Giving new life to GT40X heads

[Casper393W]

Mod 2. Clean up port surface..... We haven't measured any volumes yet..but I would say we have opened the ports 3cc give or take. And as you can see very little material has been removed from the walls

.050. 34.1. 22.6
.100. 58.8. 53
.150. 97. 77
.200. 130. 97
.250. 161. 116.5
.300. 188. 133.8
.350. 208. 146.5
.400. 224.5. 153.5
.500. 241. 157
.600. 252. 157

Mind you these heads still need to have backcut valves and. Good valvejob... That is coming up stay tuned!

[Casper393W]

Here is a pic of the SSR

Both David and I are starting to feel that this will turn into a decent head when its all said and done!

[Carnut1]

Check out my viewtopic.php?f=1&t=48919
Thread and pay extra attention to groberts advice he was right on the $ with sbf ports. Lots will transfer right to those aluminums. Be sure to look at the chamber mods D.V. made on his E7TE thread as well. Thanks, Charlie

[piston guy]

I have those heads on my 408. I did the bowls and intake guide similar to you picture. With 9.7C/R , 6.200 rods , Ford X cam Eddy AirGap and a 735 Holley from a Cobra Jet , I made 480 on 87 octane ARCO. TQ was over 520. More cam alone would have put me over 500 and 10.5 C/R would have been better. I shift it at 6,000. It's a daily driver with a stock 11" C4 converter. 12.40's @112 right off of the street in a 3,800lb vehicle.

[Casper393W]

I have those heads on my 408. I did the bowls and intake guide similar to you picture. With 9.7C/R , 6.200 rods , Ford X cam Eddy AirGap and a 735 Holley from a Cobra Jet , I made 480 on 87 octane ARCO. TQ was over 520. More cam alone would have put me over 500 and 10.5 C/R would have been better. I shift it at 6,000. It's a daily driver with a stock 11" C4 converter. 12.40's @112 right off of the street in a 3,800lb vehicle.

That is right what I am after!
People at my work think that I am crazy for driving a 71 F100 everyday but I love it... It turns heads everywhere I go. This build is going to have 11.25 ish compression so the key is having a cam that will provide around 200 psi cranking compression so that I can run 93 Oct. Im really excited. I hope that I can have the shortblock assembled this weekend

[groberts101]

Looks like a fun science project to hang out with Mr V. Couple quick things I see right away. First one is the horrible valve job(for performance anyways).. how the hell wide are those intake seats? They're(too wide seats) shrouding the valves bottom cut in conjunction with the valves backcut.. which flat out kills the lower part of the lift curve. Decent enough seat and valve profile on a 1.94" valve should have you up in the high 60's @ .100" and more from there on up till about mid-lift. Maybe even upwards of 20+ cfm gains to be had just in revamping that VJ alone.

IMO, for the bench/time investment, a decent valve job would have been my first order of business before anything else was even touched. Or at least compare stock with the newer VJ first before moving towards material removal.

The bowls aren't overly large on these heads either(cross section aside, bigger motors like bigger bowls.. become miniature fuel/pressure storage reservoirs as rpm goes up).. keep your below seat transitions short to gain bowl area fast(maybe not ideal to be really short but desperate times call for desperate bandaids) and add a shorter 82-88° bottom cut followed by good heavy digging into the bowl walls in every direction. The steeper bottom cut gets whittled out for the most part but is good for a template to aid port to port repeatability without needing so much mic'ing/caliper work along the way. This blown out bowl design can also help improve the already over taxed ssr cross sectional limitation/tolerance for bigger CID and/or higher rpm.

I get the "maximize what you have" mentality.. been doing it that way most of my life.. learned how to cheat early on in the horsepower game. So, I will also add this. To really help these fast flowing/too small heads out on this bigger motor you need to get more radical with the SSR and floor corners. Think along the lines of ported 23° Chevies with faster more aggressively shaped SSR laybacks and squar'ish floor corners to slow the mixture down over the turn. IOW, make the SSR all it can possibly be(asice from finding water.. you can never make it too big on this casting/engine size).. so it's more forgiving towards the rest of the "still too small" port cross section. Better turn size/shape more easily accepts and mitigates a really fast port speed.

Also open the PR pinch to the maximum available material allowance(.025" next to the pushrods is still plenty of meat in lower heat/stressed casting area). BUT.. DO NOT DIG OUT THAT SIDE OF THE ENTRY JUST FOR THE SAKE OF A PERFECT GASKET MATCH. Purely rhetorical, but why whittle away on the pinch's cross section to end up with nice smooth flange to pinch transition shape.. and then blow it all to hell by digging material right back out at the entry flange and recreating that same hump shape sticking into the port? Just adds more potential for turbulence at higher depressions(as in "real live running engine").. you rarely see its total effect on a bench @10 or 28" of depression. Aside from maybe shoving flow towards the center of the cylinder, basically just makes the short sides job even more difficult than it already is.

[Walter R. Malik]

Just for information ... these heads come out of the box with all different directional machining to port core shift.

What can be done to one head can not be done to another simply because the metal thicknesses are all different; some shallow short sides and some have tall short sides and the the back of the bowls follow suit. Also, the factory bowl machining, Intake & Exhaust, may be shifted a bunch toward one side or another.

When you get 10 or so heads lined-up and none of the "out of the box" valve seat inserts to the castings are the same you will understand.

[piston guy]

Just for information ... these heads come out of the box with all different directional machining to port core shift.

What can be done to one head can not be done to another simply because the metal thicknesses are all different; some shallow short sides and some have tall short sides and the the back of the bowls follow suit. Also, the factory bowl machining, Intake & Exhaust, may be shifted a bunch toward one side or another.

When you get 10 or so heads lined-up and none of the "out of the box" valve seat inserts to the castings are the same you will understand.

That is SO TRUE. BOTH of my current heads had thin areas in the intake spring seat area! Same location on each head. PAPER thin!!! "Poked" it all out to air and TIG welded up the offending areas. "Hammered" it down for hardness and re machined the spring seat area for the steel seat. I bought them "new in the box" off of the internet so i couldn't return them to Ford. ( They might have been rejects in the first place). Once fixed , they have been trouble free . I wanted a ''cheap" aluminum head and almost got it. The port to valve seat locations WERE all over the place. I was actually concerned about some of the seats but they have been fine. Valve job as received left allot to be desired but was fixed. On a a big motor these heads are a "cork" , if you want to run over 6,000 rpm. I didn't/don't so I used them.

[Carnut1]

0402171935.jpg

Looking at your last pic and compairing to this E7TE D.V. copy port I have two areas i think could use attention. Bottom left on my picture D.V. enlarged the chamber to enhance higher lift flow and "windowing". Upper right in picture ssr needs a good chunk pushed back feeding the center of the cylinder with less ssr overhang. Thanks, Charlie

[Carnut1]

20170418_185846.jpg

This is the pic I was referring to.

[Casper393W]

Charlie, I believe you are correct. David cut the seats and when we reflowed it we lost 15cfm from .400 up! Basically the SSR is way over active so we need to lay back the SSR like what has been talked about here. Hopefully once we "make the SSR worse" we can pick up...

[groberts101]

0402171935.jpg

Looking at your last pic and compairing to this E7TE D.V. copy port I have two areas i think could use attention. Bottom left on my picture D.V. enlarged the chamber to enhance higher lift flow and "windowing". Upper right in picture ssr needs a good chunk pushed back feeding the center of the cylinder with less ssr overhang. Thanks, Charlie

This.. ^^^^^.. is exactly what I was referring too with all my above rambling and in Charlies other thread. Not nearly enough material available in the roof to gain the needed cross section.. so we do what we have to do to settle the short turn down.

I have to ask. Why do you guys use such wide intake seats? Is DV using or suggesting those same seat widths too?

[Carnut1]

Picture is deceiving, that is not the valve seat. D.V. will talk about this valve job hopefully. It has altered angles and sizes.

[Casper393W]

0402171935.jpg

Looking at your last pic and compairing to this E7TE D.V. copy port I have two areas i think could use attention. Bottom left on my picture D.V. enlarged the chamber to enhance higher lift flow and "windowing". Upper right in picture ssr needs a good chunk pushed back feeding the center of the cylinder with less ssr overhang. Thanks, Charlie

This.. ^^^^^.. is exactly what I was referring too with all my above rambling and in Charlies other thread. Not nearly enough material available in the roof to gain the needed cross section.. so we do what we have to do to settle the short turn down.

I have to ask. Why do you guys use such wide intake seats? Is DV using or suggesting those same seat widths too?

Yes the factory valve seat was wide as a house! DV's seat width is much narrower.

You were dead on about the SSR... When he did the valve seats.... It made the SSR over active.

On the bench when we flowed it after the seat job... Like I said we lost from .400 up! Its time to lay the SSR back.

Hopefully I will have news to report by the end of the weekend

[jarmoyp]

Hopefully once we "make the SSR worse" we can pick up...

Your eyes seen that SSR different way than engine does. DV has not seen this port yet and get the advise? It`s just basic level for now, nothing to show up yet.
If it has a bad core for portjob, impossible to make a good head, sold it and buy a better one..