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Author Topic:   Engine problems (help Please!)
Burque
Member
posted July 26, 2004 12:42 PM
I am having a problem when my engine is under load. It is not getting up to power its sputtering and backfiring. I cannot get the rpm up as it starts to do the above it is also spitting fuel out of the carb as it back fires. I have a rebuilt 350 engine with flat tops, 480-lift cam, 462 heads with z28 springs and full roller rockers. Iím running a torker 2 intake with Holley 4 barrel.

I have tried two different carbs a vacuum secondary Holley and a double pumper. Itís doing the same with both. The only thing that I have changed that the builder did not do is the roller rockers, and put a curve kits in the distributor.

Also when the car is not under load in park it revs quick and has good throttle response. Its just when its under load when it bogs and sputters. Any help would be great thanks!


Burque
Member
posted July 26, 2004 12:47 PM
Forgot to add the roller rockers are 1.6, if that makes any difference.


BrianW
Member
posted July 26, 2004 03:46 PM
Well - just a thought - with the .480 lift cam on 1.5's that will make .512 on the 1.6's - could be coil bind or valve float

Also - with the advance kit what is the advance at idle and at 2500 or so? If the advance is sticking it can cause problems & low power.

ss99
Member
posted July 26, 2004 07:54 PM
A couple of ideas since you mentioned the fuel coming out of the vent tube: First, make sure you don't have too much fuel pressure. Too much can overload the needle & seat and overfill the fuel bowl. The second thing is make sure that your float level is not set too high.

ss99

racer17j
Member
posted July 26, 2004 08:13 PM
i'd have to agree with 99 sounds like fuelpressureif you changed carb and still the same thing what was not changed was the pump.yor cam should be alright i ran that samr setup wiht stock springs for a year and never had a problem other then it wouldn't turn over 5800


Flanndad
Member
posted July 27, 2004 06:07 AM
I had the same problem with spitting fuel out, mine looked like a drinking fountain.
It came out the vent tube.

This is how I fixed mine.
Take the carb apart, on the float arm, the place that rest against the needle had to be bent up a very small amount,
What happen was, when the float reach the top it wasn't putting enough pressure on the needle to stop the gas from entering the carb.

Mine was very easy to fix, just took forever to figure out.

Burque
Member
posted July 27, 2004 11:58 AM
Well I haven't thought about fuel pressure, itís a new stock pump. Would it make that much pressure? It only spits gas when under load and back fires it comes up about a foot and turns to fire sometimes. I thought maybe I might have the rockers to tight, but I don't have much experience with them.

If itís the carb or fuel pump wouldnít it do sitting still or would it only be when under load? Because it response good when in park, only messes up when under load.

I might take out the curve kit also we will see. Step by step! Thanks guys! Any other thoughts?


Burque
Member
posted July 28, 2004 11:31 AM
Well Last night I changed the Distribitor to an un altered one. It still did the same thing I also unloosend my my rockers a bit still the same.

I am very stumped don't know what to do next I will change the fuel pump tonight. Any other ideas guys?



Ego Racing
Member
posted July 28, 2004 11:41 AM
Check the carb!! The added air being pulled into the carb could be pulling the fuel out. The backfire might be from fuel sitting on the valve and when it opens it hits the chamber and you get the backfire. It could also be a slightly bent valve and it only causes problems when the pressuer goes up. DO a leak down test.


Burque
Member
posted July 28, 2004 11:57 AM
A leak down test, Humm? How long should pressure stay in the gauge before leaking? Or would it not leak at all? I will try that tonight!


eaton89
Member
posted July 28, 2004 11:21 PM
Go back and check rocker adjustment. Then check to make sure that the firing order is right. If you have a couple valves out of adjustment it can make it a dog. Also it only takes the right combo of 2 wrong spark plug wires to cause it to do similiar problems to what you describe


Drogo99
Member
posted July 29, 2004 06:51 AM
Well thanks guys I was wondering if maybe I got the wires off. What I noticed is that on my cap the number one plug wire is on the second prong from the power lines on the side. It starts on the first one on my 74 caprice but itís a 406. But its still a small block right or does it not matters where it starts at? I've seen it on the second prong on another 350 a friend has thatís why mine is on the second one. Well I will try to set all the wires back one space tonight and see if it works.


waltonjr1
Member
posted July 29, 2004 12:55 PM
It dont matter where #1 starts as long as its in the right order. Its best to start it on the first or second terminal or your distributor will have to be sideways to get your timing right. Hope this helps.



dirtbuster
Member
posted July 29, 2004 01:18 PM
Walton is right it doesnt matter which prong you start on as long as you go in order 1 8 4 3 6 5 7 2 from there and line the rotor up with the chosen prong for #1 @ TDC when you drop in your distributor.

I would not just start moving all the plug wires around. An easy way to check to see if you have them started correctly would be to get the motor on TDC of #1 clinder. Mark the base of the distributor directly below but inline with the prong with the #1 wire. Pull the dist cap off and see if the rotor is lined up close to your mark. If so then check to make sure your wires follow the right order around the cap and you are good.

Burque
Member
posted July 29, 2004 01:47 PM
Thanks for that info I will make sure its there right. Hope I get sum where sonn as I will race my first race in a week.


Burque
Member
posted August 03, 2004 12:19 PM
Thanks for the info guys I think I got it the distributor was pointing to the #3 wire at TDC. I got it back where it needs to be and reset my rockers. I will know for sure tonight if my other problem doesnít hinder me. Thanks again!!!



BrianW
Member
posted August 03, 2004 02:01 PM
Sounds like you need to get a timing light and doublecheck the timing of the engine before you burn something else up...


Tim Weiss
Member
posted August 03, 2004 02:27 PM
This could be your starter problems too if it is kicking back when you try to start it.


51racing
Member
posted August 03, 2004 03:05 PM
quote:
Originally posted by Tim Weiss:
This could be your starter problems too if it is kicking back when you try to start it.


Yep, I agree. I broke two new ones (Napa brand, lucky for the no-questions 3 year warranty!!) this year after I installed an weight and spring set. It turns out they were too tight on the studs, and not closing after shutting down so I was at full advance when cranking it over, it would kick back and break the nose off of them.


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