The engine is mounted in a 9N tractor and it ran great last year, but then he changed stuff. Over the Winter, he added a set of Edelbrock Al heads, a bigger cam and a hotter ignition..... I don't anything about the specs - like even what year the engine is, the size of cam, the new C/R, etc. I do know he's got a 390 Holley on it.

I took a quick look at some basic flat-head specs and I determined that most were 6.8 - 7.5 C/R, 100-125HP, 240-255cuin., with the initial timing at 2*BTDC and 8.5* at 2000rpms. The point breaker gap was 014-016" and the dwell was 28*. I don't know what jets he's got in the 390-cfm Holley, nor what his fuel pump pressure is putting out, but I'm leaning toward incorrect ignition timing and possibly low fuel pressure with the stock pump at elevated rpms.....

Tonight I'm going over to his place to check it out, put a timing light on it, check carb float levels.

I know, this isn't much to go on, but does anyone have any thoughts and/or suggestions (that might just make me look smart - not an easy task, mind you)????

Thanks in Advance,
Ryan

quote:

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Originally posted by Whitson:
Setting valve lash on them was always a major PITA. Since he changed cams, I'd be checking that first.

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10-4, Mr. Whitson.
Do ya happen to have a link to any info on the best/easiest way to check the valve lash?

After hearing it run, it sounded/looked to me like an electrical issue. The cheapo sparkplug wires they had on it may be the first place for improvement. Carbon core wires, about 7mm, looked likely to have been man-handled one too many times already. Besides, they've got a hotter Mallory 40KV coil unit on it. I'm sure the sparkplug wires were marginal for the added voltage even if they weren't broken internally. I suggested that they check them with an Ohm meter, but that was met with, "I'll just get new ones!" Fine.

The stock distributor with vacuum advance wasn't working so we pulled it and plugged in a Mallory magnetic breakerless distributor on it. Based on a single mark on the timing pulley, the timing was now advancing with rising rpm. It stopped advancing by 2000-rpms. In addition, they only have ONE timing mark (at TDC, 0*?). I suggested they measure the diameter of the pulley, locate an appropriate timing tape, find TDC and install it so they could determine what/where the timing was doing. Although it would rev to 5000-rpms, I suggested that they use that for a red-line since they DIDN'T have it balanced when they assembled it (who knows why not?!).

Another issue is with Holley #8007 390-cfm 4-barrel with VS (mounted on an Offenhauser intake with an adapter plate). Earlier they pulled the #51 primary jets and installed #64 jets(!). There are no secondary jets, they work thru a metering plate. I guess because they also installed a hotter cam, they simply assumed that they'd need more jet. I suggested that they go back to the originally-equipped #51 jets and reset the float levels.

I also suggested that they install an inline fuel pressure gage, tapped inline after the way too small (looks like for a lawn mower!) fuel filter but before the carb, mounted where they could read & confirm that they are getting >5psi from the inline punky electric pump while running it under load. "Maybe you should consider upsizing the filter while you're into the fuel line too".

The aluminum Edelbrock flat-head cylinder heads were very pretty and the paperwork said would raise the C/R to about 8.5:1. They told me they had been running TORCO 110 fuel in it. I suggested that they step back down to a good quality Premium 92-octane gasoline.

The cam is a solid ISKY, #B1 4000 8B-A, with .414" valve lift and 258* of advertised duration, lash of 018" and the custom open headers 'open towards the sky' sound like it'll be WAY when it gets all sorted out!!! The 9N has NO suspension, and when the 255cuin. 1950 flat-head passes 4000-rpms in 3rd gear, HOLY BOWLY, THAT BABY IS A WILD RIDE!

By the time he locates, obtains and installs the new sparkplug wires, fuel pressure gage and, hopefully a bigger fuel filter, it'll likely be the weekend. I'll likely slip back over there Monday or Tuesday of next week to check the progress....

If anyone has any thoughts or suggestions, please share them here........

As I mentioned earlier, the stock specs call for 2* advance and a total of 8.5* in by 2000-rpms. The Mallory paperwork indicated that it would like 16* total advance all in by 3600-rpms. But with the warmer cam, ignition, heads, it may not like that any longer. I suppose we can start at 2* and then add advance 2* at a time...running it down the road a bit after every timing addition...

Thanks for any & all advice & pointers!
Ryan

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Alex Denysenko
Co-Administrator and Moderator

NHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First NHRA & IHRA 289 automatic Superstock Mustang in the TENS 06-99
First SS/MA in the TENS 04-03
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28

The Barry of BarrysGrrl

He saw sparks jumping around on top of the coil, so he bought a new std. 12V coil, big improvement.

He re-installed the #51 carb jets, another big improvement. Dropped back to 93 Premium gasoline, which also seemed to make the motor happy......

So the ol' girl is runnin' smooth now! He'll be taking it to the tractor pulls in two weeks now!

All is good in the world again and he's grinning from ear-to-ear....