Muscle Motors Racing - Mopar Stroker Kits / Crate Engines And More!

After decades of convincing people to spend the money on aftermarket aluminum heads, the first question people ask is why? Some assume it might be cheaper, but unfortunately that is not the case. Honestly, well ported Performer RPM heads will flow as much air, weight less, and features a closed chamber for quench. Since they are made out of aluminum repairs are easy if anything ever does go wrong.

Then next question is the same as the first, why? “906” iron heads are hard and difficult to port. They also are now at least 40 years old and need valve guide work, new valves, and hardened exhaust seat for unleaded compatibility, BUT if you have a 68-70 ½ Chrysler product, these are the correct heads for your mopar big block. Since the 68-70 ½ years might be considered the “premium” years for mopars of value, there are a large amount of people who want to improve engine output, but still maintain the OEM appearance. These CNC’ed 906 heads are not only for hot street cars but for a number of OEM appearing class racing organizations like FAST (factory appearing stock tire).

To meet the demand of this niche’ market we now offer CNC porting for 906 heads. I have been asked many times about programs for other castings such as 452 heads. The problem is that because iron is much harder than aluminum, it takes more machine time to port the heads. The iron heads are also harder on tooling. Because of these reasons, CNC porting iron is more expensive than aluminum. Honestly, In a performance application other than OEM appearing, you are better off upgrading to an aftermarket aluminum head for a hot street or bracket racing application. Our CNC ported 906 heads are specifically designed for class racing and people with certain year cars that want to maintain OEM appearance.

EVERYONE is obsessed with flow numbers. While they are important they are not everything to making power. To sooth the information junkies that exist out there, here are the flow numbers.

Head flowed w/2.14-1.81 valves, 45 degree VJ, 2.375 bore, no ex tube.

As you can see the ex easily flows over 70% of the intake and with 313 cfm you can easily support well over 650 HP.

For Muscle Motors to supply complete heads that feature: CNC porting with polished chambers, Stainless valves, new bronze guide liners honed to size, hardened exhaust seats, surface milled, any hydraulic or solid cam springs, 10 degree locks and retainers, new seals and are fully assembled, $2299 outright, no core charge. If you send your core heads deduct $200.

Mike @MM

All of our stroker engine blocks are prepared the same way. First they are jet washed to remove all dirt and debris. A jet washer is like a giant dishwasher. It sprays a caustic solution that is heated to 180 degrees. This high pressure solution dissolves dirt, grease and oil leaving a clean ready to machine surface. Then the blocks are magnafuxed to make sure there are not any cracks or defects. Then the blocks are sonic checked to make sure there are no core shift issues and all cylinder walls have adequate thickness in all directions. (SIDE NOTE: there is a common misconception that blocks made after 1974 are “thin wall” blocks. THIS IS A COMPLETE FALACITY. I have sonic tested 1978 blocks that are some of the thickest blocks I have ever checked! The only real way to know if you have cylinder walls strong enough to make over 550 HP is to sonic check them. Pre 1972 blocks are made with a higher nickel content cast iron but can be thin. I believe you must sonic check any block to be used in a high performance application. That is why sonic checking is standard procedure on all engine blocks machined at Muscle Motors). After we have determined that we have a good core we then debur the block of all casting flash and enlarge the oil galleys that supply oil to the main bearings. ARP main studs are installed and the main bearing bores are align honed. This ensures not only consistent bearing sizing but perfect alignment of all bearing bores. We then bore and hone the cylinder bores with deck plates to the first oversize (usually +.030 or +.040). Next, we machine the deck surfaces square and parallel for an ideal gasket sealing surface. The next procedure is to grind the block for stroker clearance. Not all blocks need this clearance but we figure it is better to have it and not need it, than the other way around! The next step is to measure and size all of the cam bearing bores for perfect cam fitment every time (see side bar). Lastly the oil pick up is then enlarged to 1/2” and then block is again jet washed a final time. Cam bearings and brass freeze plugs are installed and the block is painted in red oxide primer.

Read more: MMR Big Block Stroker Short Blocks

The NHRA AAA Midwest nationals was a very good weekend for Muscle Motors Super Gas competitors. The inclement weather reduced Super Gas to 2 qualifying shots. Hometown racer Brian Miller qualified #1 with a 9.902 in his MM prepared 528” engine with 440-1 heads IN A full bodied 70 challenger. Unfoutunatly Brian went red in the first round. The David and Goliath story of the weekend was Scott Vandewalker. Scott definitely takes a different approach to SG racing. Not only does he use a BB Mopar, Scott uses a manual 4 sp Lenco transmission with a clutch! This is TOTALLY unheard of in “super” class racing. This was Scott first event with his new 565” BB Mopar MM engine. Scott used a series of good lights and tight packages to make it all the way to the finals. Well Scott just missed winning the event in a double breakout final.

Joe Baker qualified solidly in the Pro Mod field in 14th place. Joe used a better reaction time and a solid 5.99 to beat Brad Personett’s quicker 5.95. The Pro Mods all weekend favored the left lane. In the second round Joe had the tricky right lane. Joe made the best of it but lost with a 6.09 to Denis Radford’s quicker 6.04. After 3 races Joe is 3rd in points just 2 rounds out of first place.

All in all, a great weekend for Brian, Scott, Joe and Muscle Motors!

Good morning class! Today we are going to learn about the how’s and why’s about stroker kits. My goal is to debunk some myth’s and common misconceptions about stroking a big or small block Chrysler. As someone who has built National Championship quality racing engines for over 20 years I will share specific information about bearing clearances, bore notching and much more information. This is really required for properly building a stroker engine. I will also ”in clear terms and detail” explain what questions you need to ask so you can purchase a stroker kit that is truly “ready to go” when you receive it.

HISTORY:

We built our first big block stroker engine in the fall of 1988. “Back in the day” the only way to build a stroker engine for a Chrysler was to buy a billet crank or weld and offset grind a stock crankshaft. Since billet cranks are machined out a solid piece of steel they are very expensive ($2800+ in 88’) and took over 12 weeks to make. This was not a practical option for us. That left us to use welded strokers. Welded strokers evolved out of weld repairing damaged steel crankshafts. Someone figure out: instead of welding the journal to repair it, one could just weld on the top half of the rod journal and then offset grind it to increase the stroke. People have been doing this since the late 40’s!! While this worked well, you still are starting with a 1053 steel crankshaft that was never intended to make serious power. Not to mention any factory 440 steel crank is now 40+ year old and most likely has seen a pretty hard life.

Fast forward to1992. Mopar Performance releases the 3.75 & 4.15 stroke crankshafts. While they are a little bit more money than a welded stroker, they are brand new and can be ordered off the shelf and into you hot little hands in days not weeks! Mopar decided on a 4.15 stroker crankshaft because it makes exactly 500” in a 440 block that is bored + .060. These stroker crankshafts were made by Norton Foundries. This was a company that was in Fostoria OH that made OEM production cranks for the big 3. These cranks could be purchased for around $1200 and once balanced could be dropped right in to a properly prepared 440 block . Due to Norton’s experience with the OEM’s they held very consistent bearing sizing (clearances). These consistent bearing tolerances made them very friendly to the end user.

Read more: Stroker Kits 101