hi

i´m rebuilding a 1970 smog engine for a friend of mine...

since he want a hint of lope and a bit more power, i convinced him, to use a set of 113 L98 heads, which will give the engine about 10:1 compression

the car (1970 Corvette) is stock, the engine should run with stock converter and stock gearing...

im leaning to one of this cams...

http://store.summitracing.com/partde...3&autoview=sku

or

http://store.summitracing.com/partde...4&autoview=sku

this is a budget rebuild, but any opinions are welcome..

would this give a hint of lope?

thank you

 

Neither of those old crappy Stone Age cams....

Use a Comp XE262.

The pennies you save now aren't worth the dollars of disappointment for the entire remainder of the life of the engine.

It's kind of like pushing $100 bills laying on the sidewalk out of the way so you can pick up a dime.

 

hi

would you also like this cam, or will this be too much for stock..
http://store.summitracing.com/partde...2&autoview=sku

reason i ask...


with the 113 heads, i get 10:1 compression..

with the XE262, i will get 8.17 DCR

with the larger 270H i will get 7.96 DCR

thank you

 

Not as good a choice.

You NEED the larger exhaust lobe, to help make up for the typical poor flow ratio of stock SBC heads.

The newer cam was developed for a reason; if that older one didn't leave room for improvement given the change in conditions (fuel, driver expectations, etc.) since it was developed, then they wouldn't have bothered coming out with the newer cams that make more power.

 

That cam is ideal for your setup, with stock convertor and gearing, but personally I don't think you'll even get a hint of lope out of it. I doubt you'll know it's bigger than stock (based on sound. Power yes...)

I'd go bigger on the cam, to the xe268. But it would necessitate a bigger stall speed if you are willing.

 

Does this corvette have headers or corvette exhaust manifolds?

Consider this Isky cam http://store.summitracing.com/partde...1&autoview=sku

It will give you the moderate idle lope you're looking for, yet is mild enough to run with a stock converter.
The L98 corvette aluminum heads (113) will work fine and even better with porting and headers.
I would degree this cam in and if not already advanced, advance it 4deg to a 104 deg intake C/L
You'll get good power and torque with this tried and proven Isky designed cam. Some things just don't need improvement.
The exhaust ports on the aluminum 113 heads are actually not bad. A single pattern cam will run fine.
Actually better mid range torque than a dual pattern cam. Moderate basic home head porting and some exhaust headers will really wake this thing up.

 

hi

yes, this car have headers...and will get a relatively free flowing exhaust...

what interests me...the operating rpm range on this cams..how is it calculated?`

which compression?

the Isky cam above http://store.summitracing.com/partde...1&autoview=sku is given 2000-6200rpm

the comp cam http://store.summitracing.com/partde...2&autoview=sku
have a range from 1600-5800

they are real similar, the Isky will yield a DCR of 8.06 with 54°overlap
the XE 268 yields DCR 8.01, again 54° overlap..


so, DCR is fine in both applications..

opinions are very welcome

thank you

 

You said a funny!!!

Remember the Super Bowl ad for godaddy.com where the guy opens the door, and when he sees what's inside, comments that "everybody wants to work in marketing"?

Well, marketing generates (note that I did not say "calculates") those numbers. They're strictly a "pull out of a**" kind of thing. One mfr's idea of what constitutes a cam "working" at a given RPM can be very different from another's. They cannot be compared AT ALL from one mfr to another, and often not even from one series of products from the same mfr to another series. So I wouldn't get all hung up on how they match up to each other.

 

Don;t get all wrapped up in the listed rpm ranges.
All the cams of that .050" duration are going to operate in the same basic rpm range.
In this case 2000 to 5500+ or so.
The difference will be dependant on the quality of the rest of the motor.
Based on your listed requirements I believe the Isky will work very well for you.
I would check its installed position (intake C/L) and move it, if nessessary to enhance torque with the stock converter.

If you were to improve the stock 113 heads with porting the usuable rpm range and power will be extended.
It will easily pull strong to 6000rpm.
The heads you have only have modest flow in stock form.
But the have a ton of power potential. You have to provide the elbow grease thou. I'd plan on doing that if you want a better mouse trap. "Nothing revs like a small block chev".
Especially true with nice flowing ported heads.
Dialing in the Isky cam and home porting the heads will get you a nice running motor for this corvette.
I would not go bigger on cam, with the stock converter.