Hey everyone;

I am putting off buying a 99-04 Mustang right now and am looking at a minty 68' Galaxie 500 vert that needs a few parts to be perfect. It was restored back around 91' and then parked, I guess because of not wanting to hurt the engine with unleaded fuel.

It is the Z code 390 rated for 330-335hp and it is all original under 70,000 miles and runs great.

Now being all original the heads need to come off and have the valve seats replaced with hardened units. There is only 1 place in town that sells leaded gas and its Cam2 so its expensive stuff.

I am looking to change the heads over to a set of ported Edelbrock Performer FE cylinder heads w/ 2.19" intake and 1.73" exhaust valves along with a performer intake, roller cam, roller rockers and so on.

This article outlines exactly how I would like to build the engine with the exception of porting the heads and using roller rockers. ( http://www.hotrod.com/webonly_january/index.html )

They made 450 hp at 5,600 rpm and 460 lb-ft at 3,900 with their combo but they also used forged pistons and who knows what else but retained the stock 390 cubes.

What I am getting at, will the stock pistons, crank, rods and oiling system hold up to 450-500hp nearing 6000rpms?

Also my stock compression is 10.5:1 where their compression was 9.68:1.
I do not know what my stock head cc's are but I know the Eddys offer a 72cc and a 76cc variant. So if I run 10.5:1 CR plus roller rockers and the ported setup I may very well go over 500hp.

Just need some advice and help from other FE guys out there and how well a 10.5:1 CR motor will run on 91 pump gas. I know our 10.65:1 2003 Mach 1 motor thrives just fine on 91oc.

Thanks again everyone and I am sorry for the long post.

-Eric-

 

Complete waste of money. You'll probably get 100,000+ miles before the seats start to go, and that's assuming the past rebuild didn't already put them in.

Unless you have some gigundo compression, go with pump gas. Seriously.

 

hey neo, I've got an S code mustang with the 390 so will watch this with interest. Be sure to post up some pics of that motor as you do the upgrade. I'd like to see how it goes since I've been modding mine and read that same article.

 

At that rpm, you will be running 3800ft/sec piston speed. That is approaching the range where you need better than stock parts, but you should be ok if nothing is stressed or worn out.

As for fuel, I run 93 in my 10.2:1 motor with some detonation issues, but not too bad if I watch it. Remember that dynamic, not static, compression is what is important with relation to fuel detonation. Dynamic compression is a function of your cam timing and takes into account valve overlap, duration, etc. Not all 10.5:1 motors are created equal. Some may ping while others do not due to many factors, one of which is dynamic compression.

 

Thanks for the info guys, keep it coming!

The engine is original from 1968 in all its low mile glory. The speedo has never rolled over either and miles are documented.

Provided I buy this car I will make another post for the upgrades and finishing work I do to it.

I would still like to upgrade to all the aluminum goodies as it will cut about 125lbs off the front of the car and add extra horsepower.

As far as rpms go, I will set up a 5500rpms rev limiter just to be safe when I replace the ignition system. I would hate to destroy this engine or hurt it because I slipped past 6000rpms.

Now as far as the cam goes and DCR & SCR I will take to Crane a little more about that, thanks for reminding me about that as that will make a whole world of difference with the Cali 91 gas.

Thanks again everyone, the more info I can get about what these engines can handle and what their common problems are the better off I am.

-Eric-