Rebuilt 308 engine too stiff to crank

Hi all,

I've just finished a full rebuild of my 1978 308 after dropping a pair of valves in cylinder No. 8. New JE Hi Comp pistons, new std. bearings, new Catcam 1700402 cams & valve springs.

The unit is back in the car. Before fitting spark plugs, carbs, and ignition, I thought I'd spin the engine and get some oil circulating.

The first problem was the solenoid would drop out as soon as power went to the starter (hi-torque pre-engaging), and then chatter away.

I got over this problem by fitting an independent supply with remote button to the solenoid.. The solenoid now holds in, but even with three 12v batteries in parallel, the starter will not turn.

I did a check, and it takes 55ft/lbs to turn the engine manually.

I have the option of putting an independent 24v on the starter. Alternatively. towing the car in high gear to get oil circulation, and hopefully, a looser engine.

I've done searches here without results.

Any ideas ?

Thanks.

 

if you are having issues with oil. towing it to get oil circulation will shred the bearings. Ideally you want to get the oil pump turned with the starter as you are trying.

Was assembly grease applied to all bearing surfaces (or whatever Ferrari recommends for lubrication on rebuild)?
All bearings were clearanced? If so what were the clearance?

Have you checked that all the wiring to the starter is connected where it needs to be?
Have you checked the starter outside of the car to make sure it is operational?

 

The best way to pre-prime a 308 engine is with an "oil pig", which is essential an Accusump. That's how a profession engine rebuilder would do it. 55 lb-ft for a fresh engine is not unreasonable. High turnover friction is often due to improper ring gaps, align bore issues in the block or in the cam bores. Sounds more like a starter issue than anything else...

 

With respect, I can't see why turning the engine by towing would be any different than turning it on the starter.

Every bearing was lubed with engine oil during assembly.

All crankshaft clearances with new standard bearings were checked. After 50K miles they were all very slightly greater.

As each camshaft and crankshaft bearing was torqued up, they were checked for binding. There was no significant binding on any one.

The starter was removed and checked on the bench. It operated fine, as it did before the rebuild.

Island Guy's suggestion to use an Accusump seems a very good idea.

I will check how I can pressure feed the oil system manually, should work !

 

Good idea !

I'll see how I can arrange to pressurise the oil system manually.

I imagine the oil light sender connection would be a good place to start, while monitoring the oil pressure gauge (it works ! )

 

very simple. Towing means vehicle moving. If something goes south, the mass of both vehicle will overcome ANY binding on the motor to include throwing a rod through the block without much resistance. A starter will never do that (not enough torque) and it can be stopped as fast as it was started.

 

I agree with that proposition. Vehicle mass could result in damage if "something goes south"

But if I can manually turn the engine with 55 ft/lbs torque, I don't think I'll be throwing any rods !

 

I do not know what the minimum torque value is to hand turn but if the starter is OK and getting full voltage I would find out about the binding prior to an initial start.Could be a cam belt,dizzy or any other accessory. Better to backtrack than to make a very expensive mistake.Mike

 

What a strange problem that I have never had. 55ftlbs seems huge to me and might prevent a starter motor from turning the motor fast enough to fire. When I rebuild a motor with no heads I can turn with my bare arthritic hands. When head is on I need a short 8" or so hand ratchet. If I'm turning the motor to TDC to set up for cam timing in the chassis I need a long 18" or so ratchet. I can turn motor with very little hand pressure like a firm handshake with a bar that long. But a good starter motor has to be around 200ft/lbs. So could you have 2 issues of weak starter motor and something binding in engine that makes the starting rpm too low to fire up. In a 348 for example the electronics does not work until you get to 30RPM. There is not such spec in the 308 WSM as far as I can remember.

 

Pull the plugs and see if it turns easy would be my 1st thought.
Clutch and tranny mating ok?

 

You mentioned new pistons. Did you check and set the ring gap? 55ft/lbs is way too much force needed to turn that little thing with the plugs out. With plugs out you should be able to turn it with a firm hand.

Second..are the accessories installed? A/c, altermator? Maybe remove the accessory belts and see if that changes anything.

 

Ahem ! Check my post, the plugs have not yet been fitted !

 

Yes, I can turn it (with a firm hand ! )

No accessories fitted yet.

 

My thoughts would be to check what current the starter motor is drawing when attempting to crank the engine. I would think a good starter motor cranking a motor with no plugs fitted would probably be around the 150 amps region. If the motor is too tight to turn you'll see a massively higher amps reading, probably around what the battery is capable of delivering but certainly in excess of 400 amps. If you've got hardly any current draw then you've narrowed it down to an electrical issue/starter issue

 

You're on the right track there. I didn't check the current draw when the engine failed to turn, but my clue should have been that when I turned on the headlights, they didn't dim when I operated the starter.

In the meantime I disconnected all the electrics at the main starter, solenoid and battery, rigged an independent 24V supply direct to the starter, and rigged an independent 12V supply with push button to the solenoid. It seems the problem was poor contact at the solenoid connection. The car has been laid up for the last 3 years while the engine was rebuilt. The 24V spun the engine without plugs, then with plugs, and when I restored the original connections, it turned free enough on 12V.

The turning torque reduced to 35 ft lbs.

Thanks for all the suggestions.

Now to find out why I'm not getting sparks !

 

Geeze if you can turn 55ftlbs with your hand you are freaking Hercules.

 

I'm turning it by hand with a torque wrench !