Heads

[lbburris]

Recently purchased a Comp Cams 35-556-8 at a very good deal; '90 Fox has Explorer upper/lower, Cobra MAF, larger TB, BBK 1 5/8 shorties, 3G, World Class T5, SVE 3-row. All stock internals thus far. Street car only, no track.

I've been told best bang for the buck on heads are GT40p, but will those work with the BBK headers? Want to do top end all at once for a little bump in HP. Got one in college and a daughter getting married, so $$$$ is a little tight at the moment

 

[Dan02gt]

That's a big cam for your setup and will make your car a dog. It's also going to need good valve springs to handle the .570" lift on the exhaust side. My recommendation is to sell it. Unless you can find a freshly done set of GT40p heads I wouldn't bother with them either. They are 20 years old at this point and a pain when it comes to plugs and headers. You'll also spend enough money at the machine shop having them gone through and upgrading the springs that you could be well on the way to saving for a good set of aluminum heads.

I would buy a set of these before I spend a dime on GT40 heads.
Flotek SBF heads
They're Chinese but people have had good luck with them.

 

[limp]

I have around $600 into my gt40P heads... New Alex springs, viton seals, Checked out and simple valve job at the machine shop... I did replace my rockers with roller tip rockers ( so MORE than $600, but you have to buy rockers for your New Alum heads too) The heads came with the explorer engine I am using in my car.....

 

[mikestang63]

I prefer the GT40 vs P heads due to the fact header choice is much easier with GT40. Here is the thing though, by the time you spend the money to hot tank, magnaflux, mill, new valve springs, seals and probably guides- assuming all the valves are good- you probably have $600 or more into these heads.. Not sure how crazy prices are these days but TFS 170 or AFR 165 heads are a much better choice for flow, hardware, and supporting more mods and hp down the road. You can find them used for around $700 to $1000- again have them checked out for cracks, straightness, seals, etc all good. I've done many builds with both and it depends on what your goal is ultimately. Most guys end up swapping out their iron GT40 or P heads at some point for a good set of aluminum ones so my opinion is do it once unless you are on a budget and not looking to get the most HP out of your build.

I agree that cam is a bad choice.. Plenty of good OTC ones like TFS1, Anderson N41, Comp H268-274, etc. You want to match the cam to the heads

 

[limp]

I prefer the GT40 vs P heads due to the fact header choice is much easier with GT40. Here is the thing though, by the time you spend the money to hot tank, magnaflux, mill, new valve springs, seals and probably guides- assuming all the valves are good- you probably have $600 or more into these heads.. Not sure how crazy prices are these days but TFS 170 or AFR 165 heads are a much better choice for flow, hardware, and supporting more mods and hp down the road. You can find them used for around $700 to $1000- again have them checked out for cracks, straightness, seals, etc all good. I've done many builds with both and it depends on what your goal is ultimately. Most guys end up swapping out their iron GT40 or P heads at some point for a good set of aluminum ones so my opinion is do it once unless you are on a budget and not looking to get the most HP out of your build.

I agree that cam is a bad choice.. Plenty of good OTC ones like TFS1, Anderson N41, Comp H268-274, etc. You want to match the cam to the heads

No arguments on going with the Aluminum heads for top performance... Not what I am looking for.... Good running street machine...

Remind me to tell you how well my Big Block Chevy in my 41 Chevy ran with the HORRIBLE oval port " Pass" heads.....

 

[revhead347]

Way too much cam for any of the iron heads.

Kurt

 

[CAMTWO1070]

No arguments on going with the Aluminum heads for top performance... Not what I am looking for.... Good running street machine...

Remind me to tell you how well my Big Block Chevy in my 41 Chevy ran with the HORRIBLE oval port " Pass" heads.....

When you pick a camshaft you want to look at duration and the rpm spread to determine the overall useage and power reality..

I went w/ K35-235-3 camshaft kit....Its in Comp Cams Extreme 4x4 category.......

In my 408 I went with a camshaft w/ .477int .493"ex w 1.6 rockers and duration was 218int and 220ex and lobe sep was 111..Rpm range is 1200-5200rpm's and this is the power it made with pushrods that were .100" too short installed by the shoddy engine builder I trusted...

I know how to verify VTG and with the pushrods being .100" too short put alot of strain on my brand new valveguides and robbed me of a lil hp/torque too..

I do a similar step as this video from youtube except I just use the pushrod I have and I see what the angle is at half lift then I rotate the engine til I get the 90* valve to rocker centerline relation subtract whats needed to get the 90* relation where I need it and thats my pushrod length I need just by using a dial indicator...

Like this guy says once you get proper VTG you can get a proper pushrod length so they go hand in hand.....


View: https://www.youtube.com/watch?v=o5is9BsH5OU


Even by the naked eye its apparent,,,,,,,,,,,,LOL

pushrods .100" too short and roller tip too far forwards

Heres the witness mark on the valvetip..

Heres how the rockers sat on the valvetips too

Pushrods that arent too short . It sux when a nobody like me knows more than a veteran engine builder.....LOL

If your engine wasnt originally roller camshaft dont do the aftermarket conversion with lifters with link bars as they fail horribly on street driven vehicles.It seems these days that lots of steps are skipped or not done as long and the metal that holds the bars fatigues quickly...

In all cases most say bigger is better but with Edelbrock E-Street heads #5023 w/ 170cc intake runners w/ small stainless steel valves...Most will ask;-Why small valves?...and Ill say to show me how larger valves will produce better than this kind of power in an engine designed for brutal torque.....Intake velocity will actually drop off and torque would suffer horribly...

At idle my engine was producing a solid 21-23inches of mercury too...................My idle was as smooth as a stock vehicle off the assembly line....LOL

I run an Edelbrock 3881 EFI Performer intake that increases torque by 35-40ftlbs on a stock slightly modified engine according to Edelbrock and with my setup on a rearwheel dyno the numbers were over 60ftlbs over the engine dyno numbers tuned w/a moates qh chip finetuned with a AEM wideband controller hooked into the EGR pin #27 on the EEC...

One day either the guy who did the rearwheel dyno test is gonna retrieve the results and send then to me or Ill find the sheet and post the rearwheel results with hp and torque which was 494hp and 509ftlbs at 5200rpm's......Best torque came on around 3100rpms w/568ftlbs and stayed strong to 4400 then started dropping off and not one time did they crossover..........Torque always stayed on top........

Edelbrock and Comp Cams both said the heads were good for producing roughly 400hp and limited to 5500rpm's and the camshaft was good for 400hp and limited at 5200rpm's.....LOL

Put them together with 10.5:1 compression and a good tune and it goes way north of that 400hp with a 4" stroker crank neutrally balanced w/6.250" rods apparently.....LOL

Good Luck with your research and know if somethings worth doing its worth doing right the first time...Saving $$$ on heads doesnt mean squat if it costs you time and more money making the camshaft you bought work instead of getting a camshaft thats practical for your application......

Bigger isnt always better......

Take care..