Author Topic: Big block Mopar heads....differences and easy way to find more HP  (Read 11414 times)

Offline gomangoRT/SE

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Lots of questions here recently about bigblock Mopar heads and differences.......I have found an excellent article the addresses many of our members concerns........whether it be ways to find additional HP for cheaps........actually very cheap, to the variations of heads from the early closed chamber heads to the later open chambered designs.   Article also give graphs showing what simple porting can be done by a novice with the old Mopar template to others seeking additional advantages........I have used these templates a few times now and found (or at least think I have found) that I can increase flow fairly substancially without just going out and spending $1500 for a set of heads when all I want to do is improve my performance for the occasional race or showing off some acceleration.   Requires some patient reading and even more patience when marking off the heads with felt marker or blueing......takes a little bit of time, but if you follow the template instructions you can find some nifty improvement with any of the Bigblock Mopar heads whether it be the early 915 closed chamber design or the more plentiful 906, 346, 902, 975 or 452 open chamber heads.    This article will show improvements throughout the range in lift.......not just high lift........so there is gain thoughout the spectrum......you don't  have to be a bonefide race to enjoy gains......... In the article it will point out some fact vs fiction............so nuff said here it is        www.moparmusclemagazine.com/techarticles/5115    You can find the part 2 and part 3 to the article on the internet also.............interesting reading.   




Offline gomangoRT/SE

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Re: Big block Mopar heads....differences and easy way to find more HP
« Reply #1 on: July 13, 2005 - 03:23:47 pm »
I also wanted to add,  take a look at what improvements are made in air flow by simply back cutting the valves 30 degrees and using the $19.00 template kit...........significant improvement.  Otherwise a big block Mopar head is inferior to the Ford and Chevy design.........now we just can't have that can we.
Backcutting the valves alone provide double digit improvement in flow......when you use the template in addition to that even more..........

Offline Killer_Mopar

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Re: Big block Mopar heads....differences and easy way to find more HP
« Reply #2 on: July 13, 2005 - 07:30:05 pm »
The template kit isnt worth the 19 bucks. I bought it and realized that it was a all common sense, the template basically shows that all the sharp turns should be rounder. I might add that if you are going to back cut the valves, you should just upgrade to 1.81/2.14 performance valves and gain a huge amount. I used that same page as a referene for the heads I am doing. Right now I have the oversized valves, .600 lift springs, and keepers. Still have to buy retainers, seals, and port one head. After that, I will take them in to get machined....
70 Challenger R/T SE - The never-ending project........

Offline Mr. 6pak2go

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Re: Big block Mopar heads....differences and easy way to find more HP
« Reply #3 on: July 13, 2005 - 07:48:18 pm »
i read that artical to!! seems like a good deal 1500 aint bad for heads!! but il stick with my stock!! i like stock!!
My family, My cars, My guns three things il fight for!!

Offline gomangoRT/SE

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Re: Big block Mopar heads....differences and easy way to find more HP
« Reply #4 on: July 13, 2005 - 08:54:16 pm »
Part 2 of the article states that going from 2.08 valves to 2.14 valves actually <did not> flow as well as the 2.08 intake valves that were backcut 30 degrees..........actually was less cfm.   The template gives you a great outline and prevents a novice from cutting too much off and gettting into the water passages.......part 2 states that Mopar owners are sadly mistaken if they think that simply going from 2.08 to 2.14 provides better flow..........its only better if you use the template to port under the pockets and back cut the 2.14s.......... if you wanna pay some guy a few hundred to do the work of porting then do so.......but why when you can do it yourself with a few simple tools and a compressor..........Another article in old Mopar mag also reiterates that if you simply go from 2.08s to 2.14 w/o doing porting you are blowing your money..........

Offline firefighter3931

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Re: Big block Mopar heads....differences and easy way to find more HP
« Reply #5 on: July 14, 2005 - 12:35:14 am »
 :iagree: You need to open the bowls all the way up to the valveseats when doing the big valve upgrade. There is some descent flow to be had using just the templates with a 2.08 intake valve and a backcut as the previous poster stated. The later 346/902/452 castings respond well to these mods. The hardened ex seats are an added bonus with unleaded fuel.

Ron
68 Charger RT street/strip Bruiser & 70 Charger RT 440-6pack the ultimate Cruiser

Offline gomangoRT/SE

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Re: Big block Mopar heads....differences and easy way to find more HP
« Reply #6 on: July 14, 2005 - 06:33:35 am »
 :iagree:     BINGO!!     

Offline EVIL72

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Re: Big block Mopar heads....differences and easy way to find more HP
« Reply #7 on: July 14, 2005 - 07:31:34 am »
 Thanks for the artical gomangoRT/SE, It's got some good info.
 I remember when I ported the 906 heads on my old 70 Challenger, it wasn't that hard just watch out for the valve seats and water jackets. I didn't use a template, but they do help when trying to keep the pockets the same size.
ROB
1972 Dodge Challenger 340ci
1970 Pro Street Duster (Under Construction)