Gutless!

[86silver]

The truck's acting up.  Acting like a 180hp truck.  Pulled a pontoon and couldn't go over 55mph with any wind...then it'd have to shift to 4th gear to make any moderate incline causing it to almost over heat.

Not much for power, if I floor it from zero it tries to get up and go but not as quickly/smoothly as I think it should.

Originally the PO told me the carb had a horrible flat spot, he wasn't kidding.  Moderate acceleration killed it every time.  Edelbrock tech support suggested specific metering rods and helper springs which fixed the problem.  I also added a phenolic spacer which eliminated my vapor lock issues.

I get about 8mpg highway.  A full tank will not take me 120 miles.

We pulled plugs and they were wet...really dumping gas.  So it's a bit rich id guess but then under load it's too lean....

GM 350 Crate 290hp motor...2 years old
Edelbrock Performer carb
Edelbrock Performer Aluminum intake
Dana 44 front and Corp 14 rear with 4.10 ratio
Accel distributor

Noone seems to be able to set the timing.  Everyone has to do it by ear as I am told there are two marks on the pulley and they can't figure which one to use.

This most recent guy pulled plug from cylinder one to find TDC and then time...still want to know why we can't use the factory marks?

I'm told that after finding TDC and proper timing, I need to add in a vacuum advance kit to the distributor to allow for more power.  I understand the new set of weights, but there are 3 sets of springs...what should I use and why?

Could my timing chain or cam/crank gears be off from factory?

This truck is so caps able of more but no one not even 2 GM dealerships, can get it there!

[zieg85]

Here's my $.02...  Pull the timing chain cover and see what is going on.  Sure sounds like it is off 1 tooth...  With a 4.10 that ought to fly and give you mpg 12-13.

[rich weyand]

What needles are in it now, do you know?  Most people don't replace the jets, because you have to take the upper off the carb, but do you know if it is the stock jets?

[rich weyand]

I have that same engine and tuned it to the gnat's patoot with an A/F ratio meter.  I've since changed the cam, but here is the setup for that cam, in that engine, with a similar intake manifold.  Note I had headers, so if you don't it could be a little different, but this will be closer than "by guess and by golly":

CARBURETION
secondary metering jets: Edelbrock 1426, 0.095" (stock jet)
primary metering jets: Edelbrock 1425, 0.092"
metering rods: Edelbrock 1440, 0.060" cruise, 0.057" power
step-up springs: 8#

These carb settings will result in 14.5 A/F ratio in cruise, 13.5 A/F ratio in power, and 12.5 A/F ratio on the secondaries.

Also, forget what GM says.  Timing should be 16* BTDC, with 20* centrifugal advance, for 36* total timing.  But you need to know where TDC is!

[Fairlane514]

Its also possible you have a 305 balancer on your 350. The 305 balancer has timing marks at the 12 O'clock position and the 350 balancer at 2 O'clock. The 305 marks wont "show up" at the 2 O'clock position where your timing tab is on the front cover.  You can change out your balancer and then be able to use a timing light. 

You can verify a 305 balancer now with a timing light and shine it at the 12 O'clock position just behind the water pump. Be sure and use white out or a paint pen to mark the balancer line first. If you see the line at that position you have the 305 balancer.

[86silver]

Here's what I've done/noticed. 

On the vacuum advance canister I took an Allen wrench and backed the adjustment screw all the way out.  Then I screwed it back in 4 turns which gives me about 12 degrees.  I do now notice a more effective quicker advance under load.

Should I add in a vacuum advance kit into the distributor and use the lightest spring set, medium or heaviest?

My timing issue...my harmonic balancer has two timing groves on it...which confuses me to start with.  When warmed up and running at idle, those marks are at 11 and 10 o'clock.  The timing tab is at 2 o'clock. WTH!?! So basically we're timing from ear!

Suggestions/explanations?

[bd]

...my harmonic balancer has two timing groves on it...which confuses me to start with.  When warmed up and running at idle, those marks are at 11 and 10 o'clock.  The timing tab is at 2 o'clock. WTH!?! So basically we're timing from ear!

The outer ring has slipped around the hub and someone tried to remark it.  Replace the balancer and seal with the correct service part and continue from there.  Before removing the old balancer, however, check your timing chain for the amount of wear: 1) last paragraph, 2) last bullet, 3) next to last paragraph.

[86silver]

What about this cam???  Would it do as well as the suggested XE250H Comp Cam?

Parts #24502476

Hydraulic flat tappet I: 212 E: 222 I: .435 E: .460 112.5

Used in 350/300 HP and 350/330 HP special performance engines.

http://www.gmperformancemotor.com/parts/24502476.html

[rich weyand]

That engine does much better than that.  You do need to get it up in its rpm range where the high overlap makes it breathe.  It's a two-lane terror, and if you punch it at 45 to pass, properly set up you'll be pushing 90 before you clear the guy's front fender.

But unless you get your carb and timing issues sorted, you can put any cam you want in there and it'll still suck.  You need to get the proper timing wheel on there, tune the carb, and check the timing chain lash, though I would be surprised if it ate the timing set in two years.

Like I said, I have that exact engine (now re-cammed for more bottom).  My timing tab is at about the 1 o'clock position, and I use this balancer cover for timing marks:
http://www.jegs.com/webapp/wcs/stores/servlet/KeywordSearchCmd?storeId=10001&catalogId=10002&langId=-1&Ntk=all&Jnar=0&Ne=1%2B2%2B3%2B13%2B1147708&searchTerm=778-66518BKC

That said, the four cams I think are best choices for that engine, which has the stock heads, in a truck are, in order from most bottom end to most top end are Comp Cams 12-300-4, 12-231-2, 12-235-2, and 12-238-2.  Now these all have a lot of bottom end -- like I said, in a truck -- but that's the order from most bottom/least top to less (but still good) bottom/more top.  Probably the best all around cam for that engine with stock heads is the 12-235-2.

But I think you should deal with the other problems first.

And if you do change the cam, you need new lifters (they bed into the cam really quickly, and will eat a new cam if you re-use them) and new springs (those are old enough to be replaced when putting in a new cam).  Do not skimp and re-use either lifters or springs.  You WILL regret it.

[86silver]

I think I've made some headway.

1.  Timing set at 10 degrees.
2.  Vacuum advance set to 10-12 degrees...it was turned all the way in.
3.  Silver and blue springs put in distributor to replace stock springs.
4.  Pass side vacuum port was being used on carb, but I should have been using drivers side lower port as I have no smog control systems on the truck.  That port was full of silicone from PO so had to clean out.
5.  Also on the carb I was pinned in on the top notch of the fuel regulator adjustment arm (no clue as to it's real name) which was allowing for a rich condition and dumping in wasted gas.  I moved down a notch to midway and think I gained some power when under load (maybe under load it was running rich and drowning itself in gas?).

My tires now roll off of a dead start and I can feel the vacuum advance kinking in down low and up in the higher range.  Better throttle response.  Let's see if it stays this way....or will it create issues for me down the road?  Guess we'll see!

[rich weyand]

Still way retarded on timing.  That engine wants 16* BTDC initial timing, with 20* of centrifugal advance.  You will really notice the difference!

Sorry, I should have thought of the vacuum advance being on the wrong port.  Very common.