Fox T-Bird/Cougar Forums

I'll start by admitting that I made a mistake.  I bought a "GT40 explorer motor" from a guy late at night when I was running home from the airport.  I handed over the cash and we loaded it into the back of the truck and I took it home.  I was told that he used this in a car and consistently ran 13s in the quarter because of advancing the timing, 1.7 roller rockers, underdrive pulleys, 65MM throttlebody, ported intake, etc.

I put it on the engine stand yesterday, to break it down and see what I had.  I've learned to never trust anyone, and to always at least put a gasket set on anytime I am swapping engines.  When I tore into it, I started to get really suspicious as to what I actually bought.  To the best of my knowledge, I have a 1986 HO engine, not the GT40 as expected. :mad:  The pistons are flat-top (e67e-6110-ba), and the heads are E6's, and surprisingly it does have 1.7 roller rockers.  I am amazed that it cleared, but it worked somehow.  I am also convinced that this guy is an idiot, and am glad I took it apart.  Take a look at the exhaust gasket, for example:



I bet he had a bit of an exhaust "tick.." :hick:

I had intended on replacing the cam with a TFS1 and running it with my freshly ported and powder-coated tubular GT40 intake.  That's not going to be possible with the pistons and the heads I have.  I suppose I could still run the intake, but that's lipstick on a pig at this point.

This is going into a 1988 thunderbird with a stock as a crock gutless 5.0.

Possibilities:

1.  Throw a gasket kit on it and be done, while it's not what I expected, it's better than what I have.
2.  Use these parts to convert the existing '88 5.0 to an HO
3.  Abandon and acquire an actual GT40 and build what I thought I was doing in the first place
4.  Acquire a set of GT40 heads and have a hybrid GT40/HO build
5.  Start over with new pistons, TFS1 cam, TW170 heads, and my GT40 intake

My goal for this build is to have a streetable car with a throaty idle and enough power to keep goodyear in business by burning tires.  Something to note is that I travel a TON for work.  I'm considering what I have spent a sunk cost, and an educational expense to once again continue to never trust anyone.  I am not home enough to meet people for a craigslist ad, so I doubt I'd be able to recoup any costs.

I recognize that there are vast differences in the above.  What would you do if you were in my shoes?

I would call the guy and tell him the story. Maybe he bought it from a guy and thought it was what he told you it was.  Otherwise, I'd put it on the stand and go find a real Explorer engine. They can be found pretty cheap. It'll have the whole long block you need.

I used an '86 H.O engine (forged flat tops) and had an E-303 cam and roller rockers. No issues. I may have been a lucky person. Ran like crazy though.

Thanks for the advice Vinnie.  I have attempted to call and txt the guy all day.

I also thought of a #6 option - Buy the heads and the cam and bolt it up to see if it works.

Cut your losses. The other combos you came up with for substitutes for the GT40 package are just that, substitutes. Like Vinnie said the GT40 engines can still be had for relatively cheap money.

The only other choice that I would consider is now that you have a roller block build a stroker motor. You can find 331 and 347 kits all over the Mustang forums for less than $400.

Darren

I'm not.  PLENTY of room with the E6 heads and it'll clear with the E7's as well.

To run the TFS heads and stage 1 cam, you do NOT need to swap the pistons.  It'll run rings around a GT-40 setup with the right converter in the transmission.

There is so much folklore about what will clear and what won't that it's really difficult to discern what is actually workable, which is why I came up with option #6.

I speak from personal experience.  I have forged flat tops, TFS heads, and a cam a good deal larger than the stage 1.  No issues.

Quick update, I started scouring craigslist, and I found a 331 with a trick flow top end kit on it.  Went to look at it and had the guy pop the valve covers off and there were two busted springs, so I imagine the inside of the motor looks like metallic spaghetti.  Wy do people try to pull this ..

So I decided to just bite the bullet and go with door #6 - buy the heads and cam and bolt it up.  I came across a set of tw170s that have been cmc ported.  They look fabulous and they flow very well.  I'm now looking for another intake manifold, as tmoss says that he can't port t he gt40 won't flow enough for this setup now.

I'll let you know what I find after I bolt it all up.  Unfortunately, I am sitting on a pile of parts and I need to leave town for a week.  The life of a traveling salesman, I guess..

Geoff

Sounds good.  Keep us posted.

And yeah, some shady people on Craigslist unfortunately.  Sad thing is the fact that he will get SOMEONE to buy it for top dollar and screw them over.  If it's still posted you could always flag it.

Had a chance to get it all bolted up, and I'll post this for posterity sake. 

I went with 61cc TW170 heads that are CNC ported and polished, which means I'll need to switch out my intake to something that flows much better.  For roller rockers, I went with Miller Mid-Rise, after getting completely schooled by Jim and Paul on valve train geometry.  I highly recommend talking to either of these guys on the phone for 30 minutes if you have any questions.  Because of the education I got, I had to pay it back and give them the business, they definitely earned it!

For a cam, I put in a TFS1, and since that cam is a bit on the mild side, I used 1.7 RR ratio.  I used a pushrod checker and I came up with 6.7" for both the intake and exhaust. 

After getting all the parts, I spent a couple hours Saturday trying to figure out how to use clay to get a measurement of PTV.  Turns out that I have plenty of clearance and my issue was that I wasn't using enough clay to make an indentation.  I could have gone much more radical on the cam and still been within tolerance. 

I've now torn it apart again, cleaning things up for paint.  I'll post pics when I have something interesting.

See?  Told ya  ;)

Yep.  thanks for the inspiration.

So what's so special about the explorer engines? Im just kinda window shopping at engine options. Just trying to learn stuff if I ever decide to pull the trigger.

Gt40 or gt40p heads are essentially the best factory setup.

.. And factory intake...