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Old 07-28-2010, 11:39 AM
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Did I make a bad buy?

Hey guys! I just bought a 67 camaro 355 w/6-71 weiand blower and i dont know very much about blower motors and was wondering if i could get some help!

I have had problems with it already so im not sure if the guy i bought i from built it right. I had a problem with the balancer it kept breaking the key then working the bolt out of the crank and now i pulled the motor and found out it had a cast scat crank.. should it have a steel crank? also i have heard that you need to add another key way in the crank and run a steel balancer not a fluidampner is that true?

here is what i know about it:

335 sbc
edlebrock victor jr. aluminum angle plug heads
roller cam
weiand 6-71 w/ 2 holley 600 carbs
speed pro blower pistons
roller rockers
ford 9" 456 gears

It has stock rods so do i need to change them?

anyone that can help would be great thanks!!

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Old 07-28-2010, 11:59 AM
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first thing im gonna tell you, be very carefull with blown motors 1 backfire and your blower,intake ,carbs, blower drive and lots of other parts will be history,and if you are anywhere close to it, you might get hurt, so be carefull and make absolutly sure spark is good and dizzy is timed perfect.
Having said that i dont know cam profile,cam timing,comp ratio,crank needs to be steel, rods need to be either aluminum or steel if you are runnig low boost steel is ok. aluminum rods are like big shock absorbers in a blown motor running high boost,I dont know what blower drive ratio is either,seems to me like you have a lot of carburation on this motor,so the guy that built it was probably planning on running it pretty hard.you really need to talk to the guy thaat built the motor before you even put a wrench near this motor.
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Old 07-28-2010, 01:42 PM
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Adding another crank key is definitely a good idea, think about it, it's takes probably 20 to 50 hp to drive that blower, a crank key that's designed to keep a balancer from moving around probably isn't going to be quite up to the task of driving a 50 hp load for long, as you've seen. It's typical to cut two full length key ways on blower motor cranks. Also, I wouldn't want to be running a cast crank on a blower motor either.
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Old 07-28-2010, 02:07 PM
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I had a backfire and found out it was because the secondairy was getting all the gas and the primairy wasnt getting any gas, so i got them both working and the car ran great with no backfire!! so am i still ok? it wasnt very bad of a backfire.

the c/r is 8 to 1 am i fine at that?
also i counted the teeth on the pulleys and found that it was 38blower and 34crank which equals 11% underdriven right?
I'm buying a new dual keyway steel eagle crank from summit with a steel balancer!!! Like i said the car ran great with no backfire or anything after i fixed the primary carb...until the single keyway broke and the bolt worked its way out! So should i be fine once i get the new dual key crank and balancer? The guy has the timing locked in at 34 degrees is that right?

THANKS for the replys
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Old 07-28-2010, 02:18 PM
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Quote:
first thing im gonna tell you, be very carefull with blown motors 1 backfire and your blower,intake ,carbs, blower drive and lots of other parts will be history,and if you are anywhere close to it, you might get hurt, so be carefull and make absolutly sure spark is good and dizzy is timed perfect.
Nonsense, timing is important, but sneezing the blower happens all the time, use reasonable caution no matter what the aspiration.

Quote:
...rods need to be either aluminum or steel if you are runnig low boost steel is ok. aluminum rods are like big shock absorbers in a blown motor running high boost...
Never run aluminum rods on the street, they won't last.

Quote:
...you have a lot of carburation on this motor,so the guy that built it was probably planning on running it pretty hard.
Two 600's is light carburation. Weiand recommends two 750's for a SBC, I'm running an 8-71 on a 383 with two Demon 750 BC's on the street, it's a happy motor.

aNo offense to topwrench or any other poster, but A lot of what you're going to hear here and everywhere else, will be drama filled when it comes to forced induction, with the amount of useable data depending on whether the poster has ever owned or built a blower motor, or is passing along hearsay. Some may believe what they offer up is gosphel. Take the time to read and learn along the way, then you decide what's good, bad and ugly.
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Old 07-28-2010, 02:50 PM
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8:1 is a good place for a blower motor. Without looking at charts, I'd say you might be making 5 to 6 #'s of boost, enough for a good kick in the pants on the street. A forged double keyed crank is good, you don't want a fluidamper unit, yes, steel is the way to go. I use a ROMAC, stainless and degreed 360 deg, but here are others that work well.

Blowers also like a lot of initital timing, 18 to 22 isn't uncommon, and 34-36 total should be near the top for 92 octane on the street, all in by about 2500, aluminum heads are more forgiving than iron, and if you re-cam use a blower grind with a wide LSA, 112 - 114, and more duration on the exhaust side.
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Old 07-28-2010, 02:51 PM
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I just want this to be a nice running pro street car that i can run on the street and maybe at the track once or twice a year so around 6 quater mile runs!! thats it so if you guys can tell me what is best for the car to be set up like that it would be great thanks!
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Old 07-28-2010, 05:06 PM
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Just so you know, a harmonic damper is not required on a blown motor using a Gilmer belt drive. The belt serves the same purpose of dampening crankshaft harmonics that the damper would have served. You can run a simple solid hub and be ok from a harmonics standpoint.
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Old 07-28-2010, 05:26 PM
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well nova ss dont worry about it you didnt offend me. i learn every day!!!!
Ive just seen quite a few blowers go through the hood of funny cars,all top fuel uses aluminum rods, i never ran a blower on the street. and other than getting caught with my pants down with the wrong woman Ive never been too dramatic1
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Old 07-28-2010, 08:40 PM
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Thanks topwrench, I've seen a lot of those too, I go to as many national events as I can each year; the engine failures aren't always due to backfiring, and yep, a huge mess.

Blown67 is talking a mild street setup, not the ragged edge top fuel or blown alky racer stuff, that's where my reply was aimed.

We all learn all the time, I'm no different. No hard feelings...

Got me chuckling at the pants down thing.....now that's scarey!
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