426 Hemi Crossram Engine Running Rough & Hesitates

[jobenz]

Morning Boys, just purchased a 64 savoy with a 489 Hemi cross ram, 4235 & 4236 Holley's, 4 speed, Dana 60 that's running a little rough and cannot take off in first without it bucking wildly, runs great when I get it to rpm. does anybody know a hemi mechanic in the Northeast?? I'm in New Haven Connecticut.

 

[Fran Blacker]

Here's a thread on this. So anybody try a wideband O2 on a crossrammed Hemi yet?

 

[sam dupont]

Has it been setting? It happened to one of my carbs in three short months

 

[snakeoil24]

This can be many causes. Check the basics first.

1. Vacuum leak at intake gaskets.
2. Fuel Delivery.
3. Carb staggering at idle.

 

[jobenz]

Has it been setting? It happened to one of my carbs in three short months

Yes it was not driven much in the last 5 years. Belonged to a doctor from Florida. Has 14 inches of manifoid vacuum with a rough idle

 

[snakeoil24]

check valves by doing compression test. Is the vacuum at idle or at off idle

 

[64 Sportfury]

I dealt with a similar issue for a few years. 64 Sport Fury, Hemi w/cross ram, 770 cfm Holleys and a 5 speed TKO. I tried a myriad of things that improved the condition but still had the bucking at low speed (below 1800 rpm). My issue turned out to be the Mopar Electronic Ignition conversion kit I purchased in 2001. The distributor in the kit comes with very light advance springs which caused the mechanical advance weights to "bounce" at idle and low speed in-gear. I purchased a kit from Summit Racing with an assortment of advance springs and swapped in a set that slowed the mechanical advance down and problem solved. I offer this as a possible cause for your issue. My setup is all street. You posted in the Racer's Hangout. If your setup is for the track then my solution may not apply.

 

[Dave6T4]

I'll trade you a real smooth running 440 for it! LOL