clearancing a 350 block for a 383s 3.75" stroke

[grumpyvette]

I was asked to repost this info for the newer guys

 

Ive built dozens of 383 and 396 sbc engines and the clearancing can be done BY YOUR OWN HANDS with a standard HAND HELD drill and a few CARBIDE BURRS OR GRIND STONES in that drill in well under two hours if you take your time and total expence even if you need to buy that drill and burrs will be well under $50 total

http://www.click-onsource.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=OVAL_1-4_Shank

 

buy a 1/2" burr and a cheap drill

 

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=20776&item=4358782476&rd=1

 

place you old bearings in the block an place the crank in those bearings after coating them with axle grease

slowly rotate the crank and grind a minimum of .060 clearance anywhere the counter weights might touch the block and try NOT to grind more than about .070 any place it touches the block (use a JUMBO size paper clip as a gauge if you don,t have feeler gauges)

next assemble two connecting rods and pistons, one connecting rod and piston for the left one connecting rod and piston for the right, use old bearings coated with axle grease and no rings on the pistons, assemble them to the crank and grind anyplace the rods touch the block, grind minimum of .060 clearance and try NOT to grind more than about .070 any place the rods touche the block (use a LARGE size paper clip as a gauge if you don,t have feeler gauges)move them to the next journal and repeat untill all 4 journals and 8 connecting rods clear. now assemble all eight rods and pistons without rings and install them in thier correct locations and recheck everthing carefully.

next intall the cam and index it correctly with the timeing chain/gears, rotate the engine slowly and look for clearance issues, between the cam and rods/rod bolts ,youll need to use a small base cam if there are major clearance issues and thats almost always a good idea when building a stroker combo but in most cases if your cams lift and duration is under about 230 at .05 and .500 lift there should be minor if any clearance issues, usually the outside edge of a rod bolt head is the only area needing a touch up.

 

once everything clears, wash all the parts VERY CAREFULLY ,TWICE and re-oil then send out to be ballanced now you might ask why do that! well, first youll know its done correctly, and that a correctly built 383 will have a very significant hp and torque advantage over any similar 327 or 350

be aware that a small base dia. cam might be required in some cases,it will depend on the rods and the cam combo you chose

 

http://www.bracketmasters.com/small_block_stroker_383_cu.htm

 

http://www.prewittracing.com/newpage2.htm

 

 

 

need a few pictures?

this may help

the comon areas are the area near the block oil pan rail where the rod bolts touch

and the lower inner cylinder walls and where the cam lobes touch the rod bolts upper shoulder on some types of rods, now you can,t grind on the cam, but you can grind the edge of the rod bolt and you can use a small base circle cam to give greater clearances

 

 

 

http://www.karl-ellwein.org/2005engineprojects/388project.htm

 

[Lvcien]

oh cool -- this is great Thanks for the info.

[jakeshoe]

Good post grumpy but DAYUM man, who did that sleeve on the block pictured?

 

A sleeve is press fit into the cylinder, but the bottom of the cylinder should be stepped so that the sleeve has a positive stop on the bottom, and then pressed in, then the top machined to match the deck of the block.

 

So when it is all said and done, the block and head "catch" the sleeve. So even if thermal expansion lets it slip, it has no place to go.

 

Looking at that pic, it looks like the sleeve was not installed with a step on the bottom.

 

Sometimes a sleeve is not very pretty cosmetically at the bottom, but functionally is fine. Parts of it can protrude past the "bore" but still sit on a step around part of the bore.

 

Some of those pics are of a 400 block, are they all of the same motor?

[getZ]

Too bad I didn't see this post 8 years ago when I built my first stroker. I put small hole in the oil pan rail getting a little happy with the grinder. Since then I welded it up and regrinded it. It seems to have held up fine, but the engine has never really seen any road time. It's in a 73 camaro that just sits in the garage waiting to be finished.

 

What do you think about hard blocking the bottom inch of the block?

[grumpyvette]

"who did that sleeve on the block pictured?"

 

not a CLUE! I got that and all those pictures off differant sites on engine building, simply for an example to show, I never saw those particular engines personally

 

 

"What do you think about hard blocking the bottom inch of the block?"

 

hard block porded in the cylinder base area up to the level of the bottom of the freeze plugs has little effect on the cooling and adds significantly to cylinder strength on thin bore walls, so yeah! any time you exceed about a ..040 overbore its a good idea.

 

GOOD

http://store.summitracing.com/default.asp?target=esearch.asp&N=100&Ntk=PartSearch&Ntt=MOR-35571&x=19&y=11

 

MUCH BETTER, because it gets into the fine cracks and pores in the cast block surface, as its a liquid epoxy and holds far better than the basically structural concrete that moroso sells

 

http://www.matweb.com/search/SpecificMaterialText.asp?bassnum=PDEVCON05