Thank you for putting this out there, several of the other videos on youtube have different bits and pieces of this info, but this video really helped bring it all together for me. Especially the trick with the compass...it's so simple that it's hard!
Glad it helped out. I actually have the finished video production of these heads with flow numbers to post soon too with the 70's big block corvette they went into with a dyno run when the owner finishes his exhaust work. Good luck with your project! 👍
Not too many people will go through the effort of porting cast iron heads or pay a shop $2k to do them since the after market has more affordable aluminum heads. I personally buy AFR enforcers as good low cost heads for the 489-540 builds but these heads were for a 454 c3 vette restoration build. Thanks for watching! 👍
@@djrowe10heck I got a great deal....new bronze guides, hardened seats, new valves, 5 angle valve job, porting and valve unshrouding and heads that flow 320 cfm for $900. 👍.
@@trailerparkcryptoking5213Sounds like a hellava deal! Not around here in Cleveland Ohio area...Bronze guides alone cost $600-800. Glad you got a deal and I personally buy AFR for myself last few years.
I have 5 big block jobs going on now and 4 sets of 781 heads to do. The machine shop is 6 months backed up to cut seats and vavle guides. Maybe in late 2023 could possibly help? Only time will tell if there's gonna be another covid lockdown this winter? Hopefully not.
781 heads are the best choice for better street performance choosing OEM cast iron heads. If your application is towing then you could save more money on using traditional peanut port oval heads found on millions of 454 truck engines out there. They are best suited for low rpm max torque output related to towing. If for any other performance situation then just towing it is always better to have the 049/781 large oval port heads that flow well above the 5k RPM band with larger valves and minimal porting. Good luck with your project! 👍
I some what agree.. I was just curious about port velocity...I jabe a vortec 454 currently and I see these heads make about the same power as peanut port with a cam as the vorteca do stock..I'm just curious how the bigger ports work down low with a smaller profile towing cam.
Well that is very complex question but has been answered in the past both in theory and on the dyno. The peanut port heads can only make around 400+ HP NA with insane port work and bigger then stock valves. The large oval ports can and have made 700HP or more on the dyno with just bigger valves (2.30x1.88) and moderate port work. Google search for Dr. J 781/049 port work power. Then watch Richard Holdners TY channel for more BBC testing. I don't want to make a response as long as the bible but port velocity is directly related to how the metal is port shaped. Cylinder head intake/exhaust volumes and engine bore sizes work together as an air pump to create power. Their is direct correlations between how much air will go in and out of engine based on size and volume. That is why large oval ports will make more power all day long in the entire power band and peanut ports have a small rpm range that was made just for the powerband of towing/hauling. Watch Richard Holdner on RU-vid here about peanut port heads: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ERBi1giKLAY.htmlsi=NWTJzBChKE5g77go
Watched them all... I understand what heads work for good street builds with larger ports... I'm trying to narrow it down to what size and design ports work best with a low duration high lift cam... not alot of in depth real world tow motor builds that actaully have lower rpm in depth dyno pulls.
I would have to know what cam you are looking at and what head choice. Low duration and high lift truck cams are usually for 4x4 builds and not towing applications. Why would you want high lift for towing capabilities since lift dictates the power band rpm range and the higher the lift the higher rpm is needed to achieve the top of that power band. 4x4 trucks will have a bigger stall or manual trans to get rpms up faster into their power band. Tow trucks just need low lift low mid level rpms to get heavy loads going. Smaller valves and not the larger 2.19/2.25/2.30 sized valves or even stock sizes will be sufficient for any non racing high performance build if you do mild port work. What exactly are you trying to accomplish again?
