[chris txstang]

I planned on building a 347, and bought GT40 heads that I plan to port myself. Now I am thinking for the same amount of money I can build a 396. If I port these heads the best I can and drill out the bolt holes to 1/2" will they be enough for a street motor? It will probably hardly ever see 6,000 RPM. I know they are the same heads they used on the lightning which was a 351, but those were supercharged. Should I keep them or sell them and look for stock 1970 351 heads and port those?
Thanks

 

[tached93gt]

How much hp/tq do you want to make? What's your goals for the engine? Both the gt40 ported or 351W will be smallish for the 351 let alone the 396. You can make power with those heads, however cam specs will be more radical than if you selected a bigger head.

BTW: I have a set of DOOE heads $100 plus shipping and their [email protected]

 

[chris txstang]

It will be for street and I only want 425-450 horse power. I would like to keep it in the range of 2,000 to 6,000 RPM. I was thinking since I want a lot of low end I should keep the port volume down. From what I have looked up, ported 351 heads will flow 220 and 170 at .5 lift, while GT40s flow 190 and 130 stock at .5 lift, I dont know what they will do ported. The cost of milling off the pedestals sucks, but is it worth having the hardened seats?

 

[tached93gt]

both the gt40 and DOOE max ported will only be about 155-165cc on intake. If you will be going with the 396 I would look at a head with at least 185-200cc intake runner volume and with the 396 you don't need to be as concerned with the loss of lowend like you would in a 302. A set of Windsor Srs with cleaned up ports would be a good choice for your budget, you can find them used ported with good hardware for reasonable prices these days. With the smaller runner of the gt40/DOOE heads you will need lots of duration in my opinion which is going to affect idle,lowend,driveability more than going with a larger head and milder cam combo.

 

[tached93gt]

forgot to mention that I have seen a 347/351 with gt40 heads make over 300rwhp.

 

[qtrhors]

Ford's own 392w crate motor makes 450 hp with stock GT40X heads. A set of properly ported iron GT40's with a 1.94 intake valve should come real close to that I would think.

 

[tached93gt]

Yup that Ford 392 made456hp at 5,500 rpm and 462hp at 5,900rpm and 462tq at 4,000.

Cam specs were:232/240 at .050 with .566/.576 lift..... Compression was 9.7:1 with a single plane Victor Jr.

That same engine with a set of different heads(AFR 185s i think) gained a ton of hp and tq though.....

 

[chris txstang]

So, what I am getting from this is that I should sell my GT40s, I can get between $400 and $500 for them, and get a set of World Sr heads. How much porting should I do on them to keep my power below 6,000 RPM. I would think that muck beyond a gasket match and polishing the exaust and combustion chamber would be too much, right?

 

[tached93gt]

Windsor Srs, AFR185, TFS, Canfield, etc.. would be good choices. As far as the windsors yes I'd just clean up the runners with sand rolls, port match intake/exhaust, and fully bowl in the bowl area and guides.
It would'nt hurt to give the gt40's a try and see what happens.(I like to experiment myself)

 

[qtrhors]

[No message]

 

[qtrhors]

Yes it is true that when they switched to a set of AFR 185's they picked up a good deal of power....right at 75 HP. A big part of tha HP increase though came from a gain in compression of just over a point. Those GT40X heads have 64 CC chambers while the 185 AFR's were 58 cc and had been milled to 54 cc. They dont emphasize that a great deal in the article. Although without the increase in compression the AFR heads would make more power then the GT40X heads no doubt. If you do sell the GT40's I would consider going to an Aluminum set for weight savings. A 351W based engine with alu heads weighs nore more then a 302 based engine with iron heads. For the money I think edelbrock vic jr's would be the ticket. These heads have kind of taken a back seat to the latest SBF heads that have been released....but for 1199.00/free shipping their out the box performance is unmatched for the dollar spent IMHO.

 

[tached93gt]

The Victor Jr. would be an excellent head to use as well. I plan to actually use it on my 351/396 combo once it's finished.

 

[chris txstang]

Aren't the Vic Jr heads too much if I want to make low end power? And, at the same price as AFR 185's shouldn't I get those if I'm spending the money?
Thanks for all of the replies!

 

[tached93gt]

Not on a 396!!!!! and not necessarily on a 351 but it depends on valve timing/cam specs. Big engines need air.... AFR's would be a good choice. you win either way in my opinion...

 

[Jimmys66]

Ok same question with an alum X head. My X heads are really ported a little too much for my app. but I am hoping they will handle a stroker motor next time around. At this point they still make power past 7000rpm with a big solid cam in a 302. These heads have had big exhaust work done but only nominally on the intake side. Think they will cut it with a full on port?

 

[qtrhors]

The AFR 185's have shown on the dyno to be real good. But I have never seen them for the same price as the vic jr's. Vic JR's are closer to AFR 205's then AFR 185's in performance and potential imho.

 

[Wurf]

I agree with Tached93 on the Windsors. If you go with the Windsor Sr's and port them ( good idea ), make sure you remove the machined seat ridge in the exhaust ports. Check the latest issue of MM&FF - they are quite good with a simple bowl blend and guide boss taper, but this "box stock" flaw really hurts exhaust flow.

 

[chris txstang]

Yesterday I recieved an email asking about some GT40X heads I had for sale. I do not own GT40X heads, and I am not selling any heads on the internet at all. So, I write back to the guy and said he must have the wrong guy, but I have a pair of GT40 irons for sale. He wrote back and was interested, so maybe this guy solved my problem of getting rid of my heads for me. Now if I can get a few hundred more dollars I can get a pair of windsor Sr. and start porting

 

[89 coupe]

AFR 205s don't have near the potential of the Victor Jrs. Vr Jrs can flow over 340/245CFM when ported enough and the 205s are nearly maxed out from the CNC porting which removes a lot of metal from those heads and doesn't leave much left to really get good numbers out of. They were designed as a CNC head casting to be CNC'd and the Victor Jr is designed to be taken out quite a bit also but starts out with as cast 210CC intake ports so it is for more serious engines which need more RPMS and to make more overall power. Vr Jr heads are pretty close in flow out of the box with super mild bowl work to the already heavily CNC ported AFR 205 heads. Spend the money saved by getting the Vr Jr heads and putting the extra left over money into a port good job and they will be far superior to the AFR 205s.