1st question: is 270 something/280 something duration w/ greater than .600" lift possible on a stock LT1 block w/ "worked" but stock LT1 heads?

2nd question: i have been looking for cams close to that duration and lift and have found nothing, do they exist?

3rd question: if you have something other than a stock cam, and with my described duration, shouldnt it idle very choppy with little vacuum?

thanks

 

Do you mean 27x/280x "advertised" duration, or duration at 0.050" ?

 

Most of the cams guys use will fall into that advertized duration range, vacuum is fine, idle can sound not stock.

There are guys running .610 and under lift on a stock shortblock. Valve TIMING dictates whether it clears the piston.

Not sure if untouched heads will accept that lift. I suspect you will need longer valves in order to get enough spring in there.

 

I'm running a 224/230(.050) 605/622(1.6) camshaft with stock ported heads and the stock shortblock. Lift isn't the only thing to look for in PtV clearance. Often longer duration will be a bigger factor.

 

Duration is the MAJOR factor. Lift has very little to do with p/v clearance.

 

I'm running a 235/242 @.05 and .555/.576 with stock short blok and heads..

riming fine for me..

 

i appreciate the answers.

the reason behind these questions is im looking at buying a camaro. the owner says the motor is a 355 and he just put new, stock (but worked with new, larger valves and a p&p) heads on the car with a cam.

for the life of me i cant remember the exact cam specs, but yea it was something like 27x/28x duration and some high lift. he did mention an adjustable cam gear installed. he says the stock intake manifold has been opened up alot, but he is running the stock throttle body and maf until he gets it tuned?

the only thing that concerns me is it sounds stock! the heads you can tell are new, but the rest of the engine and engine bay look dirty and stock.

i figured with lift and duration like that there may be some clearance issues and tryin to find out if this guy is pulling my leg or not.

 

Hate to resort to a tuning tool, but I would ask him to have it dyno'd. That is the only way to tell if it has been modified or not.

A H/C car should not sound stock, does it have injectors and headers and other supporting mods that would be a sign of a cam swap?

 

If it sounds stock those are advertized duration numbers, most of us use .050" lift duration.
It is probably ground on a very wide LSA, not a particularly good thing refects badly outdated thinking.

Your heads should not be refered to as "stock" just because they are stock castings. Stock castings are a great starting point for a good porter. Problem there is there are far more people offering that service than there are folks who do it well.

Might not want to post publically where the car is just to avoid competition for it, but if you are anywhere near Green Bay WI send me a PM and I would be glad to take a look.
If you happen to see anyone else who has a location near you and they seem knowledgable maybe PM them and see if you could borrow their experiance for an hour.

 

it has headers, stock injectors, stock tb, stock intake manifold, stock maf, and some kind of "cold air intake"

 

stock injectors would be a good indication it does not have too big of a cam in it.