My 354 starts up fine and seems to idle nicely. When I give it some gas, it stops sounding good at around 3000 rpms and doesn't really want to go too much higher. Sounds like it starting to miss & sputter. What should I be checking first? I need to get some timing tape (can't easily read exactly where timing is at on the balancer now), but I think it's right around 10 btdc (give or take a degree or two). I bought a vac gauge so I can try to get the timing set by using that (found instructions here on how to do it). Plugs are gapped at .32....is that good? Distributor is the hotheads MSD ready to run unit. New plug wires and good grounds everywhere. Cam is a sig erson racing cam - I can look up the specs if needed. Everything on the engine is new except the coil...should I buy a new coil to see if that's the problem? Just looking for some ideas on things to check. I'd like to get it tuned before I put the front end sheet metal back on (more room to work on the engine).
MSD unit as well as the distributor? they go from multiple spark to single spark around 3K. supposed to, but some don't. timing too far advanced? (does it fight the starter?), running out of fuel delivery?
I don't have that stand-alone red box..just the MSD Distributor. It starts up pretty easy and idles nice right away...just starts to miss/sputter when I get on the pedal.
I would either say too much timing...or you have a bad fuel pump or fuel filter...something that limits fuel volume...collapsed sock in the tank, collapsing rubber fuel line in the rear...something like that.
I had that problem with a msd .Hook up a timing light and bring up the rpm and see if the timing mark is jumping around,is there a vacuum advance?does it do the same thing with it plugged off?
I know its not the same but I got a 426 hemi with the same type of problem once cheap becaue ti wouldn't rev. We opened up the top end once thinking we were going to find a broken spring, it was a real stumper. In frustrartion I started picking up my tools so I could ruminate on it over night. When I picked up my hammer that I was using to keep the pushrods from rolling off the bench 3 of them rolled off on the floor. I remember saying to my self damnit I should have left the hammer there. Then I realized that not all the pushrods rolled off. So I started rolling them one at a time and found one pushrod that had a slight arc to it. Replaced the bad pushrod and it ran like a scalded ape. Might be something to look at.
In your MSD distributor literature, did it mention what Ohm rating the coil should be? GMC Bubba's list of coils
It is an industrial motor, but rebuilt with a new cam so it would run at a higher RPM. Engine was rebuilt and the heads were checked...don't think it would be a bent valve. Same pistons were used, so I shouldn't have any type of piston issue that would have bent a valve already. I didn't see anything in the MSD instructions about coil specs...I'll check that. I just read the Bubba coil thread. The coil I have came with the engine (which used a dual point distributor). Could this be used with the new MDS coil or would the more modern electronic ignition need a different coil?
Race cam with stock valve springs? That'd be my first guess. Better send that engine on down here and i'll get 'porknbeaner' and we can do some ruminating! I doubt it is ignition stuff. likely mechanical in the valve train.
Things I would search first regarding this problem: Coil improperly matched to your ignition system Distributor advance not working or adjusted wrong Valve springs are weak and not rated for the cam and lifters Weak or non functioning accelerator pump Main circuit in the carb blocked or improper sized jets plugged or restrictive exhaust Do some investigative troubleshooting before you start throwing parts at it.
I would check these 3 things first. 1) replace coil 2) fuel (delivery) 3) timing If these don't work, check for springs and valves.
Check to make sure you have advance first, Dan. If you can't see the stock timing mark with a light, roll it over to TDC #1. Get under the truck or in some position where you CAN see the pulley with a timing light and put a mark of some kind on the pulley and an adjacent stationary point. Then rev the engine while looking at the mark with a timing light. If the mark doesn't move around, you don't have any advance. I don't know diddly about the MSD distributor, but that is the first thing I would check
regarding timing, if you have 10 initial, that should be OK, but it could be that you dont have enough advance, as your rpm increases you need more advance...get you timing tape and see if it goes to 28-30 degrees or so by about 2200to 2500 rpm. You can plug the vacuum to check you mechanical advance is working and getting you up to 28-30. It will run fine at all speeds without the vacuum, that mainly helps milage. If it jumps around it could be the dizzy or the MSD...or doesnt advance its the mechanical advance on the dizzy.....fuel: put a presure gauge on it and make sure you have a few lbs minumum at all rpm range, and even if you have fuel pressure in between your pump and carb, if you have an in carb filter or the jets are gummed up, your motor wont see the fuel.....I would replace that old coil as matter of maintenence....
Engine has no mufflers right now. I've got the stock exhaust manifold with about a foot of pipe running straight down (no bends) on there now. With the timing light, when I give the carb some throttle, the timing light moves, so I know I'm getting some advance. I can't tell how much ( no timing marks that far and it moves out of sight), but I know it's doing something. The valve springs match the specs needed for the cam..those were ordered when the engine was rebuilt.
Had something similar once on a motor with a fresh rebuild. The rocker arms were way too tight. I'd adjusted the rockers, left the garage for a bit and then my buddy tightened them again not realizing I'd just done it. Engine started and idled OK, but thing wouldn't turn over 2500 RPMs. After I re-readjusted, 6000 RPM.
Sounds like classic fuel starvation. Tee in a fuel gauge and duct tape it to the windshield so you can see it and drive it down the road. If it loses fuel pressure at about the RPM you say it lays down, there you go. Simple diagnosis and it will either condem or rule out the fuel system.
I agree about the coil. If the small primary wires are backwards, it will still work, but it will be weak.
Picked up a new coil today...got the MSD coil that's pictured in the instructions that came with the distributor. In reading those instructions, looks like I'm supposed to run a ballast resistor. I called MSD tech support and they confirmed that one is needed. My current setup doesn't have a resistor. Of course, none of the local parts stores carry the one spec'd by MSD, so I ordered it online today. Should have it by Friday. Just to double check things, I used my meter to try to check the coil I have. Not sure if I'm using the right setting on my coil, but when I put the leads on the pos/neg terminal, I get no resistance. When I connect from the coil out to the pos or neg, I get some resistance, but with my meter at the 2000k setting, the resistance bounces around. Will report back after I get the resistor installed.
Whenever I had a fuel problem the engine fell on its face,,it didn't sputter ,,it just flat died. The exhaust is open,,so that is out. The timing advances,,so that is out. The coil might be it,,,but I am guessing that will not fix it. How bad does it sputter at 3000 rpm,,will it go any higher than that? Does it have good fuel in the tank? Are the plugs fresh,,I mean really new,,and the plug wires? I lean to some of the other guys,,it sounds mechanical to me,,I guess either the rocker adjustment or maybe some cam timing problem,,it did check good according to the cam card,,right? Good luck,,hope you find it soon. Tommy
It almost sounds like what you think a bad rev limiter would sound like. It doesn't want to go higher. Just sputters and stays there like it's the max RPM. Not sure about cam timing or the cam card. I bought the cam, but I didn't build the engine. It was built by a local shop. Bought the parts from one of our own hambers and he helped out with some questions during the build. Rockers aren't adjustable, but the pushrods are. The preload was set by the builder and I checked them (sort of) by rotating the engine and making sure there wasn't a gap between the rod and the rocker. All wiring is new (including the plug wires) and the plugs are new too. I brought in one of the old plugs to match up to make sure I'd get the right ones.
That is helpful info,,could the dist. be screwed up inside somehow,,,,I don't know of a rev. limit built into the dist. ,,do you? Have you tried to open the throttle even further,,,,with any success? It should rev higher,,without a load on it,,it should go on up to a point at least? But,,if the rockers are too tight,,it will sputter at a higher rpm because the valves will slightly not be sealing the pressure,,,especially if they are hyd. ,,I would look there first. Tommy
I had a similar problem with a 392 (oddly enough) - it was a bad condensor -or- a bad internal distributor ground -only 2 things I changed - problem was gone. I really think it was the condensor since I noticed the points appeared a tad "warm".
Hemirambler,,that is good info. I was thinking that a MSD dist. would be electronic though. Usually either good or bad,,not much in between. But,,here is a thought. Because of the inclined angle of the Hemi valves,,the cam timing has to be very close. Could the cam be setup a little off and causing it to be a dog,,or maybe have kissed a few valves and slightly tweaked the valve heads? I don't know how much lift is involved,,,,I do know that the valves and the pistons close on each other very fast toward TDC. Just a thought. Tommy
Also, open exhaust will cause a mild engine to loose power. I would start with a compression test. If you are using stock pistons, a big cam will bleed off most of your compression. Another problem is most new head gaskets are thicker than the originals, which also brings down the CR. What are the cam specs, & is it solid? A ballast resistor is intended to limit the primary voltage runing thru your points, which makes them last longer. I don't think that is your problem - not right now anyway. Your condensor will not last either if it gets 13+ volts as stated above.
Why do people keep babbling on about points and condenser? The dist. is from MSD, it's electronic, no points or condenser!!!!!!!! Back to the valve springs, you say they came with the cam, OK, but is the installed heigt correct on them? Dave
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