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Old 08-20-2006, 09:19 PM
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350 w/ 2 bolt main and supercharger?

OK, here is the dealio: I'm on a budget like everyone else.
I bought a 350 for $100, and it was supposed to be a 4 bolt main. Didn't have any tools at the time, and turns out it is a 2 bolt main. Oh well, buyer beware.
It also has some (supposedly) poor flowing 14102193 heads.

It is going into a ~2500 lb. car that will mostly be a weekend fun driver, tire smoker. The car will have a 5 speed standard, a ford 9" with probably some highway gears. I want to use a small Weiand blower. My plan is to use the stock open chamber heads and dished pistons to keep the CR down. I figure the flow of the heads doesn't matter so much if I'm using a blower. Using the heads I have will keep the cost down, and allow me to afford the blower. I'm shooting for about 400hp, and will be using hydraulic lifters with roller tipped rockers.

According to David Vizard in "How to build max performance Chevy smallblocks on a budget", "Two bolt blocks can live with a lot more horsepower than usually accredited. And if you're working on a budget, a two bolt block can work for drag racing applications in excess of 500 horsepower with nothing more than a change from regular main bolts to ARP main studs." I have read this elsewhere, so I'm not too worried about not having a 4 bolt block.

But what about the pistons and rods? The guy I bought the engine from said it had about 180,000 miles on it. It has never been rebuilt. Will stock rods that old handle 400hp, while keeping the rpms to ~6000? Do I need forged pistons or can I use cast?

Any comments / suggestions?

I plan on calling Summit or Weiand and asking these tech questions, so I'll report back and let y'all know what they say.

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Old 08-21-2006, 06:39 AM
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check out this site. It will tell ya everything you just ask and a lot more.

http://blowerdriveservice.com/
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Old 08-21-2006, 07:49 AM
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Thanks!

Their "recommendations" page is very informative. Thanks!
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Old 08-30-2006, 02:01 PM
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From the tech guys at Holley:

I've been going back and forth about my the heads I have. Since they are plentiful and cheap, I thought others might want to know what I've found.

I looked up some information on the heads on the sallee chevrolet site, and found this:

" These heads were designed for bottom end performance, mainly torque. They are stock truck heads and not performance heads. They have restricted air flow that becomes a problem after 4,000 RPM. Used in their original application as a high torque bottom end head in a truck for towing the do fine. These heads come on GM truck engines P/N 12568758 and P/N 12520270."

I want to keep the heads to keep the cost down, but still produce 400hp. Basically, I want to overcome the restriction of the heads with the forced air flow from the supercharger. I could get 400hp from REALLY good heads, roller cam, and roller lifters, but I've always wanted a supercharger. They run $1500 or so, and I think that would be close to the good heads and roller items. So it seems kind of like a 6 of one, 1/2 dozen of the other situation.

I contacted Holley (they own Weiand) My question was:

"I recently purchased and am rebuilding a used sbc 350. It has 2 bolt
mains and late model "swirl type" heads. I'm shooting for about
400hp. I'm planning on getting whatever cam y'all tell me to. I'm
not worried about the 2 bolt mains, but I'm not sure if I should use
the heads I have. I read everywhere they are crap, but some say they
can flow good with porting. I can port them myself, but should I
bother or get some newer Vortec heads to hit 400?"

Their answer:
"For 400 HP the heads should be fine with the blower. Please contact
our cam division at 901-365-0950."

Has anyone ported these heads? What about taking the "ramp" out altogether?
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Old 08-30-2006, 04:42 PM
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The thing is if ya put bigger better heads on it, it will make more power! Will the 2 bolt mains hold more power? Will the pistons and rods take more power?

Here is the set of heads i bought for my blower motor. The look great. I have not put the motor together yet. I am still building the chassis and getting the body ready. http://cgi.ebay.com/ebaymotors/SBC-C...mZ260024913548
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Old 08-30-2006, 06:47 PM
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Which supercharger are you planning on using? I wont say they will or wont last but I will say this: I Installed a 142ci Weiand supercharger on my cast crank, 9.8:1, 2 bolt main (with ARP studs) 350. It has Sportsman II heads on it as well. It turns 6000+ rather frequently. It's been running like that for about 9 months now without any problems. However, I've also accepted the fact that it may go at any time and I'm not going to concern myself too much with it if that does happen. After all, I've got a 400 waiting... Good luck.
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Old 08-31-2006, 11:07 AM
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When I was at B&M we ran a number of the small 144 and 162 blowers on 2-bolt main engines and never had any problems. The heads will not hurt your performance up to about 4,500 to 5,000 rpm. Below those speeds bigger heads will provide zero performance. Above those speeds you will see more power.

All of our dyno tests showed that bigger heads, valves and cam had little or no effect at engine speeds below 4,500 rpm when using a blower. The blower is able to overcome those restrictions at lower engine speeds. Once the engine gets over 4,500 rpm, then those restrictions do start to hamper performance. One of those small blowers on an average engine is good for at least an additional 100 hp.

We ran literally hundreds and hundreds of dyno tests with every combination known to man.

The Weiand 142 is basically the same as the B&M 144. In fact it is a direct copy except originally the Weiand did not have teflon tipped rotors and B&M did, plus Weiand used a different belt idler system. I don't know if the Weiand blowers now made by Holley have teflon tipped rotors or not. I think they might.
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Old 08-31-2006, 11:42 AM
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Quote:
Originally Posted by jimdavis
When I was at B&M we ran a number of the small 144 and 162 blowers on 2-bolt main engines and never had any problems. The heads will not hurt your performance up to about 4,500 to 5,000 rpm. Below those speeds bigger heads will provide zero performance. Above those speeds you will see more power.

All of our dyno tests showed that bigger heads, valves and cam had little or no effect at engine speeds below 4,500 rpm when using a blower. The blower is able to overcome those restrictions at lower engine speeds. Once the engine gets over 4,500 rpm, then those restrictions do start to hamper performance. One of those small blowers on an average engine is good for at least an additional 100 hp.

We ran literally hundreds and hundreds of dyno tests with every combination known to man.

The Weiand 142 is basically the same as the B&M 144. In fact it is a direct copy except originally the Weiand did not have teflon tipped rotors and B&M did, plus Weiand used a different belt idler system. I don't know if the Weiand blowers now made by Holley have teflon tipped rotors or not. I think they might.
the Wieand 144's have teflon tipped rotors and are 3/4" shorter than the 142.
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Old 08-31-2006, 12:07 PM
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Quote:
Originally Posted by matt167
the Wieand 144's have teflon tipped rotors and are 3/4" shorter than the 142.
I don't have a recent Holley/Weiand catalog so they may have changed things since this copy. But in the 2003 catalog I have they list the Weiand 142 (without teflon) plus the Weiand 144 (with teflon). I am not sure why they would list them that way.

The 144 was the B&M size from day one and when Weiand came out with their copy a couple of years later, it was listed as a 142.

Those numbers, by the way, represent the amount of air (in cubic inches) that the blower can move in one rotation. If the Weiand 144 is truly 3/4" shorter than the 142, it would move a whole lot less air than just 2 cubic inches.

Anyway, the whole thing is kind of confusing.
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Old 08-31-2006, 07:53 PM
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Jim, I bought my 142 in December of 2005 and it does not have teflon tipped rotors.
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Old 08-31-2006, 08:18 PM
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Friend of mine in his 2200-2600 or so lb street rod built a budget blower with a cast crank, rods, 2 bolt block, flat top forged pistons, small blower cam, stock heads ect....On a 6-71 weiand blower with like 6lbs of boost and ran it to 6000+ rpm's and put over 30,000 miles with no problems.
Sbc parts in stock form are pretty stout. Its these darn magazine writeups that uses all forged everythings that makes you feel the need to use hi dollar parts. HG
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Old 09-01-2006, 08:35 AM
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Scope creep

Wow. Thanks a lot to all of you. Reading books by Vizard and reading what you guys have to say makes me feel like I'm heading down the right path.
Gremmie, you are right. I know when I open a magazine that 1/2 of what I read is designed to sell me stuff, but never hearing that less-than-high-dollar parts will get me where I want to go starts making me feel like I have to upgrade here and upgrade there. In my past job we called it "scope creep" - a little more here, a little more there....
I had almost decided to go ahead and buy better heads when I read what you guys had to say. Now I feel good about sticking with my original plan.
It'll feel good to say that I'm using a lot of parts from a $100 scrap motor to put out some serious scoot.
I'm also planning on working up a junkyard flowbench using a MAF sensor, car battery, my shop vac, and a voltage meter. I dreamed it up and then found an old thread on here about it. It gave me some better ideas. I may not get true scientific readings out of it, but I'll be able to figure out a % increase in flow that my garage porting job gets me. Plus I'll know that all my ports are flowing the same. I'll be sure to post the build and photos on here.
Now to clean those heads!!
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Old 09-01-2006, 10:06 AM
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Quote:
Originally Posted by Blazin72
Jim, I bought my 142 in December of 2005 and it does not have teflon tipped rotors.
In looking at the Holley/Weiand website, which I presume is the latest information, they list a 142 blower without teflon and a 144 with teflon. I find this rather odd. In the two photos they show, it appears to be the identical blower. Why they call one a 142 and the other a 144, I don't know.

Regarding the 4-bolt main and trick rod stuff, you have to remember that most of these high buck components came about because guys were building small block Chevys that could easily turn 8,000 to 9,000 rpm. High rpm, not cylinder pressure, is what wreaks havoc on engine components. Because of the way a supercharger makes its power, it is not necessary to turn a blown engine over about 6,500. At that relatively low rpm a two bolt main and stock rods are usually more than adequate. Even cast pistons will hold up if you have the mixture correct and no detonation.

Don't blame the magazine guys for overstating stuff. They really aren't trying to necessarily sell you components. A lot of this comes from the magazine guys talking to professional engine builders. I have been down this road many times. Most of these engine builders have a one track mind when it comes to assembling a high performance engine. Use the strongest and best stuff for every single component whether it is needed or not. The magazine guys, many of whom don't really have a lot of actual hands-on experience, take all this stuff as gospel. They basically write what they have been told.

Like I say, I have been down this road before. Talking to somebody like Gale Banks, or Keith Black (when he was still alive), you will quickly be convinced that you are the biggest dummy in the world and every piece of speed equipment you have is junk. These kind of guys seem to deal in absolutes. By that, I mean that the vast majority of their experience is only dealing with the very best components and so that is the only way they know to approach a problem. And it is from icons like this that the magazine guys get most of their information. There are a few magazine guys, like Jeff Smith, who are totally hands on, have built hundreds of engines and really know what they are talking about. But again, even somebody like Jeff tends to deal in absolutes, working with basically the best parts available.

Several of the magazines have started to do more "budget" type engine builds with great success.
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Old 09-01-2006, 10:10 AM
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David Vizard is another hands-on guy. I have worked with David on a number of projects and while he can be overly opinionated sometimes, for the most part he gives good solid information. He builds lots of engines and has run hundreds of dyno tests. I think he shows more real world practicality than a lot of his peers.
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