Timing 1600 dual port using an 009 distributor

[kitcar]

Hi from He Who Is Dangerous with Tools but doesn’t want to wreck stuff. I have a 1600 dual port 1970? Engine in my kit car MGTD. It has a 3/4 race cam and a Rochester 2 barrel carb and an 009 distributor. I’ve set the point gap and the timing static as per John Muir.

My pulley has only one mark on it but in searching for info it looks like I should use a degree wheel and timing light at 3000 rpm.

The engine was rebuilt 17 years ago but never run. It starts with a little gas pedal assistance and sounds good but occasionally backfires through the carb. I haven’t had it on the road yet.

A mechanic friend adjusted the carb but I’m concerned about the timing and backfiring.

Can anyone give me any tips?

Thanks
Russ (not the Russ who knows his stuff; the other one)

[Volktales]

When it comes to air-cooled VW's, the magic number thrown around is 32 degrees. With your 009 distributor, run the engine at a high enough RPM until the timing mark stops advancing. The 3000 rpm mentioned should be sufficient. Then adjust the timing so the maximum amount does not exceed 32 degrees. Once you do this, the idle timing could be anywhere from 8 to 12 degrees (usually), depending on the individual distributor. Not exceeding 32 degrees at maximum advance is to protect your engine. I do not have much experience with the race cams, so others could chime in here about their recommendations...

The backfiring could be timing out, but could also be too lean fuel mixture or vacuum leaks.

[mitchy965]

a rochester 2bbl? does it say 2-jet on the side of the bowl. a 3/4 race cam is a term from the flat head ford days having no actual specs on the cam makes tuning difficult.see if you can measure the manifold vacuum at an idle low vacuum indicates leaks below the throttle blades or lotsa overlap on the cam . the single notch on the pulley is tdc when lined up with the split in the case. to check the total advance and the rate of advance you can use a aftermarket degree pulley or use a dial back timing light (my preferred method). remember 2 jet carbs were designed mostly for small v8 engines which have a completely different calibration than our aircooled gems. although parts are available (i use mikes carb parts) only generic replacement power valves with no stated value are available making tuning the fuel curve very difficult. you can probably make this run but it will never be right.

[kitcar]

Wow, thanks for the info. I am obviously working from a warehouse of ignorance and have so much to learn. I’m just hoping for a motor that is reliable and understandable and less about big HP. I was talked into the horsepower mods by the rebuilder who used to race dune and Baja bugs but it looks like I wound up with a FrankenWagen.

Sounds like I may have to cash in my beer cans and take it to a pro. Any suggestions for a mechanic or shop that might understand my setup and not kill my bank account?

Russ (the other Russ)