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09-12-2018 08:47 PM #1
Please help me understand this....
Hi, Dave here. Got a fully rebuilt SBC 350 in my hot rod.
-has newish new Edelbrock
-has newish HEI dist.
-newish new shorty plugs
-160lbs every cylinder
-valves well adjusted
-adequately timed
Starts right up but runs poorly, missing on three cylinders: checked with electronic temperature sensor on header tubes.
Spark seems to be getting to all plugs, pulled and observed for spark.
WTF is going on? Totally frustrated by this! Where would you guys go next?
Thanks much for any ideas!!
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09-12-2018 09:25 PM #2
First thing I'd check is the spark plug wires, Are they Accell as well as the plugs?Ken Thomas
NoT FaDe AwaY and the music didn't die
The simplest road is usually the last one sought
Wild Willie & AA/FA's The greatest show in drag racing
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09-12-2018 09:45 PM #3
Ken, Plugs are ACCEL but the wires are likely not, but fairly new. What cha thinking?
Dave
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09-12-2018 10:08 PM #4
I've never had any luck with anything that has Accell stamped on it. If you have a decent multimeter Check the resistance of each plug wire. Anything over 500 ohms, IMHO, is too much. How old is the module in the distributor? What kind of cap and rotor bug? The module is solid state and normally they either work or don't. The cap and rotor if they are cheap can ark between contacts. I like something with a high dielectric strength.Ken Thomas
NoT FaDe AwaY and the music didn't die
The simplest road is usually the last one sought
Wild Willie & AA/FA's The greatest show in drag racing
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09-13-2018 04:23 AM #5
I’m not trying to ask a dumb question, but are you SURE that the plug wires are not crossed?Steve
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09-13-2018 09:54 AM #6
Driver50x, that was not a dumb question!! That would be something I might do :-/! Given that, I have checked the wires for correct location (but now I will do it again :-) ). Maybe those ACCEL plugs are the problem. I only used them because my damn headers are so close regular plugs would not fit or if they did, the wires were touching the header pipes. The distributor is new though I did get it off eBay. It wasn't the cheapest.... :-0.
I'll get some shorty plugs from AC or and let you all know what happened.
Thanks,
Dave
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09-13-2018 12:32 PM #7
I run E-3's in my 76 Vette and 04 Dakota. In June I drove from Springfield, Mo. to Columbia, SC to attend my grandson's boot camp graduation at Fort Jackson. Round trip is just under 1800 miles and the Dakota averaged a little under 20 mpg which I don't think is too bad.Ken Thomas
NoT FaDe AwaY and the music didn't die
The simplest road is usually the last one sought
Wild Willie & AA/FA's The greatest show in drag racing
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09-13-2018 01:15 PM #8
- Join Date
- Apr 2011
- Location
- Prairie City
- Car Year, Make, Model: 40 Ford Deluxe, 68 Corvette, 72&76 K30
- Posts
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I tried running the accel plugs back when I had my 72 Camaro and they were garbage. I'd never use them again.Ryan
1940 Ford Deluxe Tudor 354 Hemi 46RH Electric Blue w/multi-color flames, Ford 9" Residing in multiple pieces
1968 Corvette Coupe 5.9 Cummins Drag Car 11.43@130mph No stall leaving the line with 1250 rpm's and poor 2.2 60'
1972 Chevy K30 Longhorn P-pumped 24v Compound Turbos 47RH Just another money pit
1971 Camaro RS 5.3 BTR Stage 3 cam, SuperT10
Tire Sizes
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09-18-2018 02:21 PM #9
Dave here again (thread starter) about the SBC not firing on several cylinders... so as before I have 160+ per cylinder, new HEI, new carb, good wires and now new Autolite plugs. Same problem... not firing on at least one cylinder!! This is crazy. With my temp sensor #8 for example showing like 250 deg where most all others are around 450 pretty soon after startup. Also again, this is a totally rebuild engine with probably 2 hours or less of operation.
**My carb spacer does not line up the carb and intake manifold all that well. As I recall the vents are kinda offset. Could that effect fuel getting to different cylinders? Or any other ideas??
Thanks again, Dave
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09-18-2018 02:41 PM #10
Thanks Denny. Plugs were checked and all the same. The valves were adjusted... correctly?, well thats another question :-/, but I believe I got them right this time! Is spraying starter fluid to look for vacuum leaks?
BTW, should I be getting about the same temp on each of the header tubes? Even #8 for example is sorta hot (250) which may suggest it is firing but poorly... yes?
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09-18-2018 02:49 PM #11
Hold the rpm at a steady 2.000 rpm with no load if it has a steady pop through the intake it has a flat cam. You can have good compression somtimes with a flat cam. With todays oil flat cams happen on start up vary often. Take a magnet and drain the oil over the magnet if it grows hair the cam is gone.I'LL KEEP MY PROPERTY, MY MONEY, MY FREEDOM, AND MY GUNS, AND YOU CAN KEEP THE CHANGE------ THE PROBLEM WITH LIBERALISM IS SOONER OR LATER YOU RUN OUT OF OTHER PEOPLES MONEY margaret thacher 1984
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09-20-2018 04:43 PM #12
Hey you guys. So I put in new plugs and the same things are happening as above. But in looking around the net for why this could be happening I see that a leaking intake manifold or an unplugged vacuum hose/fitting seems to have all symptoms I am experiencing.
-hesitation when acceleration
-misfiring
-rough idle
-overheating
So I will do what Denny suggested and spray some starter fluid/cleaner around looking for rpm changes. Yes I have a working fire extinguisher just in case and yes it is in the garage!!!!! :-)) BTW a pic of the beast "we" are working on is hopefully attached.
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09-20-2018 06:56 PM #13
Few things to try run it in total darkness and look for spark plug wires jumping spark--------
take valve covers off and check to see if pushrods are rotating as valves lift/close( Lobe wiped on cam-----lifters should rotate and also will spin pushrods) turn carb around and see if missing cylinders change---plug all vacme lines------
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09-24-2018 03:50 AM #14
My first "go to" tune up tool when there's nothing obviously wrong with the simple things is a leak down tester. It's also a really goo way to keep track of what the engine has going on internally. JMOYesterday is history, tomorrow is a mystery, Live for Today!
Carroll Shelby
Learning must be difficult for those who already know it all!!!!
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09-24-2018 04:34 PM #15
Don't overlook a leak at the inside bottom of the intake at the interface of the cylinder head, where you may or may not find a leak with a sprayed flammable substance. Such a leak will allow oily vapors from the oil pan to be sucked into the intake port, disrupting air/fuel mixture balance and providing a vacuum leak. It will also foul the spark plugs with oil. If you find nothing pointing to a leak, pull the intake and examine the gaskets to insure that they are being pinched with equal force top and bottom, side to side. The manifold could have been mis-machined. If nothing is found there, examine the manifold for cracks. We used to use a Zyglo process back in the day, but there may be better ways today.
.Last edited by techinspector1; 09-24-2018 at 05:31 PM.
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Welcome to CHR. I think that you need to hook up your vacuum advance. At part throttle when cruising you have less air and fuel in each cylinder, and the air-fuel mixture is not as densely packed...
MSD 8360 distributor vacuum advance