM
#12
Registered
Thread Starter
Join Date: Feb 2002
Location: KY
Posts: 1,099
Likes: 0
Received 0 Likes
on
0 Posts
Re: HP500 Piston to valve clearance
STOCK 500HP.......
8.75:1, stock GM heads, 8-71 blower 7# boost, no chiller.....
I don't think 800HP and 775 tq are so bad with a 651 cam and the above set-up.
What "off the shelf" hydralic roller cam do you have experience with on an otherwise stock 500HP with a mid sized roots blower? What were your results? How did the cams you tried compare? Asuming you've done this, how was your referenced motor set up?
Crane seems torn between a 741 and 651. I've had several custom ground cams in the past and I know that would be the "best" route...BUT, I don't want to do a custom with this motor....I'm not looking for every last ounce of TQ and power, its frankly not needed.
8.75:1, stock GM heads, 8-71 blower 7# boost, no chiller.....
I don't think 800HP and 775 tq are so bad with a 651 cam and the above set-up.
What "off the shelf" hydralic roller cam do you have experience with on an otherwise stock 500HP with a mid sized roots blower? What were your results? How did the cams you tried compare? Asuming you've done this, how was your referenced motor set up?
Crane seems torn between a 741 and 651. I've had several custom ground cams in the past and I know that would be the "best" route...BUT, I don't want to do a custom with this motor....I'm not looking for every last ounce of TQ and power, its frankly not needed.
01-19-2005, 03:22 PM
#14
Registered
Thread Starter
Join Date: Feb 2002
Location: KY
Posts: 1,099
Likes: 0
Received 0 Likes
on
0 Posts
Re: HP500 Piston to valve clearance
I'm assuming you have no experience with that application, is that correct?
I also look at this from experience that 35hp usually doen't move the needle at these kind of power levels in a boat...a race car is another story. If you want every ounce, why mess with a hydralic roller? a solid will run circles around it
Patri, thanks again for the answer to my original question.
I also look at this from experience that 35hp usually doen't move the needle at these kind of power levels in a boat...a race car is another story. If you want every ounce, why mess with a hydralic roller? a solid will run circles around it
Patri, thanks again for the answer to my original question.
01-19-2005, 03:34 PM
#15
Registered
Re: HP500 Piston to valve clearance
I know Frank (10X) with COPS uses 651's in his blower motors but he has 588's and they do idle rough. I still think a cam like a 741 would be a better choice in a 502. They make power up to 5600 in a n/a application. With a supercharger pushing it should rev to 6000.
01-19-2005, 03:47 PM
#16
Guest
Posts: n/a
Re: HP500 Piston to valve clearance
jdnca1,
Plenty of experience. As I know with stock "CASTINGS" core shift is terrible and intake ports both short and long can vary as much as 20 cfm...add that difference to the valve job on the heads and you could have as much as 50 cfm difference in castings, so it is my experience to recommend camshaft after flow numbers are known. People remember the good for 15 minutes, they remember the bad for years.
Chris
Plenty of experience. As I know with stock "CASTINGS" core shift is terrible and intake ports both short and long can vary as much as 20 cfm...add that difference to the valve job on the heads and you could have as much as 50 cfm difference in castings, so it is my experience to recommend camshaft after flow numbers are known. People remember the good for 15 minutes, they remember the bad for years.
Chris
01-19-2005, 05:43 PM
#17
Registered
Re: HP500 Piston to valve clearance
cstraub,
Remember these guys aren't building NASCAR motors and in many cases these type of bolt-ons happen without even removing the heads. I am quite sure the cam issue is very debatable even if the best cam is chosen. Ideally all of us weekend warriors would get the heads flowed, then ported and matched, then choose a custom ground cam to fit the application. Unfortunately most of us can't afford to do that.
I agree with your thought process that if you really want the best possible stick this should be done.
JDNCA1
Check the piston to valve clearance by using some light springs on your motors.
Remember these guys aren't building NASCAR motors and in many cases these type of bolt-ons happen without even removing the heads. I am quite sure the cam issue is very debatable even if the best cam is chosen. Ideally all of us weekend warriors would get the heads flowed, then ported and matched, then choose a custom ground cam to fit the application. Unfortunately most of us can't afford to do that.
I agree with your thought process that if you really want the best possible stick this should be done. JDNCA1
Check the piston to valve clearance by using some light springs on your motors.
01-19-2005, 08:47 PM
#19
Registered
Join Date: Jan 2001
Location: rochester, ny
Posts: 978
Likes: 0
Received 0 Likes
on
0 Posts
Re: HP500 Piston to valve clearance
I felt the same way. I had an idea in my head and I looked for someone to validate it. Those that didn't I found myself debating my stubborness with them.
CSTRAUB knows.
RMBuilder knows.
If you are looking for a compromise, then say that.
The problem with free advice is that if it's "good", you never hear about. If it's "bad" you'll hear about it every damn day.
I don't want to argue. I compromise like crazy because I have short arms and I'm ok with that. These guys know their stuff and right is well, right...
CSTRAUB knows.
RMBuilder knows.
If you are looking for a compromise, then say that.
The problem with free advice is that if it's "good", you never hear about. If it's "bad" you'll hear about it every damn day.
I don't want to argue. I compromise like crazy because I have short arms and I'm ok with that. These guys know their stuff and right is well, right...
01-19-2005, 09:21 PM
#20
Registered
Re: HP500 Piston to valve clearance
Jeez the poor guy asks for opinions on piston to valve clearance and gets just about everything but the answer he is looking for. Now saying the cam is too large is not really what I call free advice without really backing it up with a better recommendation. The more I think about it 8.75:1 with iron heads is not ideal for a pump gas blower motor so the larger cam may kill a little power but make the motor a little less prone to detonation. Just a thought. 
Now saying the cam is too large is not really what I call free advice without really backing it up with a better recommendation. The more I think about it 8.75:1 with iron heads is not ideal for a pump gas blower motor so the larger cam may kill a little power but make the motor a little less prone to detonation. Just a thought.
