351C acceleration problems

[trigg]

Sorry to post this here, but atleast its a ford. For some reason the mustang forum I generally use seems to have died.
But I digress, Im in need of some carburetor help. Atleast I believe it to be the carb.

I am by no means a master of anything so if it seem obvious to you. Please ask anyway cause I might have overlooked it or heck didn't even know about it.

So I got tired of looking at it and wanted to start driving it. I put the holley red fuel pump on that I had from another project so its not new and to be honest it was really loud for a few weeks and for some reason it got really quite one day.

The carb is a Barry Grant and is well used and ill be honest I cant find a dang thing about it. Been driving it off and on for about 2 months now.

So here's the problem its bogging down while driving and really bad on a hard acceleration and I can feel and hear a sputter with light acceleration.

What I have done. At Temp I have adjusted both mixture screws equally to get max vacuum which is between 14-15 with a target rpm of 750-800. I never got a truly steady vacuum reading and the rpms fluctuate with a mixture of 50 up and down.

The Carb adjustment screws are 2 1/8 out evenly total. I started this process with the screws 1 full turn out from bottom.

The firing order is correct, plugs are good, and wires look great.

The tank is new and new fuel filters. The holley red fuel pump is used and loud but it suddenly got quite. But the noise didn't seem to make a difference in pump function.

To the best of my searching I haven't located a Vacuum leak yet. But I'm always on the hunt.

Motor doesn't knock and no noticeable valve clatter.

Im not much of a carb guy but i'd like to get this one working properly for a few more months until i throw EFI on it.

Thanks for the input and advice.



67 Coupe no ps/pb/ac


MOTOR

351c Stock bottom end

Stock Heads 2v

Cam is a stock/mild - not even sure of the brand on the cam

Weiand X-Celerator Intake

BG Demon what I believe to be a Road Demon JR 625 with manual choke and mechanical secondaries.

Mallory Promaster Coil

Mallory Unilite Distributor

Holley Red Fuel pump at 5psi


Trans

C4 built by Dynamic

2500 Stall


Rear

8.8 with 3.55 posi

[tnlprt]

Whats the timing set at

[colnago]

Does the distributor have a vacuum can? If so, do you know how it's set up? I'm wondering if the fluctuating vacuum is causing the timing to fluctuate, which causes the RPM to fluctuate, which causes the vacuum to fluctuate, which ...Well, hopefully, you get the point.

Just asking,

Joseph

[Ren]

Methinks it's yer fuel pump.

[trigg]

Sorry fro taking so long to get back, I've been swamped.

Timing is at 14 and all at 32 at 3000rpm

I did find a bad plug wire which was giving a misfire on No3. I changed all the wires and rechecked gap at .40 there Autolite AR34 if that makes a difference.

The distributor isn't a vacuum style.

Im starting to think its a power valve or jets something with the carb. I did rebuild it a few days ago, didnt seem to help.
I drove it today and it drove great for about a hour. Got home loaded up the family to go to a car show and it started doing it again as soon as I started it. Drove it to the car show and back to the house and it was doing it the whole way.

As I sit here thinking about it. It ran fine with the air filter off. "I've got one of those force air scoop contraptions". The filter doesn't even have 500 miles on it so I know its not bad. mmmmm....

Now since i posted last. the Fuel pump has been getting quite and will get loud sometimes. I might grab a mechanical and just see.

[fastEdsel]

First of all don't apologize for coming to this forum for advice, there are some very knowledgeable gear heads here that can point you towards a resolution for your concerns. I don't know of the Barry Grant carb that you are using and actually have never seen one. But in my opinion you have an internal vacuum leak in your carb. I wrote to this forum quite a while ago about stalling at acceleration from a stop or even acceleration for passing a car. It was in my Holley 600 on my police interceptor 361FE in my '59 Edsel Corsair. The car itself has been given a bad rap by the fake news so backfiring through the air cleaner at a green light or losing power initially during a passing process is quite alarming. I fought this FOR YEARS!! Finally my parts man son directed me to a Holley site that sells blue gasket carb kits. I know Holleys, have worked on them for most of 50 years but this problem in my car had me completely baffled until I installed the new improved kit. The difference was like night and day. That old car came back to life so fast I actually went out to try to find old Camaro's to pass! Now I don't know where you could find a kit for your Barry Grant but I'm fairly certain that is your problem Try these folks, they may point you in the right direction, or bolt on a 600 Holley and dial it in. You can try these folks directly at Holley in Bowling Green Kentucky 270-781-9741 Good luck, keep us informed.

[colnago]

Another idea is the fuel filter. While idling, everything is fine. But accelerate, and it sucks up all of the yuck in the filter can, and instantly clogs the paper element. 'Sides, fuel filters are cheap, and often overlooked.

Joseph

[trigg]

I did rebuild the carb with a Holley Demon kit. It did have some blue rubber gaskets.

I changed out the fuel pump. I went back to mechanical and replaced some bad rubber lines with new filters.

While its running way better its still got a slight stumble on acceleration. I'm starting lean towards just getting a new carb or just waiting until I can afford to throw the Holley Sniper on it.

But I think the Fuel Pump was 70% of the problem, Im going to take the carb apart and put 67 jets in and see if that changes it any. Thanks for the input and leads.