Is it normal for an engine to be 2 tenths slow after a freshen up? Made about 7 1/8 mile passe son it and now its about a tenth slower then where it was when it had 600 passes on it.

No

freshen up = no changes to the engine, consumable parts replaced with the same parts.

Happened to me when the new engine builder I used for a refresh decided that the cam should be set to something other than what I requested in the re-build. Slowed it 0.12 . Returning the cam to the correct degreeing number fixed it for me.

Did you rebuild it or someone else. If nothing changed should be the same like 1320 said

If you have race replay and the same torque converter, drop back at the shift will tell you if you're down 50-75hp, if all things are equal with the transmission, of the two runs you're comparing.

Sounds like the intake valve is opening a little different or the wrong / different thickness head gasket was used.

It could be a lot of different things I suppose, as far as power goes, but these two things might be the first to come to mind, to look at.

A tenth is quite a bit.

It was rebuilt by the same person/company who built it initially. First pass it was 2 tenths off and after all the passes it was a tenth. Now some of this could have been due to the weather I get that much as we are in the very hot times of the year. I just didnt expect it to be off that much. i called the engine builder and he said about ten passes and rings etc would be seated and motor should be right where it was before. Also said watch weather because that could be my culprit for the slowness. That could be true as I am on gas.
Head gaskets etc. were all the same as originally on it, only change was new ones were put on.

so which is it, a tenth off of your best, average or worst run?

Here in the northeast, my door cars on gas swing .05 in 60, 3 tenths and 3 MPH from the spring to the fall with a DA swing of 2500+ feet with no changes to timing or jetting.

Ran 5.35 at the end of last season in November, ran 5.55 and progressively moved up to 5.45 at 1800 ft DA. Gonna have to look back and see what DA was last time I raced it before freshen. Only other unusual thing after freshen is that it would gain about 15 to 17 degrees going to staging lanes but only gain about the 10 to 12 going down track. Im thinking that the weather/heat had the engine down on power.

Weather being equal mine ran so close to the same I never knew anything was done.

a tenth could just be bad air.

quote:

Originally posted by Da Shoe:
Ran 5.35 at the end of last season in November, ran 5.55 and progressively moved up to 5.45 at 1800 ft DA. Gonna have to look back and see what DA was last time I raced it before freshen. Only other unusual thing after freshen is that it would gain about 15 to 17 degrees going to staging lanes but only gain about the 10 to 12 going down track. Im thinking that the weather/heat had the engine down on power.

Don't forget the wind plays a role too!

quote:

Originally posted by RacerVX54:
a tenth could just be bad air.

this^^^

My data was incomplete at the end of last year because I had a computer failure. best I can make out is that it ran a 5.38 at 128 mph Dens Alt 725 wind SE at 3, (track faces north). a 5.36 at 130 Dens Alt 803 wind NE 4, 5.39 at 128 Dens Alt 200ft wind NE at 9, 5.36 at 129 and wind NE at 8.
So given the Dens Alt being 1800 im leaning that motor wasnt making as much power.

Third week in May every year without fail two things would happen back when we ran a 33 week championship season in Florida.

1. Just about everyone would have their valve covers off because they were a tenth slow.

2. Got hot and humid, tenth slow from the week before.

Third week in May every year / swamp conditions rolled in until the first week of October.

Last fall at Norwalk ran 5.22 this past weekend at Dragway 42 5.35, all in the air quality

Same ring package?

Yes ring package is the same, only difference is that they were new.

Same brand. Decided to stick with the same type of oil and not change.

ok then how about this...you're comparing your runs to the end of the season last season and it's likely your oil pan was low by a quart or two and now it's full of fresh oil. Same weight?

Oil level and weight exactly the same.