Hello from another W motor newbie

WARPT

Well Known Member
Some pics of the bastard 1961 348 engine. Damned thing already bit me!
 

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scott hall

Well Known Member
Supporting Member 2
If the rocker arms are aftermarket stock replacements be very weary of them. Most will break. Either use know originals (GM) or put a good set or roller rockers on it. JMHO.
 

skipxt4

Well Seasoned Member
Supporting Member 18
Probably, the spark plug wire stand-off's.:dunno They seem, to be always in the way, waiting, to take off some flesh.:drop Good Luck, with both engine's.:appl
 

Don Jacks

Well Seasoned Member
Supporting Member 3
Since it's down this far,,,,,,,,,,,,,I'd have to upgrade the camshaft and springs.Something like the Howards 340 horse 409 replacement grind would really wake that otherwise stock engine up.If you are pulling the heads,check if they have the stock valves in there,and if so,replace them,at the least the exhaust,with stainless valves for two reasons.I.The stock valves are 2 piece and subject to break.2,The exhaust valve is not compateble with todays unleaded fuel.
 
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303Radar

Well Known Member
Supporting Member 2
For grins, I would remove the cam shaft and verify the really important cam bearing is installed correctly.
I take that back, either get an oil primer or find instructions on how to make one. By priming the oil, you should see oil go to the heads. If you see oil in the heads, the cam bearings are installed correctly. If not, at least you found an expensive problem in a cheap manner. Oh, and you'll need to get new correct ones installed.

Good luck and nice find!
 

WARPT

Well Known Member
Thanks everyone for the advice! I will definitely prime the engine oil before firing it up. It has been sitting a long time.

Don, I will consider your advice of the cam and valve springs. Will this Howards cam make a seat-of-the-pants difference? Will any machining be required for the new valve springs?
The guy I got the '61 heads from has given me a lot of advice for installing them. I want to verify. Do all the head bolts and the lower water pump bolts pass though water passages?! What were the engineers thinking? He advised using ARP thread sealer on all those bolts.

skipxt4... yup you are right. those damned spark plug wire stand-offs!

BTW: I have another story on how I acquired the '59 el Camino.....
 

Don Jacks

Well Seasoned Member
Supporting Member 3
Yes,the cam will make a "seat of the pants" improvement.The lift on that cam is .401 in,.411 exhaust.A fresh set of stock springs[show cars] is all you'll need.The small block has always had bolts that go into the coolant area,nothing new there.Also seal some of the exhaust manifold bolts,same deal.As far as machine work goes,have the valve guides machined for the "PC" style valve seals as most of the stainless replacement valves have no provisions for the factory style "o" ring seals.
 
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WARPT

Well Known Member
Don thanks for your information. Please excuse my ignorance, but what is the lift of the factory 240 hp cam?

This is the cam you recommend?
https://howardscams.com/i-24076551-...draulic-flat-tappet-800-to-4400-camshaft.html

Howards website states that this cam is "Near duplicate of the Chev 340HP/409 cam (GM # 3744901)"

I found factory camshaft specifications and part numbers online:
http://garage.grumpysperformance.com/index.php?threads/stock-chevy-cam-specs-info.484/

Looks like the 409 340hp camshaft part number is 3744430 according to that camshaft specifications and part number list.

The set of rebuilt '61 heads w/aprox. 2k miles on them had this in the description:
"348 Chevrolet heads. These are from a 1961 250 horse 348. Date code D 27 61, casting # 3758879. They feature NEW stainless valves, NEW springs, and NEW guides. NEW stamped steel rockers,NEW nuts and NEW pivot balls. NEW ARP screw in studs. All threads are good. Used only 2000 miles since being rebuilt. I'm going to aluminum heads and these are no longer needed. Well over $450 invested in parts and machine work alone."
He and I have been texting back and forth frequently. He said that by memory those new valve springs are good up to .500 lift, so I should be good there.
 

Don Jacks

Well Seasoned Member
Supporting Member 3
With all those good parts in the heads,you're more than good to go.Did you get rockers with the heads?Yes that's the Howard's cam that I was refering to.It's got close to the same lift,a touch more duration,a better centerline and advance on the intake side.With the way these heads are set up,you could easily step up to something a little stronger,like the little 256-262 duration Comp unit from Show Cars[0949],or a little smaller 0948.As far as I can tell,the lift on the 340 horse 409,and the 250,280,and 61 305 horse 348's are pretty close to each other.
 

WARPT

Well Known Member
Thank you for your insight and suggestions. Yes, the heads I got have new stamped steel rockers. Also I received push rods that appear to be very new as well.
In a day or two I set out on my road trip to get the other 348 short block, heads and triple two set up! :clap :brow
 

blkss64

Well Known Member
So I have seen on this forum for quite a long time that the aftermarket rockers are junk. I have a set of Sealed Power stock replacement rockers I that have never used. I am sure that the rockers are probabaly a rebox from another manufacturer as Sealed Power was bought out years ago. . I bought them in 2001. Would those still be junk? When did the bad rockers hit the market?
 

WARPT

Well Known Member
The guy I bought my '61 heads from said he rebuilt the motor in 2002. So I am going to assume that my steel rockers are OK.

Got back from my road-trip a week ago with more 348 booty. I got the triple two set up, another pair of heads, pushrods, a set of exhaust manifolds, a spare carb. and a short block .040 overbore.
 

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