Cam ID
Thread Starter
Instructor
Joined: Feb 2007
Posts: 223
Likes: 1
From: Celina, TX
Cam ID
A. What cam is this? (3849347)
B. Will it work with 461X heads with 2.02/1.60 valves?
C. 327 block bored .30 over and hope to be under 9.5 compression.
D. Intake (3794129) 600 cfm carb.
B. Will it work with 461X heads with 2.02/1.60 valves?
C. 327 block bored .30 over and hope to be under 9.5 compression.
D. Intake (3794129) 600 cfm carb.
Le Mans Master
Joined: Apr 2005
Posts: 6,359
Likes: 428
From: Seattle Area WA
It's a solid lifter 30-30 cam which would really like some decent compression like 11:1.
Solid lifter (30-30) cam, P/N 3849346, Casting #3849347
254 duration @ .050" (intake & exhaust)
.485" lift (with 1.5 rockers)
The GMPP catalog says operating range 4,000-6,800 with 11-12.5:1 compression.
Solid lifter (30-30) cam, P/N 3849346, Casting #3849347
254 duration @ .050" (intake & exhaust)
.485" lift (with 1.5 rockers)
The GMPP catalog says operating range 4,000-6,800 with 11-12.5:1 compression.
Last edited by Scott Marzahl; Jan 31, 2008 at 05:00 PM.
Drifting
Joined: Apr 2004
Posts: 1,303
Likes: 36
From: Allen Park Mi
yep, thats the 30-30
DO NOT USE it under 11 to 1 compression.
Even with 11 to 1, you'll be able to run that cam with 92 octane fuel with optimum timing... I do it in 2 different engines currently.
I have found that most of the time people associate that cam with having a soft bottom end is when there isn't enough compression.
Good luck
Aaron
DO NOT USE it under 11 to 1 compression.
Even with 11 to 1, you'll be able to run that cam with 92 octane fuel with optimum timing... I do it in 2 different engines currently.
I have found that most of the time people associate that cam with having a soft bottom end is when there isn't enough compression.
Good luck
Aaron
Thread Starter
Instructor
Joined: Feb 2007
Posts: 223
Likes: 1
From: Celina, TX
My Dad parked this car (one of the reasons) in 1976 because the engine ran so bad on the pump gas at 12:1.
What is the secret to make this work in 2008?
The block, heads, and crank are at the machine shop.
The rest of this engine (parts) are to be determined.
What is the secret to make this work in 2008?
The block, heads, and crank are at the machine shop.
The rest of this engine (parts) are to be determined.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
If you rebuild that engine to original equipment SHP specs, it'll run fine on 93 octane. The advertised compression ratio was 11.25-1. People that have measured blocks, heads, and pistons have determined the actual "as delivered" compression ratio is more like 10.5-1 and your engine should run fine on that.
A block with the normal factory deck height, Speed Pro replacement pistons (domed) and unmilled stock head will put you in the ballpark. Your machine shop can calculate your final compression ratio.
As Aaron said, don't try to run this cam unless you have the compression up in the range it was designed for. 10.5-1 would be okay.
Le Mans Master
Joined: Apr 2005
Posts: 6,359
Likes: 428
From: Seattle Area WA
I'd consider using a set of Federal Mogul L-2166 forged pistons or equivalent, and a good set of rods like Crower Sportsman's for your short block if you plan on spinning this motor to 7K.
BTW, is this the original cam?? If so, it may be time for a new one.
Also, the distributor may need to be rebuilt with careful attention paid to setting up a correct timing curve.
Last edited by Scott Marzahl; Jan 31, 2008 at 06:21 PM.
Thread Starter
Instructor
Joined: Feb 2007
Posts: 223
Likes: 1
From: Celina, TX
I'd consider using a set of Federal Mogul L-2166 forged pistons or equivalent, and a good set of rods like Crower Sportsman's for your short block if you plan on spinning this motor to 7K.
BTW, is this the original cam?? If so, it may be time for a new one.
Also, the distributor may need to be rebuilt with careful attention paid to setting up a correct timing curve.
Have not spent much time thinking about the distributor yet.
I am all ears to what rods (5.7" or 6.0") and pistons.
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Drifting
Joined: Apr 2004
Posts: 1,303
Likes: 36
From: Allen Park Mi
The secret in 2008 is the same as it was in 1972... octane LOL
If it was built to race in 1968 and was a true 12 to 1 compression, then i'd suspect it would run terrible on low octane pump gas... you'll get more detonation than anything.... and if it was run for any length of time, he probably pounded the rod bearing right out of it.
THese guys are rigth about the compression thing... the original motors were specced at 11.25 to 1 but with variances in head volume and how far the pistons are in the hole... that drops the compression.
In my case, I used stock pistons... had the heads CCd and milled to drop them a bit.. and I used a shim type headgasket.
I did all the math and My motor has a true compression of 11.5 to 1.
It runs incredible and I wouldn't change anything....
I know guys who have tried the 30-30 with less than 11 to 1 and it just doesn't run right... especially in the lower end. Its hard to believe that 1/2 a point of compression can make a difference, but that seems to be the breaking point of where this cam really runs great.
Thansk
aaron
If it was built to race in 1968 and was a true 12 to 1 compression, then i'd suspect it would run terrible on low octane pump gas... you'll get more detonation than anything.... and if it was run for any length of time, he probably pounded the rod bearing right out of it.
THese guys are rigth about the compression thing... the original motors were specced at 11.25 to 1 but with variances in head volume and how far the pistons are in the hole... that drops the compression.
In my case, I used stock pistons... had the heads CCd and milled to drop them a bit.. and I used a shim type headgasket.
I did all the math and My motor has a true compression of 11.5 to 1.
It runs incredible and I wouldn't change anything....
I know guys who have tried the 30-30 with less than 11 to 1 and it just doesn't run right... especially in the lower end. Its hard to believe that 1/2 a point of compression can make a difference, but that seems to be the breaking point of where this cam really runs great.
Thansk
aaron