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Valve lash and idle

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Valve lash and idle

Post #1 by MrMootsie » Sun Aug 12, 2012 4:48 pm

Firstly, yes, I used the search function extensively.

So, new head on the 65 Mustang convertible. It's a later model head, with a 1.75" bore. I had Mike at CI send me an adapter for my 1.5" bore Pony Carbs 1100. The carburetor is less than a year old. I am running a DUI distributor. New head is on because the old one ran out of machining room. It's a better head, in any case.

Me and my real mechanic buddy installed the head and valve train. I had not done an extensive level or research on setting valve lash, because, frankly, I considered it out of my capabilities. I entrusted it to him, as he's an old school guy. The car started, roughly. We attempted to dial idle and mixture in as well as possible. Initial timing was 12. DUI is curved to 24, making for 36 with the boot in it. It just never idled very well at all. It stalled, surged, and didn't run well at all.

We played the available settings on the carb, which didn't do much. It didn't respond a ton to any changes in hot idle settings. Choke worked okay. It responded to idle mixture changes. We took the air horn off and cleaned the idle circuit as good as we could. These measures did not fix the rough idle. No vacuum leaks, either.

Since the car/carb had been sitting for a few months waiting on the purchase/delivery/machining/installing of the head, I figured it needed a good cleaning. There is an excellent local carb shop (Hobbs Carburetors for those folks in MA and NH). Hobbs cleaned the carb and mentioned only that the float setting had been off slightly.

Installed carb, no apparent change in idle. My mech and I decided that it must be valve lash. So, this morning, using the Classic Inlines procedures, we set valve lash. The problem we encountered during this is that no matter how hard we pushed down on the push rods, it didn't seem to take all of the slack out of the hydraulic lifters. We would tighten the rocker down until the pushrod could no longer be turned, add a 1/4 turn, and then the rod seemed to loosen up. In any case, we finished the procedure specified, put it all back together, and started it. The idle is a bit better, but not what I would have expected, given the amount of effort, clean carb, no vacuum leaks, etc.

Is there anything glaring, or small, that I'm missing?

thanks, and apologies for the length of the post.

65 200 convertible Mustang, Pony interior, SSBC power discs, Pertronix, 15X7 Konig Rewind Silver, 205/25/15

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Re: Valve lash and idle

Post #2 by bubba22349 » Sun Aug 12, 2012 6:27 pm

From your description it sounds like you have tighten down the rocker adjustments to much. Loosen them up and start over. your not looking to have the push rods unmovable (just a slight drag) before the 1/4 turn, so their is no excess slack and no valve train clatter. Good luck
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I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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Re: Valve lash and idle

Post #3 by Does10s » Mon Aug 13, 2012 9:47 am

There isn't any valve lash with hydraulic lifters.
With the piston at TDC, and the rocker arm adjuster loose, tighten down the rocker arm adj. until you just feel a little drag when you rotate the pushrod. Then tighten another 3/4 of a turn. Tighten the jam nut. You're done.
Other than you have 11 more to do.

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Re: Valve lash and idle

Post #4 by MrMootsie » Mon Aug 20, 2012 8:10 am

they were, indeed, too tight. I re-did the adjustments, and idle cleared up right away. Thanks forum!
65 200 convertible Mustang, Pony interior, SSBC power discs, Pertronix, 15X7 Konig Rewind Silver, 205/25/15

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Re: Valve lash and idle

Post #5 by xctasy » Mon Aug 20, 2012 11:10 pm

I've used the earlier adjustable rocker gear and the differernt pushrods the earlier Falcon sixes had when I put a 1963 vintage casting on a 1981 3.3 engine. I used the earlier Aussie 200 pushrods, the said ajustable rockers, and got lazy and used the stock 1966 Australian Falcon settings it had on the engine I raided it from. Ie, i didn't adjust them at all!

I didn't try a 6 thou lash adjustmnet, which is the ramp on a hyrdaulic cam. Due to my lack of work, I had no joy, it was always noisey as heck, and sounded like the rockers were pounding the inside of the later model baffeled rocker cover. But no, it was just that the Aussie engines lifters had a differenent height or preload spec to the stock 1981 ones.

You can adjust preload by adjusting the rockers to a new spec of 6 thou, but the rockers and pushrods must allow the valve to be a 90 degrees at when the valve is on the seat.


Its off the stock EOBE-6090-BB head I've always run up till recently Image

Rocker cover for the 3.3 remained free from contact from the non standard 1960 to 1966 spec rocker gear, no baffles got hit, even with the almost 400 thou lift from the 1981 camImage

I converted back to the stock 1981 rocker gear last week, and its been silent and a lot of fun to drive. Went to a development track where they do development work for future years vehicles, and I got 95 miles per hour out of my 91 hp engine, and its was as quiet as a mouse at 3600 rpm.
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FAZER 6Bi (M112 & EEC5) or FAZER 6Ti (GT3582 & EEC5) 425 HP 4.1L/250 I-6
FAZER 6V0 3x2-BBL Holley 188 HP 3.3L/200 I-6 or 235 HP 4.1L/250 I-6
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