gt40 head and rr questions

sn95gtvert · Oct 25, 2009

First off hello all this is my first post to this forum, I found it today and like what im seeing.

I have a set of gt40 heads and crane 1.7 roller rockers off a 95 cobra

first question is with the heads. one head as a 65 cast on it and the other a 67 near the valve cover seal is located, what do these numers mean?

second question is the rockers bolt has no lock its just a torques head, is this sufficient?

third, how do i tell witch head goes on each side of the motor? the front and back of each one seem to have identical bolt holes.

fouth do i need stepdown washers to bolt these heads to my 95gt block i heard the gt40's are 1/2" head bolts and the gt blocks are 7/16 head bolts
fifth should i be worried about my factory pushrods would they be fine for the swap or should i get a new set?

thanks everyone i hope you can help me out.

sorry bout the photo size i didnt realize my phone took such large pictures

LAFENATU · Oct 25, 2009

Welcome to the site :headbang:

I think the numbers are the foundry numbers as to where they were made.

The heads center on the dowl pin and not the bolts. Just use a set of ARP 7/16" head bolts and you'll be fine.

Your pushrods should be ok. I would recommend spending ~$20 on an adjustable pushrod just to be sure though.

sn95gtvert · Oct 25, 2009

thanks Lafenatu, now how about the roller rocker bolt?

LAFENATU · Oct 25, 2009

What about them?? They should have come with the rockers.

I don't understand the question..

BTW...Doesn't matter what side of the block you put the heads on.

sn95gtvert · Oct 25, 2009

the rr bolt has no lock you guys think they will be fine?

blackpony · Oct 25, 2009

the rockers just torque down to 25 lbs torque

Addermk2 · Oct 25, 2009

sn95gtvert said:
the rr bolt has no lock you guys think they will be fine?

they are exactly that... bolts. not studs. The way they are, is how it was intended. They are fine.

Also, if you look at the ends of the heads. the exhaust side will have a small 1/4"-5/16" bolt hole directly next to a 5/8" hole. These holes are for the Thermactor system. One end of each head SHOULD have a threaded insert in it which sizes it down to 1/2-7/16". The end with the inserts are meant to face forward. If NEITHER end of EITHER head has these inserts, you will want to go on summitracing.com and buy the Trickflow Thermactor plugs. This is very important. These threaded plugs are what your power steering pump and alternator bolt into!

sn95gtvert · Oct 26, 2009

Addermk2 said:
sn95gtvert said:

the rr bolt has no lock you guys think they will be fine?

Click to expand...

they are exactly that... bolts. not studs. The way they are, is how it was intended. They are fine.

Also, if you look at the ends of the heads. the exhaust side will have a small 1/4"-5/16" bolt hole directly next to a 5/8" hole. These holes are for the Thermactor system. One end of each head SHOULD have a threaded insert in it which sizes it down to 1/2-7/16". The end with the inserts are meant to face forward. If NEITHER end of EITHER head has these inserts, you will want to go on summitracing.com and buy the Trickflow Thermactor plugs. This is very important. These threaded plugs are what your power steering pump and alternator bolt into!

that is the information i was after. thank you very much. I might have to start my deconstruction of my motor in the next few days.

this is off topic a little but i know with this combo and a good tune it is able to get close to 300 rwhp. witch does in all fact just about max out my 19# stock injectors. would i be safe to run my stock injectors until i can afford a new maf?

LAFENATU · Oct 26, 2009

blackpony said:
the rockers just torque down to 25 lbs torque

I wouldn't do that much. The fulcrums on those rockers are not that strong.

I would do more like 18.

RossA81 · Oct 28, 2009

I am running the same setup with a TFS1 cam. I used my stock pushrods and everything seems fine but a little bit noisy. You will have a hard time getting to 300 rwhp. A few are doing it with custom cams and ported lower intakes.

Ross

LAFENATU · Oct 28, 2009

I made 281rwhp with my old fox setup.

75mm MAF
70mm TB
GT40 tubular intake
Ported GT40 heads
Crane 2031
FRPP shorty headers
3.73's
T5

Went 12.81@106

auto_x5.0 · Oct 28, 2009

LAFENATU said:
I made 281rwhp with my old fox setup.

75mm MAF
70mm TB
GT40 tubular intake
Ported GT40 heads
Crane 2031
Shorty Headers
FRPP shorty headers
3.73's
T5

Went 12.81@106

Dont wanna steal the thread, but would a ported explorer intake, ported/polished gt40 heads, e303(or TFS1), 70mm tb, 75mm maf, shorty headers, o/r x-pipe and one chamber flows make about the same?

LAFENATU · Oct 28, 2009

Probably somewhere around 260-280.

My first tune was 262rwhp. I bought UD pulleys and had it re-tuned by another tuner.

Depends on the engine and tuner but I can tell you the car will be fun.

auto_x5.0 · Oct 28, 2009

Alright, yeah I have mods I forgot to list like ud pulleys, MSD 6AL, MSD blaster coil, CAI...if they effect it any.

sn95gtvert · Oct 29, 2009

i have no idea how much power i will have or what i will run, something in the 13's i hope. total mods are cia bbk equal length shorties 2.5 H pipe high flow cats 2.5 flowmaster catback, 3.73. and along with the heads im installing a gt40 intake 70mm performance products tb 1.7 rr all on my 95's 125k mile stock block. next big mod to be done is running a 100 wet shot and a cam by next summer. after a new maf and clutch are installed.