Anyone have any suggestions for an updated mild performance cam on an old school BB? I'm not liking the low idle with the one I have now.

Which is an aftermarket hydraulic cam from the early days.

Cam lift .305 .305
Valve lift .519 .519
Lobe Ctrs 115 115
ADV DUR 284 284

Engine compression ratio 9.0
Holley 750cfm
Edelbrock RPM manifold
2 bolt mains
Cast iron heads bored to L88 equivalent sizes.

Any ideas? Keeping in the same HP range about 400.

 

Is the only problem the low idle?
Are you running manifold vacuum to the vacuum advance on the distributor?
Why cant you raise the idle with the idle speed adjustment screw?

 

Ive raised the idle to 1000 and that helps but a couple cylinders are fouling slightly anyway. Vacuum is fine at about 13, a local speed shop connected all the vacuum lines. Ive heard guys rave about newer cams being far superior to the 60s-70s cams but maybe that is political.?

 

That cam isn't that radical.....especially for 427/454.....
Check and set timing correctly and hook the vacuum hose up to full manifold vacuum as stated above......I dont care who put the vacuum lines on......verify that.
Set the timing to 36-38 degrees total......at 3000 rpm or higher.
I think the engine is way out of tune......set the timing correctly first before you make a decision.
Today's cams are better for power but are a bitch to break-in.......I have a 30 year old grind in my 406 and it makes plenty of power....the speed shop wants to sell you parts.

Jebby

 

They said were setting timing to GM factory settings. So that would not be at the manifold vacuum advance. I've got 2-3 spark plugs looking rather lean and 2-3 looking rather fat and 2 about right. Will advancing this to 36 cause these plugs to run even leaner? Thanks

 

Well there is your problem....they set it to GM specs....and no, it will not run leaner but the burn will be complete. Find another place to work on your car.
GM timing specs are pretty bad for anything but emissions......timing is checked with the hose unplugged. The setting is as I posted above.

Jebby

 

OkI'll try that but am still curious about more modern cams...

 

Did you read my whole post above?

Jebby

 

Yes I did and that very well may fix the problem but other than that a new cam may make an interesting performance change I'm thinking.

 

I would fix the current problem first before changing camshafts, that will only complicate the situation.
I take it you do not do any of your own work, such as setting timing or switching from ported to manifold vacuum for the distributor?

 

bringing the timing up to just 10 degrees advance at idle(if you feel like setting it 36 degrees at 3000rpm is too adventurous for you) and hooking up the vacuum advance to actually have vacuum at idle might be enough performance change for you. It really is a noticeable improvement from the factory GM settings.
Just my two cents, a bigger cam with emission based timing settings will be more sluggish than a moderate cam with performance based timing.

 

You will get a much better improvement in performance from setting up the timing correctly than you will from a cam swap.

 

Correct! Your speed shop sounds like a bunch of clowns.

 

I called them to find out why but apparently they are currently shut down due to Covid for now. I did find a Corvette shop near by who said they could do it but warned that it could make starting it a lot tougher. Those old BBs are so hot running, Im having difficulties getting it started even after driving it a few miles especially in the summer. So I think that is the reason they kept it at the GM Setting even though on the box that the cam came in it calls out 36 degrees BTC.
The shop was doing all it could to make the car easier starting but it struggles to start anyway. Not at cold start though.

 

What carburetor do you have?

 

Holley 750cfm but wish I had an Edelbrock so the float bowls would not be inclined to boil over.

 

Ok, Big Blocks do run warm...not hot. Retarded timing WILL make it run hot. Running hot will make the carb hot...and fuel could boil over. Hard starting is not a function of the starter......if it is hard to start with the suggested timing then the starter is weak. This has been covered here ad nauseum. I am sorry if I sound harsh but you are mashing what everyone says on your end with what we are saying here. If your cooling system is in good shape then hot running is either caused by timing or a lean mixture.
Ok.....so going back. Set the timing as suggest here and do NOT take your car to the other two places for work. Advancing timing does not make a car hard to start, a wore out starter does......but one can retard timing to make it start easier at the cost of it running poorly and hot. Both the speed shop and the Corvette shop should know this, and should suggest to you exactly what I just did....or at least suggested putting a new starter with a bakelite solenoid and shield on it..... There is no such thing as "these old cars run hot..." It has nothing to do with it being old....it has to do with improper maintenance and or repair.
That being said, if you want to never have a single starter problem again, buy a CVR 5323R and live happily ever after. It is smaller, lighter, easier to install and about 5x more powerful. There are others but this is the one myself and many others use on every build.
It is absolutely appalling even now how little the "experts" who have these high dollar shops know. There is one way to tune an engine....the right way and MANY other things happen as a result of poor tuning.
I could tune that car AND install the starter for under $500 in about three hours max.....you need to find a knowledgeable person in your area to do the same.

Jebby

 

I do have a gear reduction mini starter that I used to use but I could never get it to engage well enough. It finally broke the flywheel years later and a transmission guy recommended I go with one that is small like a mini starter but is not high energy or gear reduction. It sounds really good which is what I like and is from a late GM truck he said. As I remember the mini starter did fix the hard starting issue due to cooking the old starter.
One of the recommendations was to just take it up a few degrees more, they said it does make an improvement all around.? Is it ok to have multiple vacuum lines coming off the manifold at the same port? I guess it would just be the headlight vacuum line also connected with it.

 

What he said.

Technicians (don't know why we gave up the term mechanics - it's not derogatory) who can tune an engine without a laptop are a dying breed.

I have a starter from a '96 full size truck in my '79 (small block). Works perfectly and it has been there for about 15 years. My understanding is that it is a gear reduction style. Regardless, it is a huge improvement over the boat anchor that was in there before.

 

There are hundreds off mini starters out there......all are not equal. I recommend the CVR....I have never had issues and neither will you , I have installed 8 on different cars over the years......no substitute. read the reviews. I have never had to use a shim on any of them and all worked perfect, spin the engine like no plugs are in it.
Vacuum is vacuum....they can come from the same port.

Jebby