276 flathead test drive big improvement.........but?

[36tudordeluxe]

Shifts well through the 4 speed top loader and with the '40 steering box it's like night and day versus the '36 box. Was having ignition problems but advanced the distributor one tooth and that cleared up 90° of engine problems but still doesn't run as smooth as it should. The exhaust has a intermittent "snapping" sound at all engine speeds, plugs are clean, compression 130-142lbs. on all cylinders. The distributor is Mallory electronic with no vacuum advance and is showing 30° of dwell. Am only showing 5" of vacuum at idle & 18 1/2" when I goose it; has a L-100 cam. I found a very small piece of gasket material that is located between the carb. adapter ( spread bore to square) & carb. laying on top of block where intake mates to the block. This gasket material was located on the corner of the adapter & carb. where mounting bolt passes through.........could this be enough to cause a vacuum leak? Can't put a timing light on it, no degreed pulley. All things considered still somewhat pleased considering where I was.

[flatjack9]

5" of vacuum is not good. What is your idle speed? Spray some carb cleaner around the base of the carb to see if it has any effect. Also try advancing the spark some more. You really need to establish a timing mark. Check the archives for the procedure.

[AnthonyG]

I have same set-up on my '35 with an 8BA and had the same problem. The corner of the carb adapter gasket some times brake off ( I assume a 4 barrel ) mine did as well but it's outside the seating area and remained sealed as I'll bet yours is. 30 degrees is too far advanced. If you can't find any timing marks on crank pulley or timing chain cover try this. Mark the distributor and engine with a reference mark before you start so you know where you started then retard till engine at idle gets rough and advance just enough to smooth out and go no further. That S/B close to where it needs to be. But you should have a timing mark on your bottom pulley and an arrow on the timing chain cover to use to see how far off you are. I would bet your off the gauge a lot in the advance direction.

Here's advice I got from Babba's Ignitions "These Mallorys typically are set up with way too much advance and the advance rates are incorrect for the flathead".

You'll get there as I did, Good Luck

__________________

[Talkwrench]

Your vacuum is backwards..? Does your vacuum bounce at idle , a flicker 2" Hg. Would indicate a vacuum leak. You will need the edelbrock intermediate plate 2731 ? between the carb and adapter / manifold, if Im understanding what you have done..

[36tudordeluxe]

Idles at 850 RPM. I sent the distributor to Bubba and he reset the curve for a flathead. There are 3 vacuum ports on the front of the Edelbrock carb. One is timed, one is auto. trans. and one for power brakes. Maybe I used wrong port and that's why my vacuum reading is backwards? Vacuum at idle is pegged at 5". I do have TDC #1 marked on the pulley but I have no degree marks for advance or retard.

[Talkwrench]

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For now block all the ports unless your are running a brake booster. Check for a vacuum leak under the carb. Vacuum time your motor turn the dissy advanced and see the vacuum come up to its maximum, then back it off 1 1/2" Hg. That should get you about right. You may even come back more than that. I think John will tell you less is more with your timing. You maybe horribly over carbed , what is it a 1406 ?

[51 MERC-CT]

According to Edelbrock this is the full time vac. port for distributor.

[GEOFFNZ]

Hi. If you have TDC for no.1 marked on your pully and a pointer you can work out degrees on pulley diameter.For example a 4 inch pulley gives a circumference of 121/2 inches (4x31/7) which is 360 degrees so an inch of pulley circumference would be 29 degrees approx which would give you something to go on. Cheers.

[john in illinois]

If you use a dial back timing light you can run engine at max advance,set the light to flash at TDC and it will show degrees advance.

John

[Ol' Ron]

Use an 11A with vacuum. Put a timing mark on the pulley. You spent allot of money building this engine, now invest in a proper tune up.

[flatjack9]

Originally Posted by 36tudordeluxe

Idles at 850 RPM. I sent the distributor to Bubba and he reset the curve for a flathead. There are 3 vacuum ports on the front of the Edelbrock carb. One is timed, one is auto. trans. and one for power brakes. Maybe I used wrong port and that's why my vacuum reading is backwards? Vacuum at idle is pegged at 5". I do have TDC #1 marked on the pulley but I have no degree marks for advance or retard.

Have you used a timing light? Where is the flash in relation to your TDC mark? Take you vacuum reading off one of the full time vacuum ports, not the timed one.

[36tudordeluxe]

The carb. is a 1404 with manual choke and smaller main jets (.083), step # 11 in Edelbrock manual. Have consulted with "Richard in Florida" a many time contributor here on the Barn; his engine internally is the same as mine and the Edelbrock performs great for him. Ol'Ron has advised me numerous times during the build of my engine and I know it has the potential to perform really well. Once I get the timing issue sorted out with the Mallory am going to install the HEI type modified Chevy distributor with MSD box that Ol'Ron did the machine work on. It was a collaborative effort with Richard, Ol'Ron and Joe P. on the distributor. Going to take a vacuum reading on the correct port on the carb. "John in Illinois" mentions a "dial back" timing light and wonder if that's the same as an adjustable timing light which I don't have but will get if necessary. In the meantime will use my old light as "Flatjack9" suggest and see where I'm at in relation to TDC #1 on pulley. Although, am wondering since the the distributor is installed one tooth off to allow for more advance if this will make for false or inaccurate reading with the light?

[51 MERC-CT]

Originally Posted by 36tudordeluxe

Although, am wondering since the the distributor is installed one tooth off to allow for more advance if this will make for false or inaccurate reading with the light?

Installing the distributor one tooth off should have no effect on distributor timing, it just changes the location of the rotor in relation to the 6 o'clock position (the appox. position where #1 should be )

[19Fordy]

Make sure any unused "open" vacuum ports on your carb are blocked off. This might be why your readings are backwards.

[flatjack9]

So through all this you have never used a timing light?

[36tudordeluxe]

Originally Posted by 51 MERC-CT

Installing the distributor one tooth off should have no effect on distributor timing, it just changes the location of the rotor in relation to the 6 o'clock position (the appox. position where #1 should be )

Okay, understand now, thanks. Rotor is now at approx. 8 o'clock position. Using correct vacuum port and needle bounces between 10" & 11". Could 10" or 11" be about right with L-100 cam? Duration is 270° on intake and 260* on exhaust.

[36tudordeluxe]

Got the timing light out but am missing spark plug adapter for connection, any ideas on what I can substitute for the adapter?

[flatjack9]

Good grief, man. Go out and buy yourself a good setback timing light. There is no way in hell that you can just guess at timing. This is an essential tune up tool. Here you spend all this money on this engine and then are too cheap to buy a good timing light. Unbelievable!

[51 MERC-CT]

Originally Posted by 36tudordeluxe

Okay, understand now, thanks. Rotor is now at approx. 8 o'clock position. Using correct vacuum port and needle bounces between 10" & 11". Could 10" or 11" be about right with L-100 cam? Duration is 270° on intake and 260* on exhaust.

At this point all mention of cam and cam duration are meaningless.
Perhaps the proper adjustment of the idle mixture screws will bring it closer to where it should be.

[36tudordeluxe]

Originally Posted by flatjack9

Good grief, man. Go out and buy yourself a good setback timing light. There is no way in hell that you can just guess at timing. This is an essential tune up tool. Here you spend all this money on this engine and then are too cheap to buy a good timing light. Unbelievable!

Jack, lighten up. You don't know me other than what I profess not to know on this forum. As to your opinion about about my willingness to spend money is of no concern to me and probably no one else on this site. I find you offensive.