Building a 408 with IndyBrocks

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RAMM

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A new customer contacted me and wants to build a 408 and use these heads that he has "way too much $$$ invested in". Customer ships them and I decided to baseline them. These heads were previously serviced/refreshed and I flowed them as I received them OOTB.
Flow @ 28" 4.06" Bore 2.055"/1.6" valve diameters:
.1 62.9
.2 120.3
.3 179
.4 225.7
.45 245.3
.5 259.3
.55 266
.6 269
.7 259

I decided to clean them thoroughly and re-valve job them considering it looked like there was room for improvement. I also took a deshrouding cut which added .060" between the intake valve and chamber wall. A 30* backcut was also added to the intake valve in an effort to bolster the somewhat weak low valve lifts. After results:

.1 65.9
.2 135
.3 192.6
.4 232
.45 250
.5 265
.55 271
.6 266
.7 261

This is my first set of Indybrocks I get to look at and can see where they could use proper porting and the 93.5+% throat size is hilarious. Porting these is not part of the plan or budget. J.Rob

IMG_20171030_105103.JPG


IMG_20171031_134619.JPG
 
I'm guessing they should flow better than that? My EQ s went 272 cfm with just 2.02s and a bowl port.
 
gregsdart said:
I'm guessing they should flow better than that? My EQ s went 272 cfm with just 2.02s and a bowl port.
Click to expand...

Impressive for sure but hard to compare without being on the same bench at around the same time.

What's the 93.5% throat size thing?
 
RAMM said:
A new customer contacted me and wants to build a 408 and use these heads that he has "way too much $$$ invested in". Customer ships them and I decided to baseline them. These heads were previously serviced/refreshed and I flowed them as I received them OOTB.
Flow @ 28" 4.06" Bore 2.055"/1.6" valve diameters:
.1 62.9
.2 120.3
.3 179
.4 225.7
.45 245.3
.5 259.3
.55 266
.6 269
.7 259

I decided to clean them thoroughly and re-valve job them considering it looked like there was room for improvement. I also took a deshrouding cut which added .060" between the intake valve and chamber wall. A 30* backcut was also added to the intake valve in an effort to bolster the somewhat weak low valve lifts. After results:

.1 65.9
.2 135
.3 192.6
.4 232
.45 250
.5 265
.55 271
.6 266
.7 261

This is my first set of Indybrocks I get to look at and can see where they could use proper porting and the 93.5+% throat size is hilarious. Porting these is not part of the plan or budget. J.Rob

View attachment 1715106610

View attachment 1715106611
Click to expand...




Its a bummer you can't get in there to do some porting as those numbers are telling you something.

TURBULENCE!!!!!

.55 271
.6 266
.7 261
 
I was lucky enough to be able to attend a 2 day "theory only" head porting class giving by Darrin Morgan in Columbus Ohio. He told us if someone brought a set of heads to he and the throat was OVER 91% of the valve size he would refuse the job. I hear some argue this but I kinda like his thinking.
 
pittsburghracer said:
I was lucky enough to be able to attend a 2 day "theory only" head porting class giving by Darrin Morgan in Columbus Ohio. He told us if someone brought a set of heads to he and the throat was OVER 91% of the valve size he would refuse the job. I hear some argue this but I kinda like his thinking.
Click to expand...

Oh I hear ya. To think these heads came from a pretty big name shop in the U.S. this way. For the street I stick to no more than 90% and often prefer 89.5% for driveability and part throttle tip-in. J.Rob
 
jos51700 said:
Impressive for sure but hard to compare without being on the same bench at around the same time.

What's the 93.5% throat size thing?
Click to expand...
The number I quoted for the EQ s has been seen, or very close, on two or more independent benches, IMMs being one of them. Backed up by the power I got on the dyno.
 
I didnt know those Indybrocks didnt come CNC ported from indy. I remember Indy claiming they went 306. maybe you could get them bare?
Use offset rocker gear.
A guy on Moparts several years ago who lived in Florida had a set of those on a roller cammed 416. He posted a lot. Remember his car weighed 3000 pounds and he went 9.76@ 138 with them. Forget his screen name now, but he was on there forever. Was a trans specialist and i think his name was Woody.
 
One of the things that I dread the most is getting a pair of heads that someone else has already "ported".
 
IQ52 said:
One of the things that I dread the most is getting a pair of heads that someone else has already "ported".
Click to expand...


I flowed a set of CNC 220 AFR chevy heads for a good Friend and I'm glad he was standing there when I did it. I ended up re-porting those and 2 intakes for him. Nice little small block street strip S10 extended cab that he would drive to the track. It ran 10.50's all day long and surprised a lot of people on the street. He called the guy out on the flow numbers and he started himin and a hollin. A aaaa aaaaaaaa.
 
B3422w5 said:
I didnt know those Indybrocks didnt come CNC ported from indy. I remember Indy claiming they went 306.
Click to expand...
The CNC version has that 300+ claim.
http://www.indyheads.com/images/15.cat2014.pdf
FWIW, the way I read the site, all head pricing is without porting no matter the head.
(There is a lot to read, I just skimmed.)

Does anybody have or KNOW if the Indybrock head does what they say cfm wise?
 
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MOPAROFFICIAL said:
I'm reading something like this...

Most heads out there sold with an advertised flow sheet do not meet the numbers.

See this problem a lot.
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These heads were not advertised, but built to my specs, or should I say Brians (IMM) specs. His bench and My local head porters numbers came up real close for heads done this way, along with others on this board I believe. I understand about folks fudging the numbers. That is why I only deal with folks I trust that have a great reputation for what they do, and customers reports that back it up.
 
gregsdart said:
These heads were not advertised, but built to my specs, or should I say Brians (IMM) specs. His bench and My local head porters numbers came up real close for heads done this way, along with others on this board I believe. I understand about folks fudging the numbers. That is why I only deal with folks I trust that have a great reputation for what they do, and customers reports that back it up.
Click to expand...

Brian's solid, few are but he proved he is one of few in the industry. Ramm is doing good so far as well. I started my own because people were crooked, flubbing numbers. Got tired of it, do it myself now.
The thing with any hobby are the attitudes, haha there are some characters out there.
 
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A bit of an update on this. The project is complete and turned out quite well.
'93 Magnum block (that was also machined for LA rocker oiling)
Bored/Decked 4.03" ICON 984's 10.5 comp
SCAT 4" 9000 crank/SCAT ICR 6123 rods
Indybrock heads in the OP
Edelbrock RPM port matched/minor plenum blend

Long distance customer so I used my carb,(Holley 750XP), igntion, (old Mopar electronic), dyno headers, Moroso waterpump electric, MT v-covers.
Tested with Esso 91 pump fuel.

Love those Lunati Voodoo cams, J.Rob

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