Anyone using 1.7 rr on intake and 1.6 on exhaust with gt-40 heads?

[bjl95mustang]

I got 2 sets of rockers for my setup and I am trying to deciede if I should use the 1.6, 1.7, or 1.7 intake and 1.6 exhaust. I'm building up a budget 306 with home ported gt-40 heads between 62-58cc(not milled yet) with a tfs-1 cam and a home ported performer intake, shortie headers, off-road h-pipe and 24lb injectors. I have read about people doing half and half but i wanted to see if anyone here has done it.

Thanks,
Brandon

 

[RIO5.0]

I wanted to try that myself....If there 1.7 peds, I'll buy the other 1/2 from ya...

It may not add alot. hp wise...but every little bit adds up....I posted it some time ago after reading and article in 5.0

 

[bjl95mustang]

Do you still have the post from 5.0?

 

[wytstang]

I thought it was 1.6 intake and 1.7 exhaust if your N/A and 1.7 intake and 1.6 exhaust for power adder.

 

[Joes95GT]

I'd do the 1.7/1.6 I/E combo. If you're using a standard split pattern camshaft or even a single pattern camshaft, use the 1.7's on the intake side. The exhaust will find it's way out.

You may pick up a few...

Joe

 

[wytstang]

I thought that ford's needed help on the exhaust side so using the 1.7 on the exhaust side would benifit them more. :dunno:

 

[bjl95mustang]

I have also been thinking about using 1.7E and 1.6I. Damn, I don't know.

 

[Joes95GT]

The TFS cam has a split in it, so a 1.6 on the exhaust is fine.

A 1.7 on the intake side will give you a little more top-end by making the cam act bigger than it really is. And no, there won't be any side-effects of running 1.7's on the intake side.

Joe

 

[bjl95mustang]

Cool, I guess i will do 1/2 & 1/2 and see how it is.

 

[cmozez]

In 5.0, thier best results came from 1.7 exhaust and 1.6 intake.

 

[bjl95mustang]

Does anyone have the 5.0 mag online so i can read it?

 

[krahkin]

I do, but I will have to dig through the pile to locate which issue

 

[Joes95GT]

In 5.0, thier best results came from 1.7 exhaust and 1.6 intake.

And it was probably with the stock cam, which favors the intake side. So 1.6's on the exhaust "evened" things out. I'm not saying I'm right, but I wouldn't believe everything in magazines.

Joe

 

[wytstang]

But wouldn't having a larger lift on a N/A engine even with a cam help evacuate the cylinders better. Thus allowing the cylinders to fill back up with a more pure combustion able mixture.
EDIT: I’m not arguing with you just having a discussion.

 

[bjl95mustang]

Well, I wonder what I should do. If i do 1.6 on the intake will be at just around .499 and I think .512 exhaust. I believe my springs are good to .550-600. These are home ported gt-40 with stock sized valves.

 

[1105]

I'd do 1.7 I 1.6 E. If you feel like it, do it both ways and see which one gives you the most power.

 

[RIO5.0]

Info from the article....

I'd do 1.7 I 1.6 E. If you feel like it, do it both ways and see which one gives you the most power.

The 347 they tested in 5.0 mag with the 4 combos around 1.6/1.7. The motor had Z304 heads and an XE282HR comp cam...not exactly a stocker...They only got like 4 HP top with all the combos, 1.7s on the Ex side 1.6 Int was the best....Its kinda one of those "inching" things...theres not alot to be had, but some nonetheless...it also stated its one of those, why one combo will just pull a tad on another thats matched with the same stuff..all the gain was in the high RPM area...its not gonna be a seat of the pants thing...

GT40s are set-up for 1.7s anyway?? No?? Running 1,7 on a 1.6 can lead to valve guide wear some, due to the geometry being off some..Theres more cons than pros to doing it...rather than chg a cam for more lift, this swap can do it easier..

The article was in the Aug 2004 issue..." Lift and Invigorate" was the name..Whether its on line ???? Was a cool article on just 1.6/1.7 workings though...

 

[bjl95mustang]

The gt-40's on cobras come with 1.7rr. But i'm going to be using a tfs-1 cam.

 

[bjl95mustang]

The manufacture only has the specs with the rockers but no recomendations!!

 

[bjl95mustang]

Damn server.