To Do Or Not To Do - Cam Swap

[DorianL]

Gentlemen,

I’m starting a new thread for this.

Context !

I have a 1969 corvette with a T5 manual and a 3.36 rear. The engine in there right now is tired and unremarkable: 882 heads, non performance cam. The idle quality is good and pulling nearly 20 inches. My headlights, wiper door and brakes work well. It’s toquey at lower rpm but falls flat at 3,000. It does make driving a T5 easy loafing at lower rpm with not problems and cursing on highway at 16-1700 rpm

I just bought a 406 with 205cc aluminum heads and a custom cam. My suspicion is the cam is too big for me.

I honestly don’t know.



Part of me says: throw it in the car and see from there.

Another nagging voice is saying: install the cam that suits you while the engine is still out.

I'm on the fence.

This engine has only 100 miles on it. It’s a shame and a risk to break-in another cam.

On the other hand, will it be sufficient to run my power brakes and accessories?

Also, there’s the T5 transmission. I cruise at 1500-1800 rpm at 60-70 mph. Will that be affected? The dyno starts at 3600 rpm and I’m already under 300 TQ.

Hmmmm. If I throw the 406 in there as is with TQ under 300... will it be miserable.

Previous owner claims reasonable idle (13.4 inches at 800 rpm) and brakes work fine.

I’m worried that I spend most of my time at under 3,000

 

[johnnmo]

If you truely do spend most of the time under 3,000 rpm, you don't need or want a cam that has a torque peak at 5100!!!
Go smaller cam so torque peak is 3500 rpm and be happy.

 

[DorianL]

Yeah. I am worried. 300 foot pounds and dropping as going below 3600 rpm bothers me. I wonder what’s left of it in daily driver range.

I also wonder what kinda torque I have now with my crappy 350. Possibly not much torque either ??? I have a magnificently low performing 350 in there now. 170 horsepower? Who knows what TQ is ?

Maybe the 400 is already an upgrade?

 

[rlphvac]

You keep questioning and 2nd guessing yourself change the cam now while its easy and put in the cam you want (NEED)

 

[Indycars]

Just do it right and be done with it !!!

Buy the right cam for your application.

I have Dynomation 6 to help you decide on the right cam.

 

[Grumpy]

With the current cam, cruising around 1500-1800 rpm at 60-70 mph.
is unlikely to go very well,
you'll either change your driving style to keep the engine rpms higher or need to swap cams,
keep in mind you don,t want to totally neuter the power and your compression will require more than stock duration to bleed some cylinder pressure off at lower rpms

why not call a few cam company tech lines and get their input here?
crane (386)310-4875

crower 619.661.6477
https://www.crower.com/camshafts.html?cat=854

erson 800-641-7920
http://www.pbm-erson.com/UserFiles/Documents/Catalogs/2013 erson catalog.pdf

lunati..662-892-1500
http://www.lunatipower.com/Performance-Cams.aspx

ISKY 323.770.0930

clay smith 714-523-0530

herbert cams 714-491 -2267

 

[Loves302Chevy]

This new 400 engine nothing remotely close to your current engine. Therefore you can't make an apples-to-apples comparison.
I say throw it in as is. You need a new baseline for comparison.
What is your rear gear ratio? That will be a big determining factor.
What are plans for exhaust? If you are keeping manifolds, then change the cam now.

 

[Grumpy]

?? will any thoughts on a new cam type, (flat tappet with rhodes lifters or a hydraulic roller cam,
thoughts on that cams duration or progress on finding a solution?
have you called several vendors for their thoughts? suggestions?

 

[Mark Bradley]

Swap the cam although consider going to a small roller and then there is no break-in.
It will cost you more but you will be happier in the long run.

 

[rlphvac]

Dorian I posted a little heads up in the wrong post check out the Jeep Brakes Thread for some cam heads up

Something to keep in mind a good friend mechanic by trade put an SBC rebuild kit into his block block was machined and checked the kit came with an Erson Cam that wiped out 2 lobes completely before it even was run on the street probably less than a half hour run time setting up and adjusting things so buyer beware it had to be a bad cam not heat treated or something

 

[rlphvac]

Thank you to whoever for correcting my screw up

 

[Grumpy]

glad to help

 

[DorianL]

This new 400 engine nothing remotely close to your current engine. Therefore you can't make an apples-to-apples comparison.
I say throw it in as is. You need a new baseline for comparison.
What is your rear gear ratio? That will be a big determining factor.
What are plans for exhaust? If you are keeping manifolds, then change the cam now.

I think you are right. I can't really compare; they are nothing remotely like each other. I need a new base for comparison. If I do a cam swap, it will have to be a roller cam and I need to save my nickels and dimes for that.

The rear gears are 3.36 with a T5 transmission (2.95:1 first and 0.63 fifth). I have some reasonable headers. The best intake that still fits under my hood is the Edelbrock Performer EPS.