Edelbrock heads on early 348 Block

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smgarland

Member
I have a 1958 Impala with early 348 block and early heads with no spark plug cooling. The engine has the Scat 4" stroke, Edelbrock small port intake, stock early small port heads with bigger valves 2.07/1.72. Mild roller Cam and MSD throttle body fuel injection. My question is, can I put Edelbrock heads on this early block to make her breath better?

Also, I have the stock 2" exhaust manifolds on her now with 2" exhaust. I have a set of 2.5" Hi Po exhaust manifolds that I just got my hands on. I know they will bolt on to the early heads but will there be a problem because the early heads have small runners and the exhaust was made for the larger runner exhaust? In other words will I still get the benefit of the bigger exhaust even though the runners on the heads are smaller. I am also stepping up to 2.5" exhaust as well to help her breath better.

Not looking to build a race car but the dyno only showed it produced about 310 hp to the rear wheels which is close to stock and this build (with better heads) should make closer to 400 hp I'm thinking. Just not sure what I can do with the early block and heads as I don't want to replace both the block and heads to match.

Any advice would be appreciated.

Shawn
 
Tooth

Tooth

Well Known Member
Supporting Member 3
Im putting these BWR aluminum heads on my 348 stroker motor I’m building now, I have a hydronic roller 555/560 lift…yes you can! You’ll need a different intake though if you really want to breathe… check your cooling passages in the block… my block is a oct of 60 date code.
 

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smgarland

Member
I think I would have to fill the water passages on the Edelbrock heads as my current block and heads do not have the cooling for the spark plugs. I have an Edelbrock intake so I think I could keep my Intake. My cams is less aggressive then your at 516/512 with 113 lsa.
 
63 dream'n

63 dream'n

Well Seasoned Member
Supporting Member 4
smgarland said:
I have a 1958 Impala with early 348 block and early heads with no spark plug cooling. The engine has the Scat 4" stroke, Edelbrock small port intake, stock early small port heads with bigger valves 2.07/1.72. Mild roller Cam and MSD throttle body fuel injection. My question is, can I put Edelbrock heads on this early block to make her breath better?

Also, I have the stock 2" exhaust manifolds on her now with 2" exhaust. I have a set of 2.5" Hi Po exhaust manifolds that I just got my hands on. I know they will bolt on to the early heads but will there be a problem because the early heads have small runners and the exhaust was made for the larger runner exhaust? In other words will I still get the benefit of the bigger exhaust even though the runners on the heads are smaller. I am also stepping up to 2.5" exhaust as well to help her breath better.

Not looking to build a race car but the dyno only showed it produced about 310 hp to the rear wheels which is close to stock and this build (with better heads) should make closer to 400 hp I'm thinking. Just not sure what I can do with the early block and heads as I don't want to replace both the block and heads to match.

Any advice would be appreciated.

Shawn
Click to expand...

http://www.348-409.com/forum/threads/spark-plug-cooling-tsb.21411/
 
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Don Jacks

Well Seasoned Member
Supporting Member 3
If your block is one of the very early blocks that can't be drilled,just plug the holes in the heads and you'll be good.You're problem is that you're under camed for an engine of that siz.Another issue as you've noted is you've got severely restricted exhaust.The early 2 inch stuff will cap up 348 inches much less 430 plus inches.Unless you're prepaired to increase the depth of the notches in the block under the exhaust valves,you're limited to .550 lift on the exhaust.You should look for something like HRC-1130501-12 [hyd.flat tappet] for an engine of this size in a heavy cruiser.I would get with Bob Walla on the heads if your iron heads are anything but 333's.The 379,even with bigger valves are a cork on a 430 plus cu.in. sized engine.
 
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Don Jacks

Well Seasoned Member
Supporting Member 3
smgarland said:
I think I would have to fill the water passages on the Edelbrock heads as my current block and heads do not have the cooling for the spark plugs. I have an Edelbrock intake so I think I could keep my Intake. My cams is less aggressive then your at 516/512 with 113 lsa.
Click to expand...
If you go with any large port head[690.583,Edelbrock,or Bob Walla] you will have to change intakes.Your small port Edelbrock intake will bring decent money to help offset the cost of some of this.
 
63 dream'n

63 dream'n

Well Seasoned Member
Supporting Member 4
Don Jacks said:
If your block is one of the very early blocks that can't be drilled,just plug the holes in the heads and you'll be good.You're problem is that you're under camed for an engine of that siz.Another issue as you've noted is you've got severely restricted exhaust.The early 2 inch stuff will cap up 348 inches much less 430 plus inches.Unless you're prepaired to increase the depth of the notches in the block under the exhaust valves,you're limited to .550 lift on the exhaust.You should look for something like HRC-1130501-12 [hyd.flat tappet] for an engine of this size in a heavy cruiser.I would get with Bob Walla on the heads if your iron heads are anything but 333's.The 379,even with bigger valves are a cork on a 430 plus cu.in. sized engine.
Click to expand...
Don Jacks said:
If you go with any large port head[690.583,Edelbrock,or Bob Walla] you will have to change intakes.Your small port Edelbrock intake will bring decent money to help offset the cost of some of this.
Click to expand...

:bow:bow:bow:bow………YOU DA MAN MR.JACKS……..!!!!!
 
S

smgarland

Member
Its funny. The engine builder went to comp cams with all the specs of the engine and the cam that was selected was their recommendation for mild street car. Its actually a custom grind based on what Comp Cams said it should be. Ive noticed it is very close to some of there off the shelf cam profiles.

I do have a set of 2.5" truck manifolds. Can I use them with these early head? And will they even help since the heads runners are smaller then what the 2.5" exhaust manifolds were made for?
 
4

427John

Well Known Member
smgarland said:
I have a 1958 Impala with early 348 block and early heads with no spark plug cooling. The engine has the Scat 4" stroke, Edelbrock small port intake, stock early small port heads with bigger valves 2.07/1.72. Mild roller Cam and MSD throttle body fuel injection. My question is, can I put Edelbrock heads on this early block to make her breath better?

Also, I have the stock 2" exhaust manifolds on her now with 2" exhaust. I have a set of 2.5" Hi Po exhaust manifolds that I just got my hands on. I know they will bolt on to the early heads but will there be a problem because the early heads have small runners and the exhaust was made for the larger runner exhaust? In other words will I still get the benefit of the bigger exhaust even though the runners on the heads are smaller. I am also stepping up to 2.5" exhaust as well to help her breath better.

Not looking to build a race car but the dyno only showed it produced about 310 hp to the rear wheels which is close to stock and this build (with better heads) should make closer to 400 hp I'm thinking. Just not sure what I can do with the early block and heads as I don't want to replace both the block and heads to match.

Any advice would be appreciated.

Shawn
Click to expand...
Firstly 310 rwhp is much more than stock,the ratings used back in the late 50's and all thru the 60's was flywheel hp which doesn't account for drivetrain losses as wheel hp does.Depending on what trans and rear axle is in you car,this could mean your flywheel hp could be close to 400.If you already have the Edelbrock heads and your block is the 1st design and doesn't have the ability to be drilled,you can plug off the unneeded passage,you can also weld them up but that would require resurfacing the heads.
 
4

427John

Well Known Member
Since you already have a small port Edelbrock intake,another option would be to scare up some 333 castings and transfer your valves over to them and have a little port work done on them,they will support more horsepower than the original heads,you would still have to plug the passages,but those heads would easily support 400hp.The same would apply to the solid lifter 348HP heads but they would be harder to find and more expensive.What pistons are in the engine now? If they are for a lower compression in the early heads then it would be even lower with the 333's.Also what is the deck clearance on the pistons if too low that may be part of your problem,it may be limiting how much ignition advance you can put into the engine to prevent ping.
 
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smgarland

Member
Man I can't catch a break. Ok, on Tuesday I sent out the Impala to put on the newly acquired 2.5" exhaust manifolds (stepped up from 2") with all new 2.5" exhaust pipe and new 18" Magniflow mufflers. Picked car up today and it ran great all the way home and nice and cool. I should also mention that I had the 2.5" exhaust manifolds coated by Jet Hot with there highest temp ceramic coating to help reduce the under hood temps and they look great too.

So after I get home I shut her off and go into the house then I remember I never took a look at the newly installed manifolds under the hood to see how they look installed and to also see if the under hood temps seemed lower. Well as I get closer to the car I hear a sound that sounds like bacon frying on a griddle. I open the hood and I can hear and see that a tiny amount of water seems to be seeping onto the exhaust manifold at about the number 4 cylinder location (Passenger side of course). I look under the car and see no water on the ground. It appears the small amount of water is hitting the exhaust and evaporating before it hits the ground. So since this has never happened before and I just picked up the car today I am hoping that maybe the exhaust manifolds bolts need to be sealed? Do that hit the water jackets in the heads? I really hope it's not a blown head gasket. I pulled the oil dip stick and no foaming or anything but oil on dipstick. The spark plugs were too hot to pull so I will pull the #2 and #4 plugs tomorrow to see how they look.

I am praying the manifold bolts just need to be sealed and if so which ones and what exactly should I use?

Can anybody offer any insight on this?
 
pvs409

pvs409

Well Known Member
Supporting Member 11
All 348/409 exhaust manifold bolts need to be sealed -the ones by the center dump (the longer ones) definitely go into the water jackets
Make sure you drain the radiator below the bolts so the sealer can dry...I use the white brush on sealer to all the threads.
I even had the rear manifold mounting bolt by the firewall leak water, so would seal all the threads on all the mounting bolts on the manifolds.

Paul
 
Gofish

Gofish

Well Known Member
pvs409 said:
All 348/409 exhaust manifold bolts need to be sealed -the ones by the center dump (the longer ones) definitely go into the water jackets
Make sure you drain the radiator below the bolts so the sealer can dry...I use the white brush on sealer to all the threads.
I even had the rear manifold mounting bolt by the firewall leak water, so would seal all the threads on all the mounting bolts on the manifolds.

Paul
Click to expand...

slight highjack here ……

I knew about sealing the head bolts, but this is the first I’ve heard of exhaust and even intake bolts. This may explain why I often have a slight bit of coolant near the front bolts of the intake on my 348 3 x 2. I’ll seal and wait.

thanks!

John
 
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