I'm getting ready to purchase a low mileage rebuilt engine for my 86. Engine is an 86E, like mine, and had 6,800 miles before rebuild. Engine has all standard, like stock, equipment. I will be running my TPIS Big Mouth intake, SLP runners, ported plenum, 42 injectors, and Vortech V-2 SQ @ 10 psi; the same thing I run on my stock engine now, except my rings are shot (135,000 miles). I'm going to be running the stock heads (iron 76cc) on this.

How much more complicated would it be to stroke this new engine to 377 than just dropping in a 3.750" crank?

 

The best thing that you can do is read some articles on stroker small block motors.

It takes the whole matched stroker rotating assembly. The piston pin height has to match the given rod length and stroke.

 

A 377 is the result of installing a 3.48 inch stroke crank into a 400 block. I don't know of any after market cranks that have the short increase in stroke that would be required to get to a 377 in a 350 block. So if you have a 400 block it's easy enough.

 

A 400 (3.75") stroke crank in a standard bore (4.00") 350 block, also makes 377 CID. In which case the answer toIs that is is no more complicated to stroke this new engine to 377 than just dropping in a 3.750" crank.

 

Dropping the 3.48 crank into a 400 is easy. Dropping a 3.75 crank into a 350 requires clearancing. If you are going to clearance anyway then why not bore the block and gain the cubes? Unless you run some racing bracket that limits you to 377 then why bother?

 

Ah good catch c4techie(should have read that one a little closer!)! On the strokers that we have assembled we have had to do some clearance work on the pan rails and sometimes a little on the bottom of the stacks. It is a slow process but can be done by hand if you have the tools and does not take too long to do. Your choice of connecting rods will dictate how much has to be taken out especially for the rod bolts. The way we do it off the machines is to mock up one cylinder at a time and clearance the pan rails for that rod; once you get your desired clearance you can move onto the next one. Just be careful to clean out all the grit from grinding with some carb cleaner before spinning it over to avoid scratching things up. Do you have any direct questions about parts or anything like that? Sorry about the mistake on my first post; in racing generally when talking about a 377 you mean de-stroke, 383 stroke. My bad, getting careless in my old age lol, let me know if you have any more questions.

 

No problems. I'm really wanting to complete most of this build myself, call it stubborness or maybe stupidity. So I was trying to avoid the .030" overbore, and just stick to honing if there is no issue with cylinder wall scoring. Block clearancing is a concern. I will probably buy a rotating 377 kit from Summit or somewhere, so the rod bolts should be fine, but clearancing for the counterweights sounds interesting to say the least. I believe I read that the minimum recommended tolerances are .050". I don't think I'll have an issue with cam clearance since I would use the 5.7" rods. Of courese, I could just pick up a 3.750 crank and forged pistons, and re-use my rods.

The piston rings are also a concern. I'm not familiar with "file fit" procedures, and don't have the tools to do it either.

You know, I never asked anyone's opinion, but I'm going the stroker route because of the blower. I think the additional cubes will yield a higher increase in HP and torque than strictly doing a bottom end rebuild and throwing on a new set of heads. I'm sure there's a breakeven point between the two, but I can't afford to do both.

 

The length of the rod has very little to do with whether you have to clearance the rod bolts. The physical size of the big end of the rod is what you have to worry about for both pan rail and cam lobe clearance.

Be safe and always use a .900 or so small base circle cam.

If I was running a 3.750 and 10 psi, I would not use some junky stock rods. Six inch rods allow for longer pistons skirts and throw clearance

 

I thought I read that the piston pin heights on the 6" rods intersect with the oil ring and, as such, would require support rails for the rings. Not something I'm terribly familiar with. Although, I do understand how the longer rods, in theory, provide for more rotational torque and a less angular throw hence less sidewall loading and more HP. I definitely would need a reduced base circle camshaft or spend some time grinding the rod bolt shoulder (or both, to be safe....er).

 

Out of all my stroker projects with 3.75, 3.80, 3.875, 4.00 none of the modern pistons have any kind of support behind the oil ring. It has not been a big deal.

 

Sweet...one less thing to worry about. Thanks for all the good info.

 

And with the proper (stroker) rods with the right cap bolt configuration, or bolt head clearancing, you don't need a reduced base circle cam with the stock 400 CID, 3.75" stroke. After all... Chevy didn't.

 

My last 2 sets of pistons for my 383 had support rails for the oil rings. SRP and JE piston sets came with them in the box.

 

Well, here's my initial parts list for the bottom end. Any comments, suggestions, or disparages?

Oh, this stuff is now going in my stock 86E with 135,000 miles. I may hone to 4.010" if the walls show any evidence of excessive scoring.

ESP 3.750" stroker cast steel crankshaft w/2.450" main and 2.100" rod journals

Scat 6.000" 4340 I-beam rods w/floating wrist pin, .927" pin end bore, .940" big end width, clearanced

Either:
Keith Black hypeuretectic pistons 4.000" bore, flat w/ 2 valve reliefs, +7cc piston head volume, 1.130" compression distance, .927 pin diameter
--or--
JE Pistons forged 4.000" bore, dish w/ d cup valve relief, +28cc head volume, 1.145" compression distance, .927 pin diameter, and oil rail support

Clevite P-series main bearings TM-77 tri metal 1/2 upper groove

Speed-Pro Duroshield Competition Series Rod Bearings chamfered, no dowel, no groove

Sealed Power Standard Gap Plasma-Moly Piston Ring Sets 4.000" bore, 1/16 iron top ring and plasma-moly facing material, 1/16 cast iron second, 3/16 stainless oil ring standard tension

 

A couple of points to ponder. Ten thousandths is a long way to hone. Also, good luck finding .010" oversized pistons and rings.


Why such a variance in the pistons? The difference in the dish volumes (28 - 7 = 21 ccs) will give you in the neighbor hood of 1 1/2 points of compression ratio. Are you adjusting the dome volume to make up for the large difference (.015") in deck heights? Why such a great difference? BTW, with the greater compression distance of the forged piston, the need for an oil rail support is lessened. You don't show such a support with the tighter 1.130", deck height, KB piston.


The Clevite "P" main bearings are a good choice. You would be wise to use matching rod bearings, too. The rings look fine if your pistons have the 1/16" compression ring grooves.