69 351 W Questions

[MACH1MUSTANG]

I am a new member to the Classic Mustang family and have some questions. I have a beautiful car but need some help to fine tune it. Here is some history, it is a 69 351W, it has an edelbrock intake, 750 4bbl Holley carb., pop up pistons, 290 degree cam, headers and is bored out 30 over. It has 11:1 compression and runs on a 50/50 mix of premium pump gas and 110 octane race gas. I am trying to get the timing set right for the way this engine was built. I put it on a dyno and was unimpressed with the results of 220hp at the wheels. It does have a C6 transmission which I have been told soaks up about 70hp but at 5,500 rpm's it wasn't sounding very good and I was told the engine should push 7,000 rpm's with no problem. After checking the timing I found it was set at 4 degrees ATDC, yes ATDC. I moved it to 8 degrees BTDC and that made a huge difference. I can easily reach 6,000 rpm's now and it feels like it wants to keep going. Also I think it is set for 34 degrees total timing but have not verified that by taking off the breaker plate. The vac adv. is not hooked up, it is plugged. Any advise on where the timing should be set, total timing, spark plug gap, or point gap would be appreciated.

Thanks,
Jim

 

[rbohm]

i usually set the timing on my engines at 10-14 initial, which with the 13 degree advance plate in the dist. give 36-40 degrees total timing. i would start at 12 degrees with your motor, and if you get detonation back it off a bit. if not then move to 14 degrees.

 

[ForceFed70]

I think you'll be pretty good at 34*. Higher compression usually means you have to back off a few degrees on the timing.

 

[retro50]

You need to run as much initial advance at idle as possible. This keeps the idle fairly smooth. with pop up pistons it takes longer for the flame to reach the other side of the cylinder for a complete burn. you probably will end up with around 38-40 degrees total all in by 3000 r.p.m. I run a 302 with pop up pistons and I have the initial timing at 21 degrees B.T.D.C. at idle. and the total timing at 38 degrees. No vacume advance at all. Just listen for pinging and make sure the starter will crank the engine hot and not kick back. Every engine is different so you will have to play around. The dyno is a perfect place to play with it.

 

[69Rcode_Mach1]

Your C6 is definitely eating up your power believe me I had one and I hated it. That is why I switced to the t5. Also you will probably could not or need to spin her all the way to 7000rpms the heads are such a limiting factor you will probably hit optimum flow at around 5500rpms. I really hope you have that bottom end held together with some ARP bolts also otherwise it is a timebomb waiting to go off with those revs you plan on.