I have a 1986 Z28 with a carb, and a rebuilt 305...the problem is its never had any good acceleration...say im at a stop sign, when i push the pedal to the floor i dont get the fast response i expect, instead the engine seems to bog down and almost die then it will slowly but surely start accelerating, i cant even spin the tires unless there is dirt on the road or if its raining! this cant be normal can it? and sometimes when i push the pedal to the floor it wont bog down but it will accelerate just as slowly, my girlfriends stock honda civic hatchback takes off faster, i havent told anyone that of course haha...i bought this car because my friend had an 86 iroc(which i also bought as a donor car) which performed great, it was powerful...what could be wrong with mine?? i'll be putting the car on the road in the next couple weeks and i just want to fix this so all those import ricers wont see my baby bog down like that...

 

what kinda rear end do you have? lol, no offense, but most people w/305s experience a lack of acceleration.
if you got a higher stall torque converter and low gears you should have no bogs whatsoever.

 

Might want to check your timing also. Make sure you have a good tune up.

How many miles you got on the engine?

 

i'll do the timing today and see if that helps, i'll also check on the rear-end and get back to you...the engine has a little over 30,000 miles on it now, at least half of them were highway miles...is it true that most people with 305's experience poor acceleration? the donor car has tpi, maybe ill have to think about a swap...

 

btw has this happened to anyone else?

 

yes, I had an RS, it was my first car ever. 305 V8, best time ever was a 16.5, it was pooch.

I don't think puttin TPI on will really solve your problem. I'd do heads, cam and intake first. what kind of carb are you running? it seems to me your car doesn't have any low end power and poor gearing which is why it's losing to civics.

 

all about the gearing...
switch to 4:10s and let me know how slow it is off the line

 

you wont have any acceleration because you drive a 305. You want acceleration get a different engine. trust me i tried modding my 305 and the highest i got up to was 14.4 and that sucks.

 

I can't give any quarter-mile times, but I can relate with the "poor" acceleration issue. I've got a rebuilt L98 (TPI) engine in my '89 IROC with 2.77 gears, and I can't even squeak the tires from a stop (unless I power-brake, of course--but what good is that?). I won't say that it's slow, but something about not even being able to break the tires with a V8 (especially the torque of a TPI) makes you wonder if you're getting what the engine's got to give...

 

i got a carbed 86 firebird 305 lg4.... perhaps the slowest v8 for these cars. but, my car can easily spin the tires and i got 2.73 gears.... not doing power brakes or whatever.... just if i mash the gas from a dead stop, i can make the tires spin, and i can run low to mid 15's with just an open element..... i would check something else, its not the gears or the 305nesss.....

 

What he is describing doesn't sound like "slow aceleration casue it's a 305" crap

It sounds like something is genuinely wrong.
I am not going to pretend like I know what--but quit giving this guy stupid answers.

Car won't be a rocket ship but re-read his post.

 

It aint cause its a 305. I have an 86 IROC with a 305 and it spins the tire easily. Engine has over 200,000 miles on it and the car is all stock, except for hyperjunk chip. Transmission is the 700R4 but dont know what the rear is. I know it aint a posi.

 

hey


i know what your talking about the slow accleration. but i have had the older 4 barrel carbed cars. first thing is the carb could use a rebuild and tuned also check the base timing and then go from there.

i have a 88 305 TBI with auto and 2.73:1 gears and i have no problem blazing the tires from the stoplight.

the guy with the TPI you really have problem .

 

Yeah, I don't know what the problem is, but I need to find it out--didn't spend >$1500 on a rebuild to have a 350 that can't even spin the tires...

People were originally telling me that I couldn't spin the tires because I have a 2.77 rearend, but if there's guys out there with 305s and even shorter gears able to spin their tires, then the rearend couldn't be the issue.

I've been thinking of having my car dynoed, and then comparing the results with someone of a similar setup (or an original GM stock dyno) since I rebuilt it with new but stock-spec parts. I don't know if that would tell me anything useful, but I think it's worth a try. Problem is, I don't know of anyone around here that does that, or what it costs even...

mdr211: As for your problem... whenever I hear of an engine "bogging" on acceleration, the first things that come to mind are either: timing or vacuum (leak). Definatly check your timing with a good timing light--that would be the first thing that I check if I were having a power issue. Secondly, somehow determine if you have good vacuum. I seem to recall that when I had a vacuum leak, hard acceleration made the engine bog before it started to rev back up. Short of those two things... I'm not sure. I'm assuming that your rebuilt engine is mechanically sound (you would probably find out pretty quickly if it wasn't).

 

my 84 z l69 ho 5 spd kinda has that problem now that i have over 130000 miles on it its hard to spin them in 3rd like i use to. so just neutral drop ur car or maybe fix ur jets that could be it or ur dist isnt giving u enough spark

 

I am having the same problem as mdr211 -- slow acceleration and bogging. I have a 305 V8 with a 4 barrel carb. I would really like to get nice acceleration. That is why i went with the V8 over the V6.

 

Ya'll with the 2.73 gears. Are you spinning the tires, or tire ? And is that tire bald?

I have a 305 LG4 85 Trans AM with the Q-jet carb. 3.08 posi gears, cold air induction, and a gutted cat will let me spin off the line, and spin going into 2nd.

mdr211,

good tune is a must (timing, vac leaks, oil change, filters, tranny, etc.) check the tag on the rear end housing for gear ratio (if still there, and gears never changed). Not cheap or easy...but a gear change may be in order. I don't know much about carb tuning, but you may not be getting the proper amount of fuel when you expect it.
Additionally, there could be issues with a "rebuilt" 305...meaning what was involved with the rebuild? Cam? heads? Compression ratio? intake? etc. You could have a case of mismatched parts.


Hell, a brand new LS1 RAM AIR Trans AM is slow and boggy to me with the 2.73 gears...and good tires.

 

There was a time where my car couldn't spin the rears even in the rain Kept working on it and working on it sorting out little problems here and there. Started running a lot better than it was but the carb had problems. Changed some parts around and it was even better. Fast forward to today,was out driving in the rain to fix a guy's computer, light turned yellow so I stepped on it a little and got sideways That was cruising along at the speed limit (35 mph) in drive and just under half throttle.

 

You have a 750 cfm carb! Thats huge for a 305
My buddy has a 383 67RS Camaro that runs mid 13's with a 650. How is your mileage?

 

a 750 is too big for a 305, but i also think your buddies 383 would run better w/ a bigger carb.

 

with a 750 ur not flooding ur engine or running really really rich do ur headers or manifolds glow tooo

 

Well let me tell you this... After I bolted on the 750, throttle response was improved and the power was improved. Wish I could show a dyno sheet to prove this. It's not running overly rich, actually had it too lean at one point. This carb is going on the 350 once it's done but for chits and giggles one night I stuck it on the 305. I was supprised at the difference over the 670 Holley I was running. No, nothing glows and the gas gauge goes down about the same due to my heavy foot

Now I know someone is going to say that I didn't have the Holley tuned right. I messed around with jet sizes and springs a lot to get it running as best as I could. I do have a pump cam assortment I haven't tried out yet. The car never pulled as hard as it does now with the 750 on it. For some reason, it just works.

 

dude just do a search or something for bogging. My old wrecked 83 camaro had the same problems at WOT but dont worry because most of the LG4 carbed engines had this problem at WOT. Just do a search for it. It has somethign to do with the secondaries opening up and too much air getting in not mixing with the fuel. That then makes it lean at WOT. I dunno something like that. So some tuning and adjusting on your carb and it will help the problem. I never got it completely fixed but I made a really good improvement with it tho.

 

I have the same problem with my 83 Z. It's running an Edel 550 car/performer intake + msd ignition and Accel coil. It probably needs a good tune-up, timing adjustment, exhaust leaks repaired. Just found out today that the 305 block is from the 70's. The engine's dripping oil from the spark plugs, amongst other issues. My engine is old and has problems....that's why is so slow. BtW, if someone had a 454, they'd probably say a 350 doesn't have enough acceleration.

Brandon

 

between the large carb and ramming the pedal to the floor I'd say you are flooding the engine.

If I ram my 305 with the stock carb to the floor it will just bog down. You have to gradually push down the pedal until about 3000 rpm, then you can ram it to the floor and feel something. Remember, it is one thing to give an engine all that gas. It's another thing for it to use all of it, and it ain't gunna do very good if it isn't at the right mixture.

 

You have problems just as Big as his.. Carb size on a 305 also depends a lot on the heads..intake..ignition syatem. Tuning is the Key!

 

OH yeah I know my carb is way outta tune, but if you ram any engine to the floor from dead stop it's gunna bog a bit.

My carb is pretty bad though, secondaries barely open, and it's dirty. STUPID Q JET.

I'm planning on putting in a 400 with a holly carb soon enough so I'll just leave the damn thing.

 

When I got my camaro it needed a major tune-up and a new carb. My little 305 had a ton of acceleration to it. Even ran with an SS camaro and Mustang. Didn't really mod it much. The sad thing is that engine was a lot stronger than the 350 I put in it.