backfiring through stromberg 97

D

Dave in Denver

Member
I replaced the engine my 30 Tudor due to the previous engine snapping its crank. This rebuilt engine is an inserted non pressurized engine with snyder head on top. The distributor is a petronix 12 volt and the carb is a new stromber 97 fed from a low pressure regulated fuel pump.

The engine was timed at top dead center and the started. once started the engine will idle, but when the accelerator is pressed it back fires out the top of the carb. If the accelerator is pressed further the backfiring gets worse.

I did a compression check and all cylinders read exactly 60#.

Might any of you have any ideas where I should look next.

Thanks,

Dave
 
Sorry but in my opinion the 97 is a little over kill on a model "A". I think your flooding out the engine. ken ct.
 
Factory 97 jets were 0.045 with a #65 power valve. Available jets go down to 0.033. You need a special jet wrench to remove them. You can check the size in place if you are careful with wire size drills. Vern Tardel has a book about Stroms. LINK
 
Spitting back is caused by either too lean or too retarded spark. Check the operation of the accelerator pump. One 97 is definetly not too big for the A, I am running 3 of the 81's on my speedster with great success. Jets are stock.
 
Jim Brierley said:
Spitting back is caused by either too lean or too retarded spark. Check the operation of the accelerator pump. One 97 is definetly not too big for the A, I am running 3 of the 81's on my speedster with great success. Jets are stock.
Click to expand...

FWIW, so others reading this thread know, stock 81 jets were 0.035 with a #71 power valve. That's smaller than the 97 jets. The 40 & 48's had 0.048 & #63 PV. Stroms also do not like too much fuel pressure. 3psi is the absolute limit, even with the newer ball valves. Not enough float leverage. Holley 94's can easily take 5-7 psi, but are a PIA to set up multi, especially progressive, as their power valves are vacuum, not mechanical.
 
A stock cyl head should have more than 60# comp.you should have a lot more than that with a 5.5 head.Seems like its running too lean to me.
 
You must log in or register to reply here.
Back
Top