GT40 head question

I've got an 86 Martinique that I've been trying to modernize a bit. I've got about 2000 lbs of integrated ballast in it now, but I had it out the other day for the first time riding behind it and it felt under powered to me.

I've got the acme 542 prop on it, so that's not it. I think my motor is tired.

Is the GT40 swap just a simple bolt on for the 351? Do I have to have PCM GT40 heads or can I get heads off of a 5.0 and slap them on?

Or better yet, can I put the aluminum heads from my old 65 stang on the 351 block? For some reason I remember somebody telling me that wouldn't work because of deck height.

Any feedback would help greatly. Thanks.

So GT40p's are PCM heads?

I had a friend recommend the edelbrock carb, so I put that on. Plugs and plug wires are all brand new. Rotor isn't. I'll check on that. Carb was freshly tuned so that's not it. I'm pretty sure timing is dead on.

The last time I did a compression check each cylinder was completely random. I'm figureing I've either got some valve issues or some ring issues.

thoughts?

Thanks for the input on the heads.

Random ranged from 125 to 75 on one side of the engine.

How do you do a leakdown test?

alph wrote: Random ranged from 125 to 75 on one side of the engine. How do you do a leakdown test?

A true leakdown test requires a special tool to do properly. The tool is a small manifold made of pipe fittings, gauges, an air pressure regulator and hose and is supplied compressed air. There are two pressure gauges (0-100 psi range) which are separeted by an orifice that meters the airflow supplied by the compressor (shop air). The regulator is set to 100 psi (indicated by the first gauge). Air flows through the manifold and feeds the first gauge and the orifice. On the other side of the orifice is the second gauge and a fitting that will screw into the spark plug hole of the cylinder under test. With the piston set on the compression stroke (both valves closed), the regulator set to 100 and the outlet of the tool (spark plug fitting) feeding the cylinder... you compare the readings between the first and second gauge. Readings should be within 10% of each other. The closer the second gauge reads to 100 the better. Now, if you have a leak, you can listen and detect where the air is going and narrow down what is wrong (if anything) with your engine. I know this is rather lengthy, but it is a good test because you can often isolate where the problem is. If there's something you don't understand and like further explaination....write back. Hope this helps. Brian

Here's a link to one that I found on line: http://www.powerhouseproducts.com/catalog/Images/2006pdfs/ph26.pdf Scroll to bottom of page.

Also try NAPA, Snapon or Mac Tools. I pieced one of these things together one time about 10 or 12 years ago. The critical part is the orifice size between the two gauges. I don't remember the size though. If you get it wrong your readings will be off.

Gary: You didn't work and grab some of that double-time and a half?

john

Most every boss in my last 10 years had the same attitude. Funny...they kept coming and going and guys like me just kept on doing the job our way. Wonder what that meant.

Know exactly what you meant as to the importance of somethings. And as to the ot...always worked lots...don't have any of that money left...wish I'da spent just a ittle more time at home on the weekends and evenings. Life really changed for the better when I swore off the ot my last few years...didn't miss the money either. Have found out here latrly that you can life on lots less...you'll find out soon. Then you can come and visit.

alph; sorry for the thread jack. ReidP found me a set of GT40p heads at a very reasonable price and I love 'em. He'll have to chime in as to where he got them...I forgot...but I think they were from here in Florida.

john

I think mine came from Clearwater Cylinderhead...but not really sure...Reid would remember. And yes...in combo with my new Performer manifold I bought from nuttyskier on here I noticed a big difference. Was very happy with the upgrade. There was a thread from when the guys put everything on for me complete with pictures but I don't know how I would go back to find it and link it for you.

john

I remember reading it,but forgot they were P's

nuttyskier2002 wrote: John, that intake is actually a Power Plus Typhoon by Professional Products. The P/N is 54023 for anyone who is interested in purchasing one. They are the most reasonable priced Ford intakes (when buying new that is).

it is a knockoff edelbrock performer cast in china. The casting quality isnt nearly as good as a edelbrock. It is a great piece for the money and if you put a couple hours in with a dremel or air grinder to clean up the casting flash, it is even better value.

WOW. That was pretty accusational. I play with fords a LOT and I am part of the local mustang club and i help manage their forum board. I have done a lot of work on my car any other peoples cars in the club over the past 4 years. I have seen plenty of intakes and played and installed several. I have done a lot of porting work on intakes and am dabbeling a bit in heads now too. What I write on forum boards isnt just to say what I have heard or read on frivolus websites but what I have personally experienced. There is, in what I have seen with my own 2 eyes, more casting flash and a more porus sand used in the casting process of the PP intake than the edelbrock. I never said it was a problem, I just said there is more there than the eddy. The PP is not better in any area than price because it is based off of the performer design. It is cheaper because it is made in china and that is the difference in price.

So let me ask you this in rebuttal, have you ever held an edelbrock piece in your hands or are you quoting BS form a book or magazine.

Thanks for hammering me and acting like a jerk like I have no clue. Im not some hopped up 18 year old who never seen an engine before, but you are quick to assume that. I never once it was junk or said anything negative to justify a comment like that form you.

Wow again. J-I-H and 79 are rolling into holiday form.

Actually guys...you all know how clueless I am. Thanks Brian for clearing up just what I have. And thanks again for getting it to me at the right price. As 79 said...when it went on it looked great and performs the same way.

john

Jim; Thanksgiving to Christmas is the only time I don't do Beam and Diet Coke. Something about the Holidays.

Spell check has been here for awhile. Haven't you noticed how it cleaned up 79's posts. Used to be only us guys who knew him could make out some of his posts...now everybody can understand him.

Very bad that the '68 never got wet. I remember some of your posts with pics of the spring flooding...just kept it up all summer huh?

john

Jbear this should be the link your looking for.

jbears upgrade