BB head questions

[AJ]

I am thinking of up grading my RB to the Edelbrock heads. I was told I will have to raise the compression on the aluminum heads to get the same performance. The Edelbrocks I'm looking at are the 84 CC heads. What is an average CC on 906 heads with 2.14 intake and 1.81 exhaust valves? I have been told to raise the compression 1 to 1.5 more than the 906 heads. How much would I need to mill the Edelbrocks to accomplish this and is there any bad side effects from doing so? Thanks for any info. AJ

[ehostler]

You were told wrong. These heads are pure bolt on performance. They will give you more hp and torque, out of the box.

If you do a search, in this forum, you will find one thread where I typed in the results that Herb McCandles came up with.

[GON_RACIN]

.509 cam install

[dave571]

Ed's right.

Maybe what you may have heard ,and misunderstood, is that you CAN raise the compression more with aluminum heads, and still run pump gas. Not that you need to raise the compression ratio.

You're already gaining a little bit of compression at 84cc's since 906 heads are open chamber at about 88 cc.

What gains you see will depend on what you're adding them to. What compression, what cam, what manifolds. Adding them to an 8:1 smog motor won't help much.

[ehostler]

Here is the link the thread where I retyped the basics of Herb's test results.

You can't go wrong with these heads, unless of course you maintain an iron intake...

[AJ]

Thanks for all the comments. I plan on getting the Edelbrocks from Hughes and have them do their stage 3 porting and larger valves. I still am not sure if I should have the heads milled to raise compression-they think it would help.

[AndyF]

Unless you're making more than 550 hp skip the Hughes Stage III bs and just bolt the heads on out of the box. The Edelbrock heads run just fine out of the box and make plenty of power as is.

Summitt has them for $1150 a pair ready to go until Dec 31st.

[dave571]

I was under the impression the edlebrocks came with 2.14 and 1.81 valves?

If this is so, I can't see you wanting more.

I'm with andy on the port work. Make sure they're matched to you intake and headers, then just use them as is. This is a street application, isn't it?

[phoenix]

How much Camshaft are you using! What kind of ramps, solid flat tappet, Hydraulic???

[ehostler]

Unless you are running low compression to begin with, there is no reason to shave the heads. They already come with the 2.14/1.81 valves and there is real no need for anything bigger than that.

Like Andy said, unless you are trying to make alot of power, there is no need for a port job. Heck, look at the Hughes web site and it will explain why you DON'T want a stage 3 job, for a street engine/cam.

Just bolt them on, right out of the box (don't forget the ARP studs).

[Neil]

I think everyone has hit the nail on the hammer head. About the porting... the edelbrock's are advertised at 291 cfm out of the box (from what I hear, they don't always have that)... but thats more than a fully ported 906 or 452. And remember you are getting a closed chamber head (plus it's aluminum... better combustion and lighter). With that in mind... the machine shop I go to say that the most cfm on the intake side you can get out of an Edelbrock Performer is about 310-315 (which is good), but machine shops normally want bookoo bucks to do stage III work (which to me isn't worth it). For a direct bolt on edelbrock's are great... don't really have a lot of potential to do much more though.

Neil

[AJ]

The reasons I am looking at larger valves and the porting: 1) my compression now is 8.2 2) I am running a roller cam with .625 lift 3) this is a drag car 4) it is supercharged--and needs all the flow it can get 5) haven't dyno'd the motor but am guessing 750 HP--it runs 9.40's @ 149 in a 3160# car. Thanks again for all the advice. AJ

[Doug Wilson]

Indy does a slick job on those heads, which costs about $2200 - including the heads. With a blown engine, I'd probably get those, unmilled and see how they run. You can always cut them - but you can't UNCUT them.

What's the difference between a light bulb and a pregnant lady??

You can unscrew a lightbulb.

There is my point - sorry if I offended anyone.

[23T]

How much boost (psi) are you running? What is your c/r adjusted for boost @ altitude? Is your block O ringed? Normally the intake ports take care of themselves with the boost it's the exhaust you need to take care of, and be sure your cam profile matches all components of the car.

[AJ]

23T, I run 14 #'s of boost. The boosted C/R calculates to 16:1. I race at an altitude of 1000 feet. I don't have the block O-ringed.

[Neil]

Indy does good port work... sure. But my point is about the heads is that if you are going to spend $2200 on some heads (that have no more room for potential).... why not spend $2600 on some Indy-SR that flow about the same as a fully ported Edelbrock... and have oodles of potential if ya want to cut them up? I went to business school a few years back. One of the questions my economic teacher posed to us students was "would you rather be a good saver... or a good buyer?" The answer is that you want to be a lil bit of both... but in this hobby, unfortunatley, you have to buy a whole bunch of stuff that costs a lot of money. All I am saying is ... be smart about it.


Neil

[TJ]

The Edelbrock heads out of the box, will flow right along with the INDY SR heads out of the box. So, if no further modifications are desired, the Edelbrocks are the head to go with. In fully ported form, the INDY SRs will outflow the Edelbrocks. BUT...the Edelbrocks with the full port job will run you around $22-2400 with bigger valves in them....vs....Fully ported INDY SRs that end up around $3300 in fully ported form, from ICH.

It all goes back to the old Herb McCandless saying, "Speed costs money....how fast do you want to go ?"

[dirty dan]

Originally posted by AJ
23T, I run 14 #'s of boost. The boosted C/R calculates to 16:1. I race at an altitude of 1000 feet. I don't have the block O-ringed.

No O-ring!!
What are you useing for a head gasket?(JB weld)?
14LBS Boost.
What are you useing for fule?

[Doug Wilson]

I like McCandless - but... that saying has been around since the Romans were racing chariots.