Roller cam

-
aaronk785

aaronk785

Well-Known Member
Joined
Apr 21, 2013
Messages
1,021
Reaction score
851
Location
westmoreland ks.
Thinking of going roller cam in my drag car this winter. I'm looking at 2 cams. One is 263at .050int. and 269 at .050 ex. Lift is .675 in. and .650 ex. Other is 270 at .050in. and 275 at .050 ex. Lift is .670 in. and .635 ex. My question is what is the purpose of less exhaust lift. Most cams have more on the exhaust.
 
aaronk785 said:
Thinking of going roller cam in my drag car this winter. I'm looking at 2 cams. One is 263at .050int. and 269 at .050 ex. Lift is .675 in. and .650 ex. Other is 270 at .050in. and 275 at .050 ex. Lift is .670 in. and .635 ex. My question is what is the purpose of less exhaust lift. Most cams have more on the exhaust.
Click to expand...
More info needed about eng
Car spec would be nice also
 
i've never seen exahust lift lower than the intake, only the same or higher. That makes no sense to me. I have a 260@.050 .650 roller in mine. I would not want more cam than that unless I had more compression. What is your compression ratio or cranking compression. Also, what is the LSA on those cams?
 
Often the reason is possible valve to piston clearance. The position of the piston in the bore and the valves
You do not always need more or even the same amount of exhaust duration or valve lift to get the job done.
 
aaronk785 said:
Thinking of going roller cam in my drag car this winter. I'm looking at 2 cams. One is 263at .050int. and 269 at .050 ex. Lift is .675 in. and .650 ex. Other is 270 at .050in. and 275 at .050 ex. Lift is .670 in. and .635 ex. My question is what is the purpose of less exhaust lift. Most cams have more on the exhaust.
Click to expand...
Man those a some monster cams, just curious what is the application, street, strip or both? You must have a killer set of heads to match up the flow that cam has the potential of.
 
rumblefish360 said:
Often the reason is possible valve to piston clearance. The position of the piston in the bore and the valves
You do not always need more or even the same amount of exhaust duration or valve lift to get the job done.
Click to expand...

Dwayne did my W5 cam. It was 699/672 on exhaust. Car ran great. Every combo is different.
I had no valve relief issues. Most quality Pistons have plenty of room
 
True! Most quality pistons will have plenty of room.
Engines like the HEMI often have less lift exhaust.
 
Car is strictly drag. 3500 lbs. 10.7 comp. home ported Eddy’s, solid cam 272 at .050 and .660 lift, tunnel ram and two 800 dp, 5000 stall and 4.30 gears. Best e.t. Is 10.48 at 130. Leaning towards the smaller of the two cams for better torque with the tunnel ram.
 
I wouldn't go smaller than where you are at with it already. The roller design will yield you bit. What is the LSA on those cams?

WHat does the current engine make for power?
 
Cam is on a 108 in at 104. By the hp calculator using et and mph it shows just under 600 hp. Maybe the change isn’t worth it.
 
If it doesnt flow anymore for a considerable lift increase...I believe it hurts performance on the exhaust. Maybe to do with fps and scavenge effect.
 
Last edited:
aaronk785 said:
Cam is on a 108 in at 104. By the hp calculator using et and mph it shows just under 600 hp. Maybe the change isn’t worth it.
Click to expand...


Mine is 112 in at 110. 260@.050 .650 lift. mine made 600 on the dot. Lowering the LSA will give you more cranking compression without changing hard parts.
 
roccodart440 said:
Mine is 112 in at 110. 260@.050 .650 lift. mine made 600 on the dot. Lowering the LSA will give you more cranking compression without changing hard parts.
Click to expand...

i have cam swapped before and found that a wide LSA cam(112-114) is a dog in a typical N/A bracket type car unless you have lots of compression and convertor.
It will effectively kill 60 foot.
If you have lots of compression, real good heads and vert, they CAN shine. Especially at the big end.
As an example, you wont find Stock/ Superstock type stuff running usually anything but narrower cams
 
I have seen that type of cam spec on race engines that use aftermarket heads that have very efficient exhaust ports and headers including W7 W8 and W9 heads. They are usually combined with large intake valves and more intake lift.

it’s all based on the combination and application. Build your motor on your application, vehicle and engine components and choose your cam accordingly for best performance.
 
Rocket said:
I have seen that type of cam spec on race engines that use aftermarket heads that have very efficient exhaust ports and headers including W7 W8 and W9 heads. They are usually combined with large intake valves and more intake lift.

it’s all based on the combination and application. Build your motor on your application, vehicle and engine components and choose your cam accordingly for best performance.
Click to expand...

Actually that doesn't really mean anything about the head being a superior head.
Jones rec me a cam that had lower exh lift on my j heads and they dont shine on the exhaust. He Hemis have the exhaust valve clearance issue and well that where all that thinking comes from i figure from some folks. I stand by what I said originally
 
B3422w5 said:
i have cam swapped before and found that a wide LSA cam(112-114) is a dog in a typical N/A bracket type car unless you have lots of compression and convertor.
It will effectively kill 60 foot.
If you have lots of compression, real good heads and vert, they CAN shine. Especially at the big end.
As an example, you wont find Stock/ Superstock type stuff running usually anything but narrower cams
Click to expand...

My brother and I just had this very conversation. He just had a custom cam ground with 114 LSA ,.600 lift and 218ish duration for a Pontiac 350 .he plans on running a stock tire class and doesnt want to blow them off at the line.

This puppy should run ! Its a 69 Bird with a factory HD 3 speed ( Ford trany )
 
MOPAROFFICIAL said:
Actually that doesn't really mean anything about the head being a superior head.
Jones rec me a cam that had lower exh lift on my j heads and they dont shine on the exhaust. He Hemis have the exhaust valve clearance issue and well that where all that thinking comes from i figure from some folks. I stand by what I said originally
Click to expand...
Rocket is correct though in some applications where there is a super efficient exhaust port. IDK that’s the case here or with our equipment. For the most part I think anyway.
 
rumblefish360 said:
Rocket is correct though in some applications where there is a super efficient exhaust port. IDK that’s the case here or with our equipment. For the most part I think anyway.
Click to expand...
Yes,its possible.Though I was clearing up any misconception that if the custom profiled cam has LESS exh lift ..that it must mean the exh port flows really good. It doesn't mean that at all.
 
Thanks everybody. 108 Lsa. These are just off the shelf cams. I just liked the .050 numbers of these two cams. I see a lot of roller cams have less lift on the exhaust, especially on small blocks.
 
aaronk785 said:
Thanks everybody. 108 Lsa. These are just off the shelf cams. I just liked the .050 numbers of these two cams. I see a lot of roller cams have less lift on the exhaust, especially on small blocks.
Click to expand...
I run a 108 lsa w/ int cl on 104
Should be a neck snapper.
 
MOPAROFFICIAL said:
I run a 108 lsa w/ int cl on 104
Should be a neck snapper.
Click to expand...

Same here ... although I havent run it up in the rpms yet . Still doing slow shakedown drives close to home trying to find which bolts I forgot to tighten ...lol
70F52FF7-E759-4FD7-B3E4-11BE50EE223A.jpeg
View attachment 1715621446
 
B3422w5 said:
i have cam swapped before and found that a wide LSA cam(112-114) is a dog in a typical N/A bracket type car unless you have lots of compression and convertor.
It will effectively kill 60 foot.
If you have lots of compression, real good heads and vert, they CAN shine. Especially at the big end.
As an example, you wont find Stock/ Superstock type stuff running usually anything but narrower cams
Click to expand...

Unsure how a 60ft time even affects a bracket car. I do not have much compression and my convertor is way too tight and flashes too low, my R/T doesn't suffer but the 60 ft time isnt bad considering. Now if I had the right converter for an all out race setup i know it would be even better. Any race car shoudl have tghe right convertor. Mine was used for the sesson becasue I had nothing else and wasn't ready to drop the change or putt eh car back apart.

As far as torque which someone else mentioned, I didn't see the wide LSA hurt the torque, but that's just me.

I suggested he could go narrower with his LSA to boost his cranking compression instead of changing hard parts.
 
You must log in or register to reply here.
-

Back
Top