Hi all I am a newbie here so please be easy on me. Does anyone have flow number on the low performace cylinder heads? If not what is the block angle and I try and build an adapter for my buddies flow bench. I am going to put together a stroked 348 for my dads Impala. Also is there any single plane manifold out there. Thanks for the help.
Cylinder Head flow number?
- Thread starter Donovan
- Start date
348 stroker
You can make a stroked 348 by using a 409 crank and 348 rods and 348 pistons....030" over should give you a 383. We built one for a customer about 12 years ago and it just flew!!! Bolts right in but you'll need a 409 oil pan to clear the counter-weights on the 409 crank.
Good luck.
Phil Reed
I have to ammend my earlier message!!! You use a 409 crank AND RODS with 348 pistons for the stroker 348. The 409 crank has a .250" longer stroker while the 348 rod is .125" longer so it all works out using the stock wrist pin placement in the 348 piston.
Just didn't want to get anyone in trouble!!
Phil
You can make a stroked 348 by using a 409 crank and 348 rods and 348 pistons....030" over should give you a 383. We built one for a customer about 12 years ago and it just flew!!! Bolts right in but you'll need a 409 oil pan to clear the counter-weights on the 409 crank.
Good luck.
Phil Reed
I have to ammend my earlier message!!! You use a 409 crank AND RODS with 348 pistons for the stroker 348. The 409 crank has a .250" longer stroker while the 348 rod is .125" longer so it all works out using the stock wrist pin placement in the 348 piston.
Just didn't want to get anyone in trouble!!
Phil
Flow
High performance 348 and low performance 409 heads use 2.06/1.72" valves and flow around 210 cfm. The smaller valve ,1.94/1.66" head would flow less than that and would not be useful for performance applications. The good news is that the low performance heads will accept the larger 2.06/1.72" Or 2.19/1.72" valves. With the 2.19 valve the low performance head would flow around 225 cfm. I have 2.06/1.72" valves in a set of low perfomance heads on my 409. Smaller valve heads are great for the street.
High performance 348 and low performance 409 heads use 2.06/1.72" valves and flow around 210 cfm. The smaller valve ,1.94/1.66" head would flow less than that and would not be useful for performance applications. The good news is that the low performance heads will accept the larger 2.06/1.72" Or 2.19/1.72" valves. With the 2.19 valve the low performance head would flow around 225 cfm. I have 2.06/1.72" valves in a set of low perfomance heads on my 409. Smaller valve heads are great for the street.
Flow Bench Numbers
Donovan-
I've got flow bench numbers for unworked 333's, which will be similar, if not identical to your LP 348 heads. The only modifications were to the valves, 2.19's/1.72's were installed prior to the porting I had done on those heads. If you'd be interested, I can send the info to you.
E-Mail me:
andyb@adelphia.net
I've also got specs on 817's and 690's, if you'd be inclined for those in stock, and worked forms..... From the work I've had done, I'm running worked 817's, with stock sized 2.06/1.72 valves, some bowl blending, porting, and polishing, and they work great for the street. Good Volumes, good velocities for street lift cams.
-Andy/Oldimpala
Donovan-
I've got flow bench numbers for unworked 333's, which will be similar, if not identical to your LP 348 heads. The only modifications were to the valves, 2.19's/1.72's were installed prior to the porting I had done on those heads. If you'd be interested, I can send the info to you.
E-Mail me:
andyb@adelphia.net
I've also got specs on 817's and 690's, if you'd be inclined for those in stock, and worked forms..... From the work I've had done, I'm running worked 817's, with stock sized 2.06/1.72 valves, some bowl blending, porting, and polishing, and they work great for the street. Good Volumes, good velocities for street lift cams.
-Andy/Oldimpala
Thanks for all the info. Oldimpala I would love to have any flow numbers you have. Here is my Email Dehorton1@msn.com
and I will try to email you thanks again.
and I will try to email you thanks again.
Andy, Mayby you could post the peak flow numbers here if it's not too much trouble. With the high prices that the high performance heads are going for the re-worked regular heads are looking like a good way to go. I've often wondered how much the smaller heads would flow with bigger valves and some porting. I was also wondering if you checked the flow on the exhaust side. Knowing that would help with cam selection.
bubbletop61
Well Known Member
small heads with big valves
I have read in this post that we can get 225 cfm of flow out of standard 348 heads if we go to the 2.19 valves. Is this with additional porting or stock heads? I assume the intake ports are smaller on the standard heads than they are on the High Performance Heads. Is this correct?
If I go with my high performance heads( now 2.06 valves), with minimal grinding just to clean up the as-cast rougness, I assume I will get more than 225CFM of flow.
Does anybody know how much more?
At what rate of flow do we start to be inefficient with the 2GC
3x2 carb set-up? Or is this related. Sorry if this is a dumb question....
Thanks
Gar
I have read in this post that we can get 225 cfm of flow out of standard 348 heads if we go to the 2.19 valves. Is this with additional porting or stock heads? I assume the intake ports are smaller on the standard heads than they are on the High Performance Heads. Is this correct?
If I go with my high performance heads( now 2.06 valves), with minimal grinding just to clean up the as-cast rougness, I assume I will get more than 225CFM of flow.
Does anybody know how much more?
At what rate of flow do we start to be inefficient with the 2GC
3x2 carb set-up? Or is this related. Sorry if this is a dumb question....
Thanks
Gar
Flow Numbers
Well, to all of you that asked, I'm thinking I'm going to post scans of the flowbench printouts...
I've found the 333's (Which volumetrically, are nearly identical to the 817's, close enough so I didn't pony up the extra $$ to have the 817'a benched, too). I'm looking for the 690's I benched. I should have them shortly.
I'll scan the sheets in, and post them. Then you can check lift, velocity, and flow at all the points for the heads....
Jim- The bench numbers take into account both sides; however, we didn't measure it on the block. This was heads on a bench. From my limited understanding of the W-Motors, they've got a shrouding issue with the exhaust valve in the cylinder bore when it's open. I actually shelved my 340hp Car block in favor of a truck block for this exact reason. Who knows if it makes a difference (It's supposed to, though)!?!?!
The flow numbers were great when prototyping a motor, and later building it. I got a lot done very cheaply because my machinist was as curious as I was with these things... They actually flow a lot better than I thought...
I've got to get the page to work, and scan it... (My Scanner is not Win XP compatible, I just found out... Yippie!), then I'll post it if it's good. If not, I'll list a chart of numbers.....
-Andy/Oldimpala
Well, to all of you that asked, I'm thinking I'm going to post scans of the flowbench printouts...
I've found the 333's (Which volumetrically, are nearly identical to the 817's, close enough so I didn't pony up the extra $$ to have the 817'a benched, too). I'm looking for the 690's I benched. I should have them shortly.
I'll scan the sheets in, and post them. Then you can check lift, velocity, and flow at all the points for the heads....
Jim- The bench numbers take into account both sides; however, we didn't measure it on the block. This was heads on a bench. From my limited understanding of the W-Motors, they've got a shrouding issue with the exhaust valve in the cylinder bore when it's open. I actually shelved my 340hp Car block in favor of a truck block for this exact reason. Who knows if it makes a difference (It's supposed to, though)!?!?!
The flow numbers were great when prototyping a motor, and later building it. I got a lot done very cheaply because my machinist was as curious as I was with these things... They actually flow a lot better than I thought...
I've got to get the page to work, and scan it... (My Scanner is not Win XP compatible, I just found out... Yippie!), then I'll post it if it's good. If not, I'll list a chart of numbers.....
-Andy/Oldimpala
Out of Town
Donovan-
I work in "fault recovery" for the phone company. Which politely means, when big crap breaks, I go fix it. I wasn't supposed to be in Virginia this week (Not my on-call week) fixing the breakage from Isabel yet, but the guy who I alternate with from this region had an emergency.
I'll be back in Buffalo tomorrow night; I'll get you something either way.
I hate it when work gets in the way....
I still have to call Aubrey about some pistons?!?!?!? 
And the only nice weekend left (probably in Buffalo) and my Impala's apart! 
:
-Andy/Oldimpala
Donovan-
I work in "fault recovery" for the phone company. Which politely means, when big crap breaks, I go fix it. I wasn't supposed to be in Virginia this week (Not my on-call week) fixing the breakage from Isabel yet, but the guy who I alternate with from this region had an emergency.
I'll be back in Buffalo tomorrow night; I'll get you something either way.
I hate it when work gets in the way....
I still have to call Aubrey about some pistons?!?!?!? And the only nice weekend left (probably in Buffalo) and my Impala's apart! : -Andy/Oldimpala