aluminum heads
- Thread starter B-O-B
- Start date
richard rink
Member
B-O-B,
My 8ba, 0.060 overbore, with a Kiwi-L100 cam (0.368/9 lift) is equipped with Edelbrock 1115 aluminum heads. No problems. Manufacturer's specs state clearance up to .410.
Richard
My 8ba, 0.060 overbore, with a Kiwi-L100 cam (0.368/9 lift) is equipped with Edelbrock 1115 aluminum heads. No problems. Manufacturer's specs state clearance up to .410.
Richard
tubman
Well-known member
I like Edmunds. They have the spark plug re-located juuust enough so the the exhaust valve doesn't hit the electrode when it opens. This allows me to use extended tip plugs that puts the spark out where it is more effective. I have been lucky enough to acquire two pairs of used heads in excellent condition that I have on the last two engines I have done. I like the way these engines run. I also have spent a bunch of time on both sets making sure they were dead flat and had .050 "squish". One of these engines is a 255" Mercury that I have in my '51 club coupe, while the other is a "258" engine going into the T-Tub hot rod I am resurrecting.
In contrast, about 20 years ago I had another engine built for me by a "pro". That one was a 276" with a MAX-1, a 390 Holley, MSD ignition, and Offenhauser heads. This was before the "Barn", and I don't think either I or the builder knew about "squish" and the heads were just bolted on with no checking or anything. I realize it was 20 years ago, but I distinctly remember being a little disappointed in the way that engine ran. It was OK, but it just seemed to be lacking something, and had a slight (traffic related) overheating problem I could never solve. Looking back, I'm sure that the lack of head preparation contributed to the disappointing (to me) performance, while the overheating problem was probably caused by the MSD "Ready to Run" distributor that most likely had an SBC advance curve. I sold the car that it was in (a '36 3-window
) about 5 years later because I was never really happy with it. In retrospect, had a resource like "The Ford Barn" been around back then, I would probably still have that car.
BTW, I have a set of new Offenhauser heads on the shelf collecting dust.
In contrast, about 20 years ago I had another engine built for me by a "pro". That one was a 276" with a MAX-1, a 390 Holley, MSD ignition, and Offenhauser heads. This was before the "Barn", and I don't think either I or the builder knew about "squish" and the heads were just bolted on with no checking or anything. I realize it was 20 years ago, but I distinctly remember being a little disappointed in the way that engine ran. It was OK, but it just seemed to be lacking something, and had a slight (traffic related) overheating problem I could never solve. Looking back, I'm sure that the lack of head preparation contributed to the disappointing (to me) performance, while the overheating problem was probably caused by the MSD "Ready to Run" distributor that most likely had an SBC advance curve. I sold the car that it was in (a '36 3-window
) about 5 years later because I was never really happy with it. In retrospect, had a resource like "The Ford Barn" been around back then, I would probably still have that car.BTW, I have a set of new Offenhauser heads on the shelf collecting dust.
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drolston
Well-known member
Very happy with how my 284" 59A/B runs with Offy 425 heads (.425 valve clearance), but have also been plagued with overheating in traffic in spite of doing everything short of an electric fan. I know it is contrary to the concept of aluminum heads, but I wonder if there is something about the Offy heads that makes them prone to overheating?
tubman
Well-known member
I know it is highly unlikely, but we seem to have had a common problem. What kind of ignition are you running and have you checked the timing curve? I always thought it was the MSD setup, but this makes me wonder (but just a little, to be frank).
Ed Pitts
Well-known member
drolston
Well-known member
c
Crab distributor in very good mechanical condition regarding advance mechanism with 12v Pertronix. Spark is advanced by 3 degrees (one and a half marks on the distributor body). No sign of pinging or spark knock. Plugs show a little lean (grayish beige).
These Offy heads have been around for 50 years so seems very unlikely that such a problem would have gone un-diagnosed. But then, we just discovered that anti-bacterial hand soap increases susceptibility to infection.
Anybody out there with Offy heads that does NOT have cooling problems at idle?
Crab distributor in very good mechanical condition regarding advance mechanism with 12v Pertronix. Spark is advanced by 3 degrees (one and a half marks on the distributor body). No sign of pinging or spark knock. Plugs show a little lean (grayish beige).
These Offy heads have been around for 50 years so seems very unlikely that such a problem would have gone un-diagnosed. But then, we just discovered that anti-bacterial hand soap increases susceptibility to infection.
Anybody out there with Offy heads that does NOT have cooling problems at idle?
Pete
BANNED
The brand of heads has nothing to do with heating problems.
A properly built and installed flathead will not overheat
at idle or anywhere else in the operating range of the engine.
Almost all heating problems are caused by the engine builder neglecting to perform the first and most important step in the rebuild. That is, acid strip the block.
Stripping should be done BEFORE magnafluxing and pressure testing.
Ol' Ron
Well-known member
Allot of good information here, in some places acid stripping isn't available, but bake cleaning is very good. As for the heads, the quench is very important especially for a street engine.050" max I shoot for .040.. Another probable with heads is the CR. THe only way to check that is by CCing them.
Good luck
Good luck
tubman
Well-known member
Ron - I don't "cc" my heads anymore. The last two sets I worked on to bring them to a consistent .050 "squish". After I installed them and ran the engine for a while, I checked the compression, and it was 160 on all eight cylinders. I don't know what compression ratio that comes out to be, but the engine starts easily and runs great.
When you think about it, shouldn't the exercise of getting the proper quench automatically bring everything else (compression ratio, chamber volume) into line? It appears it has for me. (One thing I do know is that my '67 L79 SBC is factory spec'd at 160 lbs compression and 10.25 CR; I'll take that.)
When you think about it, shouldn't the exercise of getting the proper quench automatically bring everything else (compression ratio, chamber volume) into line? It appears it has for me. (One thing I do know is that my '67 L79 SBC is factory spec'd at 160 lbs compression and 10.25 CR; I'll take that.)
rotorwrench
Well-known member
Ford L-head V8s have a trade off point between good breathing and compression ratio. So many of the aluminum heads have chambers that are good for compression but may not help with breathing or flow due to the chamber's shape.
The research JWL has in his book is excellent for answering many performance questions. It's hard to say whether cylinder head design or composition has anything to do with overheating. I'd figure it to be a very minor variable unless the coolant flow in the head is poor.
The research JWL has in his book is excellent for answering many performance questions. It's hard to say whether cylinder head design or composition has anything to do with overheating. I'd figure it to be a very minor variable unless the coolant flow in the head is poor.
tubman
Well-known member
"JSeery" - You have to realize that the cam timing on the L79 is quite a bit more radical than the 8CM I am using. While the compression pressure is about the same, I would expect that the dynamic compression ratios are quite different. I think my flathead has about 7.5/8:1 with all things considered. If the SBC had the same cam timing as the flathead, I would expect the compression pressure to be much higher.