318 stroker builds

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1970 La

1970 La

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I haven't been on much lately and I'm looking for some 318 stroker builds. (390-392 ci)

I have a 318 roller block with shaft oiling heads that we were going to build a 288 ci destroked 318. Now the boy is thinking he wants a bigger engine so I was thinking on using the same block and moving a head. This will be a street car with a hydraulic roller. Would like to keep the compresion at 10.5-1 or under. And yes I have plenty of 360's but looking for something different and we think 392 badges would look good on his duster.Lol

Any help towards a build would be appreciated. Thanks
 
It's basically the same as any 4" small block. Same crank as the 340 block version, same rods. Only difference is the pistons ('cause of the bore size). If this is to be a street car predominantly, I'd suggest forged pistons, the scat cast crank, Eagle SIR rods, and to replace the heads with any run-of-the-mill 340/360 heads that have been treated to a modern performance valve job and setup, and run a cam in the 240° @ .050 range. With a dished piston the compression will be around 9.5:1 and run on anything you put in the tank and pull like a freight train from idle to 5500 or so.
 
Glad to hear your thoughts on the forged pistons. The kit we were looking at had hypers but could get forged for another 175.00. Done been down that road with kb 107's. I filed the top ring gaps to .030 and after 10,000 miles lost the ring land at the valve relief with 32 degrees total. Running on 89 octane with 9:5-1 compression.

I was also wondering about the crankshaft, would like to save all we can but don't want to deal with a broken crankshaft. The car does have a manual transmission and might go down the drag strip a few times but will be completely streetable. Not sure on the gearing either 3.55 or 3.73 depending on what he decides for tires.

The heads are 308 castings. Going to blend the bowls and clean the runners a bit. Was going to stay with 1.88 and 1.60 valves. But larger intake valves are not out of the question, maybe 1.94's. Thanks
 
2.02's and a full porting w/the 308's.... just saying...
 
rumblefish360 said:
2.02's and a full porting w/the 308's.... just saying...
Click to expand...

I'm really only looking for enough head to support 400 fly wheel hp. I'm sure I can get them in the 230 cfm range with some work on the short turn and the bowls. If I have to have guide work I was going to go with 11/32 stems. 2.02's might be needed for the bigger cubic inches. Thanks
 
The reason I recommend forged is the piston speeds are approaching failure point for hypers with a 4" stroke crank at fairly low rpm - 5K or so. I run KB hypers in a lot of things. Gapping the rings won't stop detonation - which is what probably killed yours. 10K miles they ran fine - they were fine. Maybe a poor load of gas or something.
On the heads - It's a waste of effort to leave the 1.88s in place and do porting. You have to sink the seats a hair to re-cut them. 400 flywheel horsepower can be reached with no porting. If I were doing it I'd have the stainless 2.02/1.65s valves fitted, and a modern 5 angle cutter valve job done, along with guides or liners, cutting the guides and spring seats, and new hardened exhaust seats. In other words - a proper performance rebuild. If you want to blend and gasket match it will only help gaurantee the 230+cfm, but no need to work the short turn or hog the bowls. My "stage II" heads are further ported in the bowls, short turn, pushrod pinch, and roof & walls. But I run a 2.05/1.65 valve package in them. You don't need any of that crap. You need solid basics.
 
Have you considered a 3.58" stroke crank with 318 mains? Comes out to around 349". Streetwize over on Moparts built a similar one a while back but he had a MP 3.51" 8 bolt crank which is no longer made. Just an idea, sounds like you might want more cubes.

Read about it here.
 
I've seen builds in magazines in the past using the 318 roller block. Sonic testing, then boring to 4" Bore. You end up with a 402.
 
I would use Scat I beam 4340 rods instead of the Eagle SIR rods, ,much better rod for a few dollars more.....KB Icon is probably the least expensive forged piston...they have dished and flat tops available....

I hope to start assembly of a 318/390 stroker in a few months...as I have the Scat crank...Scat rods, and KB Icon dish pistons...
 
1970 La said:
I'm really only looking for enough head to support 400 fly wheel hp. I'm sure I can get them in the 230 cfm range with some work on the short turn and the bowls. If I have to have guide work I was going to go with 11/32 stems. 2.02's might be needed for the bigger cubic inches. Thanks
Click to expand...

As you wish. In the case of a lot of cubes, you can't put enough head on top from OE iron and a larger valve will only improve everything.
A dead stock small valve head is enough on paper to support 400HP.
 
rmchrgr said:
Here's a 402" 318 stroker build.

Click linky link.
Click to expand...


Thanks Ramcharger! I get more time I will read through it better. It made lots of torque for sure. I'll have to read more to see what camshaft he was using.

Thanks to every one for their input. This would be my first stroker build if he is dead set on it so any info is much appreciated. Not sure on the 5 angle valve job, is it really needed for a street car? Don't be affended Moper because I don't know. It would be nice if I had someone local that could do this and they might be able to now, its been 2 years since i had a valve job done and it was 3 angle. Des Moines is 100 miles and Kansas City is 150 for me. I have 3 within 60 miles of me that do good work. Thanks again!
 
1970 La said:
Thanks Ramcharger! I get more time I will read through it better. It made lots of torque for sure. I'll have to read more to see what camshaft he was using.

Thanks to every one for their input. This would be my first stroker build if he is dead set on it so any info is much appreciated. Not sure on the 5 angle valve job, is it really needed for a street car? Don't be affended Moper because I don't know. It would be nice if I had someone local that could do this and they might be able to now, its been 2 years since i had a valve job done and it was 3 angle. Des Moines is 100 miles and Kansas City is 150 for me. I have 3 within 60 miles of me that do good work. Thanks again!
Click to expand...

Unless you have someone local you like and trust, I'd give Hughes Hughes Engines a call. They are not too far from you in western Illinois. I'd give them a shout and see what they suggest. They are Mopar specific and have tons of parts choices for small block strokers. They will steer you in the right direction. Their prices are fairly reasonable too.

http://www.hughesengines.com/Index/index.php
 
I really wish that we had a machine shop that catered to the mopar guys but we don't. I took my last block to a guy that used to be very good on ford & mopar. When i got the block back after machining there was a crack on the thrust main at the stud and he never caught it. It could have been there before but you would think he would have found it when aighn honing the mains. I wish Bill Richardson would move to North Missouri. Lol

I'll check them out thanks!
 
4.00 out of a 318 so your walls are thin, or just get std roller 360, no machine work (unless you need to clean the bores) and buy a 360 mains stroker crank for the same price. ONly thing different will be your main bearing size and the pan you use, and you have 3 more overbores left.
 
I've been following this thread since the beginning. Now, I'm here to be the guinea pig. I have a bone stock "70 Swinger 340. I've rebuilt the stock, numbers matching 340 with ported J heads, and a Crane hydraulic roller cam. 2800 stall converter on the original A727. I can't force myself to put the motor back in the car. I can't run the motor to 6 grand for fear of blowing up my numbers matching engine, so I've sealed it up and put it in the corner of the garage. I want to fly the MOPAR banner to it's potential without fear of grenading the original motor. Now, I have a virgin bore "72 318, and an extra set of 915 "Z" heads. ( 202/1.6).I want to make a stroker I can hammer on the street. I've been looking at Campbell Enterprises stroker kit. I'll run either a Crane Cams or Comp Cams Hydraulic roller cam set up. ( Retro fit set up.) Now I'm looking for some of you Gurus' advice. I'll pick the best street/strip set up I can afford, and put it together. I might need to move to the restoration forum, but that's okay. I have a rebuilt A727 with a 2800 converter. Right now, the car has an 8 3/4 3.23 open diff, but I have an extra 8 3/4 sure grip I can change to 3.91"s. Car is a bone stock, numbers matching "70 Dart Swinger 340. I will document the build, and give truthfull numbers when it's complete. I want a bad *** street car that will see occasional strip runs. The can of worms is wide open. I'll thank everyone ahead of time for their experience and suggestions. Game on!
 
So with this 318, you want to build something with teeth.
Is there a specific goal in mind?

In a general sense, a basic 318 - 390 stroked build with the use of stock heads, something like this could be done;

Overbore the block as needed. Thicker cylinder walls are a better power maker/retainer than going .030 over. Keep the comp ratio under 10-1. That is the pushing it ratio with consideration of today's available pump gas and what they put in it.

A 750 carb up top a RPM intake, 1-3/4 header tube (tti or Hookers) into a 2-1/2 exhaust for the street. A Hyd. cam or solid wasn't mentioned, but here are 2 examples of what could be used with your converter.

Lunatis Hyd. 60404
234-242, .513/.533

Lunati's solid lifter cam, the 60440
235/243 - .526/.546

The duration of these cams will work well with your converter and 3.90+ gears. You will have a lot of torque & good upper rpm HP. It is possible to go one size up with the cams. But I error on the side of caution due to the converter stall.
 
I plan to build a very similar 318/390 block. I currently have a mostly stock '69 318 in my all original '69 Cuda. I also have two 318 blocks in my garage. One is a 72 block and the other is a 74 block. I already have the stainless 2.02 and 1.6 valves.
My plans are for:

Cast "Scat" 4' stroker crank
Ferrea SS valves 2.02, 1.6 (already purchased)
SIR6123 5140 forged steel rods (already purchased)
Eddy RPM intake (already purchased)
92-02 "machined" mag Truck exhaust on pass side, 340 exhaust on drivers (passenger manifold machined out to 2 1/4" exit hole) already installed on my 318.
2 1/2 pipes (twice pipes with crossover) all the way back
Holley 750 carb (already purchased)
Home ported "596" 360 open chamber heads (gasket match and blending) I have the heads but still need to port. NO HIGH RPM!!

Open chamber heads should work just fine because of the piston sweep. I don't need high compression pistons with all the volume!! I'm looking for 9.5:1 compression MAX!!

I don't plan to do any drag racing!! Mostly street cruising and maybe an occasional street race. I'm looking for low end torque and drivability.

Sorry "1970 La", didn't mean to high jack, just thought I'd let you know what I plan to do based on input from other FABO members on the same subject. I would have already built the 390 stroker if my current engine didn't run so good!!!!^%$#&^%$(*^&$!!!!!. I'm slowly buying all the parts I need and I plan to built the stroker in the next year or so. I'm trying to BLOW my engine so that I have an excuse to build the stroker.

Good Luck on your build.........

Treblig
 
So.... which pistons or compression height do you use in the 349 (318 w/360 crank)? Not opposed to getting the rods with Chevy pin size.... I see some 307 pistons that look pretty close...
 
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