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Chevy 400 and Lazer Cam

7K views 12 replies 8 participants last post by  Tmod 
#1 ·
Just got an email back from Lazer Cams from the "Cam Wizard". Are there cams a good quality product? The guy sure seems to know what he is talking about. Anyway, I gave him my setup.

1970 Chevy 2 wheel drive pickup
4200+ lbs.
3.73 posi
2400 stall
Chevy 400
Vortec heads
RPM Air gap intake
770 Holley
1 3/4 headers

He recommended a cam with 235 intake 240 exhaust duration
.507 intake
.496 exhaust
108 lobe sep.

This seems like a pretty healty cam. Can the 400 handle it?
Also, I know that sometimes there is more lift on the exhaust side to make up for weak flowing exhaust ports. But why more duration, but not more lift. I noticed that a lot of his cam grinds have this too. More duration on the exhaust, but less lift than the intake? Guy really seems to know his stuff but just thought I would ask and see what you guys think?
 
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#2 ·
My 2 cents worth

The way I read cam specs.
The more lift the more HP.
The less duration the more bottom end torque.
The more duration the more top end torque.

The reason for less duration and lift on the exhaust on low flowing heads; the exhaust valve closes sooner because the exhaust gas has a tendancy to bounce of the exhaust manifold back into the cylinder. Thus having a poorer burn. Less HP.
 
#5 ·
the 400 will handle it fine.they do well with large cams.people get carried away with the names of cams and companies.to me a good cam is one that works well and is as cheap as possible cause lord knows there's no shortage of place's to spend your money once you start down the h.p. trail.cams are one of those things that you have to try to find out.thats what makes the desk top dyno's and such so nice to have.they are not perfect but help to keep you from having to spend a ton of money.and i for one don't give a danmed what the name of the cam is.if it works it works.
 
#7 ·
Those are good flowing heads (great in fact), for what they are. Especially at low lift ranges. The duration as Ctraub nailed on the head will allow the engine to carry into the RPM range some torque and therefore make HP. On the exhaust remember that the piston is pushing out the exhaust versus on the intake the piston is "trying" to suck it in. Typically you don't need the lift on the exhaust for this reason if the flow balance is reasonable between the intake and exhaust.

I don't get cams from Lazer but have talked to them at the PRI show the past few years. They seem like stand up guys.
 
#8 ·
This has been some very good input. Thank you. There is still one thing that I dont understand. Most cam companies offer more lift with more duration on the exhaust side. This particular grind has less lift on the exhaust compared to the intake. I was under the assumption that cam companies usually put more lift on the exhaust to make up for the poor flowing exhaust port.
For example:

Comp Cams XE 284
240 intake 246 exhaust
.507/.510

Lazer Cams
235 intake 240 exhaust
.507/.496

So, why less lift on exhaust than on the intake? Shouldn't there be more lift with the more duration?
 
#10 ·
Again, it's easier for the piston to push the exhaust out around the valve than for the piston to suck the intake charge in. In fact it is so difficult to get the air and fuel flowing around an intake that it greatly limits power not being able to lift the valve fully until somewhere around 104 to 110 degrees. Ideally if you could get full lift at maximum piston speed, which if i remember is somewhere around 20 or 30 ATDC (someone correct me if I am too far off on that) we'd all be driving much faster cars. The exhaust is not as critical. You also have the latent energy of the exhaust cycle on overlap and the narrow LCA to aid in the evacuation process.

Why are other cams designed different, cause they are a compromise. You asked for a grind that will specifically work with vortecs I assume, they gave you what works for Vortecs. Ask them what they would suggest for 882's or Bow Ties and you'll get something different. Call up Dema at Elgin and the specs will be pretty similar for the Vortec head.
 
#11 ·
Rick WI said:
Again, it's easier for the piston to push the exhaust out around the valve than for the piston to suck the intake charge in. In fact it is so difficult to get the air and fuel flowing around an intake that it greatly limits power not being able to lift the valve fully until somewhere around 104 to 110 degrees. Ideally if you could get full lift at maximum piston speed, which if i remember is somewhere around 20 or 30 ATDC (someone correct me if I am too far off on that) we'd all be driving much faster cars. The exhaust is not as critical. You also have the latent energy of the exhaust cycle on overlap and the narrow LCA to aid in the evacuation process.

Why are other cams designed different, cause they are a compromise. You asked for a grind that will specifically work with vortecs I assume, they gave you what works for Vortecs. Ask them what they would suggest for 882's or Bow Ties and you'll get something different. Call up Dema at Elgin and the specs will be pretty similar for the Vortec head.
Good answer for his question....................
just wear ur neck brace and do not have ur coffee in your lapp when it shifts...... :thumbup:
 
#12 ·
Rick pretty much covered it. The exhaust is under great pressure when it releases. . .you don't need lift for the exhaust gas to exit. Once you crack the valve and you have high pressure on one side and low pressure on the other the exhaust gas will exit.

Old school ground large lifts on the exhaust but that was then. . now a days you will see cams with more intake lift and less on the exhaust for most NA applications.

Chris
 
#13 ·
I just purchased a cam for my Ford truck from Bill and have yet to install it.

I can tell you the conversations that we had prior to me purchasing the cam were several as I was a bit reluctant to go with a lesser known grinder.

He was the ONLY grinder that would provide me with what I wanted in my grind.

I would recommend him and yes he usually seems to go a little big on his suggestions especially if he doesn't have the flow numbers of the heads.

Tmod
 
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