4.11s but no power

[Alvin]

Just wanted to say I understand your frustration. My first truck had the same problem and it just didn't have any get up and go.

I was young and was just happy to have a truck so I didn't bother fixing it. But I do remember one day, pulling out of the bank parking lot. I put my right foot down, just to make some noise, and next thing I know it takes off! Pushed my head back; I was holding on for dear life! That's my fondest memory of that truck. It never ran that strong again.

Wishing you luck on getting to the root of the problem!

[Mertz]

mtdave: I read your thread in hopes that I would find something to solve my problem. You and I have gone through the same tests except my cam is stock and I have never been in the engine except to install 1.5 roller tip rockers and new pushrods with the correct geomerty. I adjusted to zero lash and then, if I remember right 3/4 turn but it could have been 1/2. I had one cylinder start to tick after about a year and it got readjusted. The engine is very clean inside and the plugs look fine. I tuned in my qjet with an LC-1 and had it about as good as it can get. I also had Cliff Ruggles build me a carb and it still has the same problem. It was set up on his test motor with about the same specs as mine. I have not adjusted this one with the LC-1 yet but will this spring. I am going to replace the fuel filter and will try a hamburger tapered carb spacer. I also have to check for full throttle but I know my secondaries are opening, what a great sound! I wonder if a dyno test will help. I really would rather pull with this truck than have to go out an buy a diesel F250.

HELP!!!!!!!!!!!!!!!!!!!!!!!

[swamp rat]

Subscribed.

[Mertz]

I posted this elsewhere but wanted to finish this thread. Turns out my problem was a plugged fuel filter. I took it off and some fine grained rust came out so I decided to cut it open to see what I had. The bottom side was completely packed with fine rust particles. The fuel was able to get through the upper part of the filter. I put on a new clear filter and the truck seems to run somewhat better but I won't know until I can get it out of the garage when the snow melts. All this and it turns out to be a $3 part.

[ERASER5]

While you are looking at the filter, did you find any rubber hoses? They have been known to collaps under the vacuum of open throttle. Even little short ones on either side of an and on filter. I try to shove the tube end as close to each other as possible.

[splehigh]

If the fuel filter does not solve the problem, check all your vacuum lines and intake for leaks. That usually causes the engine to bog down and have no power. Forgive me if someone already suggested this.

[Mertz]

I checked the lines from the pump back and the hard lines all look good and the one small rubber hose connecting the hard lines on the frame rail is good. The other hoses from the pump to the carb are fairly new and are in good condition. I will replace with hard lines when I get a chance to make sure.

[splehigh]

Are you talking about the fuel lines? I'm talking about the little vacuum lines that are attached to your carb and go to your vacuum advance on your distributor and air cleaner etc... Also if you have power brakes there is a bigger line going to your booster. A good way to check for vac leaks is to spray starting fluid on all the lines and around your intake. If the engine revs up, you've found your leak. Just be careful spraying on a hot engine because its a good way to start a fire. Have an extinguisher handy just in case.

[Mertz]

Yes all those lines have been checked as well. There are no vacuum leaks in any of the hoses or at the base of the carb or the brake booster. The hose to the PCV valve is a little weak but if that collapses it does not cause a leak.

[1970 CST STEP]

Originally Posted by splehigh

if the fuel filter does not solve the problem, check all your vacuum lines and intake for leaks. That usually causes the engine to bog down and have no power. Forgive me if someone already suggested this.

+1

[bigolddog]

Just a shot in the dark , but you might want to check intake gaskets.

[Mertz]

Brand new intake gasket. I replaced it because the first one was slightly big although it was the one listed. I went with one with smaller openings and it sealed very well.

We are in the middle of a blizzard and so I won't be doing a test drive soon. I have the engine running very strong with some retiming. I can't wait to test it.

['70_402]

does the carb bog under a full throttle stomp from a dead stop?

[Mertz]

No it does not bog it is just slow to get going. I set the timing at 18 initial and it seemed to really pick up but I thought that 18, 41 and 58 were to high so today I reset the timing but put it on manifold vacuum instead of ported. I set initial to 15 so at idle I am at 38 and all in is 54. It does not have the power it did at 18 on ported vacuum.

Next step might be to go to less mechanical so I can have initial at 18. That would set initial at 18 with mechanical at 36 and all in at 52 which should be about right.

[CaptMadDog]

ok to clarify you said the tag says non posi does only one wheel turn when checking you ratio? and when was your transmission installed and was a stock mount used? i had the same problem on mine but mine is a posi with 3.08 gears. i later found that my trans mount had worked itself loose and when i put a load on it it would shift and bind that combined with the posi 3.08 it wouldnt spin em at all. hope this is some whaat helpful.

[Mertz]

Cross over is fine and in place. The rebuild was done by a very professional builder that does nothing but 350s and 400s.

What I have found appears to be timing related. I am working to get the initial to 18 and changing the mechanical stop to 18. I will be running manifold vacuum which adds about 16. The total will be 52 which is in the ballpark and the initial and mechanical will be at 36 which appears to be ideal from all I've read. I will be using manifold vacuum for economy. The idle timing will be at 34 as well as cruise. This seems to be the perfect settings all around. I will have to see if I have any detonation using this setting or if I have a hard start problem but I don't think that will be the case.