OLD 427 Chevy need help better cranking

[STREETRACE69]

Ok, new here and read for days for answers before posting. I have better understanding but need some clarification.

Engine is basically an 11:1 427 L88 with some head work and a modern flat tappet Comp Cam. It is a healthy engine that runs 12:40's in street trim on street tires.

Anyway, I bought as is and it ran great. Never runs hot or any other oil issues. I read all the Zinc threads and ran out and bought some Rotella 15-40.

I noticed car was hard to turn over and almost straining starter. I spent days thinking by coincidence I had a starter issue. I used a meter and now know the draw of every part of the system. It is fine. The lugging is exaggerated when the car sits. If the engineis warm or at temp it rolls right over. The lugging happens even if it is 80 deg and it is the first start.

I had a BMW and had left over 5w-20 or 30?(forgot) BMW oil. I emptied my new Rotella and poured in the BMW oil.

The engine now spins freely again at start up. I live in SOCAL so we aren't talking about freezing weather here.

Question I have is I know going from a 10-5 or 0 will help with colder temps but does it also help with say initial start in average temps? Will a 10w-30 have the same (less honey) less starting friction?

I don't want to get into the whole zinc? deal so I am trying to concentrate of what weight oil I should be getting without going too thin? I know technically a 10w dino would be thicker then a 10w syn correct?

I just don't want to keep throwing out oil. 10W-30 SYN?

Thanks and sorry for long thread.

 

[user52165]

Use a high torque gear reduction starter. Aftermarket or Corvette application. Also upgrade cables like to 2 or 0 gauge.

 

[OVERKILL]

The BMW oil is made by Castrol and is actually relatively heavy (HTHS >=3.5cP) and is likely perfectly safe to run as long as it satisfies the oil pressure requirements for your engine.

 

[maybehabitformin]

How much lift does the cam have ? Is it solid or hyd?

 

[Chris142]

Plenty of high compression BB chevies are running 20w50. Some straight 40 or even 50. If 15w40 is causing a problem you have something wrong with the starting system. Like an undersized battery or cables. Is the battery in the trunk?

 

[maybehabitformin]

A stock starter and a 11.1 engine is some of it.If it where my engine i would run T-6 5w40 or even mobil 0w40.I am fairly certain they have enough zinc i wouldnt run anything less than 1200ppm.If you want dino use VR1 but its not for long OCI.

 

[OVERKILL]

BTW, the oil you are using currently has the following Zinc/Phos levels:

Phosphorous 884
Zinc 1004

According to this VOA:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2888703

IIRC, the oil is SL rated. It is actually a relatively robust product.

 

[STREETRACE69]

Ok there is nothing wrong with starter or starting system. I fully understand engines turning over with 14:1 and race oil but that isn't the issue.

Starter is actually factory GM custom built that I use in all of my builds which is 10x's better then the off shore junk. Majority of low end Gm gear reductions are mix's up metric/standard that are a mess on many levels. Starter system is isolated on custom cables and relay set up. It works. I did not build engine so I am limited in what I know about it or it's internals. It is a Hyd Cam that isn't too crazy.

You can have a 15:1 race engine that turns over easier then a 8:1 350 due to quite a bit of variances such as timing, gaps, etc that have nothing to do with a starter.

I guess I worded wrong as engine turns over fine with either oil but there is a definite difference with the 15w-40 Rotella then whatever was in there and now with the BMW oil. The BMW oil is like water compared to the Rotella.

I am going to try the Mobil one just for the reason it is avail local. If they have the Rotella in lower numerical grade I will try.

I am going to actually see if I hook up tach to verify spinning RPM with different oil changes only. Curious!

I appreciate the help and will report back with findings.

 

[SteveSRT8]

I've had many a BBC, and they can tax the stock starting setup.

As mentioned above, some cable upgrades helped my LS6 Chevelle. Aftermarket starters will spin her up faster as well.

But the real issue is firing the ignition. I'd seriously consider an ignition upgrade. Spark box, big coil, and some correctly gapped plugs can make FIRE and get it running the second it gets a spark.

Good luck and enjoy that L88!

 

[BillyTheKid]

I am no expert and am more into the motorcycle scene, but I think the advice on starter and cable upgrade makes the most sense to me. I also do not see an oil difference being able to cause a cranking issue (could be wrong but find it not likely). Also, is this a true 11 to 1 compression or just piston rating? The little I know is that head-work can modify the actual compression ration when tested (both up or down depending on what is done to head). I also have heard and witnessed that most true 11 to 1 cars would usually need more than pump gas to run without fear of leaning out.

I also have seen multiple times when building a motorcycle build, the piston to wall clearance is key in making a difference of needing two batteries vs one to start the same size engine/pistons. The better builders pay very close attention and make sure the piston to wall is slightly looser to use only one battery. Not sure if this would be the case on a car though.

 

[bigt61]

Mobil 1 15W-50 - worked great in my SBC road race cars and in the BBC tow Suburban. It certainly pours thin IMO.