351 swap

1SILLYGT · 03-11-2002, 03:47 PM

Im thinking off swapping a 351W in my 90 GT. I was just wondering if a set of GT-40 iron heads off of the 302 would also fit on the 351. I was also wondering what else i would need to do the swap.

7000rpmisheaven · 03-11-2002, 04:19 PM

The heads will fit. You will most likely need to modify the exhaust. You will also need a new lower intake manifold because the deck is taller. I'm sure there are other thing this is just off the top of my head.

82 GT · 03-11-2002, 06:03 PM

The heads will bolt on but the water passages are different. There is way to make them work but I forget what you need to do. I read an article a while back that showed them putting 351C heads on a 302 block. They called it cleavor. I think the head bolts are different sizes also. I could be wrong about that though.
You will also need headers that fit a 351...not a 302. the 302's will fit but the driver's side will not clear the steering shaft. The tubes on the 351 headers are routed different. I found out the hard way!!

Fox Body · 03-11-2002, 09:44 PM

GT-40 heads will work, but the bolts are 7/16 while the 351W head bolts are 1/2" so you would have to drill them to account for this.

You'll have to get a diff flywheel and 351W swap headers. Would you plan on leaving it fuel injected? if so, I think you'd need the EFI conversion kit and you can use your upper intake (I think), but you'll need to get a Ford Motorsport lower intake. You will have some screwy stuff with the pulleys depending if you wanna keep 5.0 pulley system (brackets and all) or the 351's. The water pump will need to be a reverse flow water pump if you put the 5.0 one on the 351 (I think that's it).

Makes me wonder though, why change to 351? for the money it takes you to swap the 5.0 for the 5.8, and just bolting on some old Gt-40 heads, you could put that money into your 302, get some trick flow heads, etc. I don't think it'd be worth the time and effort to do the swap unless you do more than just bolt some GT-40 heads onto a stock Windsor--which would take money, WHICH would be money you could just put into the 302....

82 GT · 03-11-2002, 11:39 PM

Interesting point Foxbody but it all depends on what year 351 he puts in there. I would find a '69-73 351 like I have and stay away from the '74-up 351's because of reduced compression and emissions for those years.
I would have thought you would have been partial to the 351 swap since you have a 351 in your stang as well.
You could probably save some money by going with a carb setup instead of EFI.
I'm not trying to start a carb V.S EFI controversy here.
It all goes back to how much cash you have and what your goals are with your car.

Capri306 · 03-12-2002, 12:06 AM

The other point that I think is critically important is the additional thickness and higher torque than the 5.0 that the 351W has. Think about it, you have 1/2" head bolts, thicker webbing, MUCH larger bearing journals, and the list goes on. These motors are perfect for blower/nitrous setups that wanna live for more than a year. Yeah, I know, you CAN make a 5.0 live under boost and whatnot, but for the extra strain and blown head gaskets, IMHO it's worth it. This is the way I'm going, with O-ringed Trick Flow heads, forged crank, Novi 2000, etc. This is kinda the way Dan's Death Machine is set up, and it's lived for quite a while with the clutch being the only problem. I say build it once and never again. Okay, rant's over.

1SILLYGT, check out the Articles link over there on the left, you'll find a section on all that you need to swap in a 351W. Again, cost is a big thing when doing this, but is worth it in the long run. Be sure your tranny can take it, though!!!

Fox Body · 03-12-2002, 05:15 AM

Quote:

Originally posted by Capri306
... Again, cost is a big thing when doing this, but is worth it in the long run. Be sure your tranny can take it, though!!! [/B]

You guys have good points. Yes, I am partial to the 351W (I have one and I love it!!!

), but in all practicality, it sounds like he just wants to swap the 351 in and throw on some GT-40 heads and thinks that's gonna give him a quicker car, but it won't. Yes it is a more torquey motor, but the stock 351s also have lower compression (8.5:1) than the 302s. It is gonna take more than that (and more money) for the swap to be worth it. That was what I was really getting at-- sorry if I misunderstood him.

1SILLYGT · 03-12-2002, 10:30 AM

Thanks for the input everyone. Right now I am dealing with a blown motor and a limited budget. I was thinking about getting a 302 block built to a 306 for about $600 but at the same time i can get a built 351 bottom end for $200 and all i need is the heads, intake, and headers. More modifications are to come but for right now i just want to get my car on the road. What do you think would be worth it?

03-11-2002, 03:47 PM	#1
1SILLYGT Registered Member Join Date: May 1999 Location: sloatsburg NY Posts: 28	351 swap Im thinking off swapping a 351W in my 90 GT. I was just wondering if a set of GT-40 iron heads off of the 302 would also fit on the 351. I was also wondering what else i would need to do the swap. __________________ 90 GT 351W long-tube headers, flowmaster exhaust, off-road h-pipe, 3.73 gears, hurst short throw shifter, GT-40 heads, demon 650 carb, speedpro pistons, eagle rods, comp cams

03-11-2002, 04:19 PM	#2
7000rpmisheaven Registered Member Join Date: Nov 2001 Location: germantown MD Posts: 283	The heads will fit. You will most likely need to modify the exhaust. You will also need a new lower intake manifold because the deck is taller. I'm sure there are other thing this is just off the top of my head. __________________ 85 GT 4bbl roller cam 2 ch. Flowmasters, O/R H-pipe Performer intake and carb milodon water pump, FMS 9mm wires, aluminum driveshaft, king cobra clutch

03-11-2002, 06:03 PM	#3
82 GT Import Slayer Join Date: May 1999 Posts: 2,241	The heads will bolt on but the water passages are different. There is way to make them work but I forget what you need to do. I read an article a while back that showed them putting 351C heads on a 302 block. They called it cleavor. I think the head bolts are different sizes also. I could be wrong about that though. You will also need headers that fit a 351...not a 302. the 302's will fit but the driver's side will not clear the steering shaft. The tubes on the 351 headers are routed different. I found out the hard way!! __________________ '82 GT 351W (.060)Comp Cams 274* Extreme Energy cam, ported & polished heads w/ 1.94/1.60 valves 10.3:1 flat top pistons,stealth intake, Mallory dizzy,Holley 750dp carb, BBK shorties,Flowmaster exhaust,C-4 with 3700 stall converter, B&M pro shifter,8.8 rear, 4:10's, subframes, electric fan, powermaster alternator, 4 core radiator.

03-11-2002, 09:44 PM	#4
Fox Body Mustang Maniac Join Date: Sep 2000 Location: GA, U.S.A Posts: 2,266	GT-40 heads will work, but the bolts are 7/16 while the 351W head bolts are 1/2" so you would have to drill them to account for this. You'll have to get a diff flywheel and 351W swap headers. Would you plan on leaving it fuel injected? if so, I think you'd need the EFI conversion kit and you can use your upper intake (I think), but you'll need to get a Ford Motorsport lower intake. You will have some screwy stuff with the pulleys depending if you wanna keep 5.0 pulley system (brackets and all) or the 351's. The water pump will need to be a reverse flow water pump if you put the 5.0 one on the 351 (I think that's it). Makes me wonder though, why change to 351? for the money it takes you to swap the 5.0 for the 5.8, and just bolting on some old Gt-40 heads, you could put that money into your 302, get some trick flow heads, etc. I don't think it'd be worth the time and effort to do the swap unless you do more than just bolt some GT-40 heads onto a stock Windsor--which would take money, WHICH would be money you could just put into the 302.... __________________ 351W-powered 1979 Ford Mustang Ghia notchback '79 Video @ Idle Stock 5.8L under 4" cowl 'glass hood, C4 w/ Transgo shift kit, Holley 750 cfm, Edelbrock Performer RPM intake; Fluidyne Al radiator, Flexalite 175 electric fan, 1 5/8" MAC shorty headers, FRPP Al driveshaft; S&W 6-point cage; 2.5" Off road H-pipe, 2-chamber Flowmasters, 8.8" Rear w/ 3.55s; Weld wheels (15x6;15x8), Front: 225/60/15, Rear: 275/50/15 Nitto NT 555R Drag Radials; 14 x 4” K&N X-stream air filter. '92 GT (5-speed) Small In Car Video Stock 5.0L, 2-chamber Flowmasters, MAC CAI, Tri-Ax, Al pedals... "Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body

03-11-2002, 11:39 PM	#5
82 GT Import Slayer Join Date: May 1999 Posts: 2,241	Interesting point Foxbody but it all depends on what year 351 he puts in there. I would find a '69-73 351 like I have and stay away from the '74-up 351's because of reduced compression and emissions for those years. I would have thought you would have been partial to the 351 swap since you have a 351 in your stang as well. You could probably save some money by going with a carb setup instead of EFI. I'm not trying to start a carb V.S EFI controversy here. It all goes back to how much cash you have and what your goals are with your car. __________________ '82 GT 351W (.060)Comp Cams 274* Extreme Energy cam, ported & polished heads w/ 1.94/1.60 valves 10.3:1 flat top pistons,stealth intake, Mallory dizzy,Holley 750dp carb, BBK shorties,Flowmaster exhaust,C-4 with 3700 stall converter, B&M pro shifter,8.8 rear, 4:10's, subframes, electric fan, powermaster alternator, 4 core radiator.

03-12-2002, 12:06 AM	#6
Capri306 Moderator Join Date: Sep 1998 Location: Grand Rapids, Michigan, USA Posts: 1,001	The other point that I think is critically important is the additional thickness and higher torque than the 5.0 that the 351W has. Think about it, you have 1/2" head bolts, thicker webbing, MUCH larger bearing journals, and the list goes on. These motors are perfect for blower/nitrous setups that wanna live for more than a year. Yeah, I know, you CAN make a 5.0 live under boost and whatnot, but for the extra strain and blown head gaskets, IMHO it's worth it. This is the way I'm going, with O-ringed Trick Flow heads, forged crank, Novi 2000, etc. This is kinda the way Dan's Death Machine is set up, and it's lived for quite a while with the clutch being the only problem. I say build it once and never again. Okay, rant's over. 1SILLYGT, check out the Articles link over there on the left, you'll find a section on all that you need to swap in a 351W. Again, cost is a big thing when doing this, but is worth it in the long run. Be sure your tranny can take it, though!!! __________________ Capri306, Moderator The Mustang Works Online 1979 Mercury Capri 1987 5.0L Mustang LX Notchback 1993 5.8L Eddie Bauer Bronco

03-12-2002, 10:30 AM	#8
1SILLYGT Registered Member Join Date: May 1999 Location: sloatsburg NY Posts: 28	thanks for the advice Thanks for the input everyone. Right now I am dealing with a blown motor and a limited budget. I was thinking about getting a 302 block built to a 306 for about $600 but at the same time i can get a built 351 bottom end for $200 and all i need is the heads, intake, and headers. More modifications are to come but for right now i just want to get my car on the road. What do you think would be worth it? __________________ 90 GT 351W long-tube headers, flowmaster exhaust, off-road h-pipe, 3.73 gears, hurst short throw shifter, GT-40 heads, demon 650 carb, speedpro pistons, eagle rods, comp cams

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