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Discussion Starter · #1 · (Edited)
Difference in types of Cams...

whats the difference in hydraulic flat tappet and hydraulic roller cams....i was thinikn about one of those thumpr grinds from comp cams for my 408 i wanna build...any testimonials for those?
 

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in the actual cam or are u asking what the difference is between a roller lifter and a flat tappet lifter?
you cant run a flat tappet cam with roller lifters and vice versa
IIRC roller cams have a steeper ramp up and different lobe profile that will wipe out flat tappets
 

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if the block is a roller block it will not except a flat tappet cam nor would you want one anyway. the cam lobe designs are different from each other and when you look at them its a noticable difference. thats just the cam. now the lifters the rollers lifters have rollers on the bottom of them which creat a lot less friction than a flat tappet lifter which doesnt have a roller on the bottom. the lifter sits right on the cam and spins in the lifter bore. flat tappet cams you also have to break in and run the possibility of the cam eating right through the bottom of the lifter if its not broken in right. with roller lifters it doesnt matter where they go you can swap them all over the place and not have a problem the flat tappet wears to the cam so when you move them around to another bore they can ruin the cam or the lifter itself
 

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i heard one of the thumper cams, but it was in a small block chevy:tomato and it didnt sound impressive, but thts probably becuz it was a chevy....haha
 

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wow that is weird.....i woulda thot they would have went ahead and used roller cams since they had roller blocks to get a lil more power.....which reminds me the episode of trucks this weekend with the 454 SS truck vs 351w lightning..... 454 made like 198rwhp and about 295 rwt.....the lightning made 228 rwhp and about the same torque.....thats bad consider the ss has 100 extra cubes
 

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Discussion Starter · #12 ·
ok well im looking for a cam thats gonna make my 408 sound like a 60s muscle car...have a wide rpm range and be streetable.....any help??
 

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no i am correct the cam bore is bigger in a roller cam. thats why when you buy the kits to convert from flat tappet to roller you have to send the block out to be machined to fit the roller cam. so yes you can put a flat tappet in a roller block but its gunna take a lot of money to get custom cam bearings made for it. i never said the lightning motors didnt have roller cams because thye did it was a mustang h.o. motor in those trucks
 

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i really couldnt help you on a cam for your 408 what you can do is talk to a custom grind cam shop and they will ask you what you want out of your car and build a cam to that spec
 

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no i am correct the cam bore is bigger in a roller cam. thats why when you buy the kits to convert from flat tappet to roller you have to send the block out to be machined to fit the roller cam. so yes you can put a flat tappet in a roller block but its gunna take a lot of money to get custom cam bearings made for it. i never said the lightning motors didnt have roller cams because thye did it was a mustang h.o. motor in those trucks
ok please stop typing, you have no idea what you are saying. the cam bore has not changed EVER from the 289's to the end of the windsors and 302 in the late 90's. Please stop you are telling these guys something that is 110% incorrect.
 

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i am not miss informing anyone. i looked into changing my flat tappet to a roller cam not only will i need to send the block out for the bore to be made bigger they need to drill into the lifter valley so the holder for the lifters can be fassened down
 

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i am not miss informing anyone. i looked into changing my flat tappet to a roller cam not only will i need to send the block out for the bore to be made bigger they need to drill into the lifter valley so the holder for the lifters can be fassened down
Man I dont know where to start with this one. First sending the block out to enlarge the main bearing bores is 110% fiction. I have only been building small block fords exclusively for the last 16 years. The cam journal diameter is the same regardless of the type of cam. No sending the block out for anything, you are 110% wrong. As foir using the 302 hyd roller lifter setup in an early block with short lifter bores, there is 2 solutions, use a link bar lifter like comp or cranes and drop them in, OR using the standard ford hyd roller lifters, drill 2 holes in the valley and tap which anyone can do, BUT you must use a small base circle camshaft only. You are badly misinformed, find a new shop
 

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Woody is not the one to argue with on this subject, your just wasting your time. Listen to this guy, he wont steer you wrong.
 

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alright then i was told wrong by someone else and im sorry. thank you for informing me about this now i might just throw a roller set up in my block but i really want to get a new block all together since mine has 190k on it
 

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Thats all Im saying, someone gave you horrendous information that is so wrong they oughta be shot. If you have a non roller block, be it a 289-302 or 351 and you want to run a hyd roller you have 2 options.

A. Buy 8931-16 lifters from Comp, and you run ANY standard base circle hyd roller cam
B. Use factory ford hyd roller lifters, drill and tap the 2 needed holes to hold down the spider tray, BUT you must use a small base circle camshaft, of which there are about 6 to choose from and they are junk

I bet 95% of the engines I build (I will do about 75-80 this year) have atleast 150k+ miles on them, before I remachine and make like new.
 
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