Got a ZZ4 350 ci want to make less ci? Is it better to start with 265-283 or change cank, rods and pistons? Its going in new build with a 200r4 and looks like price of gas just went up.
I don't think they make a "3.25(327)1pc rear main seal crank. Or a "3.00 for that matter. Just the 2004R an a lighter right foot, will help out drastically
What rearend ratio are you running? A 3.42 or numerically higher works well with a 200 4R. It's what my car has. With a ZZ4 you may want to consider 3.73 rear gears. What kinda vehicle we talking?
With the correct cam, compression, and fuel system a 350 can be a very efficient motor. You want your rear end gearing. 3.25 and 3.00 are possibilities. Even with a four speed overdrive transmission you have to trade a little bit of acceleration if your goal is maximum efficiency.
Ive got 25 highway mpg in my 1980's el camino with a 283 t400 and a holley 650 double pumper.... Try throwing a 265/283 with spacer w/spacer bearings in a 262 block, it'll be pretty small 254 cubes....
is it a daily driver or just a cruiser. I would think the 350'200-4r(same setup I have) should be good for 20-22 mpg. If you only drive it say 5 or 6k a year what would you really save? driving habits make the biggest difference.
305 block and pistons [ same stroke as a 350 ] You might as well use the 305 heads with the smaller chambers while you're at it. Better still get a junkyard 305 and rebuild it [and keep your 350] You can get pretty good mileage from a 350 by upping the static compression [12:1] then strangle the cylinder pressures back with cam timing on the intake side. Its a waste of time if you put it in a heavy truck though. The fuel consumed is in proportion to the work it has to do!
Large journal 302 crank in the 350 block... Add a pair of TF twisted wedge heads, a solid lifter cam, Air Gap intake and top it off with a List-4779 Holley carb.. Then back it up with a 5-speed trans with a 3.35 first gear ratio...
Why less cubes? Cl*** racing? If it is to save gas, cubes are not really going to change mileage much. At least in a v-8 engine.
O/T Trans Am with an LT1 350, 26MPG at 80MPH, loaded with our weekend luggage, ac runnin the whole time. And it was fast. If you want better than that build a V6 or a 4cyl.
A ZZ4 and gas mileage aren't necessarily intended to go together. The ZZ4's a high performance SBC with an ability to breath hard - what you want for mileage is something made for small horsepower frugality - a low-performance 305 or smaller will save you a few mpg. Fuel injection is far more efficient but also way off-topic and will draw howls of derision from the haters of al things modern. There are lots of options but probably none that include the ZZ4 without destroying what its about in the first place. JMO
Three things have the biggest impact on fuel efficiency, none of them HAMB friendly, but they are fuel injection, computers, and OD transmissions. My full size daily driver has 300 HP and gets around 30 MPG on a trip because of those components. A lot of times a smaller cubic inch engine doesn't get you the improvement in milage one might think because the motor has to work harder to move the car down the road than a bigger engine that just loafs along in it's rpm sweet spot. The other thing to consider is how long it will take you to recoup the money you spend building a new engine, even if you pick up a few more mpg. Kinda like buying a hybrid...........they cost so much that you would really have to drive a lot of miles to pay for the difference in cost between one of them and a regular car. Don
keep in mind, there are 262 and 267 CSB's from the late 60's, attempting to get V6 gas mileage. Not the strongest cranks, but you can really destroke a 4" bore... still, if you try to push a brick past 30mpg, you aren't gonna be too efficient
You could pull 4 pistons and rods out of the motor, it'd need a rebalance and the intake filled for starters, but it has been done before...
Smaller zz4 is no longer a zz4. Destroke it to a 302 and you'll loose low end torque and have to rev the **** out of it just to get moving. Could step it down to a 327 and be OK. Sell it and start over. Build something that produced gobs of low end and gear to use it. LE9 style 305 would get you into 200 HP range. High compression 307 would get you into 300 + HP. And better milage than a 305 but on premium fuel these are cheap if you find a good short block.
as mentioned above a 3.42 rear gear with thar 200R is a good combo...take the cam out and replace with a rv/mialage type cam, and top it off W/ a 390 cfm holly 4bbl....have run this combo in several O/T V-8 s-trucks and could get high 20's low 30's on the free way...on another note going smaller does not always equate to better milage...guy I used to work with, put a 383 in his daily driver P/U and it picked up 4-6mpg ..the engne didn't need to work as hard with the increased displacement...Shawn
The later model blocks leak less with the 1 piece rear main (86-up, all ZZ3 and ZZ4 included) and are set up for factory roller cam. The latter of which gives you better cam options without buying aftermarket lifters. The problem with going for fewer cubes is you then won't have the drivability of being able to run lower rpm when needed in OD up-hill. The sweet spot for mileage with a ZZ4 is going to be OD with a max of 3.42 or lower gears if you're going 26" tires. 3.73 hurts mileage. 700-R4 I'd use in a heavier vehicle; 200-4R if it's lighter. Building a combination that fits the rpm range you're looking for and has good efficiency at part throttle street driving is going to take well-matched heads & cam, intake gets more critical if it's carbed.
A slight hijack, but still on topic: I have a 283/700r4 (RV cam) combo going into a Fleetline. It currently has Edelbrock 500cfm on performer intake. My thought was to swap back to the stock two barrel intake and carb. My thinking being that the low 700r4 first gear helps to get going, but better highway MPG. Wonder what you guys think about this. But, would it not be better for the OP to just go with smaller carb? No harm, no foul, if it didn't get the desired result, simply swap back!
Once aagain, sell it, go to a smaller motor, if that's what you're really set on. Building an efficent combo is how to do it. My O/T car had a 408 (.040 over 400 sbc) that managed 24 MPG, injected w/ overdrive, and put out 330 RWHP. If milage is what you want, build a car for that. Light, aerodynamic, 4-cyl w/6 speed. Putting a big block in a cab-over isn't going to get you on AL Gore's x-mas card list.
How does a 2 bbl. get better gas milage than a 4 bbl. (with smaller primaries), if you stay out of the secondaries? If you really want to run on 2 bbls only, you can unhook the secondaries.
A fine point, T. Easiest thing would be to just remove some lead from the foot, rather than change induction!
If you want less cubes destroke it. But why do you want less cubes? Are you cl*** racing? Are you trying to prove a point? Is it for fuel economy? I have a 408 cu.in. SBC with 5**+ horse in a 3268 lbs. car with a 700R4 and 4.30 gears and I get about 18 mpg on pump gas. It's all in the set up my friend.
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