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Topic Review (Newest First)
11-27-2012 10:22 PM
Bryan59EC This is probably the most civil 307 thread I have ever read.

I opted to use an old, unrebuilt, early 70s 307 in my 66 elky.

All I did was put a q-jet and intake manifold on it.

The car has a 5-speed (TKO 2.87 first) and is plenty peppy even with the 3.08 rear gears.
And gets better than 25mpg on the hiway to boot.
11-27-2012 07:31 PM
vinniekq2 Im not going to tell you to not port your own heads,,,
I wont do any porting for a few reasons
I want to know the flow numbers so I need a flow bench:\without a flow bench how do I know that I have similar flow in all my ports?:
If it takes 25 hours to port a set of heads? I know that I can make more money doing something else than I can save.
I work with engines that make more than 350 horse power and the castings cost quite a lot more than I want to risk ruining:::
11-27-2012 02:59 PM
cobalt327
Quote:
Originally Posted by techinspector1 View Post
The bottom line is that F-BIRD'88 will continue to advise grinding on your heads and I will continue to nay-nay it.
There are many who say "hog this", "grind that" and that you don't need a flow bench, etc. The guys who want to follow that advice are just setting themselves up for disappointment. And that will happen AFTER they spend untold hours trying to duplicate what they think they see- in a picture!

I'm not saying that hand porting cannot be done successfully. I was fortunate enough to have made some templates out of brass from a GOOD set of fuelie heads. Using them I can do a pretty good rendition of those heads and they show an improvement at the track.

By eye I can get a little improvement as well- being as how I've done this so many times. But a first timer? Good luck until you've made some goofs- and the goofs will cost you a casting every time unless you have a bench to show you what's happening. And /o a bench you have to port a PAIR of heads, bolt them on and take it to the track, then remove them, port some more, or port another set of heads, repeat until you're happy w/the results or you decide you'd rather spend your time earning some coinage to buy a decent set of aftermarket heads or at least for some time on a flow bench.
11-27-2012 01:49 PM
techinspector1 The bottom line is that F-BIRD'88 will continue to advise grinding on your heads and I will continue to nay-nay it.
11-27-2012 09:35 AM
F-BIRD'88
Quote:
Originally Posted by ChevelleSS_LS6 View Post
Found an article on a 307 build. Not superhero power, but I'll bet you could actually afford to drive the thing how fuel prices are (grrrr!).

307 Chevy Dyno Test - Super Chevy Magazine
This 307 could have made a lot more power if better parts and attention to details
had been done.

The resulting engine compression ratio was less than 8.5:1

8.5:1 is way too low... you want 10:1 with that cam on a 307.

This engine should have had a supercharger on it.

if the heads had been milled to 51cc (.041" gasket) or 56cc with a .015" gasket to get the compression up it would have made a lot more power and torque. 10:1 minimum compression ratio.
A finished 10.5:1 compression ratio would not be too much for this motor. (92 octane gas)

Bad intake and carb choice. The lowly performer manifold and 600cfm carb are bad choices when you want power. even on a 307.

A Performer RPM high rise dual plane and 750cfm carb will make more power and torque. Always.

This engine could have made well over 350hp if attention to details and parts choices had been better.
11-27-2012 08:18 AM
F-BIRD'88 Some pictures of ported 305 heads
http://www.hotrodders.com/forum/atta...1&d=1347917576

http://www.hotrodders.com/forum/atta...5&d=1199151813

http://www.hotrodders.com/forum/atta...8&d=1227570680
11-27-2012 07:40 AM
F-BIRD'88 One of the keys to learning to port your own heads is to not take advice from people who admitedly cannot port heads or are afraid to. Its like taking advice on baseball from some one who cannot swing the bat. You got to swing the bat to get a hit.

You learn by doing. These are an excellent head to learn on. And if you do the whole port they will flow a good bit more than when you started.. You really cannot mess it up.

There are many good books on general porting and SBC heads specificely.

Just don't grind the (*&^ out of the floor of the port. This area just needs a clean up.
The port needs to be made taller and a bit wider. That valve guide boss needs to be thinned and streamlined so the
air can go around it. The push rod pinch needs to be opened up a bit too. The port opening at the flange does not need to be huge. felpro 1205 gasket size is just right.


These heads respond very well to generous complete hand porting and the larger 1.94 valve.
They will flow a lot more air when you are done than when you started.

This is not rocket science. And you don;t need a flow bench.

I have flow tested these heads after porting. The flow bench testing did not get the gain in flow...THE HAND PORTING DID.
11-27-2012 05:40 AM
cobalt327 Good point. Doing the obvious things like the lip below the seats and removing any casting flash/irregularities should be the extent of it unless you have experience and/or a lot of time and a flow bench- along w/enough heads to find out what is helping and what is hurting. After all, if you remove too much or from the wrong place, the head is now scrap; you cannot add the metal back and welding is in no way cost effective on these commonly available heads.

FWIW, there have been good builds using the L30 305 Vortec heads on the small bore SBC engines. One member here has them on a 283 and likes them just fine. Takes a Vortec intake, self aligning rockers, centerbolt valve covers, and a spring and retainer change.

Some info and photos of the L30 5.0L Vortec head can be seen at NastyZ28.com Vortec Cylinder Heads: The Definitive Guide, post 478.
11-26-2012 09:42 PM
vinniekq2 self porting,I only ported the exhaust side of the heads and only about an inch into the port.
Now a days with flow benches,I wont touch anything at all. Porting does make a difference,but exactly what tech just posted,,
11-26-2012 09:24 PM
techinspector1 If you haven't done a couple dozen sets of heads before, then I would advise you not to go grinding on the heads. You might accidentally cut in the right places and add a little flow, but you might just as easily cut in the wrong places and turn them into junk.

I'm gonna tell a story on myself. When my youngest son was in high school, we built a '72 Chevy Luv pickup with a California Stepside conversion. We shoehorned a bone-stock 455 Olds into it, with a TH400 and 10 1/4" Olds rear diff. Took it to the dragstrip and turned 101 mph. Pulled the heads off the motor, spent the next 26 hours sittin' at the bench with a Dumore and carbide burrs, then sanding rolls. Bolted the heads back on the motor, went to the dragstrip and turned 103 mph. Picked up a crummy 2 miles per hour in return for 26 hours of labor. Now, someone who knew what they were doing may have been able to pick up some real power with those heads, but I was not that somebody and it is doubtful that you are that somebody either.
11-26-2012 09:20 PM
techinspector1 If you haven't done a couple dozen sets of heads before, then I would advise you not to go grinding on the heads. You might accidentally cut in the right places and add a little flow, but you might just as easily cut in the wrong places and turn them into junk.

I'm gonna tell a story on myself. When my youngest son was in high school, we built a '72 Chevy Luv pickup with a California Stepside conversion. We shoehorned a bone-stock 455 Olds into it, with a TH400 and narrowed 10 1/4" Olds rear diff ('57-'64 Olds/Pontiac). Took it to the dragstrip and turned 101 mph on slicks. Pulled the heads off the motor, spent the next 26 hours sittin' at the bench with a Dumore and carbide burrs, then sanding discs. Bolted the heads back on the motor, went to the dragstrip and turned 103 mph. Picked up a crummy 2 miles per hour in return for 26 hours of labor. Now, someone who knew what they were doing may have been able to pick up some real power with those heads, but I was not that somebody and it is doubtful that you are that somebody either.
11-26-2012 08:45 PM
ChevelleSS_LS6 Found an article on a 307 build. Not superhero power, but I'll bet you could actually afford to drive the thing how fuel prices are (grrrr!).

307 Chevy Dyno Test - Super Chevy Magazine
11-03-2012 09:54 AM
F-BIRD'88 Cam choice: What kind of engine and performance are you looking to end up with.
What is the gear ratio, car weight, tire size, and transmission converter stall speed.
And are you willing to change the gears and converter to match the camshaft/engine power curve?

rough racey street brat idle or ......?
11-03-2012 09:34 AM
F-BIRD'88
Quote:
Originally Posted by rube'68'03 View Post
You're not talking about porting the bowels are you?
I am talking about porting the whole intake and exhaust ports including the bowls.
Bowl hogging is just one step in the process. These heads need more than just a "stage 1" "pocket port"
"bowl port" job. The meat and potatoes flow gains are deep in the port. And it gets time/labour intenstive.
(when you are paying for the time...)

If you want a powerfull 307 you want to fully port the 416 heads as well as get the larger 1.94" intake valve so the heads flow more air than stock.

Cam choice depends on the desired rpm range, and power/torque curve desired.
Choice must be tempered to driving style, idle quality, gear ratio,vehicle weight,
purpose, trans torque converter stall speed. A cam cannot be a big race cam and a small mild cam at the same time.

Eg if you don;t want a race motor, don't use a huge racey cam.
283's 302's 305's and 307's are easy to over cam.

deck height: bring the piston to TDC and measure how far below the deck the top of the piston is, Uisng feeler gauges, a depth mic, etc. You are looking for .025" or less. Ya it matters. (to calc the compression ratio)

If you take care of the details this 307 will turn out very well.

Google search for camshaft selection and technical camshaft terms like lobe lift, duration @.050" lobe separation, valve lift, rocker arm ratio etc etc etc. many of the camshaft manufactureres have a tech section on their sites.
Crane, Isky <Comp, Lunati, Howards,, etc etc

More SBC high performance build knowledge including head porting Search for books by David Vizard on Amazon,,, local library etc.
google search for ported 305 head,, ported 416 head etc

11-02-2012 06:18 PM
vinniekq2 there are dozens of cam grinders/sellers with thousands of choices and 4 kinds of lifters or 2 styles.
decide what you want first and what engine you will use,,,then a combination can be applied.
be specific,how is the engine going to be used,where is it,what you expect from it
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