chevy89camaro

305 chevy.. tunnel ram with two 450cfm carbs. i have got the car to fire for about 15 to 20 sec at a time but is back firing through exhaust and tunnel ram.

I THOUGHT TIMING ISSUE!!

so i took out the #1 plug and roll #1 cylinder to top dead center. then i pulled the distib. cap to make sure it pointed at the #1 cyinder. all looks good. i then double checked my plug wires and the order is perfect.

it trys to run but very rough. the carbs dont seem to be fueling on there own. i have to pump it so the accel. pumps spray fuel. Help please.

Rolling Thunder

Well first thing i wonder is maby the distributor is 180 degrees out. Keep in ming TDC number 1 is also TDC for number 6 so you need to make sure your on the right stroke to really be TDC #1. If it was 180 degrees out it would run but like crap for sure. Next what fuel pressure are you running? Was any other work done becides the intake manifold?

AlkyIROC

180 out won't fire up.

I'd reconfirm the firing order. Rotor turns clockwise, firing order is 18436572. Driver side cylinders are 1357, passenger side cylinders are 2468. It's easy to get 5 and 7 plug wires mixed up.

Since you're sure the firing order is correct, the next thing I would check is to make sure the valves are not over tightened.

Rolling Thunder

I can guarent that a distributor 180 out will fire up. I got a motor back from a machine shop that was assembled improperly and it ran like an old washing machine backfireing missing ect but it did start.

Supervisor42

Couldn't be too much carb could it?

chevy89camaro

so if the timing mark is at 0 degrees and #1 piston is top dead center, and the rotor points at number one. can it still be 180 degrees off. i remember reading in my chilton manual that you have to watch the intake lifter. i also pulled the valve cover off to make sure it had lash. this engine ran perfect two days ago but i changed the intake and went from a accel super hei to a pertronix small base distrib and flame thrower coil.

bart91406

If the timing mark is at zero, then it is at TDC or 180 degrees out, the best I can tell you to be for sure is to pull the valve cover and see if both the number 1 cylinder valves are closed, if they are than it is at TDC, if not then it is 180 out. If it is at tdc then you will want your rotor to face NO 1.

Dual quads are neat looking and all, and tunnel rams are pretty intimidating, but having 2 carbs to get calibrated and tuned together sounds like a real hassle to me, do you think that maybe you have a dirty carb or vaccum leak.2 450s seems like a whole lot of carb for a 305 to me,I know I would never put a 900cfm single carb on one, but maybe dual carbs have different sizing requirements?

Good luck with your tunnel ram 305, and let us know how it works out, I am pretty curious myself.

Rolling Thunder

Well you see theres 2 TDCs for any 4 stroke motor. TDC on the compression stroke and the exhaust stroke. If the distributor was 180 out you would be firing on the exhaust stroke and not the compression stroke. Needless to say it wont run well like that. Your chiltons manual tells you to look at the lifter to figure out which stroke your on (keeping in mind the cam turns half as fast as the crank). However there is hope without having to remove even a valve cover. All you have to do is pull the number 1 spark plug and cover the hole with your finger turn the motor over clockwise untill you feel compression. Then you know you are on the compression stroke and the next TDC you encounter is where you should set your distributor to be fireing on cylinder 1.

bart91406

I was considering giving the same advice, but I did not want to confuse him, or for him to blame me if he has very small fingers and they sucked into the motor

AlkyIROC

Pull the #1 plug out. If you don't want to cover the hole with your finger, use the back of a screwdriver. A compression tester hose works well also. Bump the engine over until you hear/feel the rush of air coming out of the spark plug hole. The timing mark should be close to TDC. If you have the rocker cover off, you can also check to make sure #1 is at TDC on the compression stroke by checking the rockers. Both will be loose on #1. If one is partially down, you're at TDC on #6 cylinder.

Two 450's on a 305 is probably too much carb on the street. A tunnel ram gives no bottom end power and street driving is normally all under 3000 rpm. For street use, the two 450's should be on a minimum of a 350.

Rolling Thunder

Well i hear what your sayin but i mean turn it over by hand now so much with the starter should have said that. If you do turn it over with the starter make sure you dissable the distributor. Wouldnt want it to actually try and start would ya lol. Although im never afraid to thow things at people no matter how complex. You want to know how to change a head gasket ill tell ya, want to rebuild your carb sure you can do it ill give you what you need to do it. The truely dedicated individuals will take to it and rest will sink but then again thats evolution for ya creating a better smarter hot rodder lol. On a side note the tunnel ram is probably a bit much on a 305 and you probably have a bad bog but i suppose theres not much point in trying to talk u out of it now lol. On the bright side though with supporting mods they perform pretty well in the high RPMs 3000-3500+

transam85dudeman

You think you need a high stall converter dont you??i m not sure? and hows your fuel pump doing?? you got a fuel rail? or dual lines. many times a chip may need to be programmed. if everything worked cherry b4 the swap then i dont know. i am an amateur wanna be expert. I know that if distributor was taking out and the engine was swapped or turned over. LINE UP THE line on the harmonic balancer and place you distributor so that the rotor lines up with cylinder 1 on the cap. checking the valve cover valve is too much fun, and requires 4.1 beers. the only way im wrong is if the sleeve on the balancer has messed up. with the key in the crankshaft coordinating the camshaft timing and the distributor its key to have it rite. you may actually want to try contacting a chip programmer, you can do cool stuff like skipping teeth on the camshaft and get more horsepower or loose it. these cars are like lifting trucks, sure i can lift a pickup 6 inches and be cool, but another 3 inches and im looking at broken parts bad shocks, balljoints bigger tires, different pinion, new shift points, new calibrator for speed and abs airbags... set of smaller tires to allign the front suspension, etc. honestly people who invest big do it for show, and not relibilty. like lowering a third gen. new shocks, camber kit, coils, adjustable panhard, panhard drop bracket, adjustable torque arm. and problems that go along with it. i hate saying it but japan people are taking over with their reliable cars and awesome sounding stereos. but not to be racist, American may be obese but theres a lot of bad *** muscled out huge Americans like me. and maybe i dont speak a ching chong langauge i still got the ***** to say like, "AMERICA< F*CK YA" HAHA anyone see that movie, lol

chevy89camaro

awsome... ill let you all know tomarrow. i really think its a timing issue and with whats said here your right. i had taken out the old distrb severl times and droped it back in with no problems... i just remembered where the rotor was pointing generaly and if it dropped on the oil pump shaft i knew it was right. this new distrib didnt point right when i got it to sit on the oil pump shaft. so i rolled the engine to it first top dead center and dropped it in pointing at #1. bet thats where im off. the car did fir for 10 sec or so but backfired a couple times through the exhaust then igniting the fuel in the tunnel ram leaving me staring at to mushroom fire ***** through the carbs. nice.. NOT. probably blew the power valves out now.

chevy89camaro

no computer here fella...old school

AlkyIROC

That sounds like the problem. With the #1 piston at TDC, if you can't drop the distributor in because it doesn't line up with the oil pump shaft, use a screwdriver and turn the oil pump shaft until the distributor will line up when dropped in. If you bump the engine over without the distributor in, the oil pump shaft doesn't turn and now you're dropping the distributor in with the cam timing off.

Technically, #1 plug wire can be anywhere on the distributor. It's just easier when it's at the 5 0'clock position.

chevy89camaro

alright guys, i got the car up and running.... it was a timing issue. now that thats fixed i believe you were all curious as to how a tunnel ram would work on a 305. it runs great. it takes alot of time to tune the carbs but it is possible as long as when it starts to become overwelming you dont give up. the next thing to suprise you is this is a stock 305.!! i tore down the engine and put new bearings and rings in it. i did some very minor port work to the stock heads. the stock roller cam was put back into it. im running a Edelbrock TR1 tunnel ram with two 450cfm Holley carbs. since the computer is takein out of this car i have a pertronix distrib and flame thrower coil. hooker shorty headers. true dual exhaust. for those who wonder about the plugs fouling.... they did at first but now tuned they burn clean. idling becomes a issue after about 20-25 minutes. in town driving doesnt phase it. nearly 100 people told me this couldnt be done to a stock engine. i beg to differ. i had no intents of putting this car on the track. just making a street engine show its face through the hood. good luck to everyone working on there rides and thankyou to all that helped me.

transam85dudeman

timing issue thats it? whats the specs. btdc? was is a skipped tooth on the timing chain. since youre old school a gear drive would sound sick.(cooL)

bart91406

Yes, I agree that a noisy gear drive would go perfectly with a tunnel ram 305!