| sarahcecelia | -- 12-09-2019 @ 5:40 AM |
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If a motor misses, ONLY UNDER LOAD, I'm thinking "it must be spark plugs," any others have other ideas about that?? They are fairly new Auto lite, and people tell me that Auto lite plugs are bad news, that I should change to Champion H10's. Tell me your thoughts I can push the clutch in and it revs smoothly, and normal acceleration is okay, but accelerate like you want to pass, and it misses. Regards, Steve Lee
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| Model B | -- 12-09-2019 @ 6:10 AM |
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You didn't mention what year car you have. On my '50 Ford, when it was missing under load I replaced the plugs. Didn't help much. I use Autolite 216 plugs. They work well in my car. I finally solved my problem by replacing the vacuum advance canister on the loadamatic distributor. Works great now.
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| mfirth | -- 12-09-2019 @ 8:49 AM |
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Coil is also a possibility, or decreased fuel delivery under a load.
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| 4dFordSC | -- 12-09-2019 @ 10:31 AM |
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You might check the plug wires, too. Easiest way is to wait until dark and then start the engine. Bad wires will cause arcing from the plug base to the cylinder head. FWIW, I use Autolite plugs with no problems.
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| carcrazy | -- 12-09-2019 @ 2:53 PM |
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Suspect marginal fuel supply, inadequate to handle increased load. Weak fuel pump is primary suspect.
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| sarahcecelia | -- 12-11-2019 @ 5:04 AM |
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Car is a I950 Ford sedan. Regards, Steve Lee
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| 51woodie | -- 12-11-2019 @ 5:07 AM |
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It is hard to define the term “miss” when it comes to engines. In my experience ignition issues such as a bad/loose electrical connection is akin to turning the key on/off, or a “stumbling” (jerky) feel under acceleration. With fuel flow issues on the other hand, an engine will slow or speed up as if the throttle was being peddled. In other words, a more gentle change than an ignition issue. A restricted (plugged) fuel filter will often allow low speed operation but the engine will die under hard acceleration or at higher speed. Yes, ignition systems also break down under acceleration as well, and there are a lot of causes, which need to be checked one at a time, and preferably with test equipment such as a volt/ohm meter etc.
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| sarahcecelia | -- 12-11-2019 @ 5:17 AM |
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It has MSD ignition and very high quality plug wires. This motor was built by H&H of California, it is fully hopped up, at a cost of $9,990.00. It's bored, has Navarro polished heads, 4 barrel polished intake manifold, Isky 400 Jr. cam, 390 Holley 4bbl. carburetor, with Mercury crank, cast iron headers, and the plugs need 2 washers so the valves don't hit the electrodes !!, and a Holley electric fuel pump,with a "block off" plate where the factory fuel pump would go, and a glass fuel filter. It's very fast!! Regards, Steve Lee This message was edited by sarahcecelia on 12-11-19 @ 5:25 PM
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| TomO | -- 12-11-2019 @ 8:50 AM |
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Because you had the engine modified, it is difficult to determine the source of your miss. When you modify the engine, you are responsible for making sure that all of the components are engineered to work together. Bogging down on acceleration is often the results of poor re-engineering. It could be the MSD ignition or that the plugs are leaking compression due to the extra gasket or that the carburetor is not matched to the engine with its modifications. It could also be due to insufficient fuel delivery for your carburetor. It could also be that the cam is not meant for street driving. Here is the warning for the cam that you have: " Info Not for the faint of heart, and not for the street! This famous Isky 400 Jr. grind camshaft is full race, competition only and is recommended only for the experienced flathead V8 racer." Start with finding spark plugs with the proper reach for your heads. The electrode should be in the compression chamber. Using an extra gasket is asking for trouble, you cannot get the correct torque and may get a compression leak. Tom
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| 4dFordSC | -- 12-11-2019 @ 1:33 PM |
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In view of all the modifications made to your engine, you might have better luck your question over on the HAMB.
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| sarahcecelia | -- 12-11-2019 @ 5:22 PM |
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Nope it's neither of those. My hunch is still plugs, the are Autolite 816's., and a lot of guys have had problems with them! I had one that had about 100 miles on it; it was clean, set to .032, in good condition, and it wouldn't spark!! I took it out connected it's lead to it and grounded it on the head, cranked the motor with the button at the bottom of the starter solenoid- and NOTHING!!;put another new one in, and it sparked!!Go figure!!! Regards, Steve Lee
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| sarahcecelia | -- 12-11-2019 @ 5:52 PM |
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This motor ran fine one day and then started to miss on harder acceleration; like just normal passing. It doesn't miss on normal" "neighborhood" acceleration. And I AM! a former race driver. I raced dirt track oval with a '40 Ford sedan in the 1950's., With floor shift( ran 2nd gear) and very hopped up "Flattie;" 3 carbs, wild cam, bored, heads, headers (with no exhaust pipes or mufflers), stroked, relieved ,you name it, and then went to outboard boat racing in the late 1960's. I ran "Stock Class B Runabout" with a 20 HP mercury W/ Quicksilver lower unit, and did 57 MPH. I had a hydroplane also, B Stock. and with the same motor it did 64 MPH. I won the Florida State Championship in my class with the runabout, in the 1980's.The alky's (alcohol fueled)with the same type boat, ran in the 70 MPH range! So I can handle that 400 Jr. cam with ease! Been there, done that!! Regards, Steve Lee
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| sarahcecelia | -- 12-11-2019 @ 5:57 PM |
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I still think it's plugs, and just wanted to know what others thought. I got a new set of champion H10's and I'm going to install them and see what gives. Thanks for all the nice replies, I sincerely appreciate them! Regards, Steve Lee
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| sarahcecelia | -- 12-11-2019 @ 6:12 PM |
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Tom, Got to have that extra washer or the valves will hit the electrodes! I made that mistake. I took them out to inspect and clean them, put them back in. Ran the motor in the shop, revved it and all of a sudden it was missing, Shut her down, found the one that caused the miss, took the plug out, and The electrode was almost totally closed! That extra washer was not on it! I found it on the floor under the motor. Put it on and no miss. But that was not under a load in the shop when I revved it! NAVARO High Compression Heads need those extra washers!!It's a must!! I called Mike at H&H and he verified it!! Regards, Steve Lee
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| sarahcecelia | -- 12-11-2019 @ 6:14 PM |
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What or who is Hamb, and how would I contact them???I though that was smoked pork! HA Ha!! Regards, Steve Lee
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| 4dFordSC | -- 12-11-2019 @ 6:31 PM |
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https://www.jalopyjournal.com/forum/forums/the-hokey-ass-message-board.5/
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| sarahcecelia | -- 12-12-2019 @ 11:45 AM |
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Tom, Torque has no relation at all as the what is being torqued; unless you are torqueing something on say "rubber." It' a precise measure of "TIGHTNESS ONLY." I didn't think I had to explain this about the extra "Washer" but I guess I do, It's not an extra spark plug washer, its an "indexing washer," along with the regular Plug "Crush washer." When I raced Flatties ,"back in the day," All plugs were 'indexed, " to get the spark in the proper position for more complete combustion; and it really helps with the power! I know the plug are "indexed" on dragsters and in NASCAR. It's a "real science" when you race anything with a motor; and I did a lot of it, and it was a very exciting part of my life! I quit in the late 90's because I was always winning, and that takes all of the challenge, and thus, the fun out of it!! Regards, Steve Lee
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| MG | -- 12-12-2019 @ 2:09 PM |
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H.A.M.B - Hokey Ass Message Board. It's an online forum. See > https://www.jalopyjournal.com/forum/
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| 37RAGTOPMAN | -- 12-13-2019 @ 10:01 AM |
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HI STEVE LEE I replaced my champion spark plug with NGK, AB-6 stock 2910 fit 1933 to 1938 and made a great improvement, my 37 is not a race car, NGK has spark plugs part number, B6L stock #3212 that may be what you need,? IN their listing this is for 49 to 53 FORDS, also have the IRIDUM IX plugs for the 55 and up FORDS, part number WR51X might be also a option, it might be worth the try, you can call them they also have a listing for RACING SPARK PLUGS, with illustrations of many spark plugs in there catalogs do a little research, being you have high compression, you will have find out what works for you. are you using high test gas or racing fuel, I had a similar problem in my 57 CHEVY and it was a condenser,started to miss under load, you also may have a fuel problem, what size is you fuel line coming from the tank,? if are trying to feed 2 or 3 carburetors this may be a issue, trying to help 37RAGTOPMAN This message was edited by 37RAGTOPMAN on 12-15-19 @ 7:48 AM
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