x2.....if you're using a progressive style linkage as many factory setups did.
Your initial timing, or lack of, will make a big difference? I added tunnel rams to two SBC's for people. Both had a pair of vacuum 600 Holley's with 1 to 1 primaries with no choke.
One was for show only with 9 to 1, a 230*ish hyd cam and timing in the 18/19 range.......it started and idled almost immediately.
The other had a high 11's compression engine with a low 250's solid cam that I couldn't get more then 10* initial in without it rattling it's brains out on pump gas. That engine was a bear to keep running until it was fully warmed. But after that, hang on...:D
