Swapping out my current MP 508/280 solid cam for the MP 557/296 solid. Wondering if I should advance the cam 4 degrees or run it straight up? Provided I have enough piston to valve clearance. Its mostly street driven, only make it to the track a few times a year. Doing bowl and port clean up on my set of X heads as well. It is an old school 340 in my 68 GTS. 727 with 3800 stall, 410 gears, stock replacement TRW pistons, deep oil pain, air gap intake, 750 DP with pro form main body, cheap flow tech headers, 273 rockers for now, FBO ignition with MP adjustable advance dizzy. The old cam ran a best of 12.98 @ 105 with not a lot of tuning and that one ended up 5 degrees advanced. I freshened the motor up in 2000, still has good oil pressure and 180-185 cranking compression. Thanks guys.
MP 557/296 small block cam, advance or straight up
- Thread starter gtsdude
- Start date
-
340BABY
Well-Known Member
You will have to degree the cam with a degree wheel, but no you should run it straight up, and you will need to change the rockers, I would worry about them. This a no BS cam you are putting in, I put it in a 340, 12.5 to 1, X-headed 2.02/1.60 with an Air Gap RPM and a 800cfm, Crain Rockers, MSD Distributor and 6AL box, 29’s with 4.88 gear. 4200 stall and a 727 with Transbrake, in a 1973 Dart Sport with full interior. It is frame tied and he runs low 10’s at 7200 RPM’s through the traps. With some work I am sure he could get it in the high 9’s. He had a bad 60 foot time until we figured out he was carrying the front tires past the lights, so we were reading the back tire 60 foot times ….. oops. There are better cams out there, and with the new technology the .557 cam is rather old school but it works fine, so enjoy it and have fun. Foot braking you should get into the high 10’s to very low 11’s, with no problems. All depends how you support it, upgrade the Box, Wires, index the plugs, and fuel pump, and so on. Good Luck
340BABY
Well-Known Member
Yup if you want to trust 50 year old rockers they will work, is it worth the chance, $250 to $400 vs a lot more if they break, or losing to a Blue Oval Bozzo, or even worse yet, a Bow Tie Girl, I couldn’t live with myself. The stock stuff is getting real old, and you have to weigh out the advantages and savings vs price of new.
Yep. Ran those on 590's when nothing else was really out there
IIRC, that cam is cut on a 110 LSA and is supposed to be installed at 108. I'd install it in the 102-104 range if you have VtoP clearance.
replicaracer43
Grumpy Old Man
- Joined
- Oct 10, 2008
- Messages
- 6,051
- Reaction score
- 7,867
Id rather have a good old 273 rocker over most of the aftermarket stuff offered these days. I cant say I have EVER seen a broken 273 rocker in my lifetime......
dam..do you trust 50 yr old blocks...rods..and cranks...cylinder heads?
I got a 62 yr old crank...and it still works real good........
340BABY
Well-Known Member
Call the tech. line and ask, then you will know, or you could play with it if you have a dyno nearby. Hey crackedback Not looking for a fight, just asking what do you base that info on, have you run it like that and why did you, Dyno time, Strip time, what did you do for comparison, and what were the numbers. I’m curious about stuff, and I always ask question to see way people do what they do.
340BABY
Well-Known Member
With the nickel content in a season block yup, crank after magnaflux testing and .010 and under yes rocker (that were manufactured to run at max rpm of 5500), rods, pistons, NO, micro cracks and weight is the reason. Besides I am trying you reduce rotating drag, enemy number one for engines is Harmonic. I have seen old adjustable rockers come apart many time and cause a lot of problems, and I have seen them being run up to 6500 rpm with no problem. Like I said it IS UP TO HIM
340BABY
Well-Known Member
And as far as heads go NO, I can by after markets for $400 to $500 for a set for the street, cost me less than fixing the old stuff. And as for something I am going to try to turn over 7500 rpm I would not even think twice about it, I by new. This doesn’t mean you or anyone else can’t or shouldn’t it just means I wouldn’t do it or recommend it. Mopar heads where great in their day and the small blocks still flow OK numbers with some work, but for anything above the 425 hp range it is aftermarket all the way, Bob Mullen (He designed the W2 head and the was the lead engineer for the 426 HEMI head) said it takes a lot of epoxy to get an X-head to 500 HP.
340BABY
Well-Known Member
The hemi head itself came from Desoto and was accrued when Chrysler bought them out, Hovers first car was a Hemi. One of Hoover’s first projects at Chrysler was the Bendix fuel injection system (Electrojector), an early version of today’s electronic fuel injection systems. He later moved on to work in the engine lab to study engines, particularly the English straight six. He also was involved in the development of the successful Slant Six Hyper-Pak project. Hoover was one of the Ramchargers’ founding members, alongside Wayne Erickson, Dick Maxwell, Don Moore, Bill Koger, Herman Mozer, and Jim Thornton.
Of all the parts that have come and gone for the small-block Mopar, none are as venerated as the fabled W-2. Due to the work of airflow master Bob Mullen, (Mullen was one of the lead engineers who designed and worked 1964 Indy Hemi package, converting the hemi head to the Chrysler RB Block, designed the W2 head and designed and built the first flow bench). The W-2 was truly revolutionary when introduced in 1976. It put the small-block Mopar on the map as a serious race engine-serious enough to take the NHRA Pro Stock championship in 1979 when Ford notable Bob Glidden fielded a Plymouth Arrow for one year. It was eventually rendered uncompetitive in that venue via a rule change favoring large displacement engines. This info comes from Hot Rod Mag., History of Chrysler, and Muscle Engine Mag.
Of all the parts that have come and gone for the small-block Mopar, none are as venerated as the fabled W-2. Due to the work of airflow master Bob Mullen, (Mullen was one of the lead engineers who designed and worked 1964 Indy Hemi package, converting the hemi head to the Chrysler RB Block, designed the W2 head and designed and built the first flow bench). The W-2 was truly revolutionary when introduced in 1976. It put the small-block Mopar on the map as a serious race engine-serious enough to take the NHRA Pro Stock championship in 1979 when Ford notable Bob Glidden fielded a Plymouth Arrow for one year. It was eventually rendered uncompetitive in that venue via a rule change favoring large displacement engines. This info comes from Hot Rod Mag., History of Chrysler, and Muscle Engine Mag.
Thanks for the replies, I think it will end up advanced if there is room to run it that way. The 273 rockers would be nice to replace but going to run them cause that is what I have for now. I did change out the adjusters that have lock nuts on them to keep them from loosening up. They have seen 7k with the old cam more than a few times.
-
