[strokin]

Planning out my blower motor here. Main question is on engine balancing. I've always been confused in this area. I'm planning on using a mid 70s block, forged aluminum pistons etc... I'll be shooting for 8:1 or under compression. Im assuming most s blower motors are internal balance or have to be.

[Mojo56]

No NEED to balance but it's always a good idea... SBC's are internal balanced blown or not.

[bentwings]

If you are going to race it or run it at 6000+ I'd do the balance.
If you will just drive on the street only I'd not balance. i did not rebalance my current motor and it's well past 19k miles. I don't go over 5000 rpm very often however.

Best to compare weights of the parts of the rotating assembly against the stock parts.

[wayneooo]

gas is heading towards 5 bucks a gallon and you are gonna run a blower

[strokin]

Well if your gonna spend 10k on a motor I doubt your worried about the $10 burnouts. Just sayin'

[cobalt327]

Originally Posted by strokin

Planning out my blower motor here. Main question is on engine balancing. I've always been confused in this area. I'm planning on using a mid 70s block, forged aluminum pistons etc... I'll be shooting for 8:1 or under compression. Im assuming most s blower motors are internal balance or have to be.

A mid-'70 SBC will be internally balanced unless it's a 400 or you use an externally balanced 3-3/4" stroke crank in a 4" bore SBC block to make a 377/383 cid stroker.

Unless your budget is bare bones, balance it. Some guys don't use a damper on a blower engine, the thinking is the belt damps the harmonics well enough. I'll leave that decision up to you, but do research it.

[strokin]

Thank you, i wasn't sure if you could even run a damper on the crank after the pulley installed.

[NOlowrider]

Yes, you can run a dampner with the blower. Like Cobalt stated, some people say you don't have to because the blower belt will absord all the bad harmonics. I run a SFI harmonic balancer with no problems, but it will cause you to have a longer blower snout and account for the extra distance for your accessories.

[Mojo56]

Originally Posted by wayneooo

gas is heading towards 5 bucks a gallon and you are gonna run a blower

Blown engines can actually get BETTER fuel economy as the are more efficient... but not with wild *** cams and two big carbs. Look at Ford's Eco-Boost engine... they are turbo-charged.

[1971BB427]

Originally Posted by Mojo56

Blown engines can actually get BETTER fuel economy as the are more efficient... but not with wild *** cams and two big carbs. Look at Ford's Eco-Boost engine... they are turbo-charged.

Multiple carbs don't have to mean less mileage. But usually people who run multiple carbs like to "test" them every so often, and that means less mileage with those little bursts of power.
I'm running twin Holleys on my 327 and still get right at 16mpg at freeway speeds with 3.73 gears and no overdrive trans. But it goes down fast when I start having fun.

[Mojo56]

Originally Posted by 1971BB427

Multiple carbs don't have to mean less mileage. But usually people who run multiple carbs like to "test" them every so often, and that means less mileage with those little bursts of power.
I'm running twin Holleys on my 327 and still get right at 16mpg at freeway speeds with 3.73 gears and no overdrive trans. But it goes down fast when I start having fun.

I have a single 800 CFM Edelbrock for my blown Hemi... I figure I'll never spin this thing over 5K anyway so all those additionl cfm's from two carbs would go to waste.

That said, I also have a blower plate made for four Stromberg 97's....