[Dragon Randy]

BEST CAM FOR THE BUILD
​

I know there are better heads, I am working with what I got and would like to choose a [CAM that provides High Torque] in the "Low to Mid RPM Range" for towing power?

The motor is installing in a 1964 Chevy Step-side PU

Donor motor Spec:

A 1989 Truck 5.7-liter V8 engine 185 horsepower, 285 ft.-lbs. of torque, bore is 4.0 inches, stroke is 3.48 inches, compression ratio of 8.6:1.

Pulling the TPI heads and Replacing them with:

Cylinder heads [376450]: 1984 305 heads 60cc chambers, MODIFIED THE intake valves to 1..94 with the exhaust valves 1..5, milling to include Intake port matched, exhaust ports back cut and hoging out the tunnels.

Rest of the setup:

GM CFM Aluminum Intake: 14057053
Ellerbrock 600cfm carb
Hooker Headers 2"
Dual Exhaust
65K COIL HEI
Transmission: Turbo TH350 Auto
Reared: 3.73:1 gear ratio

NOTE: corrected Cylinder head description.

 

[AutoGear]

Those arent power pack heads. PP heads were from back in the 60s, so this might have thrown some people off. Is this a roller cam block or a flat tappet? If you don't know that, its okay - just say so. You'd be much better served for a towing cam to have the roller; much more aggressive lobe profile than a flat tappet, without a loss in driveability.
Comp XE256 or similar for a flat tappet
GM has an interesting roller cam in their 357 crate motor package. Its PN 12677151
GM probably doesn't produce it, it might be a Crane cam. But Im sure we could find something similar if you cant find a "Takeout" cam for good money. It specs dur @ .050: 215 int./223 ex with a lift at .473 on the the int/ex, cut on a 108.

A friend of mine has this is an L31 Vortec work truck. It runs VERY well. Might not be the ultimate roller cam; but it seems pretty mild at idle and has LOTS of midrange. However, without knowing what your heads can manage on the exhaust side, its a bit of a crap shoot

 

[57Nomad]

You supplied information:
Pulling the TPI heads and Replacing them with: Cylinder heads: 1984 305 heads Power Pack heads 60cc chambers, intake valves 1..94 the exhaust valves 1..5, Intake port matched, exhaust ports back cut

These heads should up compression. But the cam s/b short (205- 210, &110 or wider) and wider centers for towing in a truck. I don’t know how they flow but valve size is an indicator s/b ok on a truck w/ the implied flow work.

Are you planning on FI or Holley?

FI would need recalibration.

 

[Dragon Randy]

Those arent power pack heads. PP heads were from back in the 60s, so this might have thrown some people off. Is this a roller cam block or a flat tappet? If you don't know that, its okay - just say so. You'd be much better served for a towing cam to have the roller; much more aggressive lobe profile than a flat tappet, without a loss in driveability.
Comp XE256 or similar for a flat tappet
GM has an interesting roller cam in their 357 crate motor package. Its PN 12677151
GM probably doesn't produce it, it might be a Crane cam. But Im sure we could find something similar if you cant find a "Takeout" cam for good money. It specs dur @ .050: 215 int./223 ex with a lift at .473 on the the int/ex, cut on a 108.

A friend of mine has this is an L31 Vortec work truck. It runs VERY well. Might not be the ultimate roller cam; but it seems pretty mild at idle and has LOTS of midrange. However, without knowing what your heads can manage on the exhaust side, its a bit of a crap shoot

Thanks. Ya someone else described them like that as I pulled a 283ci out of the truck and these heads were on it, but the cast numbers showed it to be [376450]: 1975 through 1981 262ci, 267ci, or 305ci, 60cc chambers, 1.72/1.50-inch valves. should have double-checked, the machine shop installed 1.94" Intake Valve and back cut the valve chamber, I am back-cutting the Exhaust port and hoging out the Valve ports out. At this point, the 350 motor is stock so I intend to just do a basic rebuild, rings, bearings, oil pump, timing chain so the lifters can be my choice, but I don't want to have to change the valve springs, I think the Machinist on the head said 70cfm but don't quote me. I will be using the truck on my ranch hauling horses and feed/water.

You supplied information:
Pulling the TPI heads and Replacing them with: Cylinder heads: 1984 305 heads Power Pack heads 60cc chambers, intake valves 1..94 the exhaust valves 1..5, Intake port matched, exhaust ports back cut

These heads should up compression. But the cam s/b short (205- 210, &110 or wider) and wider centers for towing in a truck. I don’t know how they flow but valve size is an indicator s/b ok on a truck w/ the implied flow work.

Are you planning on FI or Holley?

FI would need recalibration.

I have a Edelbrock 1406 Performer 600 cfm

 

[Dragon Randy]

You supplied information:
Pulling the TPI heads and Replacing them with: Cylinder heads: 1984 305 heads Power Pack heads 60cc chambers, intake valves 1..94 the exhaust valves 1..5, Intake port matched, exhaust ports back cut

These heads should up compression. But the cam s/b short (205- 210, &110 or wider) and wider centers for towing in a truck. I don’t know how they flow but valve size is an indicator s/b ok on a truck w/ the implied flow work.

Are you planning on FI or Holley?

FI would need recalibration.

I have a Edelbrock 1406 Performer 600 cfm

 

[hirschdalechevy]

Those arent power pack heads. PP heads were from back in the 60s, so this might have thrown some people off. Is this a roller cam block or a flat tappet? If you don't know that, its okay - just say so. You'd be much better served for a towing cam to have the roller; much more aggressive lobe profile than a flat tappet, without a loss in driveability.
Comp XE256 or similar for a flat tappet
GM has an interesting roller cam in their 357 crate motor package. Its PN 12677151
GM probably doesn't produce it, it might be a Crane cam. But Im sure we could find something similar if you cant find a "Takeout" cam for good money. It specs dur @ .050: 215 int./223 ex with a lift at .473 on the the int/ex, cut on a 108.

A friend of mine has this is an L31 Vortec work truck. It runs VERY well. Might not be the ultimate roller cam; but it seems pretty mild at idle and has LOTS of midrange. However, without knowing what your heads can manage on the exhaust side, its a bit of a crap shoot

I have that 357 crate motor in my 77 blazer right now. Still trying to iron out the carb as we speak but you are right , it pulls hard in the mid range

 

[BogiesAnnex1]

To start with the term “Power Pack” heads refers to the preSMOG era dual quench heads that came in a variety of variations in valve and port sizes, all rather small ports by today’s standards.

Back in the late 1980’s and early 90’s as the supply of preSMOG era Chevy heads was running out and aftermarket heads including that fare from GMPP were very expensive. Figure the cost of these was then about what they are now to get an idea that these were above and beyond the financial abilities of most hot rodders and small time racers. This brought the 305 head into some popularity as if nothing else it really pumped up the compression on a 350. The downside is the 305 needed bigger valves and a lot of port grinding to be competitive. Bigger valves is not too difficult a problem but the thin wall castings didn’t take kindly to being ground thinner. It wasn’t long before they opened up even when not showing initial cut through damage. But after some use the weakened port walls would crack and dump coolant into the operating spaces of the engine. When this happens any money you saved on not buying proper heads went to the junk yard. So this needs to stand as a cautionary tale.

A big consideration these days is if you don’t have your own automotive machine shop, the cost of machine work since the 1980’s has increased with monetary inflation or even faster where to a huge extent the price of aftermarket heads has remained much more stable thanks to automated mass production. What this leads to is the cost of rehabbing old heads to near new quality of cleaning and checking for cracks which modern thin wall castings are very prone to, restoring worn valve guides, reshooting the seats much less doing porting and replacing worn valve train parts quickly brings you to the cost of lower end priced aftermarket heads in choices of iron or aluminum that bring tremendous increases in power by just bolting them on.

So in the end I for one just can’t get very excited about putting money and time into 305 heads perhaps to the extent of any of these old heads unless you’re racing in a class that requires them. I mean there are outfits like EQ and others that even offer heads that many racing venues consider a stock replacement head that use the older in and out ports feeding an L31 Vortec combustion chamber. If you’re in that class and bring a set of original dual quench heads up against these you are going to spend a lot of time breathing someone else’s exhaust as these modern chambers are so good at converting mixture to power. Everybody gets wrapped around the axle with breathing so untold time and money pours into bigger valves and porting while the quality of the burn is ignored. Modern chamber design shows that ignoring the slight but very significant differences in chamber design will cost a lot of power. To that end the L31 chamber in all of its details is to be modeled to the greatest extent possible.

Bogie

 

[Dragon Randy]

To start with the term “Power Pack” heads refers to the preSMOG era dual quench heads that came in a variety of variations in valve and port sizes, all rather small ports by today’s standards.

Back in the late 1980’s and early 90’s as the supply of preSMOG era Chevy heads was running out and aftermarket heads including that fare from GMPP were very expensive. Figure the cost of these was then about what they are now to get an idea that these were above and beyond the financial abilities of most hot rodders and small time racers. This brought the 305 head into some popularity as if nothing else it really pumped up the compression on a 350. The downside is the 305 needed bigger valves and a lot of port grinding to be competitive. Bigger valves is not too difficult a problem but the thin wall castings didn’t take kindly to being ground thinner. It wasn’t long before they opened up even when not showing initial cut through damage. But after some use the weakened port walls would crack and dump coolant into the operating spaces of the engine. When this happens any money you saved on not buying proper heads went to the junk yard. So this needs to stand as a cautionary tale.

A big consideration these days is if you don’t have your own automotive machine shop, the cost of machine work since the 1980’s has increased with monetary inflation or even faster where to a huge extent the price of aftermarket heads has remained much more stable thanks to automated mass production. What this leads to is the cost of rehabbing old heads to near new quality of cleaning and checking for cracks which modern thin wall castings are very prone to, restoring worn valve guides, reshooting the seats much less doing porting and replacing worn valve train parts quickly brings you to the cost of lower end priced aftermarket heads in choices of iron or aluminum that bring tremendous increases in power by just bolting them on.

So in the end I for one just can’t get very excited about putting money and time into 305 heads perhaps to the extent of any of these old heads unless you’re racing in a class that requires them. I mean there are outfits like EQ and others that even offer heads that many racing venues consider a stock replacement head that use the older in and out ports feeding an L31 Vortec combustion chamber. If you’re in that class and bring a set of original dual quench heads up against these you are going to spend a lot of time breathing someone else’s exhaust as these modern chambers are so good at converting mixture to power. Everybody gets wrapped around the axle with breathing so untold time and money pours into bigger valves and porting while the quality of the burn is ignored. Modern chamber design shows that ignoring the slight but very significant differences in chamber design will cost a lot of power. To that end the L31 chamber in all of its details is to be modeled to the greatest extent possible.

Bogie

Even though the post is about what Cam to use, I knew someone would have to belabor the use of 305 heads, facts are the 305 heads were already rebuilt to go back on the 283ci motor that came with the truck that ended up with a cracked block so the money was already spent on the heads the additional machine work was then done with an updated 1.94" Intake Valve for mounting them on 350ci motor block, my cost $200 plus new valves, guilds, the Porting & Polishing is my own labor so zero cost, if I used Vortec heads I have to purchase another Intake manifold plus the cost of the heads was going to be $500 dollars. I am able to use a stock GM Aluminum intake and Ellerbrock 600cfm carb, the simple fact is I been building old chevy motors since long before there were Vortec heads and I was very happy with the GM performance of the old Humpback cylinder heads, these heads will now perform like those by increasing the Intake valve size, chamber to 64cc and porting them they will perform great in my RPM operating range is 800 to 5,600 RPM being way below 7000 RPM were having those Vortec combustion chambers and bigger valves really matter. As I said this is a work truck used on the ranch for hauling horses and feed not a performance streetcar.

 

[BogiesAnnex1]

The point is if your spending money on 305 heads,,,don’t. If they are a freebie, we’ll that’s a price that’s tough to beat.

I raced many a 305 headed 350 back in the day so I speak from hands and wallet on experience, you can make them work especially when your short on cash. Though we certainly had a few that cracked in the hogged out ports after a few hot rounds.

If your starting on a set from scratch today, and I’m not where you are so don’t know about your situation, it just isn’t an effort worth burning into your VISA card limit for unless you’re racing in a limited equipment class.

The disparaging of 305 heads comes from long, or is that long ago, experience with them and having been on this forum a long time, also, back in the shop when young eager people drag ancient history into the shop like it’s the latest discovery of mankind and your left with trying to convince them that their thousand dollar investment in these heads is not in their best interests. I could always take their money, and there are plenty of shops out there that would, so unless they are running in a specific class requiring them I bust my butt to talk them out of pumping large sums of cash into them.

It should be noted that there are some guys out there that make big power numbers with these heads so it isn’t impossible to do that and have some decent reliability from them. But my suggestion based on experience is this condition is below the statistical norm. Gen I, Chevy SBC heads are not like the Chrysler LA where you can carve out a 318 heads ports to the size of a 360’s with impunity. Chrysler’s idea at that time of “thin wall” casting was a lot different from GM’s or Ford’s.

The aftermarket does provide L31, Vortec type heads that will accept the pre 87 intake pattern or the 96 up pattern. These can be had in iron which trades pounds up for less dollars or aluminum that trades more dollars for fewer pounds.So you can use your existing intake with these heads and don’t need to modify them for decent amounts of lift.

So anyway if these are a freebie in good condition, or nearly so, then take them and enjoy them. My concern is for people that spend lots of money fixing these when that investment into a modern chambered head reaps larger rewards.

Just a view from an octogenarian hotrodder/racer.
Bogie

 

[6426yy]

I used a GMPP 330 Horsepower camshaft for exactly what you're doing.
Re-ring special factory dish piston
Steel shim head gaskets, 305 heads, aluminum intake, 600 Holley and small tube headers in a 83 C10 with 3.73s.
Made good torque, didn't detonate and got respectable fuel mileage

 

[Dragon Randy]

Thank you 6426yy, I knew I was in the right place that someone had already done it when you say, "
Re-ring special factory dish piston with Steel shim head gaskets" can you elaborate some? Are you say you replaced the Factory Pistons with a "special factory dish" ones? Can you provide me with the Parts Brand & Model and what was the thickness of the gasket?

 

[6426yy]

Thank you 6426yy, I knew I was in the right place that someone had already done it when you say, "
Re-ring special factory dish piston with Steel shim head gaskets" can you elaborate some? Are you say you replaced the Factory Pistons with a "special factory dish" ones? Can you provide me with the Parts Brand & Model and what was the thickness of the gasket?

They were the factory dish piston and Mr. Gasket. 018 shim gaskets to set quench not raise compression. Cam was a $40 new take out I found on Ebay. Very tight budget deal

 

[ericnova72]

Thank you 6426yy, I knew I was in the right place that someone had already done it when you say, "
Re-ring special factory dish piston with Steel shim head gaskets" can you elaborate some? Are you say you replaced the Factory Pistons with a "special factory dish" ones? Can you provide me with the Parts Brand & Model and what was the thickness of the gasket?

"Re-ring special factory dish piston with Steel shim head gaskets"

A "re-ring special" is:

"Stock dish piston engine, torn apart, cylinder bores honed, new rings/bearings on the stock crank/rods/pistons and bolt it all back together, add your heads a cam".

Steel shim head gasket (.015" thick) used instead of thick composition replacement head gasket(.040"+) to maintain factory quench clearance and help maintain compression ratio.
The "maintaining quench" is the big deal here.