Durability in low deck strokers

hunt2elk

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Hands down the Street Dom 300-14.....

Do you remember where that Cam C/Line was installed or the final psi targeted for the 3.23/28" tall ?
Seems strange the 493 would dis-appoint down low ?
Street Dominator 300-10?
I don't know how he installed the cam. I am in WI and the motor was built in CA. He knew all the cars particulars though.
 

hunt2elk

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I am going to bet the Quickfuel q850 is the culprit. The ch of the piston has zero to do with poor performance.
Why would the carb matter that much? I have the same one on my 451 and it is fine.
 

RemCharger

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The pistons just go up and down. Air go in. Air go out.

Poor performance is to do with everything but the shortblock.
 

SlinktRR

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I have a ported street dominator on 4.15 stroke RB 499 with 28" tires and 3.23. recommend SD for sure with a gasket match, my opinion single planes only for strokers. This combo destroys tires, but I agree with hemirunner on the gear change I also have 3.55's and it runs better with those, this is a 727 though. that cam youre using is pretty conservative as well, maybe eventual cam change with more degrees at .050 if you're not satisfied.
 

TexasRoadRunner68

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A 470 will rev to the moon faster than the 512. I’d put my 470 up against my dads 505 (440 stroked) anytime.

I have always heard good things about a 470. I’d be hoping for above 600 hp with a good set of heads, intake, carb(s) etc.

I also will have a 440 block I could stroke. It would be a non matching but date correct motor for a 70 charger RT. I just have always heard the 400 will rev faster, has a stronger block that is less likely to come apart, and gives more hood clearance. It would also let me keep the correct block for originality.
 

65Fury440

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I followed your motor thread. The whole thing has been a lot of suck for you, that's a shame.

Do you know what your cranking PSI is? Those heads flow good low to moderate lift, an 850 should be more responsive down low/mid than a 4500. You'd think the intake would be helpful in the low to mid rpm range as well. (I know squat about them).

Everything about that motor looks like she should be a tire roaster.
Maybe the cam was installed retarded?

Depending on what brand timing set you have, you may be able to pull off the balancer and see the marks on the bottom timing sprocket. I used my cell phone camera, I could clearly see the 0 and +2 , +4, +6, etc marks.
There was some confusion with my machinist degreeing the cam (I had him just do it when setting thrust button clearance), I was able to see where it was definitively.
 

qkcuda

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I ran a 400/500 combo with the long rods. The pistons were very light and it revved quickly, although it had noticable piston slap when cold. My combo used a Street Dominator intake and a 236/242 hydraulic roller. I ran 3.55 gears and 28 inch tires. It made huge torque and was a great combo. My buddy built a 512 after seeing mine and stepped the cam down one to 230/236 with 3.23 gears and it was a torque monster.
 

diesel_lv

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Diesel- mind sharing specs of your build- I am putting together the same build from 440 Source this Spring. Thanks
I followed this build only using my 383 to 496 w 440 source. I used the Comp Cams hydraulic roller instead of the hydraulic flat tappet.
https://www.motortrend.com/how-to/chrysler-383-big-block-mopar-for-the-masses/
20191125_144933.jpg
 

451Mopar

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Yes it is. I want the torque down low for a fun street car. All the specs were given to the builder before before starting. 69 Bee, Hemi 4-speed, Strange 60 3.23's, 28" tall tires, Quick Fuel Q-850, TTI headers to a 3" full exhaust, Trick Flow 240's. Car has a Ramcharger hood, so he slightly ported/modifed a Weiand Action + for hood clearance. He told me the 600 ft lbs the motor puts out will make up for the bottleneck of the intake no problem. It sucks imo. I picked up a Edelbrock TM6 and have a line on a Holley Street Dominator. Both shorter single planes that I can get under my hood. I am going to try one of those this spring.....


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View attachment 1242593


Could be a few things. The 114 LSA of the cam for one? That cam is really mild for a 500" stroker.
Unknown compression ratio, and head gaskets. Make sure the head gasket is not too small for the heads chambers.
I made that mistake before, using a head gasket sized to the bore and not the cylinder head chamber size.
Engine should have good low end torque, so I would think something else is not working correctly?
If it overheats, and has low cranking pressure, then check the head gaskets as mentioned above.
Not sure what the tune-up is running? The ignition mechanical curve should be around 16 degrees in the curve, so you can run about 16 degrees timing at idle.
I understand the hood clearance issue. At least it's not a RB block, that would make the hood clearance worse.
 

451Mopar

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I followed this build only using my 383 to 496 w 440 source. I used the Comp Cams hydraulic roller instead of the hydraulic flat tappet.
https://www.motortrend.com/how-to/chrysler-383-big-block-mopar-for-the-masses/
View attachment 1243005

How do you like that cam? I used the next size up 236/242 @ 0.050" in the 505" stroked 440. It seems mild the the 505" engine, but I was looking for mild / torque and EFI friendly. I can run the car in overdrive (5 speed manual) at 1,500 RPM @ 60 MPH is no problem.
 

hunt2elk

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I followed your motor thread. The whole thing has been a lot of suck for you, that's a shame.

Do you know what your cranking PSI is?
I didn't check myself, but the builder told me 170 psi.
 

hunt2elk

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Could be a few things. The 114 LSA of the cam for one? That cam is really mild for a 500" stroker.
Unknown compression ratio, and head gaskets. Make sure the head gasket is not too small for the heads chambers.
Engine should have good low end torque, so I would think something else is not working correctly?
If it overheats, and has low cranking pressure, then check the head gaskets as mentioned above.
Not sure what the tune-up is running? The ignition mechanical curve should be around 16 degrees in the curve, so you can run about 16 degrees timing at idle.
Compression ratio is 9.6:1 with CP dish pistons, .051" head gasket. Timing is 20 initial and 34 total. Motor does not overheat and actually runs real good, just doesn't have any low end power. Sounds like my biggest problem is a mismatched cam.....
 
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Jeremiah

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Why would the carb matter that much? I have the same one on my 451 and it is fine.

The transition circuit on the QF carbs is notoriously fat making the engine lazy. Ihave several of them and all have the same issue.
 

hunt2elk

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The transition circuit on the QF carbs is notoriously fat making the engine lazy. Ihave several of them and all have the same issue.
Maybe. Although I have Q series Quick Fuel carbs on both my other cars and I was able to tune those fine.
 

451Mopar

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The transition circuit on the QF carbs is notoriously fat making the engine lazy. Ihave several of them and all have the same issue.

I was thinking the same thing. A messed up transition circuit / idle restrictor size can make an engine feel really lazy down low at shallow throttle angles.
I would use a thinner head gasket as long as the piston to head clearance is around 0.035-0.040". Might be able to get closer to 10:1 compression. The cam duration seems OK, but I think a narrower LSA would give more overlap, and likely result in the cam being installed more advanced.
With the intake installed at a 110 centerline, the intake valve closing is delayed which drops the dynamic compression.
something like a 108 LSA installed around 104 to 106 ICL would increase dynamic compression and overlap.
Just some thoughts off the top of my head.
 

diesel_lv

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How do you like that cam? I used the next size up 236/242 @ 0.050" in the 505" stroked 440. It seems mild the the 505" engine, but I was looking for mild / torque and EFI friendly. I can run the car in overdrive (5 speed manual) at 1,500 RPM @ 60 MPH is no problem.
Unfortunately, I didn't look into all the parameters of it before purchase. On the engine dyno, it was great. In the car in the real world, detonates on 91 unless extremely retarded. Used a Cam computer program recently. Even w 10.2:1 compression n aluminum heads, it's got 190 cranking pressure and 9.7 dynamic. Had I known about these things earlier, I would have gone w a cam w more overlap. I am running 3.73's w 26" tires. W Gearvendor o/d, I'm turning 2,800 at 70 n 3k at 80. Only get 9.5 mpg w fuel injection running 14.7 afr while cruising.
 

bm02tj

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Yes it is. I want the torque down low for a fun street car. All the specs were given to the builder before before starting. 69 Bee, Hemi 4-speed, Strange 60 3.23's, 28" tall tires, Quick Fuel Q-850, TTI headers to a 3" full exhaust, Trick Flow 240's. Car has a Ramcharger hood, so he slightly ported/modifed a Weiand Action + for hood clearance. He told me the 600 ft lbs the motor puts out will make up for the bottleneck of the intake no problem. It sucks imo. I picked up a Edelbrock TM6 and have a line on a Holley Street Dominator. Both shorter single planes that I can get under my hood. I am going to try one of those this spring.....


View attachment 1242592

View attachment 1242593

Did you check cam timing with a degree wheel
 

68 HEMI GTS

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4.250 stroke 400’s are flat awesome. I’ve built a few. I run one In my roadrunner that’s just a pump gas streeter. It’s been high 10’s in full street trim driving to the track. Can’t imagine a better combo for what I do with it (99% street use).
 
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