Hi guys, sure this question has been thrown out alot, but just looking for some expertise. I want to build about a 300 horse motor out of my 350. Its got number 7 heads, has the sealed power pistons with the flat tops, im thinking its going to be a little over 10 to 1, for a cam I was thinking a comp XE 224/230 duration with around 490 lift, is this going to be a bit too much? It had a mild stall fitted already, i just wonder if the cam has too much duration may have poor vaccum? I want it to be streetable, i'm also looking to run a 2 barrel, just want low down grunt with good mid range, let me know what you think. Thanks.

 

My first thought is limiting yourself to a 2bbl carb means you are not gonna achieve your horsepower target. There is no reason to use a 2bbl carb instead of a good 4bbl carb, such as a QuadraJet, that can be tuned for light throttle economy as well as full throttle power.

 

300 HP isn't asking for much. Get a good exhaust system, aim for a 214/224-ish cam, switch to a 4 barrel. Grind the AIR bumps out of the exhaust ports for fun. Easily drivable.
224/230 is getting into the slightly interesting range, but not necessary for 300hp.
And that 2bbl will choke on anything you do.

 

QuadraJet can be great on gas, if you do not have a heavy foot.

 

Is the 7111 rpm intake too much for lower rpm will it run like crap below 1500?

 

The rpm will work just fine. Trust me on that one. I built a little 300 hp appx 350 and the engine was very happy and so was my customer.

 

I hate to burst the bubble that so many on here believe is exclusive to the Qjet, but just about any carb can be efficient if calibrated correctly.

https://www.hotrod.com/articles/ccrp...retors-tested/

 

Just saying. I can get 28 mpg QuadraJet if I drive like an old lady. 2004r with lockup. And do not open the secondaries. Or less than 4 mph, all out. 1987 front end helps, it's not the brick wall front end of the older Cutlass

 

o ok so you built it with 7111?

 

Yes. Worked well.

 

Impressive. Best I could do was 26 Imperial with a 260, 24 with an Olds 350 on my 88, same Euro front. What does your 87 weigh, mine was 3750 pounds, probably a few more than my 70S. Best was 21 with 260 in the 70S but no OD.

 

must be something wrong with my 350 on my current enginw in getting 9mpg thats with a 2 barrel

 

When are you planning to drive below 1500 RPM?

Anyway, my car runs just fine in all around driving with the RPM 350 intake.

 

The 2GC might actually get slightly worse mpg than stingy driving with a Qjet. What rear gears do you have? I only pulled out 19 Imperial with 9 to 1 350 with a 214/214 cam, 2004R and 2.78 gears in my 70S.

 

Have only Alternator and power steering parasitic drag. No A/C at the time. Everything else is electric. Water pump, fans, fuel pump, aluminum radiator, aluminum support reinforcements for front and rear bumper. Procomp heads and 7111 intake but added back weight for frame stuffers. No spare tire or jack. 3.73 rear. Taller tires with corrected speedo housing and gear in transmission. 2004r with lockup botton makes a different also. Insulated the carb from engine, allowing air only from Cowl hood Think it was around 3,600 on the local dump scale. Slowly changing things over the years. See pictures on my profile. Has not been updated in years. Have made a lot of upgrades since. Adding more frame stuffers for my future DX build after I move. I know it sound weird, but I can hear the secondaries start to open in my car.

 

Electric water pump, interesting, probably helps. I also had electric fans, 3.42 gears with 225/70R14 tires,1750 rpm at 60 mph. Pretty sure my direct drive fan on my 70S is a mileage killer, it will be getting electric fans tonight.

 

 

I love the red, a very nice G body.

 

Thanks. Mustang Laser Red. Really great in the sun.

 

That is very surprising for a stock 2 barrel. Make sure the engine has good compression, make sure the carb is in good shape (has it ever been rebuilt?), and the ignition is in good shape (good plugs, good cap/rotor/points, mechanical and vacuum advance working, good wires, etc)
Of course, if you're always really into the gas trying to make full use of the 200-ish HP that engine makes, then your mileage will be terrible. Worse than what you would get from a quadrajet on the same engine. A 2bbl is a gas saver when you drive very lightly.
e.g., Top Gear did a funny test where they had a BMW M3 simply follow a Prius around the track. Prius ran as hard as possible, M3 just kept up with it. Prius used dramatically more gas than the M3.
Driving habits are the biggest impact on mileage!

 

With the previous 455 in my 72, when i went on a road trip i would swap out the 850 double pumper with a 780 vacuum secondary. I would install the stiffest spring in the vacuum housing, i could drive right at 70 mph on only the primary throttle blades. I never did the math on the mileage but it was considerably better than the 850.

 

My observation back in the day was that a decently set up Qjet got noticeably better mpg than 2 barrel........with enough right foot discipline.


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[QUOTE=bccan;1319501]My observation back in the day was that a decently set up Qjet got noticeably better mpg than 2 barrel........with enough right foot discipline.


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Yeah gotta agree i will get 3711 intake and a good q jet on it

 

Here's my '68 350 SBO build for reference, see attach dyno info for runs and engine setup. Note after doing the runs and getting home, I discovered by #2 intake's lifter collapsed, we did not notice it at the shop as the motor ran well. Collapsed lifter killed off a good 20 HP after fix and resetting all the lifters the motor very close to CompCams Cam Quest specs. Never used the Thorton Headers in the car, long story short, I'm using Dick Miller LT headers and motor is close to 400HP. Backed with a beefed up 200-4R and 3:55 posi the car moves. BTW I have the Thortons and down pipes available if anyone is interested.

 

Nice looking build, what was your compression ratio? Were those the 2.25" or the newer 2.50" collector Thornton headers? A small 600 cfm carb as well, interesting. Shows what long tubes and proper lash does for power. Looks like a fun, very Streetwise build.

 

with the mentionned combo you already passed the 300hp mark,,,,,closer to 330 hp , your problem will be to get good 94 gas to run it .....
hope you have at least 3:23 gears and 2500 stall converter
definitely 4 bbl intakje & Q-jet is the best street carb for instant response & great economy ....
have fun !
Dan

 

I believe the tork converter was replaced and no more than 2000. Thank you for the input