I think my engine is just about dialed in. Video.

[Hogger54]

So I think it's real close. New set of size .54 jets, and did some fine tuning with the throttle settings.
What do you guys think? At about 1:02 I give it gas, but it kind of stumbles and then backfires. And toward the end of the video it was slightly revving up and down on it's own. What would cause these? Timing?
How does the idle sound? My tach was bouncing all over the place, but looked to be around 500 RPM(it's a 4spd.)

http://www.youtube.com/watch?v=cfusjslqO_0

[OrrieG]

stumble and pop is timing advance.
rise and fall possible vacuum leak, old carbs are notorious for leaking around the throttle shaft. Vacuum gauge will confirm.

[hsdropout]

That is a sweet looking 6 banger for sure. Clean!

[55dude]

very cool!

[wolffcub]

Nice and clean! I gave up on my 2 singles i was using because of all the issues i was having. Installed two new double barrels and have not had an issue since. Going thru my whole inline tune one thing that made a huge difference was the valve adjustments. After she warms up check all your rockers and gaps. A vacuum gauge with an adapter fits perfectly on the side intake port.

Another thing i noticed is you cant always gut go by the timing numbers that everyone throws out. Each setup will be slightly different.

[OrrieG]

Originally Posted by wolffcub

Another thing i noticed is you cant always gut go by the timing numbers that everyone throws out. Each setup will be slightly different.

Exactly the reason for the vacuum gauge, it allows you to time for the carbs, intake, cam and exhaust you have. Start to maximize vacuum, they retard slightly to find the sweet spot. It will also show issues with the valve adjustment. Old school Chiltons have a whole section on using vacuum for tuning and engine analysis, usually the first thing they recommend you check.

[wolffcub]

this was mine prior to the valve adjustment.

https://www.youtube.com/watch?v=b4dC...ature=youtu.be

[Hogger54]

Thanks guys. Just got home from Vegas. Hopefully tomorrow I can pull the fuel lines and run each carb independently so I can check the vacuum.
Or should I just hook up two separate vacuum gauges?

[wolffcub]

Originally Posted by Hogger54

Thanks guys. Just got home from Vegas. Hopefully tomorrow I can pull the fuel lines and run each carb independently so I can check the vacuum.
Or should I just hook up two separate vacuum gauges?

As long as the carbs are allowing the motor to idle just let them be for now. Hook the vac gauge to the port on the side of the intake manifold that you currently have a brass plug in. Warm her up for 15 min so everything is hot. The heat can and will cause the rods and such to expand very little but can contribute to a valve staying open slightly. play with the distributor till you get the highest vac reading. This might be hard to do if the needle is already bouncing around like in my vid. I had the valves stuck slightly open and that's why mine was low vac and a bouncing needle.

If you need to adjust the valves im sure you know the valve cover has to come off so you can do your work.

After you sort that out then i would suggest moving to the carb flows using a carb flow meter.

[wolffcub]

use this as a guide

http://www.stovebolt.com/techtips/valveadjustment.htm

A ticking motor is a happy motor.

[Hogger54]

Thanks. I have gone through and adjusted all the valves. Although it might be good to go back and make sure they are still set right.

[wolffcub]

I always thought mine were always right after my rebuild but I was totally wrong after seeing what the vac gauge said. Yours seems to really backfire at the touch of the throttle. When I first started mine it did the same with the single barrels. You have both carbs hooked to the vac advance or one ? Should be one anyways. Disconnect the vac advance when doing your initial tune in my opinion.

[wolffcub]

Oh and also what you using to heat the intake? My vote is to get some coolant going to that for proper heating. Not a fan of the lines off if the headers as debris can build up and the air does not flow very well.

[Hogger54]

I have the vacuum hooked to just one, the primary carb(with choke). No intake heat.

[wolffcub]

I would focus hard on getting heat to the intake prior to continuing.

[OrrieG]

I doubt heat to the intake in WA will be an issue, only needed for the first minute or so until the manifold warms up from the block heat. First thing I removed, when it was there, was the heat riser flapper on the exhaust. Until this build my truck always had a manual choke with no intake heating provisions and started without any problem, coldest was -25 up on Thompson Creek in the Sawtooths. In Edmunton or other northern regions might be a factor if all you driving is short trips. I do agree he needs to get it up to running temperature to adjust the valves.