Technical Small Block Chevy 350 Rebuild

Would you guys recommend a mechanical fuel pump (the block is drilled for it. I would need a pump and a rod) or would you recommend an electric pump? I plan on having a nice diamond plate control panel with switches and gauges and starter*****on. Maybe a switch to turn the fuel pump on. If going electric, then I would just purchase a gasket and a block off plate to cover the fuel pump port in the block.

 

The crankshaft flange changed in 1986, so you have the later type, which is externally balanced. Make sure you get the correct GM bolts for the flexplate and for the starter, they are not normal hardware store items.

I'd use the big flexplate. But yeah, it doesn't really matter as long as they match.

Either mechanical or electric pump would work. Whatever you prefer.

 

The 400 is the only one externally balanced.
The flywheel depends on your starter one is for stick The other is for auto trans

 

After some more research, It appears that with my engine (a 1988, sbc 350, with a 1 piece rear main seal) would need an externally balanced flexplate. The whole diameter and the bolt pattern of the internal flexplate is larger than the whole diameter and bolt pattern of the external balancer. I would also need a neutral balancer on the front of the engine (which sounds weird to me).

I found this video that helps.

 

Just order/buy a flex plate for a ‘88 Camaro with 700R4.

 

It's not weird if you understand the history of the small block Chevy. The original 3" stroke engine had a mostly round rear crank flange, and was internally balanced. The later 3.48" stroke 350 was internally balanced also, but had a crank flange with a built in weight. When they went to the one piece rear seal in 86, they didn't have a way to add the weight to the crank flange, since the flange was now round, to work with the new seal. So, they put the weight on the flexplate, instead.

The 400 needed more balance weight than they could fit on the crank at either end, so they added weight to the front damper, and to the rear flex plate. All Chevy 400s used two piece seals, since they were made only from 1970 to 1980. This was the only entirely externally balanced small block engine.

 

Starters. I see there are two different types. I am familiar with the round nose type. I am not sure which one I will need for this engine. I do know I need to get brackets and bolts as well. And a solenoid

 

When I bought the mini starter for my kids ‘89, it was “adjustable “. (Look at the holes). But both of the starters you showed have the solenoid on them. No need to buy it separately.
Also, the one I got came with bolts as well as shims if needed.

 

Get the OEM style starter and flexplate to match each other, and mounting bolts as well. As mentioned, post 87 small block is application to order. Say 88-up pickup, or 88-up Camaro. The mid-90's one will likely be permanent magnet style, if that's what you want.

 

I guess you want to make things complicated?

just use a starter that's made for the vehicle the engine came in. 3510 is an industry standard number for the starter used on most large flywheel 350s through the 70s and 80s.

 

I am****uming these three divots in the blue tape (block is upside down right now) are the mounting holes for the starter? I know only two holes would be used depending on the starter I get (either a straight mount or offset mount)
?

 

That's right, the two that are offset from each other are the ones you'll use.

Again, make sure to get the correct bolts. They have a knurled area where the starter meets the block, that is used to align the two parts. Normal bolts will let the starter be out of line, which causes mayhem.

This is one version.


There is one by Dorman, might be this one?

https://www.dormanproducts.com/p-32903-678-107.aspx

There are different lengths and threads, so make sure what you get is what you need.

 

If it hasn’t already been mentioned the 14”, 168 tooth flywheel or flex plate uses the staggered bolt pattern and the 12 3/4”, 153 tooth ‘wheel uses the straight across bolt pattern

 

What about mini starters that have four mount holes? From what I read, I can use the two inline mounting holes on the engine block,. On the starter, two holes are for 153 tooth and the other two holes are for 168 tooth. Are these starters any good? Looking at getting a chrome one. They are a little cheaper than a chrome stock one that I have seen.

 

I plastigaged the upper (cap side) and Lower sides (block side) of the crank journal. 1,3,4,5 are all .001. #2 is .0015. Torqued to 30 ft# then 50, then 70.

 

Those are an Denso or Hitachi starter adapted to SBC use with the billet aluminum block mount. The dual patterns means it will fit with both flywheel diameters using the original inline holes on the Chevy engine block.
They are light and reliability is good if you buy a high quality unit.

I believe PowerMaster even has one that uses all three bolt locations on the block for guys that need to spin a big cube ultra high compression engine

The factory PMGR mini starter that looks like a shrunken old school starter are also nice if from a good manufacturer. These only have one bolt pattern though, you have to match it to the flywheel diameter.

 

I need to order new piston rod bearings. The ones I have are F Clevite 77 CB6639P 6.04 .020. I see I can purchase what are called .020 undersized. Are these the same size as what I have? It seems I would want .020 oversized (the crankshaft journals are slightly worn) so the bearings would need to be a bit bigger.

 

Bearings are made .020 say because the crank was turned “under sized”.

 

Did you measure the crankshaft journals with a micrometer? If not, you might want to do that before you get too far with ordering parts.

If the crank was reground 0.020" undersize on the rod journals, it would have bearings marked .020 Additional wear on the journals would require you to have the crankshaft reground to 0.030" undersize, or whatever it takes to clean it up. If 030 won't clean it up, then look for another crankshaft.

 

You had better mic that #4 rod journal,,,,,it looked really iffy to me .

Tommy

 

I believe the rod journals are supposed to be 2.100 and main journals are to be 2.450. My main journals are 2.425. My rod journals are 2.080-2.082. Which would put me at a plus .020 for the rod bearings I think.
I plastigaged the mains and was at .001to .0015 with the plus .020 bearings. With the main caps on, and torque to 70 foot pounds, it takes about 2 ft pound to turn the crank.

 

How did you measure the crankshaft journals? With a micrometer? Or with something else?

2.080" is smaller (undersized) compared to 2.100". Bearings are for "undersize", NOT "oversize". You really do need to get that sorted out in your mind. The bearing inserts are thicker, but the size is smaller, so it's called "undersize".

 

I see what he’s saying “plus .020…” but for sure he wouldn’t want to order off a “click page” that way.

 

Now a quote taken from the internet ... "The traditional bearing clearance standard for street and most performance applications has been 0.001-inch of clearance FOR EVERY INCH OF CRANK JOURNAL DIAMETER. So a typical small-block Chevy 2.200-inch rod journal would call for a bearing clearance of 0.0022-inch".

Looks to me like you have the wrong bearings. What size were the bearings that came out of it? Also, I hope you put oil on the crank and bearings before spinning. That crank,****uming correct bearings and main caps returned to their original locations, should spin with ease, no ft/lbs measurement needed.

 

.0022 is loose for a SBC rod bearing , .0015 would be better .

 

Not trying to argue here but the clearance the OP has sounded tight to me so I did a bit more googling. Below is another quote taken off the internet. This one shows Jeff Smith shooting for 0.0025 on both mains and rods.

"Jeff Smith: You have lots of questions, so let’s jump right in. Your 0.001-inch per 1-inch of journal diameter bearing clearance approach is close.

On a small-block Chevy with a large journal main bearing size of 2.100-inch, this would put your main bearing clearance at 0.0021-inch. This clearance spec****umes that everything is completely square with the main bearing housings, there is no taper or eccentricity in the crankshaft main or rod bearing journals, and that the engine is very carefully fitted to this spec.

In our experience, it’s not unusual for main bearing housings to vary +/- 0.0005-inch. It’s also common for a good used crankshaft main journal to vary by at least +/- 0.0003-inch.

So if you had a main journal on the crank that was +0.0002 and a housing bore that was tight by 0.0005-inch, this adds up to 0.0007-inch tight on the main bearing clearance. If the goal really was 0.0021-inch, this instantly puts the actual clearance at 0.0014-inch which is too tight.

It will work, but this clearance does not take into account any situations where the crank may move a bit — like under max power perhaps with a little shot of nitrous.

A much better idea is to allow for some of these inconsistencies by using the same 0.001-inch per inch formula but then adding 0.0005-inch.

So with a 2.100-inch main bearing journal size, this means 0.0021 + 0.0005 = 0.0026-inch. I generally round this off to 0.0025-inch as my goal for both rod and main bearing journal clearances for a small-block Chevy".

https://www.onallcylinders.com/2020...-clearance-cam-oil-pump-advice-for-sbc-build/

 

Not really spinning the crank. Just turning a little with torque wrench. The book I got by David Vizard mentioned once crank is installed and torqued it should turn with 1-2 ft#. I also have the 1 piece rear main seal installed and the flex plate. And yes I have used a lot of engine****embly lube.



[/QUOTE]

 

Since this is obviously a learning experience for you, I'd recommend you purchase some micrometers before proceeding, and a copy of this book. You can find "sets" of micrometers on Facebook and Ebay for reasonable prices if you take a little time. I just bought a used set of 1"-3" outside micrometers for less than $100. You NEED them, otherwise you are just guessing.......and one wrong guess will ruin the whole engine. I would also purchase a set of "inside" micrometers with 1-6" range. This will let you check installed bearing size and bore sizes. If money is too tight, you can resell them later for what you gave for them.....but if you want to do your engine right, you need them.
Also buy a copy of the book shown below. Available on Ebay used or Amazon. It will save you more than it costs and walk you thru what you need to do.
Some people just throw an engine together and it works ok for a while. Some don't.....and its expensive when they don't. I'm in the process of buying the two micrometer sets below for $100 each with free shipping. They will easily bring that much if I ever want to resell them.

 

I've put together a number of SBC and BBC engines without any mic at all. Plastigauge will give you a good idea of clearances, and whether you're within spec. I've used it to check clearances prior to any machine work on cranks, and after the machine work to ensure my rod and main bearings have proper clearances, and don't need anything else.