This is concerning. Your car is a street car. The only cars that run locked in timing with no vacuum advance that I know of are drag cars. If your initial timing is 27, be prepared to knock the nose off your starter and break flywheel teeth on a hot start if you have ignition connected.

ALL street driven cars should run vacuum advance for fuel economy, power, engine cooling, and overall performance.

How much and manifold or ported depends on what your engine wants.

Optimal timing can't be determined on a run-in stand. Your machinist is blowing smoke.

I have an ECU that controls fuel and spark on my 455, "66" casting Dports, zero mods to ports or chambers, 8.3:1. I have a timing table, in lieu of a vacuum advance or advance weights & springs, and can put the timing anywhere I want at any part of the table. For BEST performance on a chassis dyno, my motor performs best with 37 degrees timing.

The only engines I've ever been involved with that only like 26-28 degrees of timing on pump gas are LS engines. They generally came with factory timing in the 22 degree range but dyno testing showed they really responded to 26-28 degrees and a rare occasion 30.

All the old dinosaur engines I've built and tuned, including engines that have had more modern chamber cylinder heads, has never responded very well to timing as low as 28 degrees. I always shoot for zero deck and tight quench engines and as much compression as I can get away with on pump gas and the camshaft being used. Even with modern heart shaped combustion chambers it's been rare from my experience that they made best power on the dyno any lower than 32 degrees, and most of them are always up around 34-36 as the norm, sometimes 38-40. There is no rhyme or reason, but the engine would have to be dyno'd or track tested if you really want to find out what it wants.

Honestly it sounds to me your engine builder is being extremely cautious and erroring on the light side for timing not knowing how you're going to treat the engine. Can't say I blame him, when you're in that sort of business.

What heads are on this engine ?

He did not say his initial timing was 27 degrees.

That's what I thought.!! I don't think you know.. I've never quoted myself. lol.. I'm referring to the O/P?

Hmmm, What a blanket statement. I'll just wing it. All the while people are reaching out to you trying to help... :confused: I was looking for the emoji that throws his hand up.. Anybody.

My 433 is tuned pretty good and runs excellent at all points. I have 47 heads, stumppuller cam, 9.8CR and run 16 initial , 20 mechanical and 14 vacuum. Total of 36 degrees and 50 degrees at cruise.

Nobody cares what you have. We’re trying to get the O/P to respond.. jJust busting your chops. Lol

.

I don’t think you guys are getting it, key is 27 degrees with no vacuum advance.

Yes I think we are. What initial ?

I don’t think he knows only because he didn’t set it up, and probably didn’t ask.

Exactly. Thank you. That’s my point. Post # 27. Ok I’ll shut up.

See ... everyone should be required to present their timing in my suggested format :)

From the OP's original post it sounds like his timing is 27-0-0 :)

Give the op a break guys please, and stop putting words in his mouth!

He clearly stated in his first post that 27 was the total timing and that the motor spun easily when cranking, so 27 could not have been the initial setting because if it was the motor would not Crank over even when cold ( no less hot ) and might even back fire while cranking.

I don't know about that .. pretty sure I ran my GTO at 36 initial no mechanical, no vacuum for a while :)

Your not getting a hot motor cranked over with 36 degrees of INITIAL without a ignition kill switch, is that what you had to employ?

Engine was stock, had about 100K miles on it, so it turned over pretty easy. Actually, I'm not kidding, pretty sure I was running some kind of dual point distributor, many years ago when I was a kid, wouldn't think of doing it now. Had real good throttle response if I remember correctly.

Yes, the correct "365" 20 degree vacuum advance.
Running full manifold vacuum because the fairly mild 744 cam allows it.
Have found no need to reduce the amount.

9-27-20.
27 @ 4400 rpm WOT.

I have a question for a lot of you, especially in regards to the above post where it’s stated that the 744 cam is fairly mild.

I have had all the factory cams in one of my 9.5 to 1 400 motors but for the 744 cam.

Ok so now I need to ask about my info I posted here from old HO racing recommendations.

As you can see they called for 3.90 gears to be run with the 744 cam in a 400.

How many agree that in a 9.5 400 motor the 744 needs a 3.90 gear to get it done right?

When I stuffed the 041 cam in my 400 above I used Rhodes lifters due to my 3.55 gears I had in the car and the motor performed well once oil temp came up.

The 068 cam was fine without the Rhoads lifters and with the 3.55 gears.