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-   -   4 barrel has less explosive acceleration than my orig. 2 barrel (http://www.hotrodders.com/forum/4-barrel-has-less-explosive-acceleration-than-my-orig-2-a-72614.html)

drumharddriveanova 10-22-2005 09:51 PM

4 barrel has less explosive acceleration than my orig. 2 barrel
 
i got a 76 nova sm. block 305 w/ auto trans.
i just got the engine rebuit from 2 barrel to 4 barrel and had it cammed and punched its now around the 400 hp range dont know exactly how much. the timing is set at 12 as 8-10 isnt enough. the 4 barrel carb is a holly (p/n 0-80457s) electric choke i have it adjusted right as far as i can tell the problem im having is i have extremely great exceleration and i had it timed at 8-10 but since the guy that built it up told me it needed to be changed it got even better but i still cant burn out i have standard 7" wide tires and i could layer rubber longer with my original 2 barrel i have no idea what to do please help
(my carb does seem to be adjusted right it idles good and doesnt stumble since i adjusted the choke a little) please help

67 Deuce 4 Me 10-22-2005 10:20 PM

Sounds to me like the 4 brl may be too big. Was the whole engine rebuilt? Did you change to a larger cam? If you have one component that is too big for the set up, like heads,carb, or a huge cam on a stock converter or gears. it will be a pig. need more info. Tell us the cam you have, the heads, Intake, converter, exhaust system, valve train components, gears, trans etc....And Im sure we can pin point the problem.

CHEVY4LYF 10-22-2005 10:28 PM

re: carb. problem
 
It sounds to me like you might have the engine over carbureted. Does it "bog" off the line? Since your 4 barrel no doubt allows more air to flow through, you intake velocity will be slowed (even though your volume will be greater)...basic physics. Just like when you put your thumb over the end of a garden hose to make it spray harder...you increase the velocity. Anyway if you're sure the carb. is in good working order, maybe recalculate your carb. needs.

John

drumharddriveanova 10-22-2005 10:28 PM

Quote:

Originally Posted by 67 Deuce 4 Me
Sounds to me like the 4 brl may be too big. Was the whole engine rebuilt? Did you change to a larger cam? If you have one component that is too big for the set up, like heads,carb, or a huge cam on a stock converter or gears. it will be a pig. need more info.

the engine itself should be ok- it was built up by a pro that has done many engines and many race engines mines built up a lot but not for serious racing just street rod its cammed- im not quite sure how much-i dont think its too radical the engine should be ok tho and its built for the 4 brl the engine does run great and has great acceleration like i said before but i cant burn out much at all- yes the whole engine was rebuilt

drumharddriveanova 10-22-2005 10:31 PM

will get more info and get back thanks

techinspector1 10-30-2005 09:31 PM

As alluded to by 67 deuce 4 me, when you changed the cam, you changed the window of operation from low r's to either mid r's or high r's, depending on the grind you put in the motor.

Any camshaft you bolt into the motor has a window of operation of approximately 3,500 rpm's. In other words, it'll be ground to operate from idle to about 4,000 r's or 1,500 to 5,000 or 2,000 to 5,500 or 2,500 to 6,000 or whatever. If you're still operating with your stock converter, it was meant to operate with a cam that is efficient at low r's, 'cause that's where the average consumer wants the power. You were able to skin the tires with the original cam, but now you are not making enough power down low to do it. You've moved the window of operation up in the rpm band. You'll have more power in a higher range, but the low end power won't be there anymore. In order to skin 'em again, you will need some gear or a looser converter or both.

Centerline 10-31-2005 04:51 PM

I completely agree. When you had the engine gone through you changed the horsepower and torque curve and that is only PART of the equation. Now you need to modify the rest of your drive train to take advantage of your engines new peak operating range. Gears and converter are a must.

kstagger 11-02-2005 09:01 AM

Quote:

Originally Posted by Centerline
Gears and converter are a must.

When I first got my '86 Monte Carlo SS, it had a L69 305 with a compucam 2040 cam...

I had a rebuilt 200-4R put in to replace the failing one. I also installed a 2500RPM stall. You could really feel the difference with the new stall convertor.

With my new 355, I don't feel the looseness of the convertor as much...

what are the specs on the cam are you running? and what rear gears are you currently using?

Go with 3.42s and a 2500 stall, that will wake it up!

stepside454 11-02-2005 09:34 AM

drum, you said in the original post that this 305 is in the 400 HP range. If it is truely in the 400 HP range than this 305 would be a serious effort engine, with a RPM range requiring a really loose convertor, that wont have squat for low end torque...... or.... it is far from 400 HP... & you dont have the right combination of parts. a small bore engine like a 305 is very easy to over cam & over carb. 600 CFM is enough carb for even the healthiset street 305s. Give us some more info, we'll see if we can help.

killerformula 11-02-2005 01:45 PM

I think we need to hear more specs about this motor to recommend what to do with it. I have a felling after we hear the specs of this build that this 400 horse 305 is going to turn into a 220 horse 305 in a hurry.

K

2NDXRND 11-07-2005 03:40 PM

I have to agree w/ the "over-carbed" crowd. I had a Carter 625/mech. choke on a mild 351W. the P.O. had done some jetting on the carb because he thought the 625 was too small. The car ran like a pig and was getting 6mpg. I pulled the 625 and went with a 600 Edelbrock............. WHAT A DIFFERENCE! Much more power, and over doubled the mpg's.
Also, not to bust on anyone, but 400 real H.P. from a 305 would be quite a feat. I think Demon makes a 500 cfm 4bbl w/ electric choke.... maybe its a 550 cfm. Those may be closer to the needed size.

poncho62 11-07-2005 04:12 PM

Also, you said a"Pro" built it....Well, a real pro would have been talking you into starting with at least a 350. You would have been much further ahead. I have a feeling that your 305 isn't putting out near what you think it is.If it was, you would be more than happy with it.

I agree, that there is a bad combination of parts here....not necessarilly the carb.

steve t 11-07-2005 04:22 PM

if everthing else fails , go to a line lock for burn outs

Tech @ BG 11-09-2005 01:23 PM

That carburetor may be too large for your application. If you have room try installing a 4-hole spacer between the carburetor and intake manifold. It will help increase the air velocity a little and make the carburetor act a little smaller.

jeff bonnell 11-09-2005 04:40 PM

for the most part i'm in agreement with most post's , a looser converter and steeper gears would do wonders , also a smaller cfm carb would probably help too (i remember as a teen , bigger has got to be better!) . while i agree a 305 isnt the prime candidate for scaring old ladys and rattling the neighbors windows , if done right , they can be just *** bad *** as a 350. my suggestion would be if you're gonna spring for a looser converter, spend a few extra bucks and put in a shift kit as well , that would up the fun factor 2 fold


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