Does anyone have the flow numbers for a Stock 305 head? And/or ported 305 head?

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Rob
'86 TA 305 TPI
Gutted MAF, Ported Plenum
TB Bypass, Home made Cold Air Intake,
Edelbrock T.E.S.
48psi regulator, (Nickel method)

 

Try again.

 

I think I have some numbers for the 305 heads with 1.94/ 1.50 valve upgrade and they performed pretty good. The key here is that unless you do the port work yourself,, the dollar per cfm value is not good. I'll check tonoght if no one else has posted numbers or a link by then.

 

Well, can anyone guess at the horespower I could expect to gain by porting my heads?

 

Thanks BadSS, Your help is greatly appreciated.

 

I'm going to assume those are 416s....

I'd guess you should pick up somewhere around 20-25 HP, if yours look like mine inside. You'd probably get another 8 or 10 if you put undercut-stem valves in them. That's a bit extreme though, I'd only do that if I had to buy valves anyway, and I couldn't change the casting to something more worthy of having $$$$ spent on them.

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"So many Mustangs, so little time..."
ICON Motorsports

 

Yes they are 416's. Thanks for the info RB.

 

Porting your own heads can be tricky, or at least it has for me. I have done 2 sets and I am worried sick the whole time wondering how they will perform. Usualy I just try to smooth the casting flash, or rough spots of the heads. My latest set were the Vortecs I put on my new 350. They have 170cc intake ports. The AFR 195 have well, 195cc. So I know if I ported them bigger, I mean more than just smoothing the casting, they would probably still work well. But then the issue of making all the ports the same arrises. This is why I am a nervous wreck the whole month it takes me to do a set. I think most heads will benefit from a little port work. To answer your question, I would expect a good 20-30hp increase with a little port work if you have a cam and intake to supply the needed air and fuel. This is a guess, so somone else may have a better angle on it.



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Joshua Johnston
1991 Z-28
Flowmaster
K&N
305 / 5spd. (Temporary)

 

Sorry R.O.B. - I knew I had some data on a larger valve install and test,, but it was not for the 305 heads - it was the L98 aluminum head getting 2.02/1.60 valves.

I can tell you a ton of circle track guys were installing the Olds 1.995 / 1.56 in the 58cc 305 heads back in the 80's with good results. These valves are a little shorter than the Chevy's and the rocker stud pad needs to be machine for rocker alignment,, but they are the largest valves you can run without having to replace the stock seat. Summit even marketed many moons ago a 450 horse IMCA engine (13:1 406 on alcohol) with these heads. That power level is not that impressive in itself,, but does proove that the roundy round boys are very frugal (this is pre-Vortecs) and with enough cubes, compression, and drunk enough these heads can make fair power.

However,, to answer your question, sure the 305 heads will respond to porting like any other head. I agree with a prior post, expect a good pocket port / bowl job to give you around 25 horses on the 305.