1970 L46 camshaft replacement
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From: Allen TEXAS
1970 L46 camshaft replacement
Hello friends.
I am coming to your for input and advice regarding a selection for a replacement camshaft for my stock L46 350/350 with the M21.
She is in great shape, and still a very strong runner.
I recently took her to my mechanic for brake issues, and I also wanted the carburetor completely broken down and cleaned more completely than what I could do in my garage.
In test drives, my mechanic was not satisfied with the performance, and suspects the camshaft may need replacement.
My question is, should I stick with the stock spec, or select a different camshaft for better performance??
Thank you in advance!
Bill
I am coming to your for input and advice regarding a selection for a replacement camshaft for my stock L46 350/350 with the M21.
She is in great shape, and still a very strong runner.
I recently took her to my mechanic for brake issues, and I also wanted the carburetor completely broken down and cleaned more completely than what I could do in my garage.
In test drives, my mechanic was not satisfied with the performance, and suspects the camshaft may need replacement.
My question is, should I stick with the stock spec, or select a different camshaft for better performance??
Thank you in advance!
Bill
Drifting
Joined: Jun 2015
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Having had two 350/350 cars I remember what a nice all around feel that cam has. I would consider similar valve timing but a little more lift. Roller lifters are nice but the cost will pay for a lifetime of good oil that will keep a flat tappet cam alive these days.
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From: Southbound
Cruise-In II Veteran
FWIW: do you need a camshaft? Your mechanic "suspects", but he/she apparently had also just rebuilt the carburetor. Before looking at a camshaft, you want to eliminate the carb as a source of the problem.
Drifting
Joined: Oct 2005
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From: Forth Worth TX
Agree with above and make sure your timing/advance curve is set up correctly.
Unless you change the intake manifold and heads, a bigger cam really won't be much better than the OEM cam. The intake and heads just don't flow all that well to take advantage of it.
My L-46, original intake manifold, original heads (ported & valve job), Comp Cam xe262h-10, 10.4 c/r, made 341hp/387tq on the engine dyno. Probably little to no difference than if I had used the OEM cam.
Stock L46/82....0.450/0.460...222/222...................114
CC XE262H.......0.462/0.469...218/224....262/270....110
Unless you change the intake manifold and heads, a bigger cam really won't be much better than the OEM cam. The intake and heads just don't flow all that well to take advantage of it.
My L-46, original intake manifold, original heads (ported & valve job), Comp Cam xe262h-10, 10.4 c/r, made 341hp/387tq on the engine dyno. Probably little to no difference than if I had used the OEM cam.
Stock L46/82....0.450/0.460...222/222...................114
CC XE262H.......0.462/0.469...218/224....262/270....110
Last edited by Revi; Jan 6, 2017 at 07:54 AM.
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From: Allen TEXAS
Bill
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From: Allen TEXAS
Agree with above and make sure your timing/advance curve is set up correctly.
Unless you change the intake manifold and heads, a bigger cam really won't be much better than the OEM cam. The intake and heads just don't flow all that well to take advantage of it.
My L-46, original intake manifold, original heads (ported & valve job), Comp Cam xe262h-10, 10.4 c/r, made 341hp/387tq on the engine dyno. Probably little to no difference than if I had used the OEM cam.
Stock L82....0.450/0.460...222/222...................114
CC XE262H..0.462/0.469...218/224....262/270....110
Unless you change the intake manifold and heads, a bigger cam really won't be much better than the OEM cam. The intake and heads just don't flow all that well to take advantage of it.
My L-46, original intake manifold, original heads (ported & valve job), Comp Cam xe262h-10, 10.4 c/r, made 341hp/387tq on the engine dyno. Probably little to no difference than if I had used the OEM cam.
Stock L82....0.450/0.460...222/222...................114
CC XE262H..0.462/0.469...218/224....262/270....110
Thanks,
Bill
Drifting
Joined: Oct 2005
Posts: 1,615
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From: Forth Worth TX
Hey Revi, thanks for the response. I figured that the restricted flow of the stock setup would my biggest challenge, but wanted to see if anyone had success by changing cams. I will look at some spec comparisons to see if I can find a compelling reason to change.
Thanks,
Bill
Thanks,
Bill
When I first brought my engine in for rebuild and discussed what I wanted done. I asked what the HP potential was while keeping all of the stock parts? His response, "you won't get more than 350hp with that cast iron intake manifold".
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Reduced valve travel
Hi Mike. Thanks for the response. Yes, following a test run, he noted rough running, and high speed pops from the intake. He also checked and found some reduced valve travel. His preliminary assessment and update to me was worn cam lobe(s). We will look into it more tomorrow, but currently thinking it to be the camshaft.
Bill
Bill
Last edited by MelWff; Jan 5, 2017 at 03:40 PM.
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Le Mans Master
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From: RI, Now Franklin/Nashville TN
Lets start with an obvious question: How many miles on the motor/Camshaft in the car? If there are more than 100,000 miles on the OEM cam, you might want to examine the cam as an issue closely. camshafts back then did not last like today's rollers.
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From: altered state
St. Jude Donor '05
Maybe his claim was legit maybe he wants to sell parts
If hes legit he can show you whats wrong
IF you cant go HR stick an Isky 270 mega in there youll love it in comarison. Smaller in # but sure will put a smile on your face.
The OEM had a lot of hurdles to overcome to even offer a mediocre cam surprised they could offer what they did.
Try one out and see night and day differnence. Sound good driveable kick azz street torque can still use stock converter and dont go bad
Man they need to put me on pay roll as a face man.
Seriously even today love the way those things run.
CHECK PLEASE!
If hes legit he can show you whats wrong
IF you cant go HR stick an Isky 270 mega in there youll love it in comarison. Smaller in # but sure will put a smile on your face.
The OEM had a lot of hurdles to overcome to even offer a mediocre cam surprised they could offer what they did.
Try one out and see night and day differnence. Sound good driveable kick azz street torque can still use stock converter and dont go bad
Man they need to put me on pay roll as a face man.
Seriously even today love the way those things run.
CHECK PLEASE!
Drifting
Joined: Oct 2005
Posts: 1,615
Likes: 150
From: Forth Worth TX
Maybe his claim was legit maybe he wants to sell parts
If hes legit he can show you whats wrong
IF you cant go HR stick an Isky 270 mega in there youll love it in comarison. Smaller in # but sure will put a smile on your face.
The OEM had a lot of hurdles to overcome to even offer a mediocre cam surprised they could offer what they did.
Try one out and see night and day differnence. Sound good driveable kick azz street torque can still use stock converter and dont go bad
Man they need to put me on pay roll as a face man.
Seriously even today love the way those things run.
CHECK PLEASE!
If hes legit he can show you whats wrong
IF you cant go HR stick an Isky 270 mega in there youll love it in comarison. Smaller in # but sure will put a smile on your face.
The OEM had a lot of hurdles to overcome to even offer a mediocre cam surprised they could offer what they did.
Try one out and see night and day differnence. Sound good driveable kick azz street torque can still use stock converter and dont go bad
Man they need to put me on pay roll as a face man.
Seriously even today love the way those things run.
CHECK PLEASE!
CC XE262H.......0.462/0.469...218/224....262/270....110
Isky 270...........0.465/0.465...221/221....270/270....108
This cam isn't going to be any better than the rest of them. If you dyno'ed each cam in the same engine you'd get results within a couple of percentage points of each other.
FYI - The 70 L-46/M-21 doesn't have a "stock converter" it's a manual transmission.
Last edited by Revi; Jan 6, 2017 at 08:07 AM.
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I'm a big fan of the factory Cam, as mentioned it is very drivable it works well everywhere . It was Zora Duntovs favorite street small block cam. I have used that cam many times over the years and the only addition I'd make is a set of 1.6 roller rockers . You would need to make sure your pushrod slots have clearance. Add a set of aftermarket heads and you'd be amazed.same great drivability and a bunch more power.
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From: Allen TEXAS
We talked about how there was no noticeable ticking in the valves. It makes a slight ticking at start up, but my dad (long retired Chevy mechanic) told me those engines always had a little piston skirt slap when cold..
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
Your Dad is a Smart guy and 100% correct. Those engines had forged pistons and they did have a bit of slap when they were cold. Sounds to me like you might have the wrong guy working on your car.
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From: Allen TEXAS
JB, she has 98,500 miles on the odometer. I'm sure there will be a level of ware.
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From: Allen TEXAS
I am hoping that this update can be limited to cam and lifters, and not yet involved the heads...I will post an update later today to see what y'all think.
Thanks to all,
Bill
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I'd definitely look at a different cam. A single pattern/wide LSA cam can be improved upon for sure these days. Just depends on what you're looking for in power and driveability. Lots of compromises in that cam and the right one can help stock heads out.
JIM
JIM
Drifting
Joined: Oct 2005
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From: Forth Worth TX
With 98,500 miles a valve job is probably worth some consideration.
Last edited by Revi; Jan 6, 2017 at 10:23 AM.
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From: Allen TEXAS
A 70 vette is not going to impress anyone with today's cars...but damn, it sure makes me look good.
Thanks,
Bill
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From: Corsicana, Tx
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A 350/350 can be a heck of a lot of fun. Won't run with the baddest boys out there...but it can be a 12 sec car...or at least deep deep 13's which can surprise a lot of folks.
Is a HR cam feasible in the budget? Can do some neat stuff there!
JIM
Is a HR cam feasible in the budget? Can do some neat stuff there!
JIM