These are the specs as timing is set now.

intial 25*

total 40* all in by 3000 rpms

total + vacuum advance 60*



The engine seems to be running pretty good (a little too rich and bogs a little when going from part to full throttle). It doesn't seem to have a hard time cranking . No excessive heat. The timing numbers just seem off. The builder dyno tuned it and said to set it at 38* on 87 ocane and can be set at 42* on 93 octane.

I don't want to damage the engine. Should I retard the timing to 19* intial , giving me 34 total.

any suggestions? something seems off

engine specs:
carbed 355
9.1 cr
224/230 @ 50 .502/.510 cam
dart s/r heads
600cfm edelbrock carb
msd streetfire distributor

other specs in signature

 

http://www.youtube.com/watch?v=UYGU7mTwsZc

this is a great video. should help you out?

 

btw, 60 is unrealistic. your timing is way off. tell us what you think after the video.
many people dont understand total timing.

hope this helps. watch with an open mind.

total timing is the most important IMO.

 

Yeah I watchd that video before. That is actually where I got the 19* intial figure from with the 15* mechanical that would give me 34* total. I know in the video they said 19 is acceptable with a rowdy cam.

I guess the next question is with the vacuum advance hooked up to a ported source I will get 20* additional advance on top of the 34* total. I realize that my total timing (intial + mechanical) will be 34* but with the vacuum advance hooked up it will incerease timing an aditional 20* making total timing plus vacuum advance 54*. Am I going about this the right way? Should I try to dial down the vacuum advance.

Just to clarify my total timing now is 40* not 60*

 

wrong. initial + total is all there is.
how are you checking total timing? thats what counts. TOTAL TIMING.

not trying to be rude,,.....watch it again.

whats your total timing at 3,500 rpm?

 

I checked the total timing by capping ported and manifold vacuum and capping the vac advance canister on the distributor. I then used my dial back light while engine was idling(850 rpm) thats where I got the 25* intial . I then took the engine to 3000 rpms the timing there was 40* and did not advance any further past 3000 rpm. So I have 25* intial plus 15 mechanical which equals 40* total all in by 3000 rpm.

So what you are saying is completly ignore the 20* extra from the ported vacuum source?

If I am going to ignore it anyway why not just cap it and only have mechanical advance?

 

i have no info for you in regards to your your thread. i just want to say thanks for posting the vid that will help me

 

if you hook up your vaccuum advance and check your total timing again, it should have no effect on total timing. to the best of my knowlege, the vaccuum advance is used for lower rpm driving/light throttle. its been a long debate about wether to hook it up to ported vaccuum or direct manifold vaccuum. ive run many motors with no vaccuum advance hooked up before.
i found that video helpful myself. its usually easier to post that first then write a long explanation.

 

SCREW a bunch of "numbers".

The engine only responds to the relaationship of when the spark occurs, to piston motion. That's ALL.

The engine DOES NOT whup out a timing light and some "book", and check to see if what "the light" says matches "the spec" in "The Book".

This is so simple, it's easy to outsmart yourself over it; but you should NEVER lose sight of it.

"If it RUNS good, it IS good".

Once you get it to where no further change results in an improvement, write whatever "numbers" you discover that "the light" says you're set to, so that you can put it back to where THE ENGINE likes it in case some stoooopid human disturbs it.

 

if thats all it takes than i way over think it. i had some old school hot rod hereo time my enchine by sound and it ran better off the line but around 5600 rpm it sounds like its on a rev limiter , i dont have a rev limiter. so whats the deal with that?

 

well, if timing numbers werent important, then why would we use them?
i do agree in a way though,...X number means nothing. every motor has its own likeing.
timing is getting to a forgotten skill with todays new cars. i have a younger friend who is an ase certified mechanic and he doesnt even own a timing light or knows how to use it. lol.
total timing is all i ever really care about. if it pings, i back it down 2 degrees and try it again. find the best spot, write the info down and save it when its right.

 

The main thing to remember here is that vac advance is for part throttle only. At WOT there is little to no vacuum so thus there is no vacuum advance. At that point you are working only off your initial + weights. If the car doesn't ping or knock in any way on the hottest day of the year then you are fine. Check your plugs for any aluminum deposits. If everything is fine then you are good. If no then pull it back a bit.

 

I did some further reading and it said low comprression engines with bigger cams like a lot of intial timing. I know the guy who built my engine recomended 38* Total for 87 Octane and 42* total for 93 octane. I also pulled my plugs and have attached pictures. Just a Rich mixture or is it a timing issue also? Plugs are NGK R5673-7 http://www.jegs.com/i/NGK+Spark+Plug...673-7/10002/-1

plugs recomended and installed by the builder.

 

Because THE FACTORY already did all of that FOR US, and told us what they found. Then, if an engine is ABSOLUTELY POSITIVELY IDENTICAL to how it was when it rolled off the showroom floor, (hahahaha) and the timing marks are ABSOLUTELY POSITIVELY DEPENDABLE (HAHAHAHAHAHA), then AND ONLY THEN, they're good for something.

Otherwise, give the engine what it wants.