[LOPEZ5]

Guys,
I'm looking to add some ponies to my '74 400 w/4x heads. Money is sort of tight as I have a wedding to plan n pay for, here comes the what if: What if I have the heads rebuilt and add rollers in the process, along with changing out the cam to the Melling 068, or SPC-7, and finish off with a 3.55 rear ratio? How many horses do you think that'll add and how much can I expect to dish out($$$)? The car already has dual exaust and breathes thru a K&N. All ideas welcome. Thanks

[LOPEZ5]

Guys,
I'm looking to add some ponies to my '74 400 w/4x heads. Money is sort of tight as I have a wedding to plan n pay for, here comes the what if: What if I have the heads rebuilt and add rollers in the process, along with changing out the cam to the Melling 068, or SPC-7, and finish off with a 3.55 rear ratio? How many horses do you think that'll add and how much can I expect to dish out($$$)? The car already has dual exaust and breathes thru a K&N. All ideas welcome. Thanks

[LeighP]

Couldn't give you numbers, but it should make a nice street engine. I'm looking at using the same cam in a 455 (probably with 1.65:1 rockers) with some porting on 6X-4s and RARE Ram Air exhaust manifolds.... should be a nice combo.....I'm not looking for a race engine.
I have been told the 068, 744 and 041 cams do work better with some reasonable compression. I'm looking at around 9.5:1 CR....you may want to figure in some milling on those heads to lift the stock compression.

[LOPEZ5]

thanks for the input, I actually found some heads to replace the 4X that I have now. Now I need a little help to id these heads. One of the heads has a 16 on the center exaust ports. It has a small G M cast on the rear exaust port, and a 5 on the front exaust port. It also has a stamp near the valve cover lip it reads H089. The other head has a 76 in the center ports, a big G M on the rear port, and a big G on the front port. The code on this second head near the valve cover is G289. The G in the last code might be a 6. To close to really distinguish. Any suggestions on what I have in my hands?

[WDCreech]

1970 16s; small valve 400 heads with pressed in rocker studs. Use as 2bbl and low hp 4bbl heads.

[disc0monkey]

i would use the 4x heads but get them milled

[LOPEZ5]

Hey WDCreech,

when you say low hp use on 4bbl, is it low for that year or for the 74? Wouldn't the compression go up by using the 16's on a 400 as compared to the 4X's?

[scotts78TA]

Hey, let me chime in on a similar issue. Ive got a 78 TA 400 that I am reworking. Mild work on the heads, performer manifold, XE274H, roller rockers at 1.5 and a Ramair restorations exhaust manifold. Anything I should be thinking about to make this hum better? Its going to be a street machine for weekend cruises and a little fun.

[larry davis]

What rear end ratio do you have now? Not sure if the 3:55s are the way to go?

[WDCreech]

Canis, The '70 #16 heads were rated at 10/1 on a 400. They, actually, would probably be slightly less, but still too high for pump gas. I personally think you would be better off with a set of '71 or later 350 heads, preferably with screw in studs.

[LOPEZ5]

Hey WDCreech,
I'm looking to get about a 9.5 compression. If anything, I'll have the chambers openned up a bit to about 75cc or 80cc. I think these heads have the screw in rocker studs, still not sure though. Will update w/that info.

[Rockhead400]

Dude, I am running these 16 heads in my 67GTO with a mild performance 425 hp 1970 ponitac 400 engine bored to 412 (60 over). I did mill them down some to bump compression to 10.75 using pump gas premium. I did media blasting, new double springs, but used stock rockers and I did no porting. I was amazed that these 72cc heads do so well with no porting, rocker roller. Stock flat type forged speed pro pistons were used with stock rods and stock crank. A mild crane 226/233 cam with.468 lift was used , but dont quote me on the nos. Hooker headers coated, flowmasters with turn downs, edelbrock performer rpm manifold with Edelbrock 750 was used. All in a a pretty simple set up with amazing results. Ample power for street abuse and fun. Of course everything was new for the rebuild, bearings, push rods, etc. Balanced assembly, crank turned to 2/10000. My point is these heads are great for street use and can use pump gas. I wish I had paid the extra for porting. Ill do that next.

[LOPEZ5]

Hey Rockhead, thanks for the input, that's pretty much what I'm looking to get. A fun, fast, strong, street car. The premium gas is okay. I already spend $50 a week on gas for a '01 F-150, lifted 9", 4.56 gears, breathing through K&N and Flowmasters. Anything comparable to that gas mileage is fine by me...lol...