I am debating converting my 71 350 4spd to 455 power over this winter (actually Ive been on the fence about it for the last few years , now Ive got the motor). Im hoping someone can set me straight on what all I should be getting in order to do this right. I like driving this car, so Id like to have everything Ill need here and ready to go once I start so the car wont be torn apart for too long . Will my small block bellhousing work on the 455? I know the clutch/flywheel assy need to be larger, but Im on the hunt for a flywheel now. It seems most people are happy with the centerforce assy, so Ill be at least looking over that setup. My other concerns are if the fan shroud will need changed, the z-bar or other linkage not lining up. All these years Ive been thinking this would be a pretty straightforward swap, and then recently Ive ran across this site, read a ton of the postings and figure I might as well ask. Any info or a referance to a book that might help would be appreciated. Thanks
The z-bar will work fine as will the rest of the linkage.The mounting hole in the block is in the same spot.The bellhousing is the same. The flywheels are different and I love my Centerforce 11" clutch set-up( make sure you get the proper splined clutch disc as most 455s used the fine spline,but 350s used a corse spline) You'll need another fan shroud( an Electra or Riviera will work fine) as well as 455 frame and motor mounts( TA Performance has them). You didn't mention headers,but if you use manifolds,the head pipes will need to be changed as 455 manifolds exit differently than 350s.
Thanks Al for the info, I had been hopeing youd help since I noticed that you went through a similar project not to long ago. You brought up the spline issue which I hadnt thought of at all. Ill have to look at that when I pull my trans, If I remember right it is a corse spline. Due to the different splines, my tranny should still be able to take the touque shouldnt it? The engine mounts will come from t/a, and theres a shroud from a 70 455 Riv on Ebay that Im watching. And I ordered a set of those M/T repos from gsca that are not due in till years end so Im hoping to just run new exhaust from collectors to mufflers. Im not sure if my radiator is going to be up to par but will see. Im also wondering if I should be looking at an aluminum or steel flywheel. Im leaning towards steel due to the mass vs weight of the car. Now Im going to search around and see what I can find info on this centerforce setup. Thanks for the help, any input is appreciated.
I would spring for the billet steel flywheel and a new 4-row radiator( bought my radiator new on e-bay for $125).The course spline shouldn't be a problem, as a matter of fact ,the M-20 with the course spline has a much better first gear ratio.You should be aware that ANY decent 455 could shatter the rather fragile Muncie trans with enough abuse though.
Hey Carry, Add a 455 throttle cable, mounts, radiator hoses, wiring harness, kickdown (I know you have a 4 speed, but the pedal might be different). I swapped a 455 for a tired 350 12 years ago, still have the same engine in, 100k later. Maybe I'll go pop the hood and see if I remember anything else. My best advice would be to save the donor car until your project is running. Good luck, and have fun. John
Thanks guys for the input. I found the radiator supplier on e-bay, (radiator doctor) and it looks like 125+shipping still will get one. Sounds fair to me as long as its a good one. Will the radiator cover plate that is top of the radiator (has the engine spec sticker on it)need changed as well when swapping from a 3 to 4 row radiator? was hoping mine would do. Also, I did not plan on any wiring or throttle pedal cable changes. I thought they would all adapt. The centerforce clutch assy is steep, but I also want one that I wont have to worry about for a long time and isnt too rough on the leg. I need to do some more thinking and/or research on this one. Thanks, your helping alot.
As I recall, the top plate is the same. Mine still has the 350 sticker.:grin: You might have to move the rubber dampers, or modify them to fit the wider radiator. I seem to remember carving mine a bit. When you pull your 455, just unbolt the wiring harness at the firewall of the donor car and leave all the wiring on the engine (hope it's still in the car). I don't remember if I changed anything on the firewall side of my car before bolting on the 455 harness. I definately remember changing the throttle cable, but it might have been because of the kickdown, 455 is electric, 350 is a cable. It was VERY difficult to find a big block GS gas pedal, and that was 12 years ago. Just bolt the engine in and see where the cable comes. It might be the correct length. when you hook it up, have someone floor it while you make sure the secondaries are fully open. That's the best way to tell. Make sure the cable is as straight as possible going to the carb, bends are bad. Sorry if I'm repeating anything obvious, I'm just remembering things I had to do. John
Carry, I've run all different types of clutch set-ups and if your looking for a bulletproof clutch with velvet like pedal feel behind a big block,you simply can't beat the Centerforce. I can't say enough about it,and you'll thank me later. :TU:
John, unfortunatly I dont have a donor car to get a big block harness from. Ill have to break out the wiring diagrams and see whats missing or different, and good to hear yours still has the 350 radiator cover, as Im hoping that means mine will fit also. You wouldnt happen to know if I can use a new automatic style radiator, plug the holes for the cooler lines, just in case one day I end up going with an auto. And still not lose any effeciency as far as cooling is concerned. Other than a couple of small plugs in the radiator I dont think it would be too noticable but I may be missing something here. Al, unless you work for Centerforce, Im not going to look no further. Are you running the centerforce 1,2 or dual friction? Also Im curious as to the gears and rear tire size your clutch has been dealing with. Im not going to be racing, but if I ever end up next to something one of these days I want to leave a good impression. (I Cant wait) Thanks guys
Carry,no I don't work for Centerforce,I just hate replacing clutches and clutch linkages..:laugh: My buddy with a 455 Olds 442 4-speed turned me on to the Centerforce clutch. I have a 1970 GSX with a 462 (455+.030"),Lunati 230/245 cam,forged 10-1 pistons and Hooker headers,M-20 wide ratio trans,Hurst Comp-Plus shifter with a 3.42 12-bolt posi rear.I run repro Goodyear Polyglas G-60 tires. I chose the 11" Dual Friction clutch (corse spline to match the M-20 input shaft) and used the smallblock clutch linkage set-up as the big block stuff is real hard to come by.
