I went for a ride in my buddies 53 the other day. We took his truck on the freeway and I noticed that as long as he's driving, the engine runs smoothly. If he hits a grade and lets off the gas, then reapplies the gas, his engine has a flat spot or hesitates then runs good again. On surface streets it runs fine, no problems. It seems like it does it around 2500 RPM or so. He's running an Edelbrock Carb with manifold. Ignition is a pertronix. It's a 351W engine. I told him I think it was the jetting or fuel mixture? He thinks it's running rich already? Hint- he recently put headers on the engine also.. I think he's running Flowmasters for mufflers. Suggestions?

 

Sounds like a muffler belt to me. Actually it sounds like he might have a float sticking in the carb. John

 

[QUOTE=imlowr2]I went for a ride in my buddies 53 the other day. "On surface streets it runs fine, no problems."........Now this sounds like a 'very' trick question. Fess up, what was it!!!

 

Ed -

I run the same setup on my 351C and had the same problem. I bought an Edelbrock Calibration Kit. It comes with a selection of needles and step-up springs as well as pretty good instructions.

I found that my flat spot was caused by the step-up spring not being sized for the vacuum my engine was creating. The flat spot was created by an imbalance between air and fuel mix and a certain throttle position and engine load. Changing to a stronger/lighter step-up spring fixed that.

Once I put in the right step-up spring, the flat spot disappeared and it ran great. The needle selection and charts allowed me to size the needles for the best mileage. It is a trial-and-error process.

I found my calibration Kit at a local speed shop, but I'm sure you can get them thru the Edelbrock website. I think they run around $40.

 

fordman- I don't know whats wrong, that's why I'm asking you guys. LOL.... My hunch is that Randy Jack hit it on the nail. We are going to order the calibration kit and mess with that first. I'll let you guys know.

BTW- Randy, I thought you might be at the Western Nationals. Missed you. B/B was there and took a trophy for top 15. It was hot, but a good day.

 

Hey RandyJack

Could this be the same reason why when i am in reverse and mash the gas....she chokes out....that has been happening since i got the edelbrock carb and performance rpm intake....a little hesitation on takeoff but will blow those ricers out of the way quick...even when they hit NOS!!!!!!

Also could this be the reason why i am burning so much gas!!!!! might have to check out that calibration kit today!!!!

 

55 - Yep, it probably is. The needles and charts make it pretty easy to dial the carb in to your kind of driving.

Inquiring minds want to know, however, why you mash the gas in reverse???

 

I remember we use to hit the gas in reverse to do burnouts, because it wouldn't do it drive. LOL..... BTW- I checked my friends carb and the pump rod was set on the last hole furthest from the carb. I put it on the middle hole, but haven't tried a test drive yet. Will still get the calibration kit. A little info. Don't get the calibration kits from ebay. They are more than auto parts sells them for.

 

It is going lean off idle due to power valve (on Edelbrock Carb it is the metering rod piston) opening at too low of a vacuum setting. If you had a vacuum gauge on the engine, you could see what the reading is when it bogs and that is the point (or a little before) where the metering rods should be actuating. I would guess your cruising vacuum is about 14" at Sea level and your metering rods should actuate at about 10.5 inches of vacuum. If you were at a much higher altitude, the metering rods would probably be set ok. (This is because you can't develop as much vacuum at higher altitudes because the atmospheric pressure is lower.

Also, he could be running too rich at cruise but it will still bog if the power valve/metering rod system does not richen the mixture enough under power..........

It can not be an ignition problem because once you get it pulling it runs fine at Wide Open Throttle. This shows high enough ignition voltage.

Regards,

Alanco

 

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Sorry, I thought this was a test. The first thing I'd do is read the plugs, maybe the new set of headers made it go lean. If the plugs are tan (OK) then I'd advance the timing. If that didn't fix it, I'd use that metering rod money for a down payment on a new Holley.

 

Vacuum, yeah... definately vacuum.

Muffler belt. Pffft! It's ALL ballbearings now boys! There havent been muffler belts on a Ford since '32.
Black58? You put a dollar in the jar 'lil mister!

 

i dont know about you guys but it sounds like a radiator problem to me heh

on another note does the exhaust gas smell real strong like gas or like a sulfur smell