Inliners International Forums General Discussion Blown and Injected Chevy 292

The one I'm building will be controlled by my mega squirt along with a knock sensor.

Are Roller Rockers Really worth it for my application? They're $450+/- at comp cams and for $50 I can get "high energy" rockers for $50 at the same place...

What is your spring pressure over the nose? Under 350, you can get away with the roller tip ones. That's from Comp. Personally, I say buy the good stuff, so later, when you upgrade, you won't have paid twice for rocker arms, or worse, twice for rocker arms and twice for pushrods when you miss a gear, overrev and everything breaks and you have to replace it.

I'm not sure what the spring pressure will be, seems how I'm still in the planning stages of this build...

Do you plan on running a solid lifter cam, solid roller,hyd?

MBHD

Why are you posting new questions in 2 different places?

kuz I'm getting answers in both places.

the cam will be solid lifter, and after some searching&planning Here's where I'm at currently:

I'll be running a 292 with a 6-71 blower, lump ports, 3 1bbl rochesters, homemade manifold, 1.94 intake and 1.60 exhaust valves, Ross pistons, 8:1 compression, 10 pounds of boost, an MSD6 BTM ignition, water/methanol injection, 200,000 psi scat rods, cloyes timing gears, steel roller rockers, dual exhaust, and lots of chrome and SS, which will give it 10 more HP, I don't care what you guys say!

3 1bbl rochesters

Why?

or 4... mostly for looks, I think a 4bbl just looks wrong on a six...

If you can tune it and keep it tuned right I'd say go with the multi carb Just for the Cool OMG factor from most people.

And, you have that big database of prior efforts using blowers and multiple 1 bbl. carburetors to fall back on.

Oh, wait...

Thanks for all the positive responses Panic, It really helps me, because I'm not going to base my build off a site on the internet where some one like you could load me up on BS, make me spend alot more $ than needed, and possibly loose power.

Thanks for the support larry!

Oh, and Panic, my mom always said if I didn't have anything nice to say don't say anything at all. Maybe you should try asking if I knew what I was doing instead of guessing that I was clueless. I've setup dual 500 holley 2bbl's on a blown 383 chevy, so, I do have some previous knowledge.

what sounds better?:
And, you have that big database of prior efforts using blowers and multiple 1 bbl. carburetors to fall back on.
Oh, wait...

or

It sounds like you may need some help, I'm sure someone on this board can and will gladly help you, if you need it.

Lets drop it at this, and go back on topic.

if I didn't have anything nice to say don't say anything at all

That's the way all the world's problems are solved, isn't it?
That was great advice from a parent to a 10 year old.
Now... not so much.
I've found that when I'm making a mistake, my friends will tell me ("don't connect those wires. they're still hot"), and my enemies won't ("his tire is flat - that's so funny"). Guess your mom didn't get to that part?

Since you find playing the victim much more enjoyable, and since anything but "wow, what a great idea!" isn't "anything nice", I agree. Make as many mistakes as you want.

The attitude and the general snottiness that masquerades on this bulletin board as wit and 'advice' precisely represents the reason that I and others I've corresponded with refuse to join II.

Although the only Inliner I've met in person is nothing like that, one cannot follow this bulletin board long without feeling that opting to join would amount to formalizing a relationship with people who appear to view the forum as a license for sarcasm and self-righteousness.

I would assume that this rationale for this bulletin board is discuss (the word discuss is used advisedly; it is not used to imply an obligation to receive pronouncements) our plans, hopes, thoughts, and to recieve gentle guidance, and through these interactions to recruit new members. I suspect that the all-too-common open belligerence is instead driving away potential members.

By "gentle guidance", you mean telling someone what he wants to hear?
The speaker decided to fault my motive and method, since he's not competent to rebut my statement (that 3 Rochesters leaves you in an empty field with no guidance, and starting off from square one).
I intended to wait to see if he wanted some more information, or not. I was right - he doesn't want information, he wants approval, and I agreed not to offer any more assistance.

What's more important: the quality of the information, or the little happy faces?
Your statement accusing me of attitude and the general snottiness rather suggests that your opinion on these matters is also something not to be criticized?

There are none so blind as those who only see themselves in the mirror. Rather than examining my willingness to face criticism, you should be reflecting upon your own.

Everybody on this board is a full and complete person, with a tremendous body of knowledge; that knowledge may not be in the same area as yours, but the very fact that a person is asking questions implies a commonality of purpose and interest. That commonality makes it nothing less than shameful when discussion is rewarded with sarcastic dismissal.

I'm sorry, but I would suggest that the quality of the discourse, that is, the ability to openly discuss, is more important than the "quality of the information" as delivered by any one individual. In an open forum, information that is agreed upon by a consensus of contributors is more highly valued than bombastic finalities, no matter how loudly stated.


Note to all readers...

The opinions expressed in this, and im my previous message are directed not as much to a specific offender, but more to all of the respondents who feel free to indulge in sniping, petty arguments, put-downs, self-promotion, and otherwise generally poor behavior. You are collectively taking all of the fun out what should be enjoyable discussions. After all, the people that know something wouldn't have much to talk about if those of us that are more ignorant in the field were unavailable to ask the questions.

Note to all BB Members:

I don't have the time or the patience to be a babysitter, every time a topic gets started it seems like someones feelers get stepped on. The typed word doesn't have the inflections to pass on the way things are meant, if you continually get told you are a jerk perhaps you should rethink your words, if you are being a jerk, STOP IT!

This Board is about mechanical things, not about egos or personal problems. Everyone here is entitled to ask questions, talk about their project, and give advise. No one is obligated to take that advise.

Let's keep on the subject of Inliners.

Tim

lets just drop it, okay? panic, if you want to give me or anyone else some info Please feel free to do so, but don't make us feel like a dumb a$$ while your at it.

For those who would actually like some help (even if it's how to avoid a costly mistake), tell us:
1. what the project is (engine, year, transmission)
2. what you've done (is it stock? Mods?)
3. what's wrong
4. what you tried so far, and what happened
5. yes, there are some stupid questions, like those already asked and answered 5 minutes ago (another is "why can't I bore my 216 out to take 454 pistons?"). A search can be very useful.


1)292Chevy Inline six cylinder 1969 block.
2)4x1 rochesters, 6-71 blower, Homemade intake, lump ports, 1.94Intake/1.60Exhaust valves, Ross pistons, 8:1 compression, dual headers, MSD BTM ignition, Snow performance's Water/Methanol Injection kit, and my custom cam seen below, with 10 pounds of boost.

lift@1.7:i).500"E).510"
Adv.duration:i)272*E)280*
Cam Lift:i)294"E)300"
lobe center:115*
Duration@.050:i)224"E)230"

3)just want general help, is there anything else I should do before the build?
4)Not much, just getting started.
5)There's no such thing as a stupid question, just stupid answers.
let's start over, Nice to meet you panic...

Thanks - I'd much rather talk about engines than argue.

My objection wasn't that you want traditional appearance, it's that you're making (what appears to me to be) extra work for yourself. The B (or M?) has too many variations to know which body casting is best, tuning parts not easy to get.
Repeating the math: 292" @ 90% VE, 5,500 RPM (adjust as needed), is about 460 CFM. 10 psi is 1.68:1 pressure ratio, makes 772 CFM just to get 1.5" Hg vacuum. If you're jetting is good, you could run even more area down to perhaps 1.0" Hg. Even 4 needs 193 CFM each, only the largest 230 & 292 1-3/4" models are that big. It does allow progressive to keep the idle and low speed clean, though - idle on a center pair with the outers as secondaries.

IIRC they have power valves and an extra-fuel passage, don't know if it has a jet or just a drilling. I'm not sure how to reference the power system except by drilling through the body casting (this information is well-known for Holley and AFB), or address the fuel curve for extra gas on boost. This is a very ambitious project, but as we all know they have a tendency to add 2 new thoughts to the end as 1 gets taken care of - it never stops.

Cam: looks good, may need some tweaking.
You're going to need some serious work on the pan just because of the high power - scraper, baffle, pick-up surround, potentially lowered sump and extended pick-up. This doesn't even really need to be done until after the engine is built, especially since it has to match the chassis.
Headers: BIG primaries, the size is based on the power output, not the cylinder or valve size. 400 hp ÷ 6 needs the same as 533 ÷ 8, you may need 2" OD.

The intake shape can be a big advantage. The most current 14-71 blowers have their manifold inlets near the front of the case (like an Eaton), not centered in the rotor length (as did all older GMC manifolds). This both increases flow, improves distribution, and lowers charge temperature. You may need to make a jack-shaft to position the nose drive where your crank pulley can reach it.

Exhaust:I was thinking about using a header like the one you see by the inliners logo, maybe 1.75 ID to dual 3" pipes, then a X pipe, then back to dual 3". maybe a set of flow masters, but that'll come later. LOUD & PROUD.

Carbs: I believe the big (1.75) 230/292 carbs are 180cfm, (180x4=720) after a bit of shaving and polishing, and I'd set my rev limiter at ~5000~ so it'd take (1.68x422.45=709.7) so I'd be a little big, which would be good. As for jets IIRC they're just holes in the casting, so I could just drill them out little by little until I get it right, or, if possible? I could drill&tap them for ?holley? jets that are wide ranging an plentiful.

Intake: I think since I AM going with the 4x1 setup I'll do the traditional rotor legnth set up. As for the nose drive I'll just move the manifold ahead so it'll line up the blower.

Pan: I can lower the sump about another 4"-6" max. same with the pick up.

Cam: what do you suggest I change? I'm looking for my power to top out at about 3500-4000. lots of torque, even if it means HP loss.

Glad we could get that behind us, It's Tons more fun to talk about engines like you said.

Exhaust: obviously your own decision, but 1-3/4" is smaller than I would use and gives up some power. The usual argument against (low exhaust velocity = reversion) is completely removed by the blower flushing the chamber constantly during overlap.
I could drill&tap them for ?holley? jets that are wide ranging an plentiful.
Exactly - if the "power" orifice is drilled, and you can interrupt it in the casting (some require drilling in 2 places, and routing the passage to outside - not fun), insert a replaceable jet. The tap size is based on wall thickness and OD, there are some very small jets out there, many thread sizes. My (still future) book gives many alternate jetting components by thread, tap and available sizes. In addition, Jenkins used a piece of fine wire draped through a small jet to make really small changes (like a miniature metering rod).
Pan depth: that will help a lot. Keep the same depth over the pick-up to lower the oil down from crank contact.
I'll just move the manifold ahead so it'll line up the blower
You have to be very careful here, because an error is very expensive to fix. Moving the plenum changes cylinder distribution quite a bit, and inserting dams and dividers is dyno work - long and painful. Agreed, that any manifold has some distribution problems (typically #3-4 run rich due to short runners), but a centered plenum is at least symmetrical front vs. rear. Most aftermarket manifolds have fair distribution, but the rotor discharge pattern bias (favoring the front) means don't expect the same with the blower. Moving the manifold introduces another variable.
Just a thought: you're going to make a transition piece to mount the carbs to the 6-71 intake, yes? Making multiple bolt patterns will allow you to move just the carbs back and forth without moving the manifold - not as good, but still worth adding, costs nothing. Just figure out your throttle plate width (1st to last, remember they can be 4 × 1 or 2 × 2) vs. blower case opening length to see how much wiggle you have.

Demon's new 2bbl carb is 205cfm, takes holley/demon jets and float bowls, has a 3-bolt (stromberg) bolt pattern. You would be able to take advantage of holley 4 barrel knowledge to do the manifold referenced power valve mods and any adjustments to pvrc sizing to fix fuel curves etc. Isn't there a multiple rochester faq in the tech tips?

And its just me but I really think you need more cam although I may be failing idiot gearhead here. Blowers eat cam. My SBC cam was 255/262 at .050 and idled at 850rpm. There was definitely no lack of bottom end power. Also according to Stahl and Lemon's, 400+hp 6cyl blower motor should have 2" primaries.

Demon's new 2bbl carb is... $$$$ × 4

and rochesters around here = little to no $...

I was thinking of slanting the runners foreward on the intake, I don't know if you knew what I meant... I may run 5x1 if the cfm requires it...

Maybe 2"inch primaries would be the way to go. or even bigger: 2.25? what do you think of me making the manifold like the one on the one by the inliners logo, but split? I'll run a X or H pipe, Which 'd be better? And would straight pipes help performance enough to speak of or should I run smitties or something, I DON'T mind noise...

What should I do to my cam, I want my power band from about 1000 to 3500-4000...

thanks guys!

Qparker,
I think for your proposed rpm goal, the cam needs to have closer to 220 duration @ .050.
What rpm do you want full boost in? What is the max RPM level?

I'd set my rev limiter at around 5200, and I'd want full boost by around 2500-3000, or so, This'll be a red light racer, and It may only see long streches of highway a couple times a year.

all in all, which of these rockers should I get?

http://www.summitracing.com/parts/CRO-73631-12/

http://www.summitracing.com/parts/CRO-72831-12/

http://www.summitracing.com/parts/CCA-1261-12/

so basically, steel roller, aluminum roller, or stamped(like stock)

I kind of think of roller rockers as just something else to fail, but they have their uses.

I'm not particular to these exact rockers, in fact, I'd probally use a BBC set because it's cheaper for 8 than it is 6?!?

not sure of the spring pressure, but I'll be running 1.94&1.60 valves, and maybe
this cam:
lift@1.7:i).500"E).515"
Adv.duration:i)272*E)280*
Cam Lift:i)294"E)300"
lobe center:115*
Duration@.050:i)224"E)230"

I am not sure it's cheaper, but you can order from Comp cams individual (SP)sets of rockers that might be cheaper than buying a set of 16.

MBHD

because it's cheaper for 8 than it is 6?

Not sure what you mean.
The same rocker from the same manufacturer is going to cost more for 8 than 6. There are simply some rockers that are cheap and only offered for BBC, and even getting 2 extra it's less money, but it's not the same product.

I tried just selecting 12 individual ones and it showed up to be less than the cost of a pack of 12. and I also tried 16 individuals and they cost MORE than a 16 pack for a BBC. Maybe because BBC is so common? not many people buy rockers for 6's?

Besides, with a 16 pack I have 4 extras.

Should I go with the stamped ones, steel rollers, or aluminum rollers?

Should you buy apples or oranges?

bananas

really though...

are the rollers worth it? they're $100 more than stamped ones...

I still feel these rockers are a good option.
http://cgi.ebay.com/ebaymotors/ws/eBayIS...RK%3AMEWAX%3AIT

One of the surest, and most frequently followed paths to disappointment in engine building is to wheel the shopping cart down the aisle and buy shiney stuff when you're in the mood, and assume it must all work because it's expensive name brands.
The result is that you get smoked by someone who spent half as much money, and followed a plan. You're buying the dress before you meet the girl.

Think ahead: when do you actually need to install the rockers? About 20 minutes before you order the pushrods. Are you ready to do that yet? The project doesn't go any faster with big boxes all over the room.
Until the head is done, you don't know what you need for a cam.
Until that's done, you don't know what the springs are.
After that comes the rocker choice.

People with 10 years experience make the same mistake, sometimes they even realize it - but not enough.
Another fave is getting a great deal on a very nice piece ("Wow, a low mileage billet .800" lift roller cam!"), and designing the engine around it. The saying during the Civil War was "You found a horseshoe. Now, all you need are 3 more shoes, and a horse - and you're in the cavalry".

With your 5200 rpm limit you don't need to spend a lot on rockers. Stock type would probably be all you need. I have comp cam inexpensive roller tips on a small block that spins quite a bit higher with no problems.

Yep, listen to panic. Buy the cylinder head first. Then the cam, then the springs, then the rockers, then the pushrods. It's a series vice parallel evolution.