High Ports and timing
 

Well, I have the other thread about converter slip because I am was not so happy about how the new 461 with High Ports was doing. Its a 11.5 -1 CR engine and we all know that is on the high side for a pump gas engine. Right now I do mix 1/2 gal 112 to 4 1/2 gal 91 to get 93 octane. Getting it to run on 92 all gas-gasoline is the goal but not there yet.
Being a 11.5-1 engine I have been very careful with the tune. The thing with High Ports was they are supposed to like the timing in the 28-32 deg range. Or so I thought. Started out breaking it in at 28-29 deg and then 32 deg. It 60 footed great, but MPH sucked.
I had terrible converter slip or so I thought, sent my 9" PTC back to get loosened a little. Got it back and 60 foot went from 1.39 down to 1.46. I was p!$$ed. So I thought I would try 34 deg, timing light was acting weird so I put the distributor to a mark I had on the firewall for 36 deg, where the old 9-1 HO engine like to be.
This was after my time runs so it was on my first elimination run. What the heck, I was not happy anyway. The car took off, not a perfect run either because I was on the brakes hard because I was so far out in front of the guy. I made 3 passes at 36 deg, none of them were really good run. Had a spin on the line and fan belt was off my last run. Engine made a weird nose right before the shifts. Maybe the voltage was down ?
But, the car ran .80 faster than it did at 32 deg. best ever was the last 10.34 run popping. Did a 6.43 in the 1/8 too. 103 MPH.
Went from a 116 to 126 MPH. All from 4 deg timing ? No real tuning, playing with shift points, taking off at higher RPM and have not tried the 1050 I had worked for this engine.
Well, any a lot happier now. Low, low 10s are within reach and a high 9 is not out of the question either.
Now, I really wonder what the TCI 8" would do with the engine running like this ?

So, what are other High Port guys running for timing ? The 28-32 deg just got thrown out the window as far as I am concerned. Wondering if 37 or more deg would get me anything but I should raise the octane if I try that. I will leave it alone for the next race, Wally race so I just want to try and win.
But the last race I think I will try the 1050, maybe the old 850 or the 8" TCI.

There are many things that effect the ideal timing even between two motors running the same heads, like

Piston speed .

The rpm where the Cam gets into its max torque band.

Cylinder head temp increase during a pass.

The air to fuel ratio is a factor also.
Leaner mixtures take more time to burn the richest mixtures do.
This is where air density changes can drive you nuts if your trying to get a base line down.

So a lot of details have a hand in what the ideal timing might need to be for a given motor.
And even port velocity and the narrow rpm band where the tuned lenght Intake ramming takes place .

My road race engine has 330 cfm Hi Ports, 10.5:1 compression and a 3/4 race (hahaha) SFT cam. On the dyno, it made best power at 36 degrees. We tried 37 deg and power was a bit less. That was on a 50/50 mix of VP 110 and 90 octane pump gas. I'm going to run it at 34 degrees for a long happy life.

FWIW,
Eric

I don't have the dyno sheets here with me, but as I recall, the power difference from 34-36-37 deg pulls was only about 5 hp. In other words, not enough to make an 0.8 sec difference in drag race ET.

Eric

My high ports liked 34 degrees on the engine dyno and then the tuner added 36 after 5500 but I flattened that out since I'm not looking for trouble.

My pump gas map has 2 degrees pulled out after 30% tps since I'm mainly Summer day driver and the humidity here and heat just makes for a horrible MAT, not risking it. I'm usually E30+ anyways so it's not a big deal and it'll pull nice from there. Weight is a factor I can feel vs my 3300lb GN, big difference in giddy up.

My Highports is run 27 degrees.

The car just took off. I am happy it happened but that big of a jump with 4 deg timing increase still does not make much sense.
I have never heard this engine ping,
But pinging engines would not be making their peak HP, you would think ? I have never dynoed a engine in my life either.
That Sun timing light you like, 7501 ? I will pick one up just to double check my timing light.
But the way I see it, if I got a 1.37 60 foot, there is a 135 in there somewhere. If I got 126 MPH, 130-132 should be within reach.

Are you NA ?

Off topic, how much lift are you running with high ports?

Here are my numbers to compare yours to: 1.45 60', 6.39 at 109.2 mph in the 1/8, 10.01 at 134.3 mph in the 1/4. Your car is hooking very well.

At the track, we always used an MSD timing light. It worked perfect with the 6AL, 7AL and 44 pro mag. Mike has the Sun light at his shop. I'll ask him to verify the model # on here.

Eric

.7315 gross lift. I had the cam toned down a little. Just took away a little of the aggressiveness. It had a intensity number of 29, too much for a stock block. 34 now.
1.7 rockers.

I am looking for MPH numbers like yours.
My car has always hooked. Its just a Alston 32" ladder bar deal. But the shocks, are the exact same air shocks I had on the car in High School. 1983
I have no problem getting real drag race shocks, but until I have a issue I am going to see just how low a 60 foot I can get with 42+ year old air shocks.

I picked up .1 in the 1/8 going from 30 to 28. was on a 469 race engine. ended up 6.49 at 3500 lbs. even on the 517 set them to 30, went 6.26. heads are gone, temporarily have 340 butler edelbrocks i need to sell for some wedge heads.

Troy,
Remember if you picked up HP and Torque with the timing change than your convertor will as act different.

Stan

Sure, but .82 from a 4 deg increase in timing ? Never heard of that big a jump. Maybe it happens, first time for me.
There was something weird that happened earlier. After I first started the car I took it to a desolate place at the track and brought the converter up on the brake 2 step set at 3800. Converter was new so I wanted to get some input.
The tach went to 5000 RPM. Turned it up to 4000 and it went past 5000 RPM.
It acted normal after that, tach sort of matched the 2 step RPM. Maybe I have a loose screw holding a wire. I will check them before the next race this weekend.

Yes. NA. My car 60's 1.28 to 1.30. Im going thru the light at 142mph.

My 528 hi-port likes 35-36. Large dome pistons. My old kre d- ported like the same timing. That also had large dome pistons.

my race motor likes 28,proven on the dyno

Well, 2 guys having engines that like 27- 28 deg. Kina why I thought staying between 28-32 deg would be best for this thing. But it likes whatever timing it likes.
Engine has flat tops and the heads were 80cc milled down to 74 cc.