Pesky SHP Problem (?)

[Joe C.]

Hey Duke.....

I don't care about that at all. If the motor's a thoroughbred then that is just peachy with me--I just want to be sure it is what it is, and that's all. I love the lumpy idle, the exhaust fumes, and the music the engine and exhaust make--brings me back to the old days.

Re: the flywheel, I remember a post that Joe L. made a couple years ago, stating that the original flywheel was no longer available from G.M. Again, I don't remember the casting number right now, but I DO remember that I was DELIGHTED to find an original GM iron unit at Carlisle, BRAND NEW, IN THE BOX, for $4x.00. It should be the same as the one that you have on your 327/340.

Joe

[Joe C.]

Re: Pesky SHP Problem (?)

Craig:

Jerry Luck Motorsports
519 Fee Fee Hills
Hazelwood, Mo. 63042

1-314-895-1551

If you have any problems/symptoms, be sure to discuss it with him, and/or include in a note when you ship your carb.
Good luck.

Joe

[Dennis C.]

Re: Fuel and Vacuum Issues (long)

My .01 cent worth - you're missing about 2 - 3 inches of suction... DC

[Duke W.]

Re: Fuel and Vacuum Issues (long)

I think he's okay on vacuum, Dennis. The 30-30 only pulls about 10" at 900 idle speed. At the same speed, the Duntov or LT-1 cam will pull about 12" and 14" for the L-79 cam.

Duke

[Craig S.]

Re: Pesky SHP Problem (?)

Thx Joe - I have used Jerry before, he does superb work. I was just worried he was backed up and I would have to go elsewhere....and I had misplaced his contact info....thx Craig

[Joe C.]

Re: Fuel and Vacuum Issues (long)

Everett:

Thanks for the response. There is no smoke or excessive fumes from the pipes, and the vacuum does not wander off of 10.5. I am satisfied that Jerry Luck did a good job rebuilding my carb, as evidended by, among other things, fresh machining marks on the bottom surface of the throttle plate housing. He also told me that he machined all mating surfaces flat and true. Power valve is "65", and wouldn't open at idle.

I have decided that this engine is running normally, I will just try to tweak the idle mixture a wee bit, but frankly, I am not expecting dramatic results. I'll post the results if any improvement is noted.

Joe

[Joe C.]

THANK YOU ALL! *NM*

[John H.]

Re: Pesky SHP Problem (?)

"6. The idle mix screws are both set @ 1 1/4 turn out, with no afterfire on closed throttle coasting. Spec calls for 1 1/2 turns each. Do you think that the extra 1/2 turn will richen it enough to do me?"

Joe -

The "1-1/2 turns out" is a baseline starting point for the adjustment, not a "spec" as such. The procedure is to use a vacuum gauge and make the adjustment (working back and forth between the two screws to balance it) for highest steady vacuum reading. The "number of turns" really doesn't mean much, unless adjusting the screws has no effect, which signals other issues.

[Wayne K.]

Re: THANK YOU ALL!

Joe,

If you say you need to pump the gas to keep it going when starting out why not adjust the stroke on the acc. pump and see if that helps.

Wayne

[Joe C.]

Re: Pesky SHP Problem (?)

John:

Thanks for the help. I should have said "idle screws @ 1 1/4 turns out , as per shop manual, provide the best idle quality". If I turn the needles about 3/8 turn either direction, then the idle quality begins to deteriorate. I am just about at the center of the "optimal range of adjustment", and this just happens to coincide with the baseline in the shop manual.
I realize that the 1 1/2 number is just a guide, but wouldn't you suspect a problem if the engine ran best at, say, 1/2 turn?

Joe

P.S.:
In an unrelated issue, I had "Dick" tell me, "off the boards", that his 327/365 had 10.5 ihces @ idle (800RPM). He then took his (presumably, Holley 2818) carb back to the rebuilder who "took it into another room" presumably to make adjustments. "Dick" then put the carb back on the engine, and bingo, the idle vacuum was 13.5 in-hg @ 800, and the engine runs better than ever.
In my view, 10.5 should be right ("Dick" says his 327/365 is stock, presumably with the 30-30), and 13.5 too high. I have never heard of such a phenomenon! What do you think.

[John H.]

Re: Pesky SHP Problem (?)

Joe -

If highest steady vacuum is obtained at 1/2-turn out, it most likely indicates that either the needle or its seat are scored (from turning it in to seat too tightly), and the desired orifice area is thus reached with less needle movement off the seat. Dunno what happened "in the back room", but I have the same "30-30" cam the 327/365hp uses in my (stock) '69 Z/28, and it pulls 9"-10" Hg. at 900 rpm, and that's as good as it gets.

[Joe C.]

Re: Pesky SHP Problem (?)

John:

I'm glad that we agree. "Dick" didn't accept my reasoning, so I suggested that he post his story here, but he never did. I wish I knew what kind of alchemy was done to that carb of his. My feeling is that he SHOULD be pulling 13.5, and that the original 10.5 was probably wrong due to a vac leak. I guess we'll never know. "You can lead a horse to water, but.................."
Wow--your little 302 Z motor draws less vac than mine. I suppose your lash is a bit tighter than mine. It's always a pleasure talking with you.

Joe

[Clem Z.]

Re: Fuel and Vacuum Issues (long)

you are correct as warped metering bodies are a big problem with all these older holley carbs and it got worse when holley went to the 5/16" hex head float bowl screws because bubba uses a 3/8" drive ratchet now instead of a screwdriver. i have also seen warped float bowls for the same reason.the metering bodies can not be machined as you will loose the little projections that help seal the metering body passages to the gasket,you must straighten the metering body in a press using a holding jig.

[Clem Z.]

PS

the throttle body plate has the same problem of warpage causing a vacuum leak between it and the main body. it can be machined flat with a flycutter in a milling machine

[Clem Z.]

Re: PS/PS

just for the hell of it try a 8.5 power valve to see if the earlier opening may cure your problem since you say you need to pump the gas to make it work. this is after you check the metering body with a short straight edge.