Awful gas milage.

[Obwonkonobe]

Are you controlling timing with the efi? That would allow more tuning.

I wouldn’t think the stock vortec cam would be any worse mpg than an aftermarket, higher lift cam.

It’s a 70s smog short block with vortec heads, so yea **** cam lol. But no I spoke with msd and they said that aslong as I have a good coil and cdi, which I do, I can use a light if I know how and get it just as good as the atomic

 

[4WDKC]

I did the k1103 cam with vortecs and it had alot better power than the TBI cam and heads and I wasnt even close to being done with tuning it. With that bigger cam I would thinks its going to be a lot of fun.

 

[Obwonkonobe]

I did the k1103 cam with vortecs and it had alot better power than the TBI cam and heads and I wasnt even close to being done with tuning it. With that bigger cam I would thinks its going to be a lot of fun.

Should I pull the heads and do valve work to allow for more lift? Or are there cam options with only .45 lift that will still let me take advantage of the heads

 

[4WDKC]

Should I pull the heads and do valve work to allow for more lift? Or are there cam options with only .45 lift that will still let me take advantage of the heads

I prefer a cam with .500 lift other wise your are leaving power on the table.. machining the heads will allow for more spring choices, but with them on the engine means the cost of gaskets, downtime, more work and no added benefit over buying special springs to clear.

 

[Obwonkonobe]

I prefer a cam with .500 lift other wise your are leaving power on the table.. machining the heads will allow for more spring choices, but with them on the engine means the cost of gaskets, downtime, more work and no added benefit over buying special springs to clear.

Gotcha, and I’ve seen that you can use ls springs to achieve more lift, while leaving the heads on and doing no machine work, do you think that would be the way to go?

 

[shiftpro]

The shop that built my 700r4 was a racing shop and the owner advised to bypass the lock up. He died from a heart attack in the bathroom a few months ago. . . so I have been asking around for another source and was directed to a shop about 25 miles away. Had them work on my '98 Silverado. Owner is also into racing and has 40 years experience, so I will be taking the '74 out to his shop for a once over and we will chat about the lock up.

My tire and wheel selection kept the overall height of the OEM wheels (=/_ no more than .5 inches.) Guess I can look for the sweet spot for RPM/MPG but it's somewhat dependent on how the clowns around me drive. All these Hybrid, Rice-Burner Imports and even the "American" Fossil Fuel cars seem to think that they are the designated speed control nazis. . . getting any reasonable sustained speed is an exercise in futility.

The hard part to swallow is cruising the I-5 corridor at 10 MPG. . .

He died when he realized all the bad info he was dealing out. Bypass the lockup

I prefer a cam with .500 lift other wise your are leaving power on the table.. machining the heads will allow for more spring choices, but with them on the engine means the cost of gaskets, downtime, more work and no added benefit over buying special springs to clear.

Yeah me too, but how do you get 1/2" lift and keep the duration down for torque? What's the smallest duration achieved with .500 lift these days? Flat tappet or limited life span retro roller?

There's also a formula out there that shows the max flow from a certain lift dependent on the valve size. Any more lift over the curve is just wasting
longetevity of the valve train... ??

 

[Frankenchevy]

I’m happy with the stock vortec cam, but I drive slow.

Not sure increasing lift will increase your economy though.

 

[DoubleDingo]

I used this cam with my vortec heads and it has plenty of power! It's an old grind but it's a factory grind, and it kicks ass. No special work to the heads, no binding, nothing but improved power and less pedal needed to keep the beast rolling or to go up hills. The engine will wind up as tight as I let it, it doesn't seem to drop off, but I also don't run it at 6-7k rpms. I'm sure I've got it there a couple times, I just don't do it anymore. I like my stuff to last, and still have fun in the process. http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1&sb=0

My stepdad was a mechanic on a few race teams in his younger years, and he told me about circle track cams. Basically good for off-idle to about 4,500-5k rpms. I searched around and looked at many different cam kits, and this one fit the bill. I want the power immediately and I want it there when I am cruising at highway speeds or higher too.

 

[bluex]

Exactly the setup I’ve got, I just haven’t swapped my 3.73 rear end in yet, I’m running the msd atomic, and I already have the heads, but with a lame stock cam. What kind of differences did you get from the cam?

I did the cam so long ago I don't even honestly know.

 

[bluex]

Gotcha, and I’ve seen that you can use ls springs to achieve more lift, while leaving the heads on and doing no machine work, do you think that would be the way to go?

Yes you can use LS6 springs with a comp retainer an its supposedly good to around .520 lift with no machining. The spring part number is 12499244. Comp retainer 787-16 and you need ST2015 valve seals.

 

[Obwonkonobe]

Yes you can use LS6 springs with a comp retainer an its supposedly good to around .520 lift with no machining. The spring part number is 12499244. Comp retainer 787-16 and you need ST2015 valve seals.

Thanks! Those part numbers will help a ton

 

[4WDKC]

Yeah me too, but how do you get 1/2" lift and keep the duration down for torque? What's the smallest duration achieved with .500 lift these days? Flat tappet or limited life span retro roller?

Few and far in between, if you have a low duration cam and follow the guides about gears, tire sizes and trans ratios you will see it says to have about a 2k cruise speed for the engine to be efficient. Having a cam that starts at idle and a convertor that stalls to about 15-1800(stock-ish) rpm isnt benefiting from that cam, it also runs out of steam in a useable rpm range..remember towing with tbi engines that ping to death at low rpm and go slower, over heated and made more noise at higher rpm? My old truck was the same way 1500 rpm stock stall, 410s and 35s made it 1800 rpm on the interstate and it basically laid over at 3k rpm leaving me a 1500 rpm range to drive.

The stock vortec cam isnt bad, as it was also used in the Impala SS cars and the Caprice LT1s, but in stock trucks it was retarded like 6* from the factory. I look at the rpm range and the LSA, the more over lap (lumpy idle) the more your mpg is going down unless you advance the cam when installing. If you cant find a cam with the lift you want/need you may have to go to 1.6 rockers or custom ground cam.

 

[Super-Dave]

Hmmmm....makes me wonder what was going on in that bathroom?

I drove truck up and down the I-5 until the ****** California roads beat me into submission. Worst road maintenance I've ever experienced in the country. But hey, illegals now get free health care. They'll need it in that place.

No argument from me on Californicate issues. . . especially San Franfecal.

Sam was overweight, smoked, didn't eat healthy and really knew his transmissions. I always wondered when it would catch up with him. Had a massive coronary in the restroom; slumped against the door. They had a hell of a time getting through the door to get to him but it was too late.

He was a single dad who left to great daughters behind. Saddens me every time I think about it.