[petes67bird]

Originally Posted by b-man

A friend of mine built a 421 for me, a talented amateur builder who’s built dozens of engines for his friends and fellow club members.

He broke in the cam on his run stand and ran it for about an hour total.

I installed it in my car, never touching the distributor. After several hundred miles I put a timing light on it even though it was running strong and drove great. The initial timing was 5 degrees which was likely the stock setting. I’m sure my friend was being cautious and didn’t try to maximize the timing during the crucial initial break in.

I bumped the timing to 12 initial, added to the 23 degrees of mechanical advance built into the distributor I have 35 degrees total now.

So I’m sure the shop set your timing well enough to drive and enjoy your car just like my friend did for me, but when circumstances are optimal check and adjust as needed.

I do understand. I guess my thinking is this. Its too cold here to do timing. The carb needs to come off for repair due to a leak. The intake needs to come off the be cleaned and painted at the least. I am almost to the heads at this point.

My thought is I will see gains regardless if I replace the heads, intake and carb, those are all net positive. Even fully tuned current build vs fully tunes new heads/intake/carb, the new setup will be better. I can then in the spring dial it in at a different shop. Otherwise I need to wait till it's warmer, and if it was in fact set properly, I won't tear into the motor until the following winter.

[Jay S]

Originally Posted by petes67bird

My thought is I will see gains regardless if I replace the heads, intake and carb, those are all net positive. Even fully tuned current build vs fully tunes new heads/intake/carb, the new setup will be better. I can then in the spring dial it in at a different shop. Otherwise I need to wait till it's warmer, and if it was in fact set properly, I won't tear into the motor until the following winter.

With the RA manifolds and RA 4 cam it would have roughly 50 HP more to tap into at some point switching to aluminum heads. But it could run about the same until you find whatever is holding the engine back.

We had a bad TQ converter once that we kept building more engine in front of it and it just kept running the same ET. Eventually we had enough engine it pushed completely thru the converter. We changed the converter and gained 10 mph the next weekend. You never know, sometimes more power makes the problem worse, and easier to find.