Nebu

hi,

in the next month i will hopefully have my motor together. i got a 700 holley dp pretty cheap. i know its a little to big for it.

does anyone else run such a carb on a 305? which jet sizes etc. are you guys running? whats your mpg? specs are in sig

thanks,
nebu

five7kid

iTrader: (14)

As long as the RPMs are above what would be indicated by this chart http://www.holley.com/HiOctn/TechSer...fo/TI-225.html for your engine and carb size when you go wide open throttle, it will work fine.

Jets are a matter of tuning. You'll need to figure out what your particular combination likes.

mw66nova

iTrader: (13)

either i am confused on how to use this chart, or it's way off, cause it says my 310 with a 2800stall converter needs an 850 double pumper.

Nebu

hmmm, you need a 1000cfm dp, lol

i choose a 1500 rpm stall speed. its close to 700 so i think it will be ok.

nebu.

89Warbird

I don't know where this chart came from but let me say

nsimmons

Yep holley knows nothing about carbs. Your true stall speed is probably no where near what you guessed and your cam and gears are probably not properly matched to the stall anyway.

If i put a 4000 rpm stall on a stock 305 does that mean i need 1000cfm, no.

But if my car did need a 4000 rpm stall and had 4.56 gears and a proper cam then it probably would need the air flow.

five7kid

iTrader: (14)

You're all reading the chart wrong. They're trying to tell you how big of a carb you can get away with. Or, how high you'll need to have the RPMs when you go WOT with a given carb and engine size.

You should use the old stand-by formula to determine how big of a carb to put on an engine. However, the originator got a certain size carb because he got it cheap - I was only referencing the chart to show what RPMs he would need to be above in order to avoid bog with his engine and that carb.

roadthrills

You can use it and it will work.....But, no matter what you do to it the 305 has a small bore. This being understood, you can lean it out, crack open the secondaries a little, and it will still run rich and you will get horrible gas mileage.

ljnowell

Yeah, that chart basically is used to tell you what RPM you can go WOT without bogging.

89Warbird

I'm sure you can jet down to make just about any carb work, but you lose so much velocity it just ain't going to run worth a crap.

mw66nova

iTrader: (13)

actually running a bigger carb generally means you need to jet up, cause your adding more air, therefore needing more fuel to keep the ratio stoich.this is kind of an ignorant post. you don't know anything about my combo obviously. when i got my converter, i called ati and told them my cam/intake/carb/gear specs. pretty sure all my stuff is matched just fine. don't know many other carbed 305's that make 270+ rwhp and have great street manners and still get 20+highway mileage.

nsimmons

Now whos ignorant? You do realize that a converter will stall differently on different engines, hence since it wasnt engineered on your engine, you dont know the stall speed.

Follow the dots, you dont know the true stall speed, you dont know your true head flow, you may or may not have degreed your cam, you probably didnt bench flow your carb.

Now im being picky hear but dont spout off about how your combo is perfectly matched. Did you do dyno pulls with multiple parts with different tuning? At best you made an educated guess, and im sure if you have the desire, time and money it could be vastly improved.

You dont know any other 305's like that because its a stupid decision to build a 305. Im sure you'll find plenty of reading on the topic.

Got a dyno sheet to back that up? My vette ran a 100 trap with mufflers and a chip. It sure as hell didnt make 260rwhp, maybe at the crank.

mw66nova

iTrader: (13)

the exact mentality i built the motor to spite...

nsimmons

Its stupid because it costs 50 dollars for at least 40 more hp, and not to mention torque and a better platform for future mods.

Your 100mph trap speed doesnt spite anyone but your own wallet. You seemed to have over looked my entire post, or does it make sense to you now.

Especially the 270rwhp comment, i love that. HA!

Wait till you grow up a little and your entire perspective on things change. I cant possible fathom my reasoning when i was that young.

WWJD? He wouldnt build a 305.

mw66nova

iTrader: (13)

your right, i am merely speculating on mathematical equations, that happen to reflect real numbers. the trap speed was with the 1900stall converter too, no telling what she'll run now. track opens back up on the 22nd so i hope to get some good runs in.

coulda built the broken 350 sitting next to the broken 305 that were both sitting in my shop, but i didn't. i built the 305. hoping to get a streetable 305 into the 12's. i know you had goals that where outrageous when you where "that young". does anyone ever get tired of saying this comment? or are all young people ignorant? must be the case. not trying to be smart, it just seems like you overgeneralized me and my build.

nsimmons

Ignorant?

ig·no·rant ( P ) Pronunciation Key (gnr-nt)
adj.
Lacking education or knowledge.
Showing or arising from a lack of education or knowledge: an ignorant mistake.
Unaware or uninformed.

Retarded? No. Intelligent? Yes, ignorant? You tell me?

Trap indicates power, your power says your making about 250 flywheel.

Traction will play a small role in mph.

mw66nova

iTrader: (13)

with what equation are you using? especially since you don't know the weight of the car.

mw66nova

iTrader: (13)

using your definition, you did make an ignorant post, i am not flaming or anything, just simply explaining myself. i never said any of this with a negative conotation, simply stating that you where uninformed (ignorant by your definition) of my combo therefore you couldn't make a good guesstimation at the time of my power level

nsimmons

Yes i am ignorant to your combo and so are you. Thats my point.

Theory is fine and dandy in the class room. Real life says other wise.

Case 1, 91 vette 250hp stock, weighed at 3040 100mph trap
Case 2, 84 vette 205hp stock, 90 mph trap, 96 after mods, 3100
Case 3, 85 iroc, power unknown, trap unknown, weight 3120

Now from experience of not just myself but others who have driven the car the iroc is superior to the 2 vettes. There for i have to conclude the iroc is making more than 250hp.

With that said. Your car must come in at around 3800 lbs if in deed it has 270rwhp and it only runs 100mph.

I almost bought a 79 z28 that ran very similar to your times, it was 4100 lbs with stereo equipment, with a built 350, trick flows, a lot of cam. It should of made close to 350hp, there for i conclude your car must be as heavy as that 2nd gen.

Bottom line is we are arguing in the hypothetical which is pointless. If you believe your car is making that much power, fine, but dont accuse me or ignorance after you've clearly shown yours.

Besides my first post wasnt even directed to you, and I would have skipped the entire thing without your wise crack.

I tire of this. I have a dizzy to rebuild.

mw66nova

iTrader: (13)

i don't see how the countless hours spent pouring over threads and calling every company that i used parts from makes me ignorant of my own combo. hp=weight *(speed/234)^3 to caculate rwhp

hp=3400(100.5/234)^3
hp=269
obviously, these numbers are hypothetical and ballpark, but very close non-the-less

i am not sure why you assume i do not know what my heads flow and whay my converter stalls at and my cam specs, what my carb flows, etc. etc. yes, with more power, my converter would stall higher and seem looser, but what does that have to do with the price of eggs?

i still don't see where i am coming off as ignorant, other than maybe because i claimed the hypothetical numbers as real, in which case maybe i was wrong to do so.

nsimmons

You dont know what it stalls at, you dont know what your heads flow, what the documentation says is what happens in "theory"

You have completley missed the point of my first post. It does not stall exactly at the rpm the paper work says, because.... engine output changes stall speed.

Your formulas being very close none the less? Please. Have you ever studied any science? Basic physics? Calculus? Could you even calculate the integrand of a function modeled after your cars work. There are so many variables.

DD says my car makes close to 350hp and car test says it will hang with a viper using DD numbers. Simple algebra works for video games not real life.

Your last sentence sums up the entire conversation. Lets leave it at that.

BTW my dizzy works good as new now. Had to pull it in the snow as the garage door is broke.

roadthrills

mw66nova, just ignore what's said if you don't like it. Personally I like the 305. I also enjoy rubbing it in peoples faces when they get beat by one and they have more cubes. Besides the stockers in my Trans Ams, I have a mildly built 305 in my S10 Blazer. Stock 700R4 and converter from a Trans Am, stock 3:42 open diff, fully loaded with all power acc., and A/C. My little 305 is putting a little over 260hp to the rear wheels, I'm getting 20.5 mpg on the highway. Weighing in at 3800lbs with driver I'm dipping into the 14's @ 94 mph on 93 octane fuel. I say YAY for the 305!! I plan on putting in some 3:23 gears for this summer and hitting mid 14's and yes, you did read that right 3:23. Here is a pic.

Tech @ BG

A 700 carb is going to be a touch big on an engine of this size. If you have room, installing a 4-hole carburetor spacer between the carb and intake will help increase the air velocity, and help your drivability, and overall performance.
As far as using any formula they are set up as a guideline, or starting point, but not an end all be all since there are many other variables they do not take into consideration. Overall, your combination would probably perform better with a slightly smaller combination.

five7kid

iTrader: (14)

What most of you seem to be ignoring:

1) The originator is in Germany. If you think you have trouble finding performance parts in Podunk, USA, try spending a week in his shoes. I spent 3 years there, and I had the advantage of APO and AFEES - and it was still tough.

2) He found something that is available and for what, at least to him, is a decent price. The question isn't, "Is this the absolute best for my engine?", but rather, "How do I set this up?"

So, unless what you have to say takes those factors into consideration, it's better if you just keep quiet.

P.S.:
Hey, look at that - real live tech from BG! Understand my terse, "not my turf" opinion expressed above is not directed at you. What you say is true, admittedly. But what the originator really needs is the best approach to his less-than-ideal situation. However, now that you've made an appearance here you can expect to be tested/called upon on a regular basis.

five7kid

iTrader: (14)

By the way, Nebu, the line you drew on the chart is a little off. With 1500 RPMs and 305 cubic inches, a 700 cfm double pumper is right at the edge of acceptablility. Raise that stall a couple hundred and you'd be better off. However, if the converter stalls a little lower than that, you may have to get going a little before you can floor it.

Again, the carb is probably bigger than it needs to be, but it probably isn't too big to work okay on your engine.

Nebu

@five7kid: thanks! sometimes its really not easy to find performance parts in germany. and when you have found them, thay are well overpriced.

Example: New 650 Holley DP, ~ $500 in germany....

at ebay usa i bought a good used one for about $140 with shipping. so i didnt care if it was 50 cfm more than needed this car is a weekend fun driver, and for meetings.

and im probably going to swap these parts to a 383 sometime.

i just wanted to know what jet sizes etc. you are running, because i think its not an everyday combo this week ill get my replacement parts for the starter. i will keep you updatet if it runs or not

thanks,
nebu

EvilCartman

iTrader: (1)

I ran my 750 Speed Demon on the old 305 for a few months while building the 350 up. Never once had a problem with it, still got 22 mpg on the highway, ran much better than the Holley 670 ever did. I was running the same trans and converter so that may have helped on the lower end of things, still though, throttle response was way up over the Holley.

chev496

I had an edelbrock 750 on my 85 truck, 305 with performer eps intake, hoker headers, full 2.5 dual exhaust. You had to get going a little bit before you hit the gas or she would bog out. I even changed the timing, and did a few things, but the bores were just to big on the carb. Called up edelbrock for hopefully something that will work, the pretty much told me to screw off and that carb was extremely to big and stupid to even put it on there. I explained i am building up an engine, and just needs some guidlines, still no help. The reason I will never buy a edelbrock carb. But good luck at getting that to work.

ljnowell

Sooo, you will never buy an edelbrock carb, because you screwed up and put too big of a carb on an engine?

chev496

Screwin up and having what you got at 16 is one things, asking for advice and they tell you nothing but your screwed is another... read inbetween the lines.


Called up edelbrock for hopefully something that will work, the pretty much told me to screw off and that carb was extremely to big and stupid to even put it on there. I explained i am building up an engine, and just needs some guidlines, still no help.

Thats why.

Plus, yes, they wont flow enough for high hp engines. I have only seen gains by taking them off a 400+ cubed wild engine.

ljnowell

They dont "flow" enough. Ok, whatever.

They told you that, because basically, it was true. There was nothing they could do to help you make it more streetable. There was a member that posted a link one time showing dynos on the exact same engine, with different carbs. Between the holley, Qjet, and edelbrock, there was a whopping 10 hp spread. That is between all three carbs. I couldnt find the link, otherwise I would have posted it. Its a matter of tuning.

chev496

Look in one of the latest issue's of hot rod. Took an Edel. 800 and put it on an engine, then a Holley 850 and gained an instant 10 hp. Well, maybe your thinking it wasnt tuned? You think they didnt tune it before they pulled it off? Naw, it was tuned. Maybe cause it wasnt flowing enough. Yeah, probly. I even had the Eddy on my engine, 468. I did a number of htings, couldnt get it to run right. Now with my Demon, runs like a Champ. No stumble, no unstable idle, no big holes in the primaries, and very crisp throttle. That is what I like. To have it run like a fuel injected car. Thank you and have a nice day.

ljnowell

So the edelbrock doesnt have as good of manners as the demon? Sorry, thats the whole point of an edelbrock, friendly street carb. I guess maybe some people cant comprehend how to use one. Hmmm, 10hp, sounds familiar. Nice to know thoug, that since you "did a number of things" that didnt work, edelbrock carbs are junk.

five7kid

iTrader: (14)

I'd suggest we not hijack this thread into a Holley vs. Edelbrock debate. The originator had specific questions, specific restraints, and this bickering isn't contributing to resolving his specific issues.

chev496

Agreed. Best wishes with your 700 holley to work. If it doesnt work, just get a stall converter or ease into the throttle for a while. I am sure you will be more than pleased with it.

Nebu

update:

installed the new parts for my starter. now it works fine again

but....

1. ive got a header leak....
2. the carb is leaking....

idle is fine and it starts good. when i rev it slowly it sounds good. but when i rev it a bit faster, the motor dies. what could that be? accelerator pump? fuel pressure is around 5.5 psi.
idle screws are both 1 1/2 turns out. maybe i play with them a bit....

nebu.

my3rdgen