Stroker Rod Ratio and Piston Selection

Hi Gents! I'm a new subscriber and I thought that I'd share some "rod ratio" detail with you.

First of all it makes no difference which stroker you choose, 393 or 408. The ratio of the rod to stroke has a benefit, and that benefit is due largely to the greater dwell of each piston at TDC with a longer rod. The longer the rod (to a point) the better and more complete the combustion. Moreover, the long rod will enhance performance, and decrease the amount of octane needed keep the engine from detonation. The stock 351W rod measures 5.956 C to C. This will work fairly well with any 302 piston to build a streetable 393. However, an increase in rod length would always be better. Your choice here would be either a 6.125 Chrysler SB rod, or a 6.200 rod from a 300 cid 6cyl ford. Incidentally, both rods in stock form fitted with ARP wave lok rod bolts, and stress relieved will prove to be very reliable for either the street of the track. Sure Eagles are better, but some of us have a budget in mind. Furthermore, piston selection could be made simpler by doing the necessary math yourself and relying on a piston chart for your selection. Example: A 408 stroker has a 4 inch bore by a 4 inch stroke. If you use a stock length 351w rod, the rod length will be 5.956. You can either use an after market piston in your build (expensive) or you can choose a piston with the compression height that you need from a piston chart, in this case a piston for a 305 Chevrolet with small combustion chambers. Since Chevrolets are plentiful and popular, part prices are CHEAP! You could inexpensively choose a chevy piston with the same bore and compression height either forged or hyperutectic, or you can opt for a more expensive slug from Ross or JE. The choice is yours, but researching is more cost effective.

Compression ratio should be chosen via three ways. By the compression height of the piston, the volume of the combustion chamber ( better closed then open), and the amount of dish in the piston. Dished pistons offer better flame travel which enhances the performance. This along with the proper squelch and you will have a 9 to 1 motor running like an an 11-to 1.

Anyone with any questions may email me. I will send you to different web sites with the necessary information needed to help you with your piston and rod selection. Good Luck![img]/phpBB/images/smiles/icon_bow.gif[/img]

<font size=-1>[ This Message was edited by: teecee on 12/9/03 5:24pm ]</font>

<font size=-1>[ This Message was edited by: teecee on 12/9/03 5:26pm ]</font>

<font size=-1>[ This Message was edited by: teecee on 12/9/03 10:24pm ]</font>

<font size=-1>[ This Message was edited by: teecee on 12/9/03 10:26pm ]</font>

There's a lot more to it than just TDC dwell...less rod angle, less frictional area due to shorter skirt piston. Take a look at this post from a few weeks ago. There are many other posts discussing your comments over the years.

http://fordmuscle.com/phpBB/viewtopi...;forum=1&amp;7

Excuse me, but I can't help but feel there are alterior motives here when I read your post. Is this FYI or are you trying to promote something?

_________________

Tracy Blackford: Corona, Ca
'65 FB Mustang 329 with H-beam 289 rods, KB 322's, 282S cam, race preped 351W heads. Built C4 and 3.50 9" posi

<font size=-1>[ This Message was edited by: blkfrd on 12/10/03 4:49am ]</font>

[img]/phpBB/images/smiles/icon_confused.gif[/img] Boy, aren't we skepticle here?? What would I being trying to promote Tracy? Most readers don't want to have to take a course in advanced calc, and analytical geometry just to be able to choose a rod combination. Yeah, you've proved your point. Now, explain it all to the rest of the crowd.

BTW, you sure that seat is NHRA, AHRA approved??

<font size=-1>[ This Message was edited by: teecee on 12/10/03 9:22am ]</font>

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On 2003-12-09 17:52, teecee wrote:
[img]/phpBB/images/smiles/icon_confused.gif[/img] Boy, aren't we skepticle here?? What would I being trying to promote Tracy? Most readers don't want to have to take a course in advanced calc, and analytical geometry just to be able to choose a rod combination. Yeah, you've proved your point. Now, explain it all to the rest of the crowd.
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I'm not skeptical, I understand what your saying and it's all good. I felt the post was more than what one would expect from a new member and I got in impression of self-promotion from the post.

In the past, there have been members on this forum and other forums that have only one goal in mind and that is to try to promote their business. They have a certian bias that doesn't come out from other members who are just Ford owners in search of unbiased information or advice. I apologize if this description does not fit you.

What I meant to say was "Excuse me if I have the wrong impression, but..."

I'm probably getting off track here...I am a very intuitive person, but I apologize again if I had the wrong impression.

[addsig]

Hey, I don't have a problem with that Tracy. Everybody is entitled to his/her own opinion. Your apology is accepted. No damage done.

It just seemed to me after reading a few recent posts that some of the members weren't sure as to how or why it was a good idea to consider a different rod combination, and I felt the necessity to share with them some simple ABC's of that choice. I am not biased in any fashion. From what I've seen from some of the recent posts these family guys, with all of their new found responsibilities have all that they can do with just trying to find an inexpensive way to build a street motor and enjoy the sport without breaking the bank, and getting chewed out by their wives. I've got nothing to gain here but friendship, and knowledge. For even I don't have all of the answers.

Your experiment was interesting, and proved true. If every build was a Winston Cup motor, I would have asked you for permission to reprint because of some very interesting points, but I hardly think that most would really apply to the average "grocery getter." Just trying to help keep the costs down and the performance up.[img]/phpBB/images/smiles/icon_lol.gif[/img]

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On 2003-12-09 21:42, teecee wrote:
Hey, I don't have a problem with that Tracy. Everybody is entitled to his/her own opinion. Your apology is accepted. No damage done.

It just seemed to me after reading a few recent posts that some of the members weren't sure as to how or why it was a good idea to consider a different rod combination, and I felt the necessity to share with them some simple ABC's of that choice. I am not biased in any fashion. From what I've seen from some of the recent posts these family guys, with all of their new found responsibilities have all that they can do with just trying to find an inexpensive way to build a street motor and enjoy the sport without breaking the bank, and getting chewed out by their wives. I've got nothing to gain here but friendship, and knowledge. For even I don't have all of the answers.

Your experiment was interesting, and proved true. If every build was a Winston Cup motor, I would have asked you for permission to reprint because of some very interesting points, but I hardly think that most would really apply to the average "grocery getter." Just trying to help keep the costs down and the performance up.[img]/phpBB/images/smiles/icon_lol.gif[/img]
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Right on!

Speaking of wives, i'd like to build a 351w based stroker someday. I'm sure my wife would have other ideas.

I have enough traction problems with my 331. I can't imagine the torque unleashed by a 393/408 in an early mustang.
[addsig]

[img]/phpBB/images/smiles/icon_frown.gif[/img] The first stroker I attempted was in 94 when all of the publications were putting out articles on building 408's by utilizing a 400 modified shaft. I figured "what the hell" so I attempted to do the same, since Scat was not manufacturing shafts for that application as of yet. I would not recommend that anyone attempt to build a 408 by this means. You will not save any money or time. What a "Pain in the Ass..." By the time I got done machining the 1 plus inches of material off of the bob weights to fit the block, clearencing the block to fit the shaft, grinding the shaft for proper rod side clearance, cutting down the snout to fit the balancer, and balancing the assembly with over $100 bucks worth of Mallory, I could have purchased 2 scat shafts, and I still has a cast iron shaft! Even though the application was for a Bronco that would never see 4500 RPM. I did however utilize a set of 305 Chevrolet cast pistons for the build for it was to be a budget motor. I relieved the original "89" heads with some minor port work mostly in the exhaust area, minor bowl work on the intakes, and I cleaned up the combustion chambers to remove the chance of hot spots for it was gong to see 5 pounds of boost. I left the valve sizes alone. Installed a Reed cams flat tappet hydraulic grind with a 112 degree lobe separation angle, and put her together with a set of moly rings, and all of the EFI equipment that it cam with as stock. Static compression was at 8.3 to 1.

I originally put on a Paxton SN95 with the original 19 pound injectors. Everything worked out great, but I had to replace every sensor on the motor there was, and all of them had to be from FMC because after market units did not work right for some unknown reason. Once I ironed out the bugs and managed to get the ECM to accept 112 degree LC cam change, it ran great. After about a month, I installed a set of shorty headers, and upgraded to a 3 inch exhaust system.

What a torque monster! It ran good, and is still running with over 45,000 miles on the engine, however, the Paxton took a puke due to bearing failure, so I replaced it with a Novi, which also too a puke from the same. So I told Paxton to shove it. I was a dealer for them, a they treated the issue like sh_t, so I packed up their display, kits, and literature and sent them a Dear John letter, and told them that I will bad mouth them until my death because of the way they handled the matter. 4 grand down the tubes.

<font size=-1>[ This Message was edited by: teecee on 12/12/03 1:16am ]</font>