problem with my 77 chevy truck, with 350 crate engine?

Question

The truck runs good, pops periodically when idling. the main problem is when I give it gas it will run strong till about 3rd gear and then it seams to hit a wall of power, it will stop accelerating, it wont stall or die, just stops accelerating. I have recently replaced the fuel pump. I am thinking maybe timing to far advanced? The crate engine does not have timing marks to check, any ideas? Thanks.

Answer 1

Any engine has timing marks to check on the harmonic balancer. You can double check the TDC mark by pulling the #1 plug and sticking a soda straw down into the cylinder...when it stops moving as you SLOWLY crank (with a breaker bar and socket on the harmonic balancer center bolt), that's TDC.

It sounds like your vacuum advance is not working, as in you don't have enough advance. That is, you don't want to change your idle advance setting (it should be at most 5 degrees BTDC), you want to make sure the advance changes with rpm/throttle. Often, a vacuum advance fails due to a missing vacuum tube or a vacuum leak somewhere.

Another thing to consider is that your main jet size may be too small or your float setting is too low, which will cause you to run too lean, especially at higher RPM. You should also verify the fuel pressure is at least 4 psi at 3000 rpm (you can buy a fuel pressure gauge at any NAPA or Sears).

If al those check out your next concern might be making sure your plugs are all gapped right, your distributor rotor not arcing, or that you don't have any vacuum leaks due to bad gaskets/improper tightnening of manifold bolts/vacuum hoses missing or broken. The next thing mught be the eGR valve (unlikely), or...that the cam wasn't degreed in right or that the valve lash is set incorrectly (both unlikely though). If you have hydraulic lifters valve lash shouldn't be a problem though...

Good luck!

Answer 2

350 sbc engines run best around 10-12 degrees BTDC. The timing mark showing TDC is a single groove in the crank pulley. There should be a little piece of metal with teeth on it above the pulley. the center tooth is TDC when the #1 cylinder is used with a timing light. MAKE SURE you disconnect the vacuum line from the distributor and set the idle between 600-800 RPM prior to trying to set the timing. Also,make sure your coil is putting out a good snap and blue spark at least 1/4 inch long. However, I think your problem could be a clogged fuel line/filter or your float level in your carb is too low, or the secondary jets are too small. Also, how many miles do you have on the engine? It would be worth the money for you to buy a repair manual such as a "Chilton's" for your vehicle. l don't think there's a better engine out there than a 350 Chevy Small Block. I have one in my 78 ElCamino that's bitchin.

Answer 3

If you want to get it right, and not just trial and error it, make your own TDC mark on the crank pulley and figure where the timing mark goes from there. You can borrow a dial gauge that screws into the spark plug hole to get the TDC mark perfect. Also, make sure the vacuum and centrifugal advances are working. A bum carb or 1 notch off cam can do that too. The mid range jets on the carb might be working, but the main jets are messed up somehow.

Answer 4

I find it hard to believe it has no timing marks on the harmonic ballancer.

Have you replaced the fuel filter?

Answer 5

Dude its now 2007, its time to get a new truck.