252br 7.4l surging/ tug over 3k rpm
 

Ok so i had what i thought was a misfire, found cylinder 5 low on compression, redid the topend, valvejob, headgaskets ect…. I put a new edlebroke(lol) 750 1410 carb on it. It still tuggs and surges and sometimes wants to die. Im at a loss with tuning. I have changed springs, took the metering rods out…lol still does it. Anyone had this. Ive also replaced coil, and verified timing 12dbtdc. Start normal idles run normal, I will do it above 3000 RPM. And sometimes it acts like it’s lean. Im at a loss. Any help would be appreciated.

Carb should be 8* BTDC
Does the motor have a flat tappet or roller cam?

Fuel psi stay at 5psi or more ?
Which distributor set up ?
How many hrs on everything ?

flat tappet. I can bump the timing down and try that.

Oem, hei distributer, top end has maybe 5 hours, i had the heads machined, valvejob, all new topend. Im goin to have to get a gauge and check fuel pressure… whats the best way with the hardline set up to the carb?

so…thunderbolt iv or v ?

I have flared to nipple fittings and use rubber line for the test. So, undo steel line and install that. 3/8” inverted flare (mine are swivel) by 3/8” id hose bard fits many fittings on mech fuel pumps and fittings on inlet of carb. Obviously get a 3/8” hose fuel psi gauge adapter and 1/8” npt psi gauge.
That’s how my set up is, surely other ways.


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Were the rockers adjusted to zero lash and then 1 additional turn?

zero lash - push rod is being moved up-and-down until no up or down movement is felt with fingers. The push rod can still be rotated but there is no up/down