The Ford Barn

drolston · 10-05-2020, 02:01 PM

Earlier post noted that stronger return springs on the secondaries (Offy 3x2) fixed the erratic idle. It also seems to have fixed the problem of engine stalling when coming to a stop. Having those secondaries at anything other than tightly closed at idle creates all kinds of problems. So, hurray! However,

https://www.fordbarn.com/forum/showt...light=drolston

Testing this fix involved getting on it hard enough to fully open the secondaries. The sound and fury is wonderful but it produces a minor but very noticeable miss. It is not an erratic or sputtering miss, but regular; like one or two cylinders are not firing.

The ignition is all new 12v Pertronix; it just does not feel like an ignition problem. But, as often repeated on this forum, "most fuel problems are ignition problems," and vice versa.

Schneider 245f cam with .350 lift is not radical, and valve springs are Lincoln with about 60-70 lb seat pressure. Happens at 3,000 - 4,000 rpm, so pretty sure it is not valve float.

Electric fuel pump feeds through mechanical pump and a regulator that holds steady at 2.5 PSI. It does not act like fuel starvation, which would be sputtering and erratic.

I suspect that one barrel of one of the secondaries is not feeding. The carbs are Speedway 9super7, which makes them automatically suspect. Is there any way to test for that in the garage? Pretty sure the floats are set right. Any other suggestions?

10-05-2020, 02:01 PM	#1
drolston Senior Member Join Date: Jun 2014 Location: Williamsburg, VA Posts: 1,811	Missing at full throttle. Earlier post noted that stronger return springs on the secondaries (Offy 3x2) fixed the erratic idle. It also seems to have fixed the problem of engine stalling when coming to a stop. Having those secondaries at anything other than tightly closed at idle creates all kinds of problems. So, hurray! However, https://www.fordbarn.com/forum/showt...light=drolston Testing this fix involved getting on it hard enough to fully open the secondaries. The sound and fury is wonderful but it produces a minor but very noticeable miss. It is not an erratic or sputtering miss, but regular; like one or two cylinders are not firing. The ignition is all new 12v Pertronix; it just does not feel like an ignition problem. But, as often repeated on this forum, "most fuel problems are ignition problems," and vice versa. Schneider 245f cam with .350 lift is not radical, and valve springs are Lincoln with about 60-70 lb seat pressure. Happens at 3,000 - 4,000 rpm, so pretty sure it is not valve float. Electric fuel pump feeds through mechanical pump and a regulator that holds steady at 2.5 PSI. It does not act like fuel starvation, which would be sputtering and erratic. I suspect that one barrel of one of the secondaries is not feeding. The carbs are Speedway 9super7, which makes them automatically suspect. Is there any way to test for that in the garage? Pretty sure the floats are set right. Any other suggestions?