Cam selection
April 20th, 2018, 12:50 PM
#1
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Join Date: Apr 2018
Posts: 47
Cam selection
Hello Everyone,
New here on the group.
I've got a dilemma on my build coming up in the next few months. My 79' T/a has a 403 in ir currently, Runs pretty good still but the oil pressure starting to get low and there is a slight knock when i start her up; so I know a rebuild is coming up soon
I picked up about 3 mos ago a 70' olds 350 w/ correct #6 heads on it. I've been contemplating building this motor instead of the 403 since it's pre emission.
My question is, Are the cams 307/330/350/403/455 all the same as far as fit goes? IE do a 403 and 350 share the same cam size, not specs but the physical fit in the motor?
My goal for the car is just fun on the weekend with family. I'm not looking to do any crazy engine work, basic rebuild type stuff. I'd like to bump the cam up a step or 2 (The old RV cam logic) Other than that looking at a stock build. Not looking for any lopey idle or anything. Also I've got a Th350 trans with shift kit, Rear end ratio is a 3:42
I've narrowed it down to the following cams and was hoping someone on here could steer me towards the better fit for my goal. I'm a bodyman by trade so forgive my ignorance on major engine building.
Cam #1 : .450/.474 Valve lift, 204/214 @ 50 duration
Cam #2 : 473/.497 Valve lift, 214/224 @ 50
Is there much of a difference, Will either of these work better in basic stock for 70' 350 vs 403? Is stock valve train capable of handling this or will new springs be in order?
New here on the group.
I've got a dilemma on my build coming up in the next few months. My 79' T/a has a 403 in ir currently, Runs pretty good still but the oil pressure starting to get low and there is a slight knock when i start her up; so I know a rebuild is coming up soon
I picked up about 3 mos ago a 70' olds 350 w/ correct #6 heads on it. I've been contemplating building this motor instead of the 403 since it's pre emission.
My question is, Are the cams 307/330/350/403/455 all the same as far as fit goes? IE do a 403 and 350 share the same cam size, not specs but the physical fit in the motor?
My goal for the car is just fun on the weekend with family. I'm not looking to do any crazy engine work, basic rebuild type stuff. I'd like to bump the cam up a step or 2 (The old RV cam logic) Other than that looking at a stock build. Not looking for any lopey idle or anything. Also I've got a Th350 trans with shift kit, Rear end ratio is a 3:42
I've narrowed it down to the following cams and was hoping someone on here could steer me towards the better fit for my goal. I'm a bodyman by trade so forgive my ignorance on major engine building.
Cam #1 : .450/.474 Valve lift, 204/214 @ 50 duration
Cam #2 : 473/.497 Valve lift, 214/224 @ 50
Is there much of a difference, Will either of these work better in basic stock for 70' 350 vs 403? Is stock valve train capable of handling this or will new springs be in order?
April 20th, 2018, 05:24 PM
#2
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Join Date: Nov 2008
Location: Central Fl
Posts: 7,822
All Olds cams from 64 up are the same dimensions.
The cams you listed are all old GM generic grinds.
i can set you up if you like or you can do something else, no problem. It’s just that you can do better than those for sure. And you should replace the springs no matter what, it’s cheap insurance.
The cams you listed are all old GM generic grinds.
i can set you up if you like or you can do something else, no problem. It’s just that you can do better than those for sure. And you should replace the springs no matter what, it’s cheap insurance.
April 20th, 2018, 07:32 PM
#3
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Join Date: Apr 2018
Posts: 47
What would you suggest? I’ll be honest I’m on pretty tight budget hence the minor overhaul on either the 350 or 403 (not sure which I’m going with at moment anyvsugestion?) if a better budget I’d go 455 route for sure. What does a custom grind run from you? Just ball park
April 21st, 2018, 01:21 AM
#4
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Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 13,734
The 403 will outperform the 350 with a similar build due to the larger displacement. You should be able to rebuild the 403 with decent compression (those #6 heads will really help) and a good cam (Mark can set you up with that).
April 21st, 2018, 02:33 AM
#5
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Join Date: Jan 2018
Posts: 400
Mike Jones in Denver, North Carolina. Best cams I've ever used. http://jonescams.com/
April 21st, 2018, 04:40 AM
#6
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Join Date: Nov 2008
Location: Central Fl
Posts: 7,822
What would you suggest? I’ll be honest I’m on pretty tight budget hence the minor overhaul on either the 350 or 403 (not sure which I’m going with at moment anyvsugestion?) if a better budget I’d go 455 route for sure. What does a custom grind run from you? Just ball park
April 21st, 2018, 12:05 PM
#7
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Join Date: Apr 2018
Posts: 47
Are the starter/water pump interchangeable 350/403? I know all SBO but didn’t know if any changes since early vs late 70’s.
Oh man I think $275 is just outside of my budget unfortunately. I have no doubt at all that they’re the best but just can’t swing it. If it changes or I don’t like what’s in there after awhile I’ll be in touch with you
Oh man I think $275 is just outside of my budget unfortunately. I have no doubt at all that they’re the best but just can’t swing it. If it changes or I don’t like what’s in there after awhile I’ll be in touch with you
April 21st, 2018, 01:17 PM
#8
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Join Date: May 2011
Location: Delta BC Canada
Posts: 3,688
Fyi
Are the starter/water pump interchangeable 350/403? I know all SBO but didn’t know if any changes since early vs late 70’s.
Oh man I think $275 is just outside of my budget unfortunately. I have no doubt at all that they’re the best but just can’t swing it. If it changes or I don’t like what’s in there after awhile I’ll be in touch with you
Oh man I think $275 is just outside of my budget unfortunately. I have no doubt at all that they’re the best but just can’t swing it. If it changes or I don’t like what’s in there after awhile I’ll be in touch with you
There are three different water pump lengths depending on your accessories.
Last edited by oldsmobiledave; April 21st, 2018 at 01:19 PM.
August 13th, 2018, 01:43 PM
#9
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Join Date: Apr 2018
Posts: 47
Hey guys,
heads are at machine shop currentky. Got a call today and they said my cam is pretty radical.... want some true Oldsmobile guys opinion here.
.473/.497 lift
112 seperation
214/224 @ 50
from the amount of research I did before buying seems it was pretty weak really? Stock motor aside from the cam. Looking to go very mild with nice smooth idle. Should I have gone with stock cam or the old Melling MTO1
heads are at machine shop currentky. Got a call today and they said my cam is pretty radical.... want some true Oldsmobile guys opinion here.
.473/.497 lift
112 seperation
214/224 @ 50
from the amount of research I did before buying seems it was pretty weak really? Stock motor aside from the cam. Looking to go very mild with nice smooth idle. Should I have gone with stock cam or the old Melling MTO1
August 13th, 2018, 01:51 PM
#10
Registered User
Join Date: Nov 2008
Location: Central Fl
Posts: 7,822
Hey guys,
Heads are at machine shop currentky. Got a call today and they said my cam is pretty radical.... want some true Oldsmobile guys opinion here.
.473/.497 lift
112 seperation
214/224 @ .050
From the amount of research I did before buying seems it was pretty weak really? Stock motor aside from the cam. Looking to go very mild with nice smooth idle. Should I have gone with stock cam or the old Melling MTO1
Heads are at machine shop currentky. Got a call today and they said my cam is pretty radical.... want some true Oldsmobile guys opinion here.
.473/.497 lift
112 seperation
214/224 @ .050
From the amount of research I did before buying seems it was pretty weak really? Stock motor aside from the cam. Looking to go very mild with nice smooth idle. Should I have gone with stock cam or the old Melling MTO1
And find another shop, they clearly don't have a clue.
August 13th, 2018, 09:22 PM
#12
Registered User
Join Date: Mar 2017
Posts: 163
Thats funny, radical no, but the heads would need a little work for the amount of lift. This cam works with stock stock valve train:
http://www.compcams.com/Company/CC/c...csid=1168&sb=2
http://www.compcams.com/Company/CC/c...csid=1168&sb=2
August 13th, 2018, 09:24 PM
#13
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Join Date: Mar 2017
Posts: 163
August 13th, 2018, 09:39 PM
#14
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Join Date: Jun 2009
Location: Palm Bay, FL
Posts: 4,249
August 14th, 2018, 06:14 AM
#16
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Join Date: Dec 2006
Location: Melville, Saskatchewan
Posts: 8,909
Get new springs, the Edelbrock Performer springs are cheap, you should really look 2"/1.625" valves as well with the bowls opened. I assume a rering, new bearings and a crank polish or grind on the 403? Either way degree that cam, a lot of timing sets and cams are off where they are supposed to be. I have one of Cutlassefi's cams and like it.
August 14th, 2018, 01:38 PM
#17
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Join Date: Apr 2018
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