Help me build my SB Stroker

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Haney

Haney

www.carsonandironmt.com
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Jan 14, 2005
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Location
Piney Flats, Tennessee
I have been wanting to build a SB stroker motor for my 69 Barracuda notch for some time now. I am pretty sure I have my other project car sold, so this winter I want to concentrate on building my new motor and having it in my car for early spring. My car is currently a mild 340, stock x heads, TRW 10.5:1 pistons, MP 509 cam (way too big for this motor), FBO Ignition, dented headers of unknown brand, Edelbrock 750 carb, LD340 intake. It is a 4-speed car with an 8 ¾ rear fitted with a 3.91 sure grip. Right now the rear tires are 235/60’s at 26” tall. I will be changing these to 255/60’s which will get me to 27” I think.
I am assuming that I will reuse my ignition, pulleys, accessories, starter, tranny, rear, etc but everything else will change.
The car will be a street car with minimal track time. Some trips down the track during local street-fight nights, but this is NOT a bracket car. I would like a motor with gobs of torque and nice street manners. If I could get my car to run low 12’s ON PUMP GAS I would be really happy.
Since I have been wanting to do this for a while, I have been gathering parts so here is what I have:

• 1971 Model 360 block @ standard bore – It has rust in one cylinder but I am thinking that it will clean up at .060 over. Since these are supposed to be thick walled blocks, I was thinking about using .030 over 340 pistons at 4.070. I will use whatever the minimal clean up takes. If I go to 4.070 I will have it sonic tested.
• MP cast 4" Stroker 360 crank
• Eagle H beam rods
• Edelbrock Heads. These heads have had major porting done to them. I do not know what they flow but I was told 290cfm on the intake at .600 lift. I would like to have them flowed. Do we have any members that have a machine shop that can flow heads?

The first question I have is about pistons. Should I use dish pistons or a set of flat tops? I know about quench and the effects it has on a motor and I want to be in about the .040 to .060 piston top to head range for good quench. I want this to be a PUMP GAS motor so CR is my question. What is the highest CR I can get by with on PUMP gas and aluminum heads. I realize this has to do with cam overlap / duration, weight of car and a whole lot of other things but what static would you recommend? So my first set of questions is:

• Flat tops or dish pistons and why?
• What brand would you recommend?
• What static Compression ratio would you shoot for?

I would love to run a hydraulic roller cam but due to the cost of lifter and the cam, I will probably be limited to a hydraulic flat tapped or solid.
• For a 408-416 ish cubic inch STREET motor, what cam would you recommend?

As for intake and carb, I was thinking of RPM Air Gap and 950HP Holley. For headers, I am assuming that the best I can do are TTI steps?
Give me your opinions on this build and any info on my questions above…..
Thanks in advance……
 
I'd suggest boring the one rusted hole to find out where it cleans up. May be smarter to do that and sleeve it, than tear all the fresh good material out of the other bores to get to a sizing that works.

Shoot for 10.5 with aluminum heads.

All flowbench results are a little different. The peak numbers might be great, but, if the mid range numbers suffer, then the heads may not be as good as thought. It's a balancing act.

Hyd cams like the 60404 lunati or Comp XE275HL will get you to the 500+hp point with a stroker.
 
I know it is just personal preference. I am building a 408 from a 360 I have. I just think for the money I like the stroker 4" crankshaft over the 3.58.
 
Well if the 360 block is the block you want to use, OK. The 340 has a larger bore to start with. Less labor in going larger.

• 1971 Model 360 block @ standard bore – It has rust in one cylinder but I am thinking that it will clean up at .060 over. Since these are supposed to be thick walled blocks, I was thinking about using .030 over 340 pistons at 4.070. I will use whatever the minimal clean up takes. If I go to 4.070 I will have it sonic tested.
• MP cast 360 crank
• Eagle H beam rods
• Edelbrock Heads. These heads have had major porting done to them. I do not know what they flow but I was told 290cfm on the intake at .600 lift. I would like to have them flowed. Do we have any members that have a machine shop that can flow heads?
Click to expand...

Thick wall blocks seem to be a myth. Later year blocks have been sonic check to equal thickness.

The MP 360 crank is good foder to sell for cash to roll over into the stroker.

H beems should do fine. I beems are better.

BJR racing (Web site and contact info in my sig.) is a head porter for many many years and has a flow bench.

• Flat tops or dish pistons and why?
• What brand would you recommend?
• What static Compression ratio would you shoot for?
Click to expand...

I myself would look to flat tops if the ratio doesn't climb over 11-1 with the aluminum heads which is about the limit for pump gas. Like you said, cam and overlap of cam can allow more ratio, but in general, 11-1 is a safe max limit that will use 93 octane for your street stomper.

Brandwise, there is a slew of makers that all have a good reputation. A way to look at pistons is weight. Less the better!

I would love to run a hydraulic roller cam but due to the cost of lifter and the cam, I will probably be limited to a hydraulic flat tapped or solid.
• For a 408-416 ish cubic inch STREET motor, what cam would you recommend?

As for intake and carb, I was thinking of RPM Air Gap and 950HP Holley. For headers, I am assuming that the best I can do are TTI steps?
Give me your opinions on this build and any info on my questions above…..
Click to expand...

Shy of a custom cam, I would simply look for a high rate lifting ramp cam ethier from Comp's extreme hi-lift series or Lunati's selection.
Clickables below;
http://lunaticams.com/
http://compcams.com/DefaultWide.asp


Once you know what the head flows and where it stalls, look for a cam that has the most lift your heads can use before stall. (Also in the duration, aka, powerband you'll be operating/driving in.)
(Though it is possible to use a larger cam lift than the head flows well, this may not be the best ave. to take for the street and valve spring considerations. Long life and ease of instalation and use. Etc..... on your street car engine.)

I'll agree on the intake and carb for street use. I do beileve the tti's are best in an A body car in the area you described. 2-1/2 exhaust pipe is the min. I would consider. A 3 inch system will free up the top end power well.
Thanks in advance……
Click to expand...
No problem!
 
I would go as small as possible on the bore, you dont want to thin out your cylinder walls. I am dealing with an 060 318 that my radiator cant keep up with, runs too hot. Thin cyl walls are probably the culprit. Do what was suggested and sleeve that cylinder that is rusted, you may be surprised too - it might just clean up at .030.

good luck.
 
What he said above is good advice, the less you bore the thicker the cylinder walls will be and that will make for a stronger block that runs cooler. And the early 360s do have the thicker 340 sleeves. Its the thin wall 440 that is the myth.

If you can get it to clean up with a 4.060" bore then off the shelf pistons are available. I went with the Keith Black KB745 step dish on my 414 SB stroker. With closed chamber edelbrocks milled to 62 cc, zero deck pistons, and .039" head gasket I will have 10.3:1 compression.

You should also buy the book "How to Build Big Inch Small Block Strokers". Tons of good information in there.
 
Thanks for all the good advice.... I truly appreicate it....

I miss typed in my original post. The crank that I have is a MP 360 4" Stroker Cast Crank. Sorry!

Any suggestions on where is the best PRICE on some LIGHT pistions?
 
Check Summit for the best prices. Also do a google search because summit will match any price you can find. Summit has free shipping and a flat $11 handling fee per order.
 
You want to stay within normal sizes for cost issues. Oddballs (meaning over .030 beyond factory bore) are considered "custom" and more $$. I use Diamond. Use the dished pistons, at zero deck. Keep the overbore at .030. The more you leave the better. Seeve that one hole if it's rusty. I sonic test every non-stock stroke combo. I would do yours. That right year yes, but you dont know until it's checked if the guy building the castings got the cores in the right spots. I dont think a mild oported set of RPMS will reach anywhere near 290. Closer to 260-270 is more realistic assuming they were ported and not just sand rolled... That last 20-30 cfm takes a bit of work to reach 290-300. For low 12s, a cam in the 245-250°@.050 range with lifts in the .530-.550 range will work fine and make mad torque. A roller is nice, but I just did a similar one using a hydraulic flat tappet cam and it's fine and in a 3700lbs car with 3.23s goes 108+mph in the 1/4 on street radials. Iron heads, pump gas.
 
moper said:
You want to stay within normal sizes for cost issues. Oddballs (meaning over .030 beyond factory bore) are considered "custom" and more $$. I use Diamond. Use the dished pistons, at zero deck. Keep the overbore at .030. The more you leave the better. Seeve that one hole if it's rusty. I sonic test every non-stock stroke combo. I would do yours. That right year yes, but you dont know until it's checked if the guy building the castings got the cores in the right spots. I dont think a mild oported set of RPMS will reach anywhere near 290. Closer to 260-270 is more realistic assuming they were ported and not just sand rolled... That last 20-30 cfm takes a bit of work to reach 290-300. For low 12s, a cam in the 245-250°@.050 range with lifts in the .530-.550 range will work fine and make mad torque. A roller is nice, but I just did a similar one using a hydraulic flat tappet cam and it's fine and in a 3700lbs car with 3.23s goes 108+mph in the 1/4 on street radials. Iron heads, pump gas.
Click to expand...

Thanks for the reply Moper. I do plan on staying with normal sizes. If this EARLY 360 block truly is the same block that a 340 is then I wanted to use .030 over 340 pistons (4.070) if I needed to bore it that much. It would be nice if a set of .030 Over 360 pistions (4.030) would work. I guess I need to take the block to the machineist and let them see what rough bore will clean up that one bore.

The heads I have have been heavily ported. I am not a head guru by anymeans but looking at these, they have been worked heavily. I have some good pictures at home of the the ports. I will try to post them here tonight.
 
rumblefish360 said:
I like Mopers cam idea.
Click to expand...

That sounds like a BIG cam for a street car. I have heard that these extra cubes the stroker brings to the table can eat duration on cams but that much? How will the idle be? I don't mind an aggressive idle but don't want it sounding like a pro-stocker Ha.
 
Haney said:
That sounds like a BIG cam for a street car. I have heard that these extra cubes the stroker brings to the table can eat duration on cams but that much? How will the idle be? I don't mind an aggressive idle but don't want it sounding like a pro-stocker Ha.
Click to expand...

It will be very street friendly with good idle characteristics. The problem with a SB Stroker is if you don't put enough cam in the engine won't be able to breath above 5,000 rpm. I really wanted a nice street friendly SB Stroker and I was afraid to go with a "big" cam. But after so many told me I needed more cam I went ahead with a cam similar to what Moper is suggesting.
 
Adding 40 cubes in stroke can eat up 10* in duration. All that extra stroke provides a serious torque gain that comes in quicker and ends sooner, a shorter rpm band. It has to do with piston speed.

This increase is huge and it needs to breath. Increased cam timing is with all this stroke doesn't go far as compared to the shorter stroke of the 360 (3.58) or the almost mini stroke of the teen or 340. (3.31)

Idle quality comes with the cam design, ramp rate and overlap.
Sound of idle also comes from the above but is made more prominent by the amount of cylinder pressure, header tube size and to some extend, design, exhaust pipe size and length, muffler type.

Add in all that extra stroke, it mellos out a little more.

most cams are ground on a 110 C line and sound fine. Try a 106 knocked down 2 degrees on the road in a short stroke engine. Many would balk at the idea just on sound alone
 
It's all about the "suck factor". The longer the stroke, the harder the suck at any rpm. 4" is 11% more stroke than a 440 has. That is why everything in the intake port should be bigger. The port runs from the back of the intake valve to the bottom of the carburetor bore. So strokers can run bigger cams and bigger ports and bigger intakes and bigger carbs. In fact, they run much better with them. By running a smaller port or carb, you actually cause problems in idle and fuel metering that can be hard to tweak out. That and the faster piston speeds mean a small port will go turbulent and stall at lower rpms. When a 4" arm is out of breath early, the power peak drops like a rock. My mild 4" engines get 770wet flowed carbs, and a cam under 240°@.050 will not make any appreciable power over 5K in most packages, and will be low even on torque below that.
Oh and I just heard this morning. That 3700lbs E body I mentionned went 12.84 at 109+ last night on drag radials.. Still can't hook for 25' of first gear... 2.01 60's..lol.
 
One nice deal about going with a 4" arm is the 340 or 360 deal really becomes moot. If you have a 360 block you can nail a 4.000 or 4.030 piston, then if you need a .040 piston, you grab a std bore 340 for a 4" arm. Need +.020 340, grab a 360 + .060, same thing.

Lots of combos in the SB with an arm, so pistons are really available in a size that will work.

I'd sleeve the one bad hole if it got too big, as it keeps more material on the walls and allows for potential future rebuilds.

Good luck with it.
 
Thanks for all the good info in this thread. I really appreciate everyones time and information!

I am going to look at using a dish piston at zero deck to get good quench and a static CR of around 10.5 to 1. I will also try to find the lightest pistion I can. I will take my block to the machine shop and have them rough bore the one rusty hole to see if it will clean at 4.030, 4.060 or 4.070 all of which I can get a standard piston for...... It may not be as bad as I think.....

Once I get my bottom end going, I will look into cams. Moper has "sucked" me in to his way of thinking..... LOL. I would also like to get a reputable shop that is use to porting heads to flow a couple cyliners on each of the heads I have so I know where I am at on flows. I would think this would also be helpful in picking the cam. I will give BJR a call soon. I looked and I can't find my pictures I took of the heads anywhere...... I will try to shoot some soon and post here.

What about intakes? With the info on this thread sould I be looking at using a single plane instead of an Air Gap RPM?
 
BTW, I may be back in the planning phase again. The guy interested in my 73 project car backed out on me. I have listed it on the for sale page here......... Can't really do anything on this motor until I sell it. It is nice to get a plan though.....
 
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