I am experienceing some trouble with my newly rebuilt 351C 4V engine.
For some strange reason i get backfires thru the carb once the engine reaches normal operating temp. and the engine starts to feel very weak when i drive the car...when this occurs i just shut it off.
First i thought that it was an ignintion related problem but after doing all the tweeks in the book with no results we started looking at the valve adjustment.
The valve adjustment was done after Cranecams specs. with the new lifters installed zero lash and then 1/2 to 3/4 turn on the rockernut. Anyway now to the strange part. A bickfire thru the carb would suggest that one or more of the intake valves doesnt close properly right ?
But when i remove the valve covers after i have warmed the engine up to operating temperature the rockerarms are so loose that i can lift them out of position and even remove the lashcaps on the valvestems...realy strange.
And since the rockers are this loose i cant understand how the valves could fail to close since the rockers barely is able to open them with this loose adjustment.
Now we have tried to set the valve lash both the slow way by turning the crank and adjusting the and also the messy way with valvecovers removed with no luck.
On thing that i also is confused by is that the "springy" feeling that the lifters had when i installd them seems to be gone and the lifters feel "solid" even though the valve is in non-lift and the rocker is very loose.
I know that the backfire is somehow related the the valves but not how..so if someone could shed some light on this i'd be more than happy....summer is slipping away.
My engine combination looks like this:
351C Block
4V Open chamber with 2V valves "mildy ported"
Compcams 305H cam 0.585 lift int & exh
Compcams matching springs % anti pumpup hydraulic lifters.
351C stock Crank
351C stock connecting rods
Speedpro Flattop Pistons
Hastings cast iron rings
Crancams guideplate pushrod kit.
Harland Sharp roller rockers
Ferrera Stainless valves
Edelbrock Torker II intake
Barry�grant SpeedDemon Carb
MSD Billet distributor
MSD Blaster 2 Coil
MSD 6AL ignition control
/Jonas W
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