Trouble taking off (plenty of power..) ???

[bowtiedriver2]

Problem:
When I try to take off in first gear, the truck wants to die. It seems like it is trying to choke out. I have to take the engine up into the 2500 RPM range or higher before I can really get the truck to take off. But, dropping the clutch at 2500+ causes me to spin the tires everytime. I should have plenty of power to take off from damn near idle. Any Ideas???

I have a 350 that has been modified with a high lift cam and holley carb. I am sure it is overjetted just not sure by how much (bought it like this). I think this may be contributing to it but I have not had alot of experience on carbed motors.

The trans is a saginaw 3-speed that has been converted to floor shift. (sucks but works for now)

Why can't I take off reasonbly without it dying?

[turp mcspray]

What gears are in the rear? I could see 3.07s and a tall tire giving you grief. I would check out your distributer. Make sure all is well in ignition land.

[68gmsee]

First thing I would check is the throttle pump to see if it's pumping gas in when you step on the gas pedal. Float adjustment could be off as well as distributor timing or vacuum advance may not be working.

Check to make sure the timing is adjusted correctly and that the vacuum advance is actually moving when you introduce suction on the hose from the carb to the distributor. Doesn't require a lot of suction.

Here's a short Youtube video on how the carb works.

YouTube - how car carburetors work , 4 barrel too.

[bowtiedriver2]

Okay. So after putting on a timing tab since the PO didn't have one on it... I found that the timing is confusing to me.

Has anybody ever seen a vehicle run with 14* advance? I have not, until now that is.

If I move the distributor one gear tooth either way, it will either bogg out as soon as it starts or it will attempt to diesel and backfire (depending on which direction).

So....it runs at 14* advance. (that is a statement, not a question)
but how can it be that far off? could the cam have been installed at the wrong position? If so, why would it still run decent?

I am thinking if the cam is off, wouldn't it be running really rough if at all?

Please help.

[crazy-101]

Have you checked you points? That's the big problem with my '68.
Also the cap and rotor might need replacing.

And if anyone else has more info, could the carb be flooding the motor out?? My friends '85 does it all the time.

[BCOWANWHEELS]

sounds like too big of cam and a 3.08 rear end gear to me....

[mikajo39]

If it's cammed 14* initial advacne isn't too much I run 16* on mine. .Make sure you check your total timing as well at 3000+ RPM. If all is well there it could be your rearend is too steep 3.07s will do that

[ll____b0t____ll]

First ide take it for a drive and keep at a costant speed of around 35 mph and then shut it off and let it coast to a stop.
Pull a couple plugs and check them for color.
My guess would be despite the jet size you think is to large what your dealing with is to small a acceleraer pump nozzle, and a lean condition.
Pay around 12 bucks get .. a size 34as im betting you have a 31 now .
If so its to small .
If you notice that helps but it could use more go ahead but dont go higher in size than 36 max.

[BluTrukker]

If he has enough power to chirp the tirees, he has enough power to overcome a 3.08 and tall tires. You would have to have tractor tires on the back to make it bog out like that. I would guess you have accel pump and jet problems. Timing could be an issue as well, but if it runs good at all other speeds its probably ok. Also do you have a tach or are you guessing that it is revving that high? You said dropping the clutch, does it die if you let the clutch out slowly?

[cdowns]

did you just bolt on a timing tab or did you accurately find TDC and line up the timing tab so it's pointin at what it's supposed to b pointin at??

[bowtiedriver2]

Right now I just bolted on the tab. I have not had the time to take to do a thorough investigation.

It has a later 70's 350 with a HEI setup. Tires are 235/75R15. Cannot read the axle tube to see gear set and haven't jacked it up to rotate the tires to get approximate idea either.

Engine will bogg down and die out if I let the clutch out slowly.

I do not have a tach in the truck but I am using a non-contact lazer tach on the balancer when in the drive. We use these to test electric motor RPMs at work. Right now i have to run around 1050 or higher to maintain an idle without it dying. I am estimating RPM at takeoff.

I would be surprised if it is running lean just from the exhaust fumes being as potent with gasoline odor as it is. I can't rule anything out right now though.

[69GMCLonghorn]

You may need to get the distributor re-arc'd. I had a similar (albeit less severe) problem with my truck. I had the dist re-arc'd and that did it. He also did something I had/have never seen before. He disconnected my vacuum advance and capped it off. AND! My base timing is up at around 25°!!!!! It doesn't ping AT ALL, no dieseling and runs GREAT! I don't know how it works, but it works GREAT!

[Beefcake]

I believe the last cam i installed said it needed a 12deg advance.

Id put a vacuum gauge on that motor and see whats going on.

[Beefcake]

while your at it, check fuel pressure to. You should be getting 6lbs atleast. Just 2 things to check.

[BigMikeBB]

Where in Illinois do you live? I'm in North Eastern Illinois. If your not to far away you should bring it by my shop. I'm sure it's nothing a few adjustments and some cold beers won't fix.

[screamin_c10]

Vaccum leak perhaps? Having to have the idle set that high, the lack of power and the inability to adjust the timing sounds like a broken line or mismatched carb gasket sucking atmosphere. Start with the basics...