Rotating Assembly for My Charger?

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I have been keeping up with stoker build threads here and learned a lot on the Steve66 and firefighter thread!

Now it is time for me to ask for some help.

Well I am getting ready to build my motor for my 68 Charger R/T 4spd car with a Dana 60 (3.54).

Gonna keep my stock hood (limits head and intake options) so I plan on going with worked 84cc Eddy Heads with a Street Dominator Intake and mechanical flat tappet cam.

I have 71 HP Block that is already .030 over.

Planning on taking the block out to .055 over.

Decided to build a stroker motor since I need to buy a crank, rods, and pistons anyway.

My questions are these:

Which stoker combo would you go with?                                                     4.15 crank with 6.76 rods and standard MOPAR rod journals.
                     4.15 crank with 6.76 rods and Chevy 2.200 rod journals.
                     4.25 crank with 6.76 rods and Chevy 2.200 rod journals.
                     4.25 crank with 7.10 rods and Chevy 2.200 rod journals.

Plan on using Tri-Metal bearings, but should i go 1/2, 3/4, or full groove mains?  Should they be thin grooved?

Thanks

Andy

[67_Dodge_Charger]

What are you looking for power, how are you going to drive it and is this a daily driver?  Answering these questions will help you decide what stroker kit would work best for you.

Robert

[firefighter3931]

I would bore the block the least mount possible....this will maintain structural integrity. If it'll clean up at .040 i would go with that. It wouldn't hurt to have it sonic checked and pay close attention to the thrust side of the cylinder walls. 

The 4.25 stroke with a 7.1 rod is a nice combo for a stock sized cylinder head. Increased dwell time at the top of the cylinder has shown to be effective. The better rod ratio using a 7.1 rod will also decrease side loading and improve longevity.

If you use Steve's build thread as a guideline and substitute the rotating assembly....you can' go wrong. The same principles apply to any stroker (or non stroker) build....balancing, oil system, static compression ratio and quench. Cam selection will depend on the stall speed, gearing and tire diameter. 



Ron

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Hi Robert

Yes more info is better, sorry.  I meant to include that info and overlooked it as I focused on the stroker details.

Weekend warrior, summer driver ( I live in the Northeast), and MOPAR track days.  I have no intention to cage the car.  I do have welded in frame connectors and drive shaft loop.  18 spline 4spd with with a shatter shield and Mark Williams drive shaft.  I don't want to break 11.5 secs on track days but this will not be a problem since the car is not tubbed and running a stock length 3.54 Dana.  I expect to go through the traps at between 5800 and 6000 RPM based on my gearing.

It is essentially a very nice rotisserie resto with a big powerful motor!

I was leaning towards the short rod 4.15 with 2.20 journals, but I wanted to air out all my options.

Thanks

Andy

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Ron

Thanks much for the feedback.

Keep in mind I am not an engine builder as you read this.  My comments are based on my readings and my experiences as an engineer only!

Yes I should definitely have the machinist see if the block will clean up at 40 over.  It should the cylinder walls looked great on it when I picked up.

I agree the 4.25 / 7.1 combo is better suited to the smaller intake ports and dual plane manifolds but the 4.15 / 6.76 combo is better suited for lower RPM (street cars) with tall gears and tires.  This is part of my confusion and appeal for advice and experiences.

Going from a Rod/Stroke ratio of 1.67 for the 4.25/7.1 combo to a ratio of 1.63 for the 4.15 / 6.76 combo should only increase piston side loadings by about 1%.  The kicker in the side loading analysis for these two crank / rod approaches is the CD of the pistons.  The 4.25 / 7.1 combo requires a piston CD of 1.485 while the 4.15 / 6.76 uses a piston with a CD of 1.865, a difference of almost .4"!  Since the actual side loading is so close between the two approaches, you end up applying those very similar loads to the cylinder walls over much less area resulting in much higher load per unit of surface area with the long rod and short piston than you do with the short rod and long piston.

My real worry is short piston stability in the bore which is a direct result of the increased forces per unit area!  Short pistons tend to wear out rings much faster, break seal, and burn more oil.  Is the piston CD issues and concerns something I am over reacting to?

Thanks again, this discussion is very helpful to me.

Andy

[firefighter3931]

Andy, you are correct....the difference between the 4.15/6.76 vs 4.25/7.1 is minimal in terms of side loading & rod ratio. But there will be a noticable improvement in bottom end power and torque....not huge, but you can quantify the difference in the "seat of your pants" if you were comparing them back to back. 

As for the compression height issue ; the 451 lowdeck stroker uses a shorter piston yet survives quite well on the street....it's a proven combo that is very durable. Certainly the 1.80 rod ratio helps. Inmo, compression heights that put the oil ring into the pin will suffer on extended street duty builds. The 4.25 lowdeck (511ci) combo is one such build....compression height = 1.12

With the recent availability of affordable stroker kits....the RB 4.25/7.1 combo is a no brainer. 


Ron

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Ron

Thanks a lot for your help on this!  I find you posts and info always educational!

On a side note the 2.2" crank rod journals are OK in your opinion for both stroker combos?

In terms of main journal bearings would you go with 1/2, 3/4, or full groove?  Would you go with a thin groove?

Andy

[firefighter3931]

Andy, no concerns with the 2.2 rod journal.....it's plenty strong. The added bonus with the 2.2 journal is increased clearance for an internal pickup. The 4.25/2.2 rod has more clearance than the 4.15/2.375 (stock BB journal) will have. Basicly, using the smalller journal facilitates the use of an internal pickup.....you might have to do some minor grinding on the PU boss but that's it. 

These new stroker cranks are much stronger than the factory originals....4340 vs 1053 steel. 

1/2 groove bearings are fine. I like to use a HV pump along with a higher capacity pan and windage tray. The Hemi replacement oilpan is baffled and holds 6qts....and it won't hang below the K-frame and get hammered when you drive over a speedbump. 



Ron

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Ron

Excllent thanks again for you help.

One more question if I can.  I don't want to bug you.

Using your guidance from the steve66 thread I plan zero decking any direction I go.  On the 4.25 / 7.1 build is 10.5 CR OK or should I shoot for something lower?

Andy

[firefighter3931]

Andy, anything between 10 and 10.5 will be fine unless you plan to go real small with the cam. The tight quench will make it detonation resistant but you also have to contend with cylinder pressure. Keeping the cylinder pressure below 180 psi with a tight quench, aluminum head build is the key.  The reality is that a 4.25 stroke build is gonna make gobs of torque....there's no reason to push the compression ratio envelope and risk detonation. The increased cubes and stroke will do all the work.


Ron

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Thanks Ron

I will start fine tuning the Plan for the long rod 511 build!

Since I am going with the stock hood would you go with the 84cc E-Heads or the 75cc EZ heads.  Since I will order the pistons to achieve 0 deck and 10.5/1 I am not worried about the chamber volume because I will order the correct dish.  Just want to get the best workable head that will fit under the hood with TTI headers and exhaust system.

Andy

[firefighter3931]

Andy, based on the 425 stroke and 500+ cubes the EZ's are a better option.....if you are willing to do a bit of tweaking. The EZ-1 with a max wedge port will move lots of air. To fit this under the hood....you will have to use the Indy Dual plane intake and have it opened up to max wedge dimensions. There is enough material in the runners to do this mod. The MW port would be worth ~ 75hp over an RPM head with a stock port window and a street dominator intake.  If you're unwilling to do the modifications and use the std ez head i would just say there's not much to be gained vs using the Eddy performer RPM....they're pretty close out of the box. 

It just depends on how much power you want and where you want it to come in at. 


Ron

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Ron

The dual plan Indy intake is 5.25" tall front and back.  It doesn' have a front to back rake like the SD, RPM, or Torker II.  They all start in the mid 4" height up front and go as high as 5.8" in the rear of the manifold for the RPM.  Have you seen the 5.25" tall Indy dual plane installed under a 68 Charger stock hood?

Thanks

Andy

[firefighter3931]

Andy, i have seen one 68 charger with a set of 440-1 heads and the ICH dual plane underneath a stock hood with a 4150dp and drop base aircleaner. Lemme contact the fellow and confrm fit and report back.....i'm thinking it'll fit but be close. You will want some type of engine restraint to keep everything in place....but that's no problem, i have a fix for that. 


Ron

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Ron

Thanks!  I am sure it will be close.  It sure would be a bummer to put all that money in the top end and not be able to close the hood.  I have a Schumacher Tourque Strap to keep that motor in it's place!

Andy

[firefighter3931]

Andy, i just got a message back from him. He says it should fit fine (thanks Robert)...he was running a Victor with stock heads which is approx 1.25in taller than the ICH dual plane. With the Victor, Rob was using a 2in air cleaner assembly which is a little shallow. K&N makes a nice 14x3in 1.25in drop base air cleaner assembly that would be the ticket. He hasn't installed it in the car yet but based on the previous manifold....he's confident the new setup will clear fine. Hope that helps....


Ron

[BLAM]

Thanks for checking it out Ron!

Andy

[firefighter3931]

You're welcome Andy 


Ron

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Well since I have found this thread to be very beneficial and I have a couple more questions that others may find helpful for a future build of their own, I will ask them here.

I have been planning on strengthening my long rod 512 build (thanks again Ron for the advice) bottom end with a girdle from the beginning, but that plan always included stock main caps.  Then I read about recommendations using aluminum caps.  I always thought aluminum mains were a big no-no for a street car!  Has this frame of mind changed?  Why?  Is it a shift from 6061 to 7075 aluminum?  Is it the inclusions of the girdle?  In other words without the girdle system you should go with steel caps.

If a girdle system like the BCR setup was used what are the oil pan challenges with a stock suspension and stock hood 68 Charger R/T?  I would rather not have to use motor mount bushings to ensure oil pan fit give I will have little hood clearance to start with.

Thanks

Andy

[firefighter3931]

Those are good questions Andy....i was wondering when you were going to get around to the bottom end. 

Personally, i like the idea of an aluminum main cap. The weak link in stock blocks is the main webbing which is prone to cracking under severe load. Detonation is a killer on bottom ends so anything you can do to strengthen the main saddle (including preventing detonation) is a huge bonus. The aluminum caps act as a shock absorber to dampen the harmonics that cause the crack issues....i think they're great.    A lot of racers are having good success with the aluminum caps and swear by them. The newer generation aluminum is much less brittle than the earlier stuff which had issues with cracking. I suppose a cracked cap is much better than a split cylinder or fractured main saddle....especially after spending lots of $$ machining the block. 

The BCR girdle looks very well thought out. My friend (member Blown68) just bought one for his supercharged 446 which is making in the 750hp range. He was running the stock caps and ARP studs but that's really pushing it !  Time for an upgrade  As far as fit, that has still to be determined....for sure the pickup will have to be extended to account for the additional 1/2in girdle plate. How that will affect clearance to the centerlink is another potential issue....there could be problems there. For a blower guy running an open hood setup with a bug catcher it's a matter of simply shimming the motor mounts to raise the engine. For someone running a stock hood...this could concievably cause problems. 

Depending on the power level....aluminum caps by themselves with studs (no girdle) has also shown to be effective as well. Heck, some guys get by using just the stock caps with studs. Personally, i would run the aluminum cap/stud combo as a minimum and keep the output at 650hp. If you want more than that....an aftermarket block or main girdle/alum cap should be considered a necessity....assuming you want it to live for a long time. A lot will depend on driving style and how often you intend to push it to those limits, inmo.


Ron

[BLAM]

Yes I will have to get some info on the possability of oil pan fitment issues with girdles installed on 2nd generation Chargers!

I sent an email to Gregg, owner of BCR, and asked for any info he had om his girdle system and oil pan fit issues.  He replied that so far his personnel experience is with A-Bodies only.

Perhaps I will post a question on Chenworth as well.  Their girdle is a 3/8" plate.

I suppose if worst comes to worst I can look into a Charlie's Custom Pan.

[firefighter3931]

The Charlies pan will work good....but those require an external line with a static (or swinging) pickup.....i don't believe you can use an internal PU with that pan. 

Another option that i've seen done is to drop the K-frame down by using spacers....this is usually done to gain hood clearance. It is however a lot of work.  But if you lowered the K-frame 1in and raised the engine 1/2in to account for the girdle it would work with an OEM style pan.....and you would still gain 1/2in hood clearance. 

Something to think about 


Ron

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I would like to extend my rotating assembly discussion to block options.  As I said I will be going with a 4.25" crank and 7.1" rod build.  I have a 70 block which is in for a sonic check of the bores which are already 30 over.  When I get the sonic check results I will post them here for feed back.  I know from searching the forums the concensus is to go go no less than .125" on the bore thickness.

In my preparation of the battlefield, if the bores are unacceptable, I have decided not to search the old 440 stock of blocks any longer.  I will probably buy a new MOPAR Performance block.

My question is this if I do go with the new block what would you all recommend: the 2 bolt main water jacketed block or the 4 bolt main siamese bore big block?  Will cooling be an issue for the siamese bore street car?  The 4 bolt main would be nice!  Anyone with any experience building either these blocks for a larger stroker street car application?

Thanks

Andy

[firefighter3931]

Andy, i'm not aware of any overheating issues with the siamese blocks. If you have a good cooling system it should be quite streetable. My friend member Blown68 runs a factory block with a partial fill (hardblock) on the street and that big heat sink 671 on top of the engine. With an aluminum rad it works fine. I would think that something like that would be harder to cool than a naturally aspirated siamese block. 


440source is bringing an aftermarket big bore block to market later this year....supposed to be good to 4.50 and priced at 2k or less. I'm not sure what your timeframe is like for this build ? There are a couple of other companies coming out with aftermarket blocks as well....If you're looking to make more than 650hp ; the aftermarket block is the way to go, inmho.



Ron

[BLAM]

Thanks again Ron.  I was thinking the same thing, a good cooling system and I should be all set.

Andy

[Chryco Psycho]

I too have never seen a cooling problem with the Mopar siamese blocks unliek the Chev 400 small blocks 

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Well I got my ultrasonic inspection data back for my block.  The data below shows the wall thicknees if I have to go 55 over bore, which is what the machine shop thinks will be required to square everything up.  These are calculated thicknesses=measured thickness-0.0125".

I would like recommendations on using this block for my planned 4.25" stroke 7.1" rod 600hp to 650hp motor build plan!

1970 440HP block calculated bore thickness at a 55 over bore.

Cylinder #8          Top          Middle          Bottom                    Cylinder #7          Top          Middle          Bottom
Inside                .3175         .3385           .4065                      Inside                .2975         .2705           .2885
Outside             .2655         .1885           .1995                      Outside              .2555         .2755           .3225
Front                 .1885         .1625           .2065                      Front                 .2275         .2035           .2165
Rear                  .3945         .2885           .2655                      Rear                  .2625         .2485           .2685

Cylinder #6          Top          Middle          Bottom                    Cylinder #5          Top          Middle          Bottom
Inside                .2615         .1955           .2345                      Inside                .3075         .2435           .2625
Outside             .3245         .3445           .3875                      Outside              .2845         .2915           .3765
Front                 .1585        .1355           .1525                      Front                 .1895         .1705           .1945
Rear                  .1725         .1465           .1525                      Rear                  .1745         .1215           .1425

Cylinder #4          Top          Middle          Bottom                    Cylinder #3          Top          Middle          Bottom
Inside                .2945         .2235           .2575                      Inside                .2905         .2375           .2515
Outside             .2785         .2915           .3975                      Outside              .2575         .2595           .3065
Front                 .1495         .1425           .1445                      Front                 .2035         .1655           .1945
Rear                  .2155         .1885           .2095                      Rear                  .2505         .1485           .1615

Cylinder #2          Top          Middle          Bottom                    Cylinder #1          Top          Middle          Bottom
Inside                .2675         .2385           .2765                      Inside                .3575         .3055           .3015
Outside             .2995         .2975           .3295                      Outside              .2975         .2865           .3345
Front                 .2545         .2395           .2575                      Front                 .2925         .2595           .2785
Rear                  .2395         .1795           .2045                      Rear                  .1895         .1495           .1705


So would you build this block or replace it with a new MOPAR Performance siamese block that I asked about on an earlier post?

Thanks!
Andy

[firefighter3931]

Andy, just to clarify ; when you're referring to inside vs outside....what exactly is the point of reference. I usually see a sonic check chart with each cylinder from an overhead view and the numbers posted on all 4 sides top to bottom. Just want to make sure of what i'm looking at. The major thrust side is the critical dimension.....the passenger side cylinder wall on both banks.

Thanks, Ron

[BLAM]

Hi Ron

Sorry!  Inside refers to lifter valley side of the block and outside would be the exhaust manifold side.  So in the case of my table the outside measurements on 2,4,6, and 8 along with the inside measurements on 1,3,5, and 7 are the thrust sides.

Thanks

Andy

[firefighter3931]

Andy, want to sell me that block       Looking at those numbers  have to say i'm impressed......that's probably the best OEM block sonic check that i've ever seen. I see no problem using it for a 4.25 stroke build......i would use it in a heartbeat. Some MP aftermarket blocks don't look that good ! 

I haven't checked my 75 block yet but i'd be tickled pink if it looks anything like yours ! 



Ron