I just installed a freshly rebuilt L36 427 in my '69. The car used to have 454 as of two months ago at which time, ran perfectly. The 454's flywheel and starter have been reused. For simplicity, just to make sure the rebuilt 427 would crank over without fuel & ignition, I connected all of the starter/solenoid wires, but left the alternator and ignition coil disconnected. Also, the clutch is disconnected so the pedal is to the floor thus closing the safety switch. So it was just a simple battery/ignition switch/starter setup (and fuse buss). With full enthusiasm, I connected the battery, checked voltage, sat in the seat, put her in neutral, and turned the key. The starter spun but the Bendix would not engage. The battery is fresh and the headlights shine brightly. I tried again with the headlights on just to see if there excessive amp draw when trying to start the engine. The headlights dimmed just a little, but only to the degree expected when trying to start a car. There was nothing out of the ordinary with the dimming. Dash lights work, and the taillights and brake lights shine bright.

I climbed under the car and had a buddy turn the key. I swear the starer motor spins, just no Bendix engagement. I thought that possibly the Bendix was engaging, but the starter motor wasn’t strong enough to turn the engine, and that maybe the sound I was hearing was the starter motor “buzzing”. I seriously doubt this since the headlights work normally, and also, I would think the start motor would get very hot. However, I’m very open minded on this, but for now, I’m assuming it spins. It spins, then when letting go of the key, it winds down. I measured the voltage at the main battery connection on the solenoid and read 12.8VDC when they key was off. I then measured the voltage with the key rotated and starter motor spinning, and read 7.7VDC right at the main battery connection. I get very similar readings at the ignition switch terminal (on the solenoid) and also the ignition coil terminal. Does this sound correct? The starter motor sounds like it's spinning normally.

So I yanked the starter and removed the solenoid. I suspected the solenoid may have been weak and so wasn't throwing out the Bendix out to full sroke to engage the flywheel. But as I looked at how the mechanism works, I can't see how the actual starter motor can operate without the Bendix actuating fully. In the solenoid, there's a little button that when depressed, pushes a metal disk that makes contact between the main battery terminal and the starter terminal. It looks to me that the button can’t be depressed unless the metal cylinder (that connected to the Bendix linkage) throws fully (I plan to bench test the starter/solenoid this evening). I took measurents to see if it looked like the Bendix could indeed engage when at full stroke and everything looks fine. Any ideas? Thanks for your replies.

 

How do you know that the Bendix mechanism is not moving? With it assembled, you can't actually see it (unless inspection cover is removed). Could it be engaging but the starter motor not turning?

 

Thanks for the reply 7ZTvette. You're right, I don't know if the Bendix is moving or not, but the starter motor sure sounds and feels like it winds up, the winds down when the key is let for. My buddy held the key in the start position for 4 seconds. I can understand if the Bendix was throwing properly and perhaps is missing it's target (flywheel) but I find this hard to believe. Nothing's changed with the bellhousing, flywheel, and starter. The only this that's literally different is the crank, but I can't see why this would be different than the 454's. I measured the crank and Bendix depth and it sure looks like they line up.

 

You are aware the 427 is internally balanced and the 454 is external? Complete different system.

 

Thanks for the reply TimAT. Are you referring to the harmonic balancer? I'm using the 427's. What other differences are there? Is the crankshaft different, particularly length? Is the 454's flywheel incompatible with the 427?

 

If you still have the starter on the bench apply a GROUND to the case and 12 volts to the "S" terminal.
The Bendix should extend.

You can do the same test if the starter is in the car but disconnect the big positive cable first.

 

Both the balancer and the flywheel are different between the 427 and 454. The 427 is internally balanced and uses "neutral" balance balancers and flywheels. The 454 is external balanced and both have weights made into them.

 

Thanks, it's on the bench and I'll test it his eve.

 

You can't use the 454 flywheel on the 427. You need to get a neutral (internally) balanced flywheel for the 427 (as well as the appropriate vibration damper). That's not why the starter isn't working, but if you get it started, you are going to have major vibration.

 

Ugh, I had no idea. Thanks for the insight. However, I still can't figure out why the starter won't engage (although I will bench test the starter this eve). Are the crankshaft lengths different too, and maybe the Bendix is over/undershooting the flywheel?

 

You need to "bench" test your starter using jumper cables and see if the Bendix is snapping all the way out against the thrust bearing in the nose. A Bendix can slip but it's unlikely in your case since it was operating fine just recently. If you're in doubt about the state of charge of your battery but a trickle charger in it overnight to make sure it's fully charged when you go to test your starter.

As far as the flywheel goes it sounds like you installed a smaller 153 tooth flywheel when it needs the larger 168 tooth flywheel.

 

Thanks 71VetteLover. The flywheel/starter combo is the exact one I took from the 454, so the teeth count match. That is, unless there's something geometrically different about mounting the 454's flywheel onto the 427's crank. I can't imagine there's a difference in centerline location (side to side), but may the crankshaft length is different. Could this be possible?

 

The 427 and 454 use the same block. In fact, the blocks even had the same casting number on them for a late 69 427 and a 70 454 but the difference in cubic inches is from the stroke of the crank. You cant use a 427 flywheel or balancer on a 454 crank or it will vibrate to pieces and you cant use a 454 balancer or flywheel on a 427 for the same reason. A 454 is externally balanced with the offset balanced flywheel and balancer used for the equally offset crankshaft while a 427 has a neutrally balanced crankshaft, balancer and flywheel. It will vibrate and ruin the bearings along with the crankshaft if you mix them up. Do not start and run it if those are the parts you used.

 

Thanks a bunch CanadaGrant, I really appreciate the info and you l(along with other replies) likely saved me a great deal of heartache. When you say "offset balanced flywheel", are you referring to the where the weighting is on the 454, or are you referring to the geometry? Is the centerline on the 427 somehow different to that of the 454?

 

Due to the longer stroke on the 454 crankshaft it was not feasible to balance the crankshaft to "neutral" so they used a balancer and flywheel which are permanently offset weighted like you would use weights on a tire and wheel only it is not adjustable or removable. If you look at a balancer on the rear side it has a counter weight cast in on the back side on a 454 and is perfectly round on a 427. They will both fit on either but will not work for very long... That faulty starter probably just saved your bacon but as previously mentioned, you might also have a 153 tooth flywheel on it.

 

Bench Test Results... I did this on my bench with the pulled car battery and my own wiring. The Bendix strokes just fine, enough to engage the starter motor (the metal disk inside the solenoid pulls in and makes contact between the main battery terminal and the motor terminal). It's what I pretty much expected. The starter motor won't run if the Bendix is more that an 1/8th inch retracted. Plus, I can't imagine the thing would stop working just sitting on the garage floor for two months - it worked fine before. So, I still racking my brain as to why it wouldn't work. I know I need to invest in a new flywheel. Thanks guys, SO much for pointing out this near disaster! But, I'd sure like to know why my setup wouldn't work. I just want to flush out any other possible issues since I have to pull the engine. Is there anything geometrically (not balance) different with the 454 flywheel being mounted on the 427 crank? There has to be an explanation. I can't see it being a tooth count issue since it worked before. Or maybe it is a tooth count issue as related to now being on the 427. I don't mean to beat this issue to death, but it just doesn't make sense to me and certainly don't want to yank the engine and swap the flywheel only to have the issue repeat. This has been a great learning experience!

 

The bolt pattern and other things are the same between the flywheels. The difference is the added weight on the 454. THE tooth count/diameter is interchangeable between both 427 and 454 PROVIDED the balance issue is taken into account. Some bell housings don't have the inner size to fit over the 168 tooth flywheel. There are also differences in the mountings for the clutch, some flywheels are drilled for both 11" and 10.5", others are just drilled for one or the other.
There are several pictures around showing the differences in both internal and external balance flywheels/flexplates/harmonic balancers.
External Balance: https://www.bing.com/images/search?v...x=0&ajaxhist=0

Internal Balance: https://www.bing.com/images/search?v...x=5&ajaxhist=0

 

Since you have to pull the engine, you can bolt up the starter for a trial fit with it out of the car to measure things up. Without the bell housing it will be easy to see where your problem is. If you are using the exact same fly wheel and starter combination as before it has to be a starter problem but you still have to change the flywheel and front balancer to neutral balanced 427 items.

 

For a 1969 L36 427 this is the stock flywheel and balancer you will need:

http://www.parts123.com/corvettecent...050g&ukey=8904

http://www.parts123.com/corvettecent...050g&ukey=8052

After you look at the correct flywheel in the top link, look up one there for a 1970 454 and it clearly shows the cast in offset balance weights in the pics. Think what that would do to your neutrally balanced 427.

 

Thank you very much, all, for the replies. CanadaGrant is exactly right, the weak solenoid (has to be) saved my bacon. Phew. I should have done a little more homework! I'll get a flywheel on order once I verify the tooth count, which I'm pretty sure, is 168 but best to verify before ordering. The harmonic balance is the correct one fortunately (not the one from the 454).