Thread: lookin for thoughts on blowers

Tweet

Im thinking of buying a blower for my truck.to start with I have a 350 bored ..030 over,2 bolt main,open chamber stock heads, 280h cam,eldelbrock manifold ,holly 600 carb and headers.the motor runs good as it is but have always loved the look and sound of a blower.I not looking to dragrace or make huge horsepower.looking to run maybe 5lbs boost and keep it streetable.looking for some thoughts from some members on what size blower.and what modifications I will need to do to the motor ( will need to keep it low budget) my other option would be to buy some alum. heads with closed chamber heads to make some more horspower and wait on the blower.but I think blowers are much cooler.ant thoughts??????? thanks

I assume you are talking about the GMC .71 series blowers??? 4:71, 6:71

many ways to go done some there fun

I'm like you, I think a blower on an engine moved it into a whole new level. Just the looks and sounds are enough to make most rodders sit up and take notice when you drive by.

Probably the best bet would be to get a complete, matched system from someone like Blower Drive Service or Dyers. Not maybe the cheapest way to go, but their kits make it pretty much plug and play and are engineered to fit your particular application.

Some people pick up a manifold here, a blower there, the drive somewhere else, but not only is that a pain to get all the little bits and pieces, but buying a used blower is really a crap shoot. You never know how the clearances and internals are and because of what they are lots of them have been ridden hard and put away wet. I often wonder how many of the used blowers you see at swap meets and on Ebay actually end up being usable.

No question that a mild blower setup on your engine will make it's presence felt. And from what I understand they can be very reliable..........look at how many over the road trucks are running them for a zillion miles.

Don

Don has laid some sterling advice on you. Step up to the plate and buy everything new from one source.

I would suggest you go to Blower Drive Service and read EVERYTHING they have written. They've been doin' this for nearly 40 years, so they have probably "been there, done that" no matter what the subject.

They suggest a small bore 6-71 for a street 350....
"There are two different 671 blowers commonly used. They are the larger diameter blower and the small diameter blower. The large bore blower (case thickness 1/2"-) is approximately 11 percent larger in volume than the small bore. The small bore blower (case thickness 3/4"+) is recommended for 370 CID engines or less for street applications. The larger bore blower is recommended for 371-500 CID engines in high performance, racing applications."
www.blowerdriveservice.com

BDS is nice over price stuff they may make some of there stuff but not every thing i used some of there stuff but like the TBS blower kits very nice for the money the only thing is i think they stick there name on to many parts of there kit

1st thing ......blowers are very cool.........and I agree with everyone else here.buy from one source.
I work for Evans cooling and have had many customers with new blowers on their motors and call to say the motors is running hot. The biggest problem I have seen is the tune-up.
I had a customer who did everything I told him to do and the motor still ran hot. So he said a friend of his had a chassis dyno. I told him to put his car on it and check the tune-up. Sure enough, at highway speeds, the carbs were leaning out making the motor run hotter. They fattened up the carb and solved the problem.

With the incobsistency of todays fuel a wide band O2 sensor in the collertors is going to be a big help in tuning the car day to day( well maybe weekend or monthly ) as the seasons change

thank you for the info im collecting its very usefull.im lm thinking about a 4-71 gmc with a single carb.or heck who knows maybe a 6-71 dual carb setup.whats your suggestions.has anybody had any experience with the 4-71 blowers or 6-71 on sbc and were they good or bad ? thanks again

I had a 671 on a 350 years ago. Got the car in a trade & it had stock pistons and was forever burning them.

We found 9:1 was too high compression, so we took the blower off till we could build a decent bottom end with low comp forged pistons. That blower is on my current bucket with a properly build 540 cube big block under it. My compression ratio is around 7.6:1

Really, you need to build the engine to handle the blower, because one day, somewhere, you are going to stand on it. I dont buy the "its just for looks and a bit more power stuff" because we arent wired that way. You can trust me on that.

I do see that people seem to run around 9:1 compression on the vortex style blowers tho, so they may be an option too. Havent used one of them yet, but have one on an engine in a project Im slowly working on.

Here's the way I see it. 1st if you don't have 9 to 1 compression or preferred less, you need to make this happen before you go any further.

If you don't know much about blowers go with a blower and drive kit from any of the blower co. They all are pretty good. I like Don Hampton as he is a real hands on guy. You will need blower carbs ( Holley is my favorite) these will be calibrated pretty close out of the box. They use a manifold referenced power valve which is very important for street use. There are fuel line kits for each of the various carb combinations. There also are throttle linkage kits for each combination. You will need either air cleaners or a scoop with air cleaners. BDS is the only one I like as it is big and very authoritive looking as it sticks out of your hood.

You will need something like an MSD distributor with vac advance. It needs to have the large bushing installed and one light and one medium spring installed. This will give you very quick advance which is a must. 32-34 deg total all in by 2000 or so. 10 deg of vac advance will make it run very smooth and shift properly as the vac will be very nice.

You will need at least block hugger headers with as big of tubes as you can find. Have them Jet Hot coated. I have a full 3 in ex front to back and it works just fine. You will need a roll of header wrap to insulate the starter from the heat. Maybe some near the oil filter and anything else that is close to the ex. pipes.

You will need an ign. box like an MSD 6A. I don't use a retard feature. Guess I don't need it as I have almost 8000 miles this year and 1500 last year on mine and it is still in one piece.

It doesn't matter whether you plan on getting after it or not, if you don't have the right stuff it is not going to be fun at all.

My current ride took only 36 hours from the last strip of rubber unblown to the first strip with the blower. I drive nearly every day rain or shine. It starts very easy and idles at 750 all day long. I can drive in heavy traffic anytime and often do.

Here are a couple pictures. 9 hours in the rain. haha, in traffic, and the car.

oh yes I forgot.....this will be very close to $5 grand. on top of a reasonable 350 long block. There is a little more to it but this will get you started.

Humm, is that 104B-35E & Randolph? It's been awhile since I've been down that way, just a day or two before the bridge fell into the river.

Pat

thanks for that info ,very informative!!!!

I have a 671 on a Donovan small block. The only time I have had a problems is when I'm goofing around. If I would leave it alone I do believe it would be trouble free. I love the noise and horsepower.
Ken

OOPS, sorry!!!!