l46 cam change
Thread Starter
Instructor
Joined: Apr 2017
Posts: 125
Likes: 38
From: Sacramento
l46 cam change
I have a l46 rebuilt @ 20k miles ago but sitting for many years. It looks like when they rebuilt it they went with flat top pistons 30 over and switched to 202 angle plug heads ( I have originals but they would need rebuilt ) I'm thinking about switching to a bigger cam while its out. I have 373 gears with M21 4sp. any suggestions on cam profile? Also plan on going to Holley sniper fi.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Every cam company has a 1-800 number with a tech guy that will gladly take all your information and come up with a perfect match cam.
That's what you want right?
They will need additional info than what you provided.
That's what you want right?
They will need additional info than what you provided.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
You can select 3 or 4 companies. Write down every part number they suggest and if they give you the specs on the cam, all the better.
What you are looking for is a common denominator in Duration, Lift and LSA.
Then you can go to Summit and snoop around for pricing on the selections you were given.
What you are looking for is a common denominator in Duration, Lift and LSA.
Then you can go to Summit and snoop around for pricing on the selections you were given.
Thread Starter
Instructor
Joined: Apr 2017
Posts: 125
Likes: 38
From: Sacramento
Thanks for the help. I just felt there must be a better choice than the stock cam since that cam had to work in corvettes running automatics and or higher geared rear ends. I don't want to change my heads so I'm not looking for anything crazy just hoping to get 30 or 40 more HP out of my 350/350 small block.
Instructor
Joined: Feb 2007
Posts: 114
Likes: 18
From: McKinney TX
You indicated a desire for a 'bigger cam' but you also stated that a previous owner replaced the original domed pistons with flat top pistons. You also indicate the heads have been replaced. I agree with previous posts suggesting technical assistance from several cam vendors but before going this route you need to determine your current compression ratio. The original piston/head combination created an 11:1 ratio. The stock cam was designed for that figure. Unless the head was decked, removing the piston dome cut that ratio down. I believe the original heads were 64cc combustion chambers. (Don't hold me to that.) If you can find the combustion chamber size for the current heads, great. If not, you need to measure it. Once you have this data, my guess is you'll discover the existing cam (assuming it's the original) is actually to 'big' for the current combination. I'm suggestion basically that your heads/piston/cam combination produces a dynamic compression ratio that's too low and your '350' horsepower and associated torque have been severely compromised. If I'm right, you can probably get much of the original performance back with a cam of less duration, but whether you or a vendor figure that out - you'll need the CR data I just discussed.
Thread Starter
Instructor
Joined: Apr 2017
Posts: 125
Likes: 38
From: Sacramento
You indicated a desire for a 'bigger cam' but you also stated that a previous owner replaced the original domed pistons with flat top pistons. You also indicate the heads have been replaced. I agree with previous posts suggesting technical assistance from several cam vendors but before going this route you need to determine your current compression ratio. The original piston/head combination created an 11:1 ratio. The stock cam was designed for that figure. Unless the head was decked, removing the piston dome cut that ratio down. I believe the original heads were 64cc combustion chambers. (Don't hold me to that.) If you can find the combustion chamber size for the current heads, great. If not, you need to measure it. Once you have this data, my guess is you'll discover the existing cam (assuming it's the original) is actually to 'big' for the current combination. I'm suggestion basically that your heads/piston/cam combination produces a dynamic compression ratio that's too low and your '350' horsepower and associated torque have been severely compromised. If I'm right, you can probably get much of the original performance back with a cam of less duration, but whether you or a vendor figure that out - you'll need the CR data I just discussed.
Last edited by talentscout; Jan 29, 2021 at 02:02 AM.
Le Mans Master
Joined: Oct 2010
Posts: 6,929
Likes: 842
From: melbourne florida
2023 C3 of the Year Finalist - Modified
The angle plug heads were very good in thier day. Modern aluminum aftermarket heads are better. I think the right cam would give you back the power lost by the flat top pistons quite easily.
Instructor
Joined: Dec 2017
Posts: 169
Likes: 29
I've got the same car, basically, but I still have 11:1 compression. I put some 200CC heads on, performer intake, Sniper EFI, and I put a Jones Cam in. He did a custom grind for me with a reverse duration pattern due to how high altitude I live at. I would suggest a single pattern for you, but here are my specs. It runs really well, gobs of power. 224/220 @.050"
.330"/.310" Lobe Lift
.495"/.465" Valve Lift
110 LSA
106 ICL
.330"/.310" Lobe Lift
.495"/.465" Valve Lift
110 LSA
106 ICL
Last edited by beneharris; Jan 29, 2021 at 11:38 AM.
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Thread Starter
Instructor
Joined: Apr 2017
Posts: 125
Likes: 38
From: Sacramento
I've got the same car, basically, but I still have 11:1 compression. I put some 200CC heads on, performer intake, Sniper EFI, and I put a Jones Cam in. He did a custom grind for me with a reverse duration pattern due to how high altitude I live at. I would suggest a single pattern for you, but here are my specs. It runs really well, gobs of power. 224/220 @.050"
.330"/.310" Lobe Lift
.495"/.465" Valve Lift
110 LSA
106 ICL
.330"/.310" Lobe Lift
.495"/.465" Valve Lift
110 LSA
106 ICL
Instructor
Joined: Dec 2017
Posts: 169
Likes: 29
They're Flotek heads - don't buy from them. The heads are fine for the money, but I should have gone with a better company.
Who knows how your heads are set up. The valve lift isn't a lot on this cam, so probably, but if it was me, I'd probably start from scratch. Valve springs aren't a lot of money.
