[Twisted Tempest]

I have a '65 Tempest with a 400, 4 speed. When I shift the gears hard, 1st and 2nd pull strong but when I shift to 3rd there is a surging in the motor. When shifting normal no issues at all. The fuel filter, mechanical fuel pump and stock lines are new, however I might go with a electric fuel pump to eliminate one possibility. Was thinking maybe dirt in the fuel tank, any other ideas. Thanks

[shaker455]

What carb, Dist & cam you running?

How's it jetted and how is your dist curved?

Are you runing vacuum advance to a ported of full source?

How's your plugs looking?

[track73]

Sounds to me like you are running the Q-Jet out of gas in the float bowl. I have the same problem with a mech fuel pump, so I switched to my Holley 850. Problem solved with the 455 cid motor.

[Kenth]

An electric fuel pump, like the Carter P4594, mounted close to the tank will cure the symptom.
Bypass or remove the mech pump.

[Twisted Tempest]

Shaker455, Running a Edlebrock 750, just had distributor rebuilt it has a crane electronic conversion kit,no points. Plugs are good, and running a ram air 4 cam only has 500 miles on the motor. No vaccum.

[David Jones]

Float bowl is running dry.

[Twisted Tempest]

Was looking at that Carter P4594 ..think I might try that.

[shaker455]

Originally Posted by Twisted Tempest

Shaker455, Running a Edlebrock 750, just had distributor rebuilt it has a crane electronic conversion kit,no points. Plugs are good, and running a ram air 4 cam only has 500 miles on the motor. No vaccum.

Okay what dist and how's it timmed and curved?

What rpm does your total come in at?

[geeteeohguy]

Agreed, not enough fuel. But the stock pump should be fine. Mine are. I'd hunt down the gremlin and get rid of it. Check all rubber fuel lines...they can crack and suck air, but not leak fuel. An electric pump will "fix" it, but it is a band-aid solution, IMO. We're talking street here, I hope!

[David Jones]

Condition of the sock in the tank?

[screamingchief]

The "surging" symptom suggest the Ecarbs fuel curve is too lean,or it has fuel supply problems as has been mentioned already.

That's kinda why many of us here dont care for those Ecarbs...

As a side note,the 041/RAIV cam in a 400 is going to require the proper companion hardware to work well,if this does'nt have a fully adjustable valvetrain & good valve springs,as well as a higher CR,with a decent stall (if A/T) and the proper rear gears out back,well it's just not gonna run very well with that much cam in the 400 cid engine.

Anyhow,it would really help us to have a full rundown on the combo to give more detailed advice where to look to fix this problem.

Things like precisely what mechanical fuel pump and exactly which fuel filter you have are important details,as well as things like what CR this engine has (which heads???) not to mention what trans & rear gearing the car has,all that would be helpful to know.

Bret P.

[Twisted Tempest]

Originally Posted by shaker455

Okay what dist and how's it timmed and curved?

What rpm does your total come in at?

Stock distributor, have to check on timing and curve, had Stray Cat over yesterday helping to set up and we got a total timing at 2000rpm

[Twisted Tempest]

Originally Posted by geeteeohguy

Agreed, not enough fuel. But the stock pump should be fine. Mine are. I'd hunt down the gremlin and get rid of it. Check all rubber fuel lines...they can crack and suck air, but not leak fuel. An electric pump will "fix" it, but it is a band-aid solution, IMO. We're talking street here, I hope!

Thanks never thought of checking the rubber line from the tank to the steel line.

[Twisted Tempest]

Originally Posted by screamingchief

The "surging" symptom suggest the Ecarbs fuel curve is too lean,or it has fuel supply problems as has been mentioned already.

That's kinda why many of us here dont care for those Ecarbs...

As a side note,the 041/RAIV cam in a 400 is going to require the proper companion hardware to work well,if this does'nt have a fully adjustable valvetrain & good valve springs,as well as a higher CR,with a decent stall (if A/T) and the proper rear gears out back,well it's just not gonna run very well with that much cam in the 400 cid engine.

Anyhow,it would really help us to have a full rundown on the combo to give more detailed advice where to look to fix this problem.

Things like precisely what mechanical fuel pump and exactly which fuel filter you have are important details,as well as things like what CR this engine has (which heads???) not to mention what trans & rear gearing the car has,all that would be helpful to know.

Bret P.

I am learning the hard way that the Ecarb was not the way to go. I have a Edlebrock fuel pump, and inline glass type filter above the manifold, got the 6x-8 heads with the motor which I know are big chamber heads for the ram air IV cam. I'm running a ST-10 4 speed, 342 ratio first gear with a 342 rear.

[blueghoast]

Yep running out of fuel.

[Twisted Tempest]

Checked rubber fuel line from tank to steel line, very weak looks like original hose. Gonna change that tomorrow maybe hose is collapsing or as geeteeohguy said a small hole in hose.

[straycat]

let me jump in here guys. I'm helping to get Twisted Tempests car ready to run at the track. 65 Tempest,78 400 super low compression motor, RA 4 cam,1.5 rockers, performer rpm intake, edelbrock 1407/750cfm carb, headers,3.42 1st super t-10 4 speed, 3:42 rear. This is how the car came to him and it drives real nice on the street. But when you take it thru the gears at the top of third it bucks just like starving for gas so I also mentioned the need for an electric pump. The stock distributor is set up for mechanical advance with 34* in at 2,000rpm. The carb does seem to run rich (black plugs) so we are going to try to lean it some. Thought it had low vacuum and was keeping the metering rods up and running rich but the motor has 13" vacuum at idle, but we changed springs anyway and ran it some with cleaned plugs and they looked better. Next is a primary jet change and different rods. But of course this won't matter if we can't solve the stumbe problem at the top of third gear. Twisted Tempest appreciates all your suggestions as he is a newby at this.

[screamingchief]

Stock distributor?

You mean a points distributor???

If so,then ya'll probably need to try some better points in there.

Get the HD point set with the 32oz. springs and see if that improves.

That topic has been discussed here a bunch in the past,Accel,Mallory,and Standard blue streak are the prefered brands for the HD point sets.

And I'd advise avoiding the UNI point sets too.

Also,I'd probably slow down the advance a bit too (get it in closer to 3000) with some slightly heavier springs,but that aint causing ya'lls problem.

HTH

Bret P.

[track73]

IMO, If it runs great at launch and through 1st and 2nd it "ain't" ignition.

[screamingchief]

Originally Posted by track73

IMO, If it runs great at launch and through 1st and 2nd it "ain't" ignition.

I tend to agree,but the catch is I also never say never.

The actual engine load can often be greater in the higher gears as there is less gear multiplication to help keep the car moving along nicely,and many times that sorta additional engine load will magnify any ignition related shortcomings.

Also it tends to spend more time @ a given RPM in the higher gears than it would in the lower gears,so often you'll move thru the RPM range quick enough in the lower gears that the problem is'nt nearly as noticable as it is when it's pulling harder.

Also,some igntion related problems will compound/magnify other issues like fuel curve related issues.

An engine is a complex machine that requires everything to work together for best results.

Plus we only have his description of the symptoms,so who knows for sure what's really going on with this,sometimes alot of valuable info gets lost while trying to describe these sorta things via brief written descriptions like this.

FWIW

Bret p.