corvettdreamin

Stock L48 with true dual exhaust

I have ordered summit headers and edelbrock performer 2101 manifold and am looking at this cam to compliment them

http://www.summitracing.com/parts/SU...e%7c5.7L%2f350

I have stock heads for now and may do the heads at a latter stage.

Will it be streetable with stock heads and will i get that desired lumpy idle and note.

Timsride

If your going to put a cam like this in your L48 I would recomend getting the smallest combustion chamber head you can get to increase compression. Also I would put a 2000 stall if its an automatic. If you cant do the heads right now at least do converter if auto. You will get a lumpy cool idle, but will need some compression, converter and maybe a bit of gear to get full benefit of the cam.

LB66383

I would agree. With the current heads and compression ratio, this cam will most likely hurt your lower-end performance. You need some heads with that combination of cam and intake for higher compression and better breathing.

scottyp99

Does your car pass inspection? Then it'll be "streetable". And yes, it'll idle all messed up, like a race car, but it'll be a dog. It won't make any power until at least 2500 rpm, and you'll be lucky if you can hit 5000 rpm with those old, stock valve springs without floating the valves. Sorry, dude.


Scott


Edit: I just took a second look at the cam in question, and I may have been a little harsh on it. it's not THAT bad! But I think you'd be happier with the next one down from that one.

http://www.summitracing.com/parts/SUM-K1103/


You could probably get away with the stock converter with this cam, but it would be money well spent to install a set of new valve springs. Might as well put new valve seals on while yer at it. If you want it to idle funny, take one of the plug wires off. Ya know, it's funny......some people want a big cam because they want their car to idle funny because it sounds cool, like a race car. Some people have a big cam, and brag about what good tuners they are because they got it to idle nice. Well, it'd be an awful boring world if we all liked the same thing, wouldn't it? See ya,


Scott

corvettdreamin

It is a 4 speed and the engine looks to be previously rebuilt as there is no engine number visible on the block as it may have been machined.

Would this make the cam more suitable or should i play it safe and get the 1103 cam.

Ganey

Go ahead w/ it or 268H.

DRIVESHAFT

If you want a cam that will give you a bit of lope, and still be friendly with your compression, you going to need a cam with a tighter lobe separation than the one you linked to.
Take a look at this one - http://www.summitracing.com/parts/CRN-100172/ It will give you a bit of lope and build more cylinder pressure than that Summit cam.

zwede

I'd recommend the 1103.

scottyp99

Well, well, well!!! It's a 4 speed, eh? That's a different story altogether! I like a nice, even idle with an automatic, low end torque, low redline, but with a manual, you can let it all hang out!!! I like a nice, revvy engine with a manual transmission. You may be able to get away with it. Listen to Driveshaft and ganey, and make your decision.


Scott

77vetteluva

Disclaimer: I am not an engine expert.
That being said, I have a similar setup. I rebuilt my L48 and wanted a streetable cam that would function with my semi-stock set up. I have summits long tube headers, the performer intake and Holly 4150 carb, but had no idea what cam to us. Thankfully Comp Cams and probably some others have programs online you can input your motor specs and they will give you a couple cam recommendations depending on what results you want. I ended up with the extreme energy cam and am very pleased so far. (I only have a couple hours on the motor.)

What I have learned is: A cam can only affect the performance as much as the motor can breath. Too much cam could hurt the performance. Know the motor details a try the web programs or call em. Can't Hurt!

corvettdreamin

Which cam did you go for?

77vetteluva

Comp Cam's XE262H-10 I think I paid $180 for cam and new lifters ...not sure, memory is failing me at midnight.

Ganey

Comp XE262 is similar to 268H w/ more ex. duration.

Eulentier

+1

The Summit 1103 is a good cam and close to the profile of the one in the GM 350HO crate engine. I'd swap in new heads though, the GM iron Vortec heads are always a good choice on a budget and make reasonable power.

scottyp99

Here is the thing ya need to know when thinking about camshafts: There is nothing "magical" about them. All they do is control the timing of the intake and exhaust valves, and how much they open. No black magic, no voodoo, (except maybe Lunati Voodoo cams, they might have a little voodoo in them........) no Santeria, just physics.

The engine in your car can only be made to produce good power in a narrow rpm band of maybe 3,000 rpm. So you have to decide where you want that powerband to be. 4,000-7,000? 1,500-4,500? 3,000-6,000? The camshaft will have a "sweet spot" (rpm range). If all of your engine parts are made to perform best in the same operating range, you will have an engine that makes crazy, stupid power over a good range of rpm. If your cam is made to perform best from 4,000-7,000 rpm, and your heads are made to perform best from 1,000-4,000 rpm, you won't be happy with it. At low rpm, the valves will be held open too long for the small head ports to develop any velocity, and at high rpm, the small ports won't let the engine "breathe" enough to be able to utilize the big cam's potential.

Scott

Rich's'78

Lobe Separation (degrees) such as 110 will give a nice slightly lumpy idle. A higher number smoothes out the 'lumpiness'.
Even with a 4 speed, I think that is too much cam. The L48 heads, even when milled, will not support much rpm / power. Spend some money on good heads and do it now - that is where the power comes from. And don't forget that the L48 short block is not safe to the high rpm range (above 5500) many of the 'performance' cams are advertized for, so pick your cam to make max power by 5000.
You will enjoy a cam that pulls well much below that and don't have to worry about missing a shift (over revving).

I have the Comp 268. My big mistake was wasting money having the stock heads rebuilt (because of cash shortage at the time).

corvettdreamin

O.K now you got me thinking about cylinder heads.

I am looking for the cheapest.

Will these make a difference?

http://www.summitracing.com/parts/SUM-152123/

scottyp99

I think these would be better, they have smaller valves, but they are vortecs, so they'll flow nice. Check 'em out, they have the modifications so you can run more cam lift. A little more compression, too, and they are about the same price:

http://www.summitracing.com/parts/SUM-151124/

But........(there's always a but, isn't there?) you will need a vortec style intake, here's one for 130 bucks:

http://www.summitracing.com/parts/SUM-226018/

corvettdreamin

i have ecided to keep the stock heads and am now about to order this cam and installation kit.

http://www.summitracing.com/parts/SUM-K1103/

http://www.summitracing.com/parts/CMB-08-0019/

Stock rebuilt (dont know when) 1975 L48 with 4 spd.

Have true duals and will install Summitt full length headers, edelbrock performer 2101 manifold and advance distributor recurve kit.

I beleive it made 165HP stock and currently maybe 180hp with the dual exhaust and rebuilt.

Will the above make a difference to the seat of the pants feel as currently i feel dissappointed when i gas it and struggle to spin the wheels from 1st to 2nd.

I beleive this cam is as big as i can go with the stock heads and i dont want to spend another $1500 on heads with this car as eventually i want to buy a 1969 as a keeper.

If i cant feel the difference after the mods and only gain a few HP, is it worth it, or am i just wasting my money.

tnovot

You have been given lots of very good advice from several people. Sounds to me like you need to decide whether you want it to be the best performer that it can be or if you just want it to sound strong. If it's the sound you are after, you can do a lot with the right exhaust.
Terry