I am curious as to what determines the redline of a motor and how fast you can safetly spin a 305 tpi motor.I have a 88 transam with a 305 tpi auto and it has a 5000 redline and i looked at a 87 transam with a 305 tpi 5 speed and it had a 5500 redline.Why is that,and how high can they spin. thanks

 

I'm no expert in this feild but I do know a few things...The reason to a redline is for how fast ur internals can handle (Crank, rods, pistons, valve train) Now a stock 305 has all cast internals...Cast is the weakest and cheapest of intearnals...Cast is where u pour a metal into a sand mold and let it harden....forged is metal being pressed together very hard/ high pressure (best for nitrous and such) and billet which is where u take a soild chunk of metal and CNC machine it to shape. But cast internals cannot handle very much high speed RPM's...if you were lookin to up ur RPM redline...rebuild ur motor usin all forged or billet parts...that way it takes ur redline way up into some very safe high RPM's. I think the safest RPM that a auto 305 can go is 6000 or so.

The reason why manual tranny Fbirds and Camaros have a redline of 5500 instead of 5000 like the autos. Is because GM through the good 350 cam into the 305 w/ manual. The cam is the same as the L98 cam in 350 TPI's

Any one who knows that anything that I have said is incorrect please let me know...like said earlier I am no expert just know a few things here and there

J

 

oh and welcome aboard redtail:rockon:

stick around and u'll learn alot

 

up untill 90 the 305 tpis got the peanut cam..in 91 and 92 all tpi cars got the l98 cam...

the max rpm before damage starts to occur is 6034 rpm...this is for both 305 and 350's..i have a file that gets into great detail but its on my girls computer in new york and im in michigan lol...

 

id have to dissagree with that

1985 5.0TPI autos had a 5500rpm redline bein that they had the largest cam shaft then any other year 5.0tpi auto car. all 5spd manual cars with a 5.0TPI engine received the larger 5.7s camshaft up to 1989. the size of the 5.7 cam varied through the years but still maintained the 5500rpm redline. in 1990 unless ur 5spd 5.0tpi had the G92 option u got the same cam as the 5.0tpi with auto. with g92 u had the same cam as the 5.7

heres the cam specs for each year:

1985 (L69 & LB9)
Duration @ 50: 202/206
Lift (1.5): 403/415
LSA: 114.5
GM Part #14088843


1986 (LB9)
Duration @ 50: 178/194
Lift (1.5): 350/385
LSA: 109.0
GM Part #14094097


1987 (LB9 Auto)
Duration @ 50: 179/194
Lift (1.5): 350/384
LSA: 109.0
GM Part #14094097

1987 (LB9 5-Speed, L98)
Duration @ 50: 202/207
GM Lift (1.5): 404/415
LSA: 114.5
Part #10088155


1988 (LB9 Auto)
Duration @ 50: 179/194
Lift (1.5): 350/384
SA: 109.0
GM Part #10088155

1988 (LB9 5 speed, L98)
Duration @ 50: 207/213
Lift (1.5): 415/430
LSA: 117.0
GM Part #10066049


1989 (LB9 Auto)
Duration @ 50: 179/194
Lift (1.5): 350/384
LSA: 109.0
GM Part #10088155

1989 (LB9 5 speed, L98)
Duration @ 50: 207/213
Lift (1.5): 415/430
LSA: 117.0
GM Part #1006604


1990 (LB9 5 speed & auto)
Duration @ 50: 179/194
Lift (1.5): 350/384
LSA: 109.0
GM Part #10088155

1990 (305 5-speed w/G92 & 350)
Duration @ 50: 202/207
Lift (1.5): 413/428
LSA: 114.5
GM Part #10111773

 

The thing is, those stock red-lines have more to do with the limits of the valve-train, and specifically valve float caused by weak valve springs, rather than the bottom end. The stock internals can probably handle 6000-6200 revs. 350 or 305 cam, neither of them are any fun and should be changed out along with the valve springs.

 

well the thing is my top end and valvetrain is all aftermarket,big cam comp cam matched springs set to the installed height,i did it all myself last summer i know my valvetrain will spin up to well over 7k ,just wanted to be sure i dont kill the bottom end.I figured the difference in redline was either the 5 speed cars breathed a little better up top cuz of the cam or they came with better valvetrain overall including the cam.My bottom end is also rebuilt still the same crank and rods all refinished.thanks guys for clearing it up though.

 

if you got your infor from the tech articles here, then your wrong everyone knows that the information there is wrong...

basically all u posted was facts that meant nothing to the original post...it has been documented that all SD tpi cars have a l98 cam..think what u want..
ohhh yea those g92 305's hey i got one of those

redline is more valvetrain then botom end like said before...the bottom end will take 6034 rpm, but at 62-6300 you start to get valve float..

 

what is valve floot??? I have an Idea but I want to know for sure!

And are u saying that all TPIs have the 350 cam?? Or just the manuals?? cause I have an 86 IROC w/ 305 TPI kinda would like to know the figures

 

Valve float is when the valve train and valves start moving to fast and what happenes is the valve opens and when it goes to close it hits the valve seat and bounces back off the seat before it comes to a full stop.The cause is a valve spring that doesnt have enough seat pressure to keep the valve from bouncing back off the seat.hope this helps

 

just the SD cars, and the lb9 t-5 cars

yea ive floated the valves a few times..ive over revved it to 6300 many times..i think thats why i spun a bearing lol