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Will this make a good streetable 350 SBC combo?

6K views 8 replies 6 participants last post by  RippinRon 
#1 ·
Hello guys I am getting ready to start gathering up some parts for a 1 piece rear main seal 350 chevy small block for my 96 s-10 wich has 4.10 gear ratio and will be putting in a 350 turbo with performance rebuild kit and a shift kit. Here are my specs for motor

350 4 bolt main new block
3.480 cast steel crank by Scat
Scat 5.7 forged rods
Flat top pistons Hypereutectic KB
Edelbrock Performer Intake
World Product sportsman II 200 ccheads, 72 cc combustion chamber with roller setup springs etc
Comp cams XR 270 HR hydraullic roller cam
Specs 270/276 advertised, 218/224 @ 50 495/502 lift 1.5 roller rockers

Carb is Edelbrock 600 performer.
HEI with performance coil and control modual.

Will this setup be able to squeeze out around 18-19 mpg by chance and also on comp cams camquest it says around 390 hp and around 420 lbs of torque. I used the world heads on an old 355 build 6 years ago and got 13 mpg with a 750 carb and 292h comp cam with 10.6 to 1 CR. Will this build work good for a mild performance daily driver with out issues of cruising through town? Any suggestions on changes? Thanks Eric
 
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#3 ·
Well I was going to swap out the 4.10 gears later on this summer for some 3.73 or go down to a 3.42 ratio. I know the 4.10 is a little low and will hurt mpg wise but its only temporary. I already have a 700r4 in the truck but don't care for it plus cheaper to build a turbo plus they can handle more hp for way less greenback wich I am on a budget right now.
Eric
 
#4 ·
The 700R4 is far superior than a TH350 will ever be. You can build 700`s to be just as stout. If you want mileage the overall goal to shoot for is cruise RPM`s. And in that case gear ratio, carb, intake, and especially cam plays a role. Engine RPM says alot for mileage, and it`s not always true "the lower the better" as if it cruises at a speed that is below the cams power band the engine will only lug which will cut it`s life in half. So it`s all a game of getting the right parts and making them work together. I used a 880 Vortec block, a TH350C which is a lock up tranny with the lock up not working, with a small 204 duration roller cam, Vortec heads and a few other performance mods. On the interstate it knocked off great mileage with 3.23 gears. So since you have already a 700R4, use a gear ratio that puts you at the lowest of the cams power band without it lugging and you`ll come out fine. Don`t forget, carbs, intake and tune play a big role in this as well. Me, I used a Quadrajet, which is the only carb I would ever use for a mileage application.
 
#5 ·
Hello thanks for the info I guess I will have to see how it goes. I was able to get 13 mpg with an old 350 with a lot more stuff then the build I am going to do and it ran decent with its setup. I currently run the 350 vortec with the edelbrock performer intake along with the edelbrock 600 carb and don't have a clue what cam is in it. Heck I don't even know if its a roller cam or not. Is there a way to calculate what rpm's I would be at a certain speed? I know there was something on compcams website that would tell you but I don't know what specs to put in on certain spots.
Thanks
Eric
 
#7 ·
Hello thanks for the link. Sorry to say I should know my tire stuff since I used to work in a tire shop but its been a while and kind of forgot but I did find out what meant what tire height wise. I was able to find out how much rpm with my tranny would be at certain mph etc. Thanks everyone for help.
Eric
 
#9 ·
DoubleVision said:
The 700R4 is far superior than a TH350 will ever be. You can build 700`s to be just as stout. If you want mileage the overall goal to shoot for is cruise RPM`s. And in that case gear ratio, carb, intake, and especially cam plays a role. Engine RPM says alot for mileage, and it`s not always true "the lower the better" as if it cruises at a speed that is below the cams power band the engine will only lug which will cut it`s life in half. So it`s all a game of getting the right parts and making them work together. I used a 880 Vortec block, a TH350C which is a lock up tranny with the lock up not working, with a small 204 duration roller cam, Vortec heads and a few other performance mods. On the interstate it knocked off great mileage with 3.23 gears. So since you have already a 700R4, use a gear ratio that puts you at the lowest of the cams power band without it lugging and you`ll come out fine. Don`t forget, carbs, intake and tune play a big role in this as well. Me, I used a Quadrajet, which is the only carb I would ever use for a mileage application.
And the 200-4r is far superior to the 700-r4. Gm still has problems with the 700. You think they would they would have designed something better rather than trying to fix a bad one.
 
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