Is a 351 worth it?

[pvillese]

So I see that a stock 351 is only rated for about 10 more horse than a stock 302, talking back in the 80's at least. So the general question is, is it worth swapping a CFI to a 351?

I have an 85 with a CFI 302 that has low miles(75k) but I'm sure the PO helped take years off its life by running around without coolant in it(at least it had none in it when I picked it up and she said she had driven it short distances after a bunch of smoke came out one of the wheel-wells, I got a really good deal) I have not done a compression test yet to see if its life was just shortened or if I need to address it immediately. If I need to address it immediately then my decision will be made and I'll pick up a running 302 and put it in for now and rebuild my current 302 to have more power. It seems to be running ok though so I don't think that is the case. So if I have some time I'd like to pick up a rebuildable engine and start building it the way I want it.

Once I found out the CFI won't take me far I've decided eventually it will get a 4-barrel carb so then I was thinking if I do that I might as well go to a 351. But then I saw the 351's have barely anymore stock power than a 302. With that in mind and the fact that the 351 is heavier I started to wonder if a 351 was even worth it. I would like to end up with a fun car to drive, it doesn't need to be anything extreme but I also need low end power since I plan to tow my camper with it. I will be changing the engine from stock so I'm more curious if the 351 has enough added potential that it would be worth the swap.

[Freshmeat]

Go 351 and don't look back. There are plenty of significant upgrades you can do for cheap during the rebuild process that will get you great results.

[DuceAnAHalf]

Go with the 351 it is about as easy as installing the 302. With a mild build your looking at about 50hp difference right off the bat

[Pirate]

If built correctly....a 351w is the way to go.

[Outlaw440]

Try finding a 87+ truck 351, if you can, they were rated at 210hp/315 ft lbs. which is much better than what you have now. add some 1.7 rockers, shorty headers, exhaust and an intake and you'll have the cheapest 250+ hp/ 330+ ft lbs you ever got.

[andymac0035]

but I also need low end power since I plan to tow my camper with it.

351 will always make more low end grunt. I had a 351w (put into) a 1981 (it had a 255 originally). Car was fun to drive and had lots of low-end grunt. It was an 84' truck motor that was basically stock other than an edelbrock performer intake and a holley 600 4-barrel (and no emissions). The 85' police car I almost bought before the motor-swap felt weak by comparison.

[pvillese]

Try finding a 87+ truck 351, if you can, they were rated at 210hp/315 ft lbs. which is much better than what you have now. add some 1.7 rockers, shorty headers, exhaust and an intake and you'll have the cheapest 250+ hp/ 330+ ft lbs you ever got.

Late 80's still had carbs on them right, so the added power wasn't from efi?

That would probably be the way to go then, my brother said his gf's dad who owns a junkyard would probably sell me a running 302 or 351 for a few hundred bucks.

Ok, so you guys have me pretty well convinced to go with the 351(it wouldn't have taken much) so now I have some questions about the swap.

If I found them cheap would it still be a good idea to put gt40 heads on the 351? I see those are the recommended heads for the 302.

What does the swap from cfi to a carb all entail? Can I continue to use the same logic module and just disconnect the cfi stuff, since I believe it controls advance right? Or should I just get rid of the logic module and get an ignition setup that doesn't need it? Does the logic module control/do anything else that I would car about after the swap?

Thanks for the info. I'm pretty mechanically inclined, I've pulled engines, rebuilt them and put them back in before and beefed them up, but never switched engines and never removed efi, so I want to make sure I now the basics of the swap before I buy anything. I know there will always be things I encounter I can't plan for but I'd like to be as prepared as possible.

[pvillese]

351 will always make more low end grunt.

That's what I figured but I wanted to get some real world info from you guys, thanks. This is only my second V8 vehicle(well third if you count my old 3.9L V8 Caddy I had) I've had so I'm pretty new to the feeling of really torque and low end power, I'm used to high revving 4-cylinders. I still remember the first time I floored my 84 302 mustang(sadly I no longer own) and sent the rear end sideways, I just couldn't believe that a 150hp could do that.

[Outlaw440]

in 88 (might have been 87 but i dont know) they were switched to efi but that isn't why they made more power. They got upgraded with e7 heads, and a different camshaft. You can easily put a carb and carb intake on this motor and actually gain a little power, as the efi truck intake was a turd. GT40 heads are fine for a budget upgrade, the 93-95 lightning used them and had 245hp on a 351. The biggest problem is that they were dogged down with a crappy 8.9:1 compression ratio. So if you can budget a set of pistons that'll bump the compression ratio up a tad or shave the heads some it would help you immensely.

[Lazerbeans]

Get the 351, and forget about it. Right off the bat you start out with a block that has bigger mains, rated several hundred horses higher (450 vs 750 according to Ford) in durability. The 351 is heaver because the block is made studier, and taller. The difference in horsepower might be slight, in stock form, but its the torque of those extra 49 cubes makes a real difference. And on the street, that where it’s at. A 302 will need at least 20 horsepower to cover the torque difference of a similar 351. In addition, you can stroke the stock block out to 427ci vs the 302's 347.
In a mustang a 302 might have a advantage, because its a light car that has a light rear end, so there is only so much power that you can put down easily. Yes, mustangs can be made to get as much traction as they need. But in stock form or close to stock form it might be a waste to have the power band lower as in the case of a 351. But I tend to think to man up and figure out how to put the power to the ground. However, with our Panthers being at least 400 pounds heavier, and having somewhat better inherent rear wheel traction, the 351 is the way to go.
Oh yea add 3.73 gears, and your next upgrade will be wider tires, if you want traction under 50mph.

[pvillese]

in 88 (might have been 87 but i dont know) they were switched to efi but that isn't why they made more power. They got upgraded with e7 heads, and a different camshaft. You can easily put a carb and carb intake on this motor and actually gain a little power, as the efi truck intake was a turd. GT40 heads are fine for a budget upgrade, the 93-95 lightning used them and had 245hp on a 351. The biggest problem is that they were dogged down with a crappy 8.9:1 compression ratio. So if you can budget a set of pistons that'll bump the compression ratio up a tad or shave the heads some it would help you immensely.

Did the lightning actually have higher compression? Or would I be looking at even higher hp numbers if I raised the compression. I think my brother mentioned that they got a new machine at his work that he could use to shave heads and I've done enough computer work for him to get that done for free. I'm sure I can do some research into this on my own but what compression ratio do you suggest, considering I'd like to still be able to run cheap gas, and I want it to be reliable.

So the list so far
-351 from 88(maybe 87) or newer f-series(can it be an e-series?)
-GT40 heads, shaved(how much?)
-what to do with ignition, can I just use what is on the engine?
-mustang shorty headers, will the stock cats bolt up to them?
-h-pipe, some crown vics came with h-pipes that bolt up right?
-some decent flowing mufflers
-some kind of tail pipes(I believe I've read impalla tails work), can't just go out the side since its a 4-door
-carb and intake - thinking Edelbrock Performer and holly 600, if I find deals on CL or ebay this may change, any suggestions of stuff I could pull from the junkyard?
-I already have an MSD 5 box which should be sufficient for the new motor, I doubt I'll be revving beyond 6000 RPMs
-1.6 roller rockers (is this only if I stay with the e7 heads?)
-I believe I have to make some changes with the fuel pump/regulator for the carb swap.

This sounds like I should be around or over 250hp and I think if I collect the parts over a year or so this should be very affordable. Other than freshening up the engine with new gaskets/seals and basic part, doing a valve job(possibly 3-way cut) and hopefully get my dad's friend to port the heads, are there any other cheap things I should do to improve power/reliability?

[gadget73]

94+ block if you can get it. Roller cam vs flat tappet cam. Modern oils are crap for flat cams, and roller cams will give you a much more aggressive ramp rate.

ignition, you want duraspark or something stand-alone. The TFI stuff you currently have is not useful with a carb. A Dspark distributor will wire into an MSD box just fine.

mustang headers will be too wide to mate up to a 302 exhaust. You need 351 swap headers to do that, and even then the flanges on the stock box exhaust aren't going to mate. It could be hacked to fit, but with a decent 351, the stock exhaust is kinda puny. I would plan on something totally non-Vic for exhaust if you want any sort of performance. Have a gander over various exhaust threads, they discuss how to mix and match Impala and Mustang parts to fit on a panther.

Holley if you're gonna go that route. Eddys are easy to tune, but mostly because they are limited in how tunable they are. No, I haven't got a clue how to make a Holley work either.

Stock rockers are 1.6, pick your rockers after you determine what cam and other hardware you're running. You may want 1.7's.

Ditch the stock fuel pump completely, make a pickup in the tank with brake line. Or, if you can find one, use the tank plate from a 79-82 model with a carb, or get one from a 351 car. I would be concerned about how much fuel you can suck through the stock pump before it becomes a choke point.

If you want something serious, I'd be looking at aftermarket heads. You can probably pick up something used and runnable for what you'd pay for gt40s and a shave job. The Lightning motor in and of itself is not that special. Mediocre cam, OK heads, nice intake. You'll pay such a stupid premium for one that its not worth it, and unless you're going EFI, theres no point in paying extra for the intakes. I would personally EFI it, but thats just me.

[Smokestacklightnin]

I'm planning on going to a 4bbl this summer and replacing my CFI also. No junkyard parts for this build though. (It's in the junkyard for a reason.) The ignition system i'm planning on building will be a Duraspark,HEI, TFI hybrid. Duraspark distributor, HEI module, and stock TFI coil. Will probably go with the edelbrock carb and intake. Plan to try and use the stock fuel pump with a Holley regulator w/bypass. After I get it all working will probably start saving for a rebuilt 5.0 HO longblock.

[pvillese]

Thanks for the info. I would love to go to a multi-point EFI but this needs to be on a budget, at least for now. Maybe if I give myself a longer timeline I could afford EFI but I'm thinking I could go carb for now and then do aftermarket EFI later so I would have more control over tuning it anyway. The body and frame of my car are in really good shape for a car in WI. Its got several dents I plan to fix but almost no rust. Also I was only asking about the lightning engine to get an idea of the hp I'd get out of my build, I'm not actually going to look for a lightning engine to put in it unless I happen across one and I can get it cheap.

I don't know a ton about carbs other than I was able to tune the one on my old accord really easily(had it get 38mpg on the freeway) and I've played with carbs on my go-cart and snowmobiles when I was younger. Also most people I know that have dealt with carbs usually talked about putting a holley on. I didn't realize they were harder to tune. My brother does have a 650cfm holley he would sell me cheap and then I would have to freshen the seals and what not so I was thinking about using that but I'm not set on it yet.

I found a guy selling an early 80's 351w HO(I was thinking maybe he was calling it an HO since it was the larger engine option but I found out some interesting info) so I did some research and found out (at least in the trucks) they made a HO, which had 210hp, all the way back to 84 and according to the forum I was read it was the only 351w put in the trucks from 85 until they went to efi. It has a beefier cam, 4v heads(not sure which yet though or did they only make one type of 4v heads, the e7's are 4v right?) and then a different intake and a 4-barrel carb.

[CheeseSteakJim]

A 650 won't be enough for a built 351.