409 blower intake

1961BelAir427

Well Known Member
Supporting Member 3
#4
So Brian.....did you ask for permission or are you going with that whole forgiveness plan? :rub :pop Either way it's gonna be worth it I'm sure. Looking forward to it.
I've forgotten, what induction are you running now?
 

MRHP

 
Supporting Member 1
#5
I have dual 600 Edelbrocks on my 474, but I don't know yet what this 380 will get. I have dual Predators, but they look too new for this build. I am thinking another pair of Edelbrocks. I have read they are decent on Roots blowers and do not have to be blower referenced if large enough cfm and proper step up springs used. I guess time and my wallet will tell. Next big purchase will be some 348 forged Pistons. Sheesh...... They are expensive. How come the 9.5 compression pistons all seem to be cast! Anybody have forged ones?
 

63 dream'n

Well Known Member
Supporting Member 3
#7
[TE="MRHP, post: 247736, member: 25"]:D:dance:flag:danceI just talked to Don Hampton and ordered a blower intake from him for my 380. Hell of a nice guy. Six to eight weeks for the intake.[/QUOTE]

Brian,are these manifolds custom made ?.are they for small and large port both?
 

1961BelAir427

Well Known Member
Supporting Member 3
#8
If you use a 409 crank, 6.385" rods, and the KB pistons for 4" stroke/6.135" rods.....they would be the cheapest by far. Aren't they rated at 10.5:1? With the small chamber in a set of 333's I bet you could get close to that 9.5:1 without having to run too thick of a head gasket and killing quench completely.
 

Don Jacks

Well Seasoned Member
Supporting Member 3
#9
The K-B piston is rated at 11-1 when using car heads ,a 4 in stroke crank,and 6.135 rods.With a 3.5 stroke,6.385 rods,and car heads,it should come out to around 10.5 -1 with car ,10-1 with 333's,which would still be a good blower set up IF while doing the work for the bigger valves,you open up the combution chambers for an increase in size to say 25-30 cc's to get to the 9.0-9.5 range.If you cc it during mock up,it might not take much to get you in the compression range that you want.8.5 is lower than you'd need or want given the 5-6 psi of boost than your planning on running.Just my opinion,others may differ.
 

1961BelAir427

Well Known Member
Supporting Member 3
#10
Thanks Don!!! I didn't think about the effect of displacement on compression when I posted above. Less swept volume equals less squeeze on the same amount of air. Thanks for that reminder.
Wonder how much it would open up the 333's if you were to just give the chambers a real good polish? Smooth polished combustion chambers are usually good for helping with detonation resistance. If you were installing larger valves in them, then you could open the chambers around the valves some more to unshroud them better. Maybe take the time to debur the valve reliefs in the pistons and blend in the notch in the block should take away some compression and quell detonation as well.
Seems weird talking about combustion chambers in the heads on a 409. I've never built a blown engine, but I think I'd rather be between 9.5 & 10:1 than between 9 & 9.5.
 

MRHP

 
Supporting Member 1
#11
Well,with a truck block, and 333 heads, 3.5 stroke, 6.385 rods I would think it would be in the 9.5 range?If I could get it in the 9.0 range or a touch less perhaps, I think I would be fine. Math hurts my head.
 

MRHP

 
Supporting Member 1
#13
Well since I have 702 heads with no chamber, I might as well have somebody make a set. At least I will know my compression will be right. Just cant find a cheap good way out. Budget? It keeps expanding.
 

Don Jacks

Well Seasoned Member
Supporting Member 3
#14
You've got a late truck block,right? You could save money by scoring a set of 333's to use,and sell/trade the 702's.Valve guides,valves,valve job cost the same either way.Take a set of unmoolested 333s and cc them,I'm betting they will come inaround 20 cc's.I've never seen the specs posted for thembutNHRA blueprint sprec's for 690's,I belive I've read were around 12,and the Edebrock is around 15.Thess 333 chambers are bigger than either one.
 

MRHP

 
Supporting Member 1
#18
Oooh.........the question. I am sure it will find a home in my 62 for a while, but it would be best suited in a 40 Willys or a 55 Chev. Both gasser style of course. That may be a ways down the road though. I just always wanted to build a blower motor.
 

Fathead Racing

Well Known Member
Supporting Member 7
#19
Oooh.........the question. I am sure it will find a home in my 62 for a while, but it would be best suited in a 40 Willys or a 55 Chev. Both gasser style of course. That may be a ways down the road though. I just always wanted to build a blower motor.
55 Chevy 2 dr. Post. 55 Chevy 2 dr. Post. Oh, did I say that twice? :flag:pepper
 
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