[greensmurf20]

i hear the 71 and newer heads are better than the 70 and older head for the 1.9. the newer heads have 4 cam bearings instead of 3 so thats a bit stronger. but outside of that is there any differences? valve size, port size, cam lift and duration, combustion chamber CCs? i looked for a while trying to find something on here but all i found was stuff about roller cam and rocker sorts of things.

 

[greensmurf20]

aslo my origional motor had a 1968 head on it...... that worth anything being the first year for a GT. it must be good since the car had 90 pounds of compression across the board BUT also consider it had broken rings in every cylinder.

 

[opelgt73]

71 is the year to have, after that they switched to a thinner sidewall and they had a tendancy to crack (I have had two with cracks that came from 73' cars)
The 71 has more robust construcion and 4 bearings.

 

[greensmurf20]

so i should stay away from my 72 heads? i just wanted to ask since they were completely rebuilt before the motor snapped a rod so the head great. but if its prone to cracking i guess its not so hot.

 

[Mach1Tom (R.I.P.)]

Later 72 heads & on with the extra 2 bolts going into the timing cover are the ones to stay away from. (12 bolts total) Later 70 til mid 72 will have 10 head bolts, 4 bearing cam & hyd lifters. These are the ones to rebuild.

Tom C

 

[ravn99]

cool

yeat,another quest. that has been answered while looking for the same info.. thanks guys,,,this is the greatest forum!!!

 

[greensmurf20]

thanks alot guys. i woulda used that 12 bolt head since it was recently rebuilt, but rather rebuild my own and have it right the first time. i have a 1968 head that is great and a 1971 head that needs work. oh and 2 72 heads. the 1968 head has different valve spring retainers but i assume thats because its the older head right? should i take all the head internals out of the new 72 head and put into the 71 head?

 

[greensmurf20]

and i'd still like to know if anybody at all knows the specs between the 68 head and the 71/72 heads. so i can compare valve sizes, port sizes, and cam lift and durations. i'd rather know all the info and know what i have instead of just listening to what people prefer, although i know they prefer them for a reason. i would love for somebody to shed some light on this for me

 

[greensmurf20]

let me guess.......this is one of those kinds of questions that only rallybob could pop right out of his head, and therefore took his knowlege for granted......................?

 

[opelgt73]

yes he would be able to pop out all the specs on those years too bad he left.......

anyway why are you worried about swapping out parts from one head to another? Why dont you just take the 71 head that you have and rebuild it? I took mine to a local Car Quest machine shop and they re did all of my valves, ordered and installed new bearings, acid dipped it to clean it like new, installed hardened valve seats(it was a 69 head), and milled it flat, and it was under $200 for the parts and the labor.
It is better to just get new parts than try to salvage motor parts from a motor that was rebuilt by someone else.

 

[kwilford]

That'd be my guess.

A brief look at my '69, '71 and '72 FSM's reveal that the intake valves head diameters are the same for all three years (1.574 inches), as are the exhaust valves (1.338 inches). I can't speak for port sizes nor cam lift or duration, since I just don't know

 

[greensmurf20]

cuz i'm 15/broke. i have a summer job but he gets behind in paying bills to say the least so i go without money for quite a while sometimes. i'm waiting for my bosses father and law to get his jasper motor in so i can put that in his tempo to pay for my gasket set, main/rod bearings and rings.(second time since march changin that tempo motor) i just wanna use the best of everything i have to save money and get all i can get. i wanted to put a chevy 151 HO 4 cylinder in that out of a vega GT but living with dad its hard to do what you want. he argues i have already gotten a new clutch kit and tune up(less that 50 miles) so might as well use it. i'd like to know what makes everything better. everybody just says 71 due to 4 cam bearings and they dont crack. is it really nessasary to have 4 cam bearings for a 9:1 stock GT? if i have a head with larger valves or ports i'd like to know. we have a valve grinder in the garage so its really nothing to do a valve job but unless the bronze guides for a small block 350 fit a 1.9 liter head...... its not getting any. i can't affored hardened seats so i'm going to take some advice i was given by a engineering friend of my fathers. which is dont waste money on led substitue, a cup of diesel fuel to 12 gallons is more than enough led content for any motor, yet not enough diesel to affect performance and if it dont work i have many more heads and motors for that fact. so is the 68 head i have special? i already know what happens to 72 heads. the seventy one head i have is not great at all. it has a broken spring and it just happens to be that the same valve is bent. so it would have to be all changed out anyway and thats why i asked about swapping the 72 springs and valves to the 71 head

 

[greensmurf20]

sorry guys i know i'm asking alot of questions that ya'll dont wanna answer. its probably going to be useless anyway since a father controlls all of the car related things i do. if he has it his ways its goin to the the 72 head because it looks like new, even tho i told him they are prone to cracking, his argument is i have 2 of them and neither are cracked so what makes them prone to crack? can't win

 

[opelgt73]

It is fine to use a 3 bearing head and I would use one over a later easier cracking head, in fact I did....

when I went to have my head rebuilt I took them the 71 that I had, but it was cracked due to a blown head gasket(but the previous owner kept driving it), so since I wanted to get it done I just gave them a 69 head that I had, and they installed my Autocross cam from OGTS which is actually made for the 4 bearing head, but it works anyway. It ran fine and I never noticed any cam flex.

You will only really notice the difference between the 3 and four bearing heads if you run a really high profile and race. (the kind of profile where the car barely idles!)

I was 15 when I restored my first GT(I am 22 now) so I know how it can be not having any money to buy parts, but I skimped on stuff and then had to redo it, a reall pain in the a$$

 

[Travis]

All the 1.9l heads have the same valve diameters. There are some minor differences in the ports but I don't know the specifics.

I would suggest using either an early or mid head, depending on the application. The early three bearing heads do not have the tendency to crack and unless your running high valve spring pressures the three bearings will be fine. The heads in and around '71 have four bearings and don't have the tendency to crack. These are the best starting point for a hot motor. The later heads are supposed to have been cast with a lower quality iron and the induction hardening that they did on the seats caused brittleness.

BTW, the year of the head does not always coincide with the year of the car. Between the German and US model years beginning at different points as well as many heads having been swapped over the years. To identify an early head, just look for three cam bearings. To identify a mid head, look for four bearings and NO holes in the front for the timing cover. The later heads, the ones that are prone to cracking, have the extra holes in the front.

I think Bob said it best. 'It's not if they will crack, but when?'.

BTW greensmurf20, unless you've had the heads magnafluxed you can't be sure they are not cracked.

-Travis

 

[opelgt73]

BTW greensmurf20, unless you've had the heads magnafluxed you can't be sure they are not cracked.

-Travis [/B]

Thats so true, the one that I had magnafluxed that was cracked only showed the crack with the magnaflux stuff on it, when I wiped out the stuff you couldent see the crack anymore.

 

[greensmurf20]

so since i'm not going to have a hot motor at all(9:1 compression and a weber) it dont matter betweent he 71 head and the 68 is what you guys are saying correct? it seems like somebody said they used a 3 bearing cam in a 4 bearing head? i found a head like that which was my 71 head. until i thought about it i assumed that would kill your oil pressure.lol. after this motor is dont i'm going back to my simple chevy products, afterall i know just about all there is to know about a SBC. sorry about previous posts. i was pissy to say the least because i thought i had to use a 71 head because it was the most reliable and it was the only messed up one. i appoligize to all. i owe everybody here quite a bit.

 

[opelgt73]

yeah you can use a three bearing no problem, my wasent all that hot I had a autocross cam, bored .40 over and 10:1 compression, with a weber and a "sprint" exhaust manifold, and like I said I never had a problem.

You can use a four bearing cam in a three bearing head but not a three bearing cam in a four bearing head.

 

[kwilford]

I think I read that you CAN use a three bearing cam in a four bearing head, so long as you re-install the "dummy" cam bearing such that the oil hole in the bearing doesn't line up with the hole in the head. Otherwise you lose oil pressure and bad stuff happens. Apparently the three bearings are on the same centres on both heads. Now WHY you would want to do that, I just don't know...

 

[greensmurf20]

i dont know either keith...... i think the germans did alot of crazy stuff when i work on that car.