You might wanna check is that marquis motor a roller? It may very well have the gt-40 heads on it, so you might check that as well. ON the front of the passenger side head, facing the side of the car, look below the valve (not under) cover to the right to the head bolt nearest the front, you should see "GT" stamped, or on the front of the passenge side head, facing the front of the motor, to the left of the freeze plug you should see three visible vertical lines. Good luck hopefully that is what you have, later

 

Good call, JW. I recommend that you not focus on a number, but try to optimize the 5.0 as-is. The SD will work fine if you work within its limits.

I have a magazine article that describes how to put some bigger valves in the E6SE heads and make good power. Those heads are considered 'restrictive' because of shrouded valves, but they make 200 hp in a 302 engine and more torque than the E7TE heads.

Some of the true engine guru's, the guys who build and tune engines for others, say that the stock HO cam is a good part. You can make the cam seem bigger with good heads, headers, and intake.

Bob Cosby, a Mustang guy, tuned a stock SD 5.0 HO to about 300 hp but he went to quite a bit of trouble; extrude-honed intake, big valves in the head, custom tuned computer. He ran 11.93/110mph quarter mile and got 24 mpg on the way back home.

Cheap bolt-on's? GT-40p heads and headers. Holley SysteMax I lower intake (compatible with the stock HO upper). 60mm TB is good enough. 19 lb injectors.

Make all the smog equipment work. If you're gonna be a professional mechanic, learn how that stuff works and make it work right. It will actually help the engine run better. Example; the car magazines like to remove the AIR bypass/diverter system when they swap heads or headers. It's in the way and they say it doesn't help performance, it hurts performance.

Bullcrap. It keeps the Oxygen sensors clean and warms them up faster during cold starts. And the amount of flywheel power it takes is so small it can't be measured. It just takes patience to keep it working.

Spend your time making the bottom end right and use ARP or SPS studs and rod bolts. Install a windage tray and HV oil pump. The rest can be changed later. Don't remove smog equipment, it all helps the engine run better. Sorry about the lecture.

 

THanks guys, So would it be more benificial to go with gt-40s and get some light porting done or junk pick a pair of 351w heads and have to have them redrilled for smog? i could probably obtain either on ebay. BTW the marquis does not have gt-40s stock and has 3.08s out back if im not mistake. thanks again

 

That sux, I know some lincolns have gt-40 on the 5.0's. Did you check or is that what someone told you? Don't touch any 351w heads in the 80's because they are 302 heads with 1/2" head bolt holes, more or less. Try and stick with 69-mid 70 351w heads if you wanna go that route. Gt-40 would be about the same maybe a little better not much the gt-40p are better than both of them. later

 

ONe last question, will i need to make any ignition upgrades for nitrous, and in general, or will the stock ignition hold up? THanks

 

I would install a msd just to be sure, might wanna get one with a retard function that activates with the nitrous, required no, but definitely a nice thing to have just in case. later

 

ANy special kind of spark plugs? maybe gapped to a certain degree?

 

Is it possible to step up to a 351 crank for a stroker motor? I'm new in the ford game but i know that in a 350 chevy you can bolt in a 400 crank and rods and have a 383 stroker. anything like this in the ford world? Thanks again.

 

Adjust the plugs as needed, or as recommended by the manufacturer, you will learn when you get into it when its a good time to go to a colder plug, certain gaps etc.. You can use a 400m crank in a 351w to make a 393/408/427 but the 351 crank would require too much work to put into a 302 to be worth it. You might consider just upgrading to a 351. You can use the 351 shortblock with your heads, get a new/used (5.8) 351 lower and upper intake, modify the fuel rail slightly and you have a 351. Thats up to you though, you may look into a 331 stroker crank for your 302 from say scat, there is a 347 crank as well, there used to be a concern for the pistons leaking oil due to how they had to be configured to allow for the 347's stroke, this is a thing of the past and has been remedied with the newer kits or that is what I have read, manufacturers make all kinds of claims but I think this one is accurate, I saw were a fellow pushed a fullsize ford 2wd into the 12's with 10psi of boost on a 331, thats nice. later

 

THanks for all the help JWtaylor and all, means alot i should be able to assemble a better truck for the money. IF you get anymore information don't hesitate to post. THanks again

 

I was looking into the 351w a little bit more and i was wondering what cars/trucks came with them from the factory with mulitport fuel injection? Also what cars came 400m crank for the stroker mentioned above? THanks

 

Just look at scat stroker cranks, by the time you figure it up you will pay about the same to have the 400m crank modified. The scat cast crank is only $290-350 depeding on where you look. Otherwise, some 70 trucks and cars had the 400m or modified motor, they were scattered about. Then again a 400m crank and I believe mopar 360 rods will net you 408+ cubes in a 351w with some machine work. Other than a couple of mustang special additions the only efi 351 came in trucks, 87 1/2-96 they were batch fire, I don't think they ever came multi port that I know of. Look for a 93+ 5.8 (351) block that has F4TE stamped on it. That would be a roller compatible block, they came with flat tappet cams in most cases, but its as easy as using any off the shelf cam with any roller lifter, aftermarket or stock 302 h.o./351 roller lifters and you have a roller motor. Otherwise they were scattered about in different 70's cars and trucks, they pretty much came in anything fullsize such as cars, so its a matter of looking around. You can still go roller in a 93 down block but you will need retrofit roller lifters or a reduced base circle cam. Someone might be able to get more specific on cars and years but they are out there, sometimes hard to find, but out there, good luck, later

 

If i did end up going with an EFI 351w could i reuse the 86 marquis speed density computer? Ive heard you could but it may cuase i little bit of drivability problems but i was planning on getting a new chip anyways. any suggestions THanks

 

If the car 302 uses batch fire like the 351 then you should be fine. Others have done it and changed nothing but modify the 302 fuel rail to work, other than the intakes being different. So you should be okay.

Actually I was incorrect earlier, batch fire or sefi are considered, mpfi, so I was hasty in saying that the 351w didn't have mpfi.

Just ditch the efi and go carbed and save yourself a lot of trouble, just kidding, later

 

CAn you point me in the right direction to anyone who has done a 351w swap or modifications. i would ditch the EFI but i have to meet emmisions, tough times, THanks man