I have a 81 4 speed that is all stock that I think I'm going to dig out of the barn & put back into DD status. I already have a Tremec 5 speed, AFR 195 75cc Eliminators, a Weiand Stealth Intake that was Exude-honed to match the heads, BG 650 Mechanical secondary carb & a retrofit Reduced base circle Hydraulic Roller Cam that was spec'd for a 396 SBC Stroker(530/530 @ 230/238 with a 112 lobe). I have made up my mind to use a aftrmarket block, probably a Dart SHP. I am having trouble deciding which stroke. A 3.875" with the stock 4.125" bore of the SHP block yields 414 cubes, everything seems to fit well with. A Friend in the business seems to like the 4" & says it's much stronger! Hard to believe 13 cubes on a 414 would make that much difference! Please give me some input! Thanks.

 

In an aftermarket block the 4 inch stroke will work. As for strength why would a 4 inch be stronger? Cubes make torque. The afr 195 heads and that cam are pretty small for 410+ cubic inches unless you are building just for torque. If you are using a hyd roller then the rpms are limited anyway. It will make gobs of torque and be good to about 6000 rpm. I would go with a 4 inch stroke if you don't already have a crank.

 

9.8 to 1 comp. with 8.28 to 1 DCR with 6" rods figuring your intake closing point @ 58 degrees 4.200 gasket bore, 4.125 bore, zero deck, 75 cc heads, 3.875 stroke, 12 CC dish pistons. This combo is a good match for your heads, carb and cam. I would be tempted to use 1.6 rockers. It will be a torque monster and pull hard from 1500 to 6000 RPM and all components are well matched. A 4" stroke will get you a little more torque but then you are getting past the capacity of your carb, cam and heads. It will also require more block clearancing. I think the Callies Compstar 3.875 crank and rods will just clear that block or possibly need minimal clearancing. If you don't want to deck the block you can go with custom pistons with a .025 taller compression height to get to zero deck. This will bring the rings up a little reducing the pin, lower ring interference. With a 4" stroke your lower ring will be into the pin. Measure the block height before ordering pistons. These can vary.

 

Hi, Thanks for the reply. I was unclear..."stronger" meant more power, not the stregnth of the crank.

 

63 Mako.............How much does the custom piston add to the cost? I'va also been told the cam is a tad litle. What should the compression height of this be? Sorry for the ignorance!

 

Compression Height = Deck Height - Rod Length - (Stroke/2)...assuming zero deck.

I've ordered a number of custom pistons and was surprised at how easy, fast and cheap it was as long as you don't need anything way out there in terms of dome shape or valve reliefs.

 

1.062 is what JE considers standard for a 3,875 stroke with 6" rods so if this piston is in the hole .025 you need a 1.087 compression height with 6" rods. Measure your deck height before ordering a custom piston. Deck height is never exactly 9.025. The cam is a little small but 1.6 rockers will help. Figure it will add 3 degrees to your duration and some lift. Custom pistons are not real expensive, less than $200 extra which is less than zero decking the block. There are quite a few manufacturers out their. Adding the extra height to the compression height does two things. It allows you to move the lower ring up that .025 to move it out of the pin bore and keeps you from having to deck the block.

 

I have built several 396 small blocks, they make great power and torque.

I like a 5.850 rod, last one i built I put a 252/258 roller on a 110 lc.

 

There is an interesting idea. Using Billa's formula if the deck height is 9.025 and the rod is 5.850 and the stroke is 3.875 you get
9.025 - 5.850- (3.875/2) 1.9375 = 1.2375 compression height is zero deck. A standard compression height is 1.250 for a 3.48 stroke with 6" rods. This readily available height would put the piston .0125 out of the hole. Twelve.5 thousands out of the hole with a .061 thick head gasket gets you .0485 quench. This might work and not require custom pistons. Callies compstar rods are available in a 5.850 length and Mahle makes a 4.125 bore flat top piston with a 1.250 compression height. Felpro makes a 4.200 bore .061 thick MLS gasket for aluminum heads.
http://www.summitracing.com/parts/FPP-1144-061/
This will get you 10.3 to 1 compression so you will need to go bigger on the cam or you could have the piston tops milled. 12.5 thousandths would get you below 10 to 1 leaving the piston flush with the deck get you an aceptable .061 quench and you could use your cam. Just bouncing some ideas around.

 

Interesting discussion and learning a bunch.

I tend to stick with combinations that I've worked with (very conservative) but I can see the advantages of pushing the envelope with this one a bit.

I start to wonder a bit at how short and light the piston is getting as we're well into the oil control rings and I start to worry about counterweight clearance and bobweight. Beyond my experience to be sure.

Sometimes I wish you could order a resin mock-up of one throw of the crank, rods and pistons just to be sure before shelling out the big bucks

 

I understand that. 6" rods and bigger strokes run into this issue. Lighter pistons have advantages but I see the 6" rod 4" stroke pistons and they look too small and light and the lower ring is into the pin. I also question the stability of the piston in the bore when you shorten them up that much at the higher power levels. The advantage of the above combo is the taller compression height gets you a taller piston that seems it would be more sitable in the bore and not need the lower oil ring supports, not needing to deck the block to get good quench, longer rod than the 5.7 reducing side loading but not a full 6" where you run into block interferance, ability to use all off the shelf parts including the head gasket to keep costs down.
I am not an enguineer so all good questions. Do the counterweights clear the skirt? Don't know but I would think so considering it is for a 6" rod. Is 12 thousands out of the hole a problrm? Don't think so. Is the top compression ring being a little higher in the cylinder an issue? I know KB does this and also has a different end gap on their top ring to offset the higher expansion due to that ring being closer to the combustion chamber. Might require opening the top ring gap a hair like done on a nitrous application.

 

Agreed - frankly the main challenge I have with going this far out is just that it's tough for a home builder to do the little tweaks that will be required during final ***'y. Sucks to be back and forth to the machine shop.

Should be one helluva build!

 

Figured out how to make sure the skirts will clear. Call Mahle and compare the skirt design and pin to bottom of skirt distance between the piston I referenced and one for a 3.875 stroke with 5.850 rods. If they are the same skirt design and distance or shorter it will clear.

 

If your going aftermarket block and big stroker cranks, dont choke your combo by sticking to heads, cam and intake best suited for a 383 combo. either build a 383 or just sell the top end and buy what your +400 cube motor really needs to make big power. you can easily make over 550-600 hp with a 427 cube motor and still be perfectly streetable. I would say you need at least 230cc runner heads and a tall single plane intake with a 850 cfm carb. your cam should be around .580-.640 lift.

 

I just sold a friend my 414 kit 3.875, 350 mains, 5.850 rods, Wiseco 20 cc dished piston which make something like 9.8 C/R with 64 cc head.

We are using the Dart SHP block. The block out of the box is only setup for 3.750 stroker. only mild grinding is required for a big 7/16th H beam rod bolt clearance.

You have a couple of weak links in your build. TKO 500 is made for less foot pounds of TQ and your aluminum rear end. So the mild build 414 is probably the better overall choice.

I've bought several sets of Wiseco pistons for my 414, 427's & 434 ci

buy a complete rotating kit from some place like www.flatlanderracing.com

 

If you plan on reving to 7000 RPM+ or drag racing. With a street build limiting RPM with a hydraulic roller and under 10 to 1 compression I think his heads, cam and intake will be fine and not choke the engine. It will pull from off idle to 6000, I would bet put out at least 525 HP and torque with a real wide powerband and pull like a big block. Not everyone wants a really radical build. This would be a solid, really durable street build with plenty of power. His heads flow what most 220 heads flow. 1.6 rockers and a 750 would be a good idea. I had a similar idea when I built my 383. I want my power peak @ 6000 RPM with a rev limiter and rev kit so I can pull 6500. NO more. RPM kills engines and I can't afford to build another one. High RPM engines are fun but expensive. You get into solid lifters and big lift and heavy springs maintenance goes up and life expectancy goes down.

 

if going big cubes, i would build a 434 or 454 combo

 

63Mako is on to my thinking. I have other, more radical cars. This is just a cruiser & I'm desiring big block type performance without putting one in. I have found that probe makes a selection of 3.875 stroke pistons. Here is the link;

http://www.probeindustries.com/Produ...9&Show=ExtInfo

It's kinda interesting, a guy could take a 350 4 bolt roller block, the compstar 3.875" crank & rods, & the probe pistons & make a nasty little smallblock without breaking the bank!

 

That 20 CC piston gives you under 9 to 1 compression. Can't find a standard piston that gets you just under 10 to 1 compession with a 3.875 crank and a 5.850 rod. Probe makes custom pistons. There is a custom order form at the bottom of that page. The 350 roller block with the 3.875 crank is a 396 if it is bored .030 over. You need a 400 4.125 bore block to get 414 CI. The SHP block is the way to go to get the cubic inches. You can get them with 350 mains so you can go with an internally balanced rotating assembly. The 350 roller block is externally balanced stock as is the factory 400.

Here is a good article:
http://www.strokerengine.com/RodStroke.html
If you read it you will see a longer rod has advantages but the disadvantage is a shorter compression height causing rocking of the piston in the cylinder. The 5.850 rod with a 3.875 crank looks like a good ratio combo. This also keeps the compression height at 1.237 if you go with a custom piston in a 9.025 deck height block, You get zero deck with no decking of the block needed, again a good compromise. This custom piston needs to have a 12 CC dish and a .040 gasket to get the optimal compression with your cam and head combo with perfect quench.

 

63Mako. I am going the SHP block. I think I will have to either sell the 75cc heads or have them milled, whichever comes out cheaper. I think I want around 10 to 1 compression. I understand about the 396. I was just adding that if someone was thinking about a 383, I think this would be a viable option....flat top pistons, extra stroke, cheap factory roller stuff with the tradeoff of buying a flywheel.