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How to mellow out a 505 stroker?

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Kevin74

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Hello,

I’m new to the hobby and still have a lot to learn. My thanks in advance for all the expert advice. Here is my story:
I bought a 67 Charger with no engine or trans. I then found a great $2500 Craigslist deal on a barely used 505 and 727 trans. Also a set of Doug’s headers. Here are the engine specs from the previous owner:
440 stroked to 505
10.5 compression
Ported 905 heads
1.5 roller rockers
Comp cams XR292R solid roller
Anyhow, I installed the engine and I don’t like it. Just way too much cam, I think. Idles very rough, and I had to add a vacuum pump for my power brakes.

So here is my plan:
Swap cam to Comp cams XR272R
Install thick 0.080 to 0.100 Cometic's head gasket to lower compression to 9.0 to 9.5. I’m thinking the smaller can won’t tolerate 10.5:1 on 91 octane.

1. Do you guys like this plan? I’m not a racer. Mostly just want to cruise around in an old muscle car.
2. Anything to be concerned about with the super thick head gasket? Does it make my pushrods too short?
3. Can I reuse my lifters?
Thanks!
 
I think you're on the right track, but a secondary concern would be the porting on the heads currently installed. In my opinion you're going to want good overall port velocity for good street response, and a super duper porting job might not help with that.

I've a big block someone else put together and they spent a fair amount of money having someone port a set of 906 heads. (why I don't know, since there would be better performance for about the same cost buying some aftermarket aluminum heads) They then went with a reasonably mild hydraulic cam, supposedly to make sure the engine was streetable. The car is a pooch until you really get the engine winding, so much so that it's not much fun street driving. I'm pulling the heads.

You didn't say how large the header primary tubes were. Large diameter tubes flow really well but sometimes don't help with low end responsiveness. I've seen guys all fired up about putting a set of Hooker super competition headers on their car only to find it runs worse on the street than it did before they were installed.

I don't think you'll have a problem with push rod length. I have seen guys reuse roller lifters. I'm sure you know that's not advisable with conventional style lifters. There are plenty of people on here a lot smarter than me, so you may well get better advice to follow. I'm just speaking from my own experience.
 
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First thing I would do is check your timing with a vacuum gauge. Also, what intake/carb are you running?
You could have mixture/timing issues which would lead to the rough idle and poor street manners.
I'm not running a stroker but have spent plenty of time tuning Mopar. Don't start throwing parts at it until you've exhausted all other avenues.
 
As has been mentioned tuning might help allot.... Where is the timing? With that much cam you probably want base timing around 20-24 degrees & limit the total to 34-36... After that it should idle cleaner & tuning the carb should be easier...

Just doing that might raise the vacuum enough for power brakes...

Thick head gaskets are going to create port alignment issues, in my opinion pushrods will need changing & who knows what else....
 
Just put it up for trade for a stock build 440 ,as you said you don't race something like this is going to be more issue then it's worth for street driving ! I'm sure someone out there would love to get it
 
Have you verified anything that the seller told you? What evidence do you have to support the seller's claims?

Why would a guy sell a $12,000 motor for $2,500? Hate to be negative Nancy.

Finally, without knowing the engine details, and without knowing what you've looked at to fix your your "I really don't like it" condition, and exactly what those symptoms are that you don't like, there can literally be dozens of reasons you don't like it. The cam being one of them.
 
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An iron headed 4.250 stroke engine should run like a truck engine even with that 292 cam. Tons of torque at low rpm, not much power up top. Not at all what you’re describing.
 
You can tune what you have, but in my opinion your cam is WAY too big for a cruiser and even the replacement is on the big side. If you can ONLY get 91 octane (93 would work for you) then you may want to look for a high overlap cam with duration/lift on the smaller side....maybe a "thumper" cam??? Some guys on here can help you pick a good cam. Otherewise, if it were me (it isn't) I'd run what you have with just a cam change
 
BSB67 said:
Have you verified anything that the seller told you? What evidence do you have to support the seller's claims?

Why would a guy sell a $12,000 motor for $2,500? Hate to be negative Nancy.

Finally, without knowing the engine details, and without knowing what you've looked at to fix your your "I really don't like it" condition, and exactly what those symptoms are that you don't like, there can literally be dozens of reasons you don't like it. The cam being one of them.
Click to expand...
 
Hi BSB67,

It’s not negative, I do agree that I haven’t verified any of the engine details.

I think I got a good deal because the previous owner was running a Holley EFI on the engine, and it was belching fire when I went to look at it. He was a rich guy who had just ordered a new modern Hemi crate motor, and he wanted the old engine gone.

So I installed a new Holley 850DP on the Torker single plane intake. The engine has great power, but I have to crank up the idle really high or else I fear stalling at a stoplight. And the electric vacuum pump for the power brakes is really loud and irritating.

Anyway, great point by you guys about double-checking the basics of timing and tuning.

I just wonder if a XR292R cam will idle nicely, even with proper timing and carb tuning. The Summit website for this cam describes it as having a “radical idle”

Thanks,
Kevin
 
It will have a "Radical Idle" in a 383 or a 400... It'll have an "Aggressive Idle" in a 440... But a 4.25 stroke eats up allot of the radical nature of camshafts so while it won't idle like a stock cam it should be pretty streetable...
 
1 Wild R/T said:
It will have a "Radical Idle" in a 383 or a 400... It'll have an "Aggressive Idle" in a 440... But a 4.25 stroke eats up allot of the radical nature of camshafts so while it won't idle like a stock cam it should be pretty streetable...
Click to expand...
 
Thanks for the hope, it sounds like this setup might not be a hopeless situation. I’ll give timing and tuning another chance, maybe even swallow my pride and ask the local speed shop for a tune-up.

By the way, the other thing I don’t like about this motor is the smell of gasoline while idling. I got the impression that radical cams just pass through a lot of unburned fuel at idle due to the large overlap. Is this true?
 
What is your base timing?

Short test... Go out & add 10-15 degrees of base timing & see what happens to the idle.... It'll go up & smooth out, now back the idle speed down & see how it idles... You'll have a stronger vacuum signal & the idle will be more stable... At this point you might add even more timing & back the idle down further....

If you want to drive the car be aware it has wayyyyy to much total timing so if you hear a rattle get off the gas...

What needs to happen is the distributor needs to be modified to limit the advance...

Find out how much base timing your engine likes & the starter can handle, especially when the engine is hot...

Now reduce the timing in the distributor so with base plus advance total timing is around 34-36 degrees...

What you probably should do is figure out what you want & pull the distributor & have it curved by a shop that does that sort of work...

If you want to try it yourself we can offer guidance, but the easy way is have someone who knows the tricks handle it..
 
Oh, the smell of raw gas? more timing will help that too..
 
1 Wild R/T said:
What is your base timing?

Short test... Go out & add 10-15 degrees of base timing & see what happens to the idle.... It'll go up & smooth out, now back the idle speed down & see how it idles... You'll have a stronger vacuum signal & the idle will be more stable... At this point you might add even more timing & back the idle down further....

If you want to drive the car be aware it has wayyyyy to much total timing so if you hear a rattle get off the gas...

What needs to happen is the distributor needs to be modified to limit the advance...

Find out how much base timing your engine likes & the starter can handle, especially when the engine is hot...

Now reduce the timing in the distributor so with base plus advance total timing is around 34-36 degrees...

What you probably should do is figure out what you want & pull the distributor & have it curved by a shop that does that sort of work...

If you want to try it yourself we can offer guidance, but the easy way is have someone who knows the tricks handle it..
Click to expand...


I can do it if needed. I had to go to a mechanical on my 440 Dart kept breaking starter noses off the mini starters till I figured out when cranking it was pulling the vac advance in. Man that sucked to figure out.
 
Kevin74 said:
Hi BSB67,

It’s not negative, I do agree that I haven’t verified any of the engine details.

I think I got a good deal because the previous owner was running a Holley EFI on the engine, and it was belching fire when I went to look at it. He was a rich guy who had just ordered a new modern Hemi crate motor, and he wanted the old engine gone.

So I installed a new Holley 850DP on the Torker single plane intake. The engine has great power, but I have to crank up the idle really high or else I fear stalling at a stoplight. And the electric vacuum pump for the power brakes is really loud and irritating.

Anyway, great point by you guys about double-checking the basics of timing and tuning.

I just wonder if a XR292R cam will idle nicely, even with proper timing and carb tuning. The Summit website for this cam describes it as having a “radical idle”

Thanks,
Kevin
Click to expand...

No, I have had the xr 292 in two diff. engines , around 1150 idle rpm in both mototrs, one a hot 406 sbc , the other my 505' strker , which I
 
So you had the intake off and verified it's a solid roller?

Its not uncommon for the intake to head surface to leak resulting in crappy idle and burning eyes.

If there are no vacuum leaks, your initial timing is 24°, and you loosen the lash to 0.022" - 0.024", it should have an acceptable idle, but not great. Although opinions vary considerably on acceptable idle.
 
A 292 street roller is not a huge cam in a 500 inch stroker. It will have a rumble at idle but it isn't a race cam in that large of an engine. It should be driveable if you have 20 degrees of timing at idle. The carb tuning will have to be spot on and that can be hard to do for a beginner.

I'm not a fan of your plan since the thick head gaskets will cause a bunch of problems. Cast iron heads are also going to be a problem with an engine like that. If it was my engine I'd probably swap over to a set of aluminum heads but there are a bunch of "it depends" hidden in an engine like that. The pistons in the engine are the big unknown so until you figure that out you'll just be guessing.

The good news is that a 500 inch engine with a solid roller cam would cost you more than $10,000 at any engine shop so you got a good deal. What you won't know until you have it reconfigured for you needs is how good of a deal you got. It might end up a wash once you're done with it or it could end up being a really good deal.
 
A Holley Sniper with a full Hyperspark ignition setup can be used to mellow out an engine like that but it is a whole new learning curve if you don't know EFI. A sharp EFI guy could tune that combination in less than an hour but if it is all new to you then you could out in the garage for a month of weekends before you get it working.
 
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