305 TPI - LT4 Hotcam
10-03-2018, 01:14 AM
#1
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Car: 1987 Trans AM WS6
Engine: 305 TPI
Transmission: TH700R4 Stock
Axle/Gears: 3.08 LSD
305 TPI - LT4 Hotcam
Hello!
I think I'll go crazy trying to use an LT4 hotcam in my 305 TPI
My engine seems completely stock
Stock manifolds and intake
Stock 700r4 1470 stall
My combo project is:
1.5 stock rockers
Lt4 Hotcam 492 lift int. exh.
Manley 22409-16 springs and 23652-16 retainers in order to let the heads work with that lift
Now my question is:
What size of shim should I use under the spring (if one is necessary)?
Will it work with my stock converter?
Will it work with stock lenght pushrods?
I know this cam is like giving gold to pigs but I live in Italy and that cam is my dream
The 2032 costs me twice the LT4 so no way
An LT1 cam is like putting 1.6 rrs to my peanut so I wanna go bigger in order to support future mods
I can't swap the engine because here is not legal
I think I'll go crazy trying to use an LT4 hotcam in my 305 TPI
My engine seems completely stock
Stock manifolds and intake
Stock 700r4 1470 stall
My combo project is:
1.5 stock rockers
Lt4 Hotcam 492 lift int. exh.
Manley 22409-16 springs and 23652-16 retainers in order to let the heads work with that lift
Now my question is:
What size of shim should I use under the spring (if one is necessary)?
Will it work with my stock converter?
Will it work with stock lenght pushrods?
I know this cam is like giving gold to pigs but I live in Italy and that cam is my dream
The 2032 costs me twice the LT4 so no way
An LT1 cam is like putting 1.6 rrs to my peanut so I wanna go bigger in order to support future mods
I can't swap the engine because here is not legal
10-03-2018, 06:36 AM
#2
Re: 305 TPI - LT4 Hotcam
I would rather see you with the 22410 springs
but for a tpi powerband and those cam lobes, they should work with those pressures to 4800 rpm give or take. Not ideal tho
You need to measure the current installed height. The retainers add .050” so you would want to add .050” or likely a .015 plus a .030 shim since they may not make .050”. Do not do a .060 unless its needed to maintain a specified 1.70” install height for those springs. Thats why you need to measure.
also measure pushrods. Might be ok with stock but may not
It will need a tune. It likely can work with stock converter but its gonna be jumpy on cold starts. I mean put in gear and let off brake it will accelerate itself. May even do it in hot idle conditions. Depends on how well you can tune and how low you can get it to idle. If you cant get it below 800 rpm then its not gonna be too friendly i dont think. Lt4 works well in a 350 tpi car so it shouldnt be too radical in a 305 but stock converters i dont like. But can be done
but for a tpi powerband and those cam lobes, they should work with those pressures to 4800 rpm give or take. Not ideal tho
You need to measure the current installed height. The retainers add .050” so you would want to add .050” or likely a .015 plus a .030 shim since they may not make .050”. Do not do a .060 unless its needed to maintain a specified 1.70” install height for those springs. Thats why you need to measure.
also measure pushrods. Might be ok with stock but may not
It will need a tune. It likely can work with stock converter but its gonna be jumpy on cold starts. I mean put in gear and let off brake it will accelerate itself. May even do it in hot idle conditions. Depends on how well you can tune and how low you can get it to idle. If you cant get it below 800 rpm then its not gonna be too friendly i dont think. Lt4 works well in a 350 tpi car so it shouldnt be too radical in a 305 but stock converters i dont like. But can be done
10-03-2018, 09:19 AM
#3
Senior Member
Re: 305 TPI - LT4 Hotcam
Have yoi thought about going with the regular lt4 cam? Smaller then the hot cam but bigger then the lt1 cam.
10-03-2018, 10:09 AM
#4
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Car: 1983 G20 Chevy
Engine: 305 TPI
Transmission: 4L60
Axle/Gears: 14 bolt with 3.07 gears
Re: 305 TPI - LT4 Hotcam
I would rather see you with the 22410 springs
but for a tpi powerband and those cam lobes, they should work with those pressures to 4800 rpm give or take. Not ideal tho
You need to measure the current installed height. The retainers add .050” so you would want to add .050” or likely a .015 plus a .030 shim since they may not make .050”. Do not do a .060 unless its needed to maintain a specified 1.70” install height for those springs. Thats why you need to measure.
also measure pushrods. Might be ok with stock but may not
It will need a tune. It likely can work with stock converter but its gonna be jumpy on cold starts. I mean put in gear and let off brake it will accelerate itself. May even do it in hot idle conditions. Depends on how well you can tune and how low you can get it to idle. If you cant get it below 800 rpm then its not gonna be too friendly i dont think. Lt4 works well in a 350 tpi car so it shouldnt be too radical in a 305 but stock converters i dont like. But can be done
but for a tpi powerband and those cam lobes, they should work with those pressures to 4800 rpm give or take. Not ideal tho
You need to measure the current installed height. The retainers add .050” so you would want to add .050” or likely a .015 plus a .030 shim since they may not make .050”. Do not do a .060 unless its needed to maintain a specified 1.70” install height for those springs. Thats why you need to measure.
also measure pushrods. Might be ok with stock but may not
It will need a tune. It likely can work with stock converter but its gonna be jumpy on cold starts. I mean put in gear and let off brake it will accelerate itself. May even do it in hot idle conditions. Depends on how well you can tune and how low you can get it to idle. If you cant get it below 800 rpm then its not gonna be too friendly i dont think. Lt4 works well in a 350 tpi car so it shouldnt be too radical in a 305 but stock converters i dont like. But can be done
The 305 in the Tahoe really woke up with headers and a converter stalling 2,500 rpm. Idle vacuum increased about 1-2 in/hg in drive with the converter change as well.
10-03-2018, 10:18 AM
#5
Re: 305 TPI - LT4 Hotcam
Yeah just saw a vid of a 305 tbi truck running hotcam. Sounded smooth. Just worried on cold starts with the high idle speed its gonna be jumpy off the brakes in gear. My stock 305 was lol. Might not tho with the cam. A 280xfi 350 i tuned had stock converter for a bit and seemed ok and that was a lumpy 750 idle
10-03-2018, 10:42 AM
#6
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Car: 1983 G20 Chevy
Engine: 305 TPI
Transmission: 4L60
Axle/Gears: 14 bolt with 3.07 gears
Re: 305 TPI - LT4 Hotcam
Yeah just saw a vid of a 305 tbi truck running hotcam. Sounded smooth. Just worried on cold starts with the high idle speed its gonna be jumpy off the brakes in gear. My stock 305 was lol. Might not tho with the cam. A 280xfi 350 i tuned had stock converter for a bit and seemed ok and that was a lumpy 750 idle
10-03-2018, 10:50 AM
#7
Re: 305 TPI - LT4 Hotcam
I am fully aware of that i have tuned dozens, however did not mess with the 305 cold start idle. But some seem happier idling higher when cold. It the hot cam is fine lower then no real need to idle higher it might end up being fine. Just have to play with that
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10-03-2018, 05:05 PM
#8
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Car: 1987 Trans AM WS6
Engine: 305 TPI
Transmission: TH700R4 Stock
Axle/Gears: 3.08 LSD
Re: 305 TPI - LT4 Hotcam
I have a full TPI setup ready to port out on the shelf so I could see some over 5k out of my 305
So with Manley 22410 springs - 23652 retainers - 0.15 + 0.30 shims could my heads handle this cam?
So with Manley 22410 springs - 23652 retainers - 0.15 + 0.30 shims could my heads handle this cam?
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