Flathead blower setup

K

ken-r-mer

Senior Member
Ok, refining my choices:

Have the TR Roberts Blower kit with 6-7 psi boost.
Settled on the Schneider cam (Potvin grind)
Edelbrock 1116 heads (low compression ratio, high lift capacity, and high air flow)
The 8BA block has 258 cu inch

A few Q's.
The Edelbrock 1116 heads have a max lift of 0.56" intake and 0.515" exhaust. The Potvin cam grind by Schneider has 5 different lifts:P-3/4-0.325", P3/4S-0.350", P-3/8-0.375", P-400-0.400" and P-425-0.425". The higher the lift the more air flow. For mostly street use, will a higher lift be good or bad (rough idle)?
Then, Cometic makes head gaskets of varying compressed thicknesses from 0.27" all the way up to 0.140". The standard compressed thickness is around 0.55". Cometic has a 0.60" and an 0.080" which would fractionally lower the compression and guarantee no pre-detonation even with 89 octane.
Was also thinking the varying thicknesses will help me acquire that 0.40" quench between the piston and head without needing to do any machining on the head. Is my thinking correct?
 
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Your engine is very close mine. I have 425 Offy heads which means the area over the valves is 4.25" deep. They have been milled a further .040" which reduces the chamber volume to provide reduced compression ratio and better flow over the valves. My cam is also schneider which replicates the Potvin super 3/8. It.s really the cam duration which affects idle along with the centerline, mine is 112 deg. The engine has 286 cu in which mitigates the more radical cams somewhat. I use Graphtite big bore head gaskets. To do it over again I would have chosen a milder cam as my idle is 900 rpm. The blower is a B&M 144 and boost is 5lbs at 5000 rpm. The engine was built by Motor city Flathead. I also have boost control which reduces the ignition timing by 1-3 deg per lb of boost.
My engine now has 40,000 on it and has been quite reliable except for the keyway on the blower pulley rounding out which required a new Scat crank and complete balancing.
The engine is quite strong to say the least yet still gives 22 mpg on the highway thanks to a T5 overdrive trans.
 
I have no experience with blowers, but have never seen a set of heads that did not need a bit of "tweaking" to obtain optimum quench.
 
Did you ask Schneider cam what they recommend? I guess another grind
Lift is your friend, lots of duration not so much…
Who needs boost at 5000 rpm ?if you drive it on the street
The cosmetic gaskets will help you to seal the engine.
Use a good stud kit
258cci is 3 3/4 x 3 5/16?
It is is the duration the creates the sound
Micky
 
Just installed an original NOS Potvin 400 in our Ital blown Deuce coupe. Replaced the L-100 I'm impressed with the improvement overall. Been doing this blower stuff for a long time your combustion chamber CC volume is important so if it was me I would determine what that number is on the Edelbrock heads.

Using cometic gaskets to control quench in my opinion is an expensive way to go. Reason i say that is if you determine your not happy with the heads or anything else related to removing the heads those expensive gaskets are now junk.

On all of my blower combinations from a street engine to one of our 200 MPH flatheads. I simply use Clark copper head gaskets. Clark makes dead soft solid copper gaskets in just about any thickness you would need. Solid copper gaskets besides their superior strength are also reusable for a life time.
Ronnieroadster
 
hotrodcbx said:
Your engine is very close mine. I have 425 Offy heads which means the area over the valves is 4.25" deep. They have been milled a further .040" which reduces the chamber volume to provide reduced compression ratio and better flow over the valves..
Click to expand...

Ronnieroadster said:
CC volume is important so if it was me I would determine what that number is on the Edelbrock heads.
Ronnieroadster
Click to expand...

The Offy numbers 375 400 425 refer to the dimension for valve relief, that is .375, .400 or .425" for this relief.

The number on my heads is located on top edge surface near the intake manifold

572637
 
Ronnieroadster said:
Just installed an original NOS Potvin 400 in our Ital blown Deuce coupe. Replaced the L-100 I'm impressed with the improvement overall. Been doing this blower stuff for a long time your combustion chamber CC volume is important so if it was me I would determine what that number is on the Edelbrock heads.

Using cometic gaskets to control quench in my opinion is an expensive way to go. Reason i say that is if you determine your not happy with the heads or anything else related to removing the heads those expensive gaskets are now junk.

On all of my blower combinations from a street engine to one of our 200 MPH flatheads. I simply use Clark copper head gaskets. Clark makes dead soft solid copper gaskets in just about any thickness you would need. Solid copper gaskets besides their superior strength are also reusable for a life time.
Ronnieroadster
Click to expand...

Hi Ron,
I only use Cometic as they hold the pressure.
I will try to get the solid copper gaskets, sound like good alternative.

I use steel heads with 76cc cleared for 0.4 lift
 
HotRodmicky said:
Hi Ron,
I only use Cometic as they hold the pressure.
I will try to get the solid copper gaskets, sound like good alternative.

I use steel heads with 76cc cleared for 0.4 lift
Click to expand...



Your at a very good CC volume. The supercharged flathead Ford V-8 engine's I'm involved with will put out as low as 5 pounds to as high as 23 pounds of boost. The solid copper head gaskets hold up perfectly.
Ronnieroadster
 
Micky once the carbs are wide open the boost begins. So even off idle I see pressure on the boost gauge when I floor the throttle. The carb throttle plates act as a valve so once the plates are open a good amount the air starts to flow and thus pressure begins along with the RPM climbing. As the RPM's climb the boost will continue to climb as well. There's also a notable sound when the blower starts making the boost
Ronnieroadster
 
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