4v heads questions

[hollenjoe]

Whats up folks, anyways one of my 2v heads was giving me hell, so a friend of mine is selling me 2 recently rebuilt 4v quench heads almost for free. So i got a couple of problems and not too much money to fix em, so i came up with a couple of ideas and wonders. 1. Ive got some expensive yella terras adjustable roller rockers 5/16 for pedestals, I know 4v heads come with 7/16 holes but there are 2 solutuions for this, theres enough space to machine my rockers to accept the 7/16 holes or i could use a double width bolt, it doesnt really matter, my question is, will the guide plates hold the rockers in place using the push rods? will i need hardned push rods? (imagine adapting stock crappy pedestal rockers to the 4v 7/16 stud head) 2. Ive heard people adapting 2v dual plane intakes to 4v heads, so besides the difference in port width, are the bolt holes in the 4v heads the same as in the 2v head? Cuz i could port my intakes ports to match the 4v head ones( sorry for my ignorance here, never worked with a 4v head before) 3. I asume the 2v headers have different bolts as well? this is a lesser prob, I could easily modify my headers to fit...

[mark a.]

1.The quench boss heads are drilled & tapped for 7/16" studs & guide plates. The rest have a 5/16" hole & slot, no guide plates. If you use guide plates you have to use hardened push rods. You have 2 choices here, 1 get the heads pedestals milled off and drilled & tapped for 7/16" studs and guideplates. 2 find a conversion kit.
2. All the bolt holes are in the same location. What are you working on here ? 351C, 351M/400 ? If you have a 351M/400 you will need spacer plates so you can run a 4v intake. I don't think you could grind that much out of a 2v intake port.
3 The headers bolts are in the same location.

[hollenjoe]

Im worikng on a 400, i know i need the spacers, i know the ports are way smaller, but will the bolts of a weiand 400 intake mate with the 4v heads?

The 4v heads were driled for 7/16 and guide plates, my question was, ignoring the fact that i have 5/16 roller rockers for pedestals( i could machine them for 7/16 bolts), could guide plates hold them in place?

thanx

[grclark351]

yes a 400 intake will bolt to 4V heads on a 400. the intake bolt holes are in the same place 2V / 4V but the ports are not centered the same, and the 2V intake may not have enough material to seal the tops of the 4 ports. i'm not sure if 2V exhaust will seal on 4V heads either?

guideplates have 2) 7/16" holes each that they locate off of under the stud, they're supposed to be chamfered slightly and proper studs have a taper under the hex that centers the guideplate. yes, the pushrods in the guideplates will locate the rockers, that's how it works, and yes with guideplates you need hardened pushrods.

i would use a Cleveland 4V intake with proper spacers, and trade/sell/buy the correct rockers for screw-in studs. let that 400 be what it was supposed to be prior to 1972 but never was!

[hollenjoe]

Thanx, yeah thats a good idea, yeah it was running amazing, it has the good tmi stuff in it

[johnboy427]

I have bolted a 2V header to a 4V head and there was a visible gap due to the larger port of the 4V head, but it could work on some. Get the right intake and headers for this thing, if you do manage to get the intake ported enough to match the head it still won't flow enough to justify switching to a 4V head. As for rockers you will most likely have more in remachining the old ones than a set of 7/16 stud mount rockers will cost. You could just buy this set of 4V heads and resell them and get a set that is still setup for the pedestals, but the studs better so why not just upgrade. Are your current heads open or closed chamber you might want to look at your compression ratio before doing this the quench heads will bump you up pretty good.
-Johnboy