Hi there, am looking at rebuilding the 302 in my father in laws 89 F150. He is curious about possibly stroking the 302 but is concerned about any issues that may cause while still retaining speed density. Does anyone have any feedback or experience with this?

Thanks for your insight.

 

Stroking the 302 with speed density is not a problem , it will be fine , some cams won't work with SD because they won,t give you the engine vaccume that SD needs , so you need a SD compatable cam ....Lew

 

Well, it won't be a problem to chip the ECU to tell it it's got a larger engine, but if you don't do that, it will calculate the same air flow it always did, and fuel for that air flow.

As your stroked motor will be flowing more air just because of the stroking, never mind the cam, the mixture will end up lean.

 

In other words, it's perfectly fine to run a stroked 302 w/ SD, but you will need to choose the cam carefully to ensure you get something that the SD will still be happy with and get a custom tuned chip so that the EEC knows that it has more displacement and airflow than it did previously to keep A/F ratio good.

 

Sure its allways good to get a custom tune , the question was will it work with SD ' i had a custom chip dyno tunned & burned for my truck & its worth the money when your doing major modifications , also it would be good to upgrade the exhaust with headers & free flowing exhaust & upgrading the air intake system , the 5.0 intake is good but the stock air box system sucks...

 

Since a 351 is basically a stroked 302, I would think a 351 SD computer would be better for you, & probably cheap to buy.

 

Thanks for all the info. Been getting a lot of mixed reviews. Some day no problem, some so be careful, some say nothing but trouble. Of course these reviews come from those who have actuall done a stroker with SD and those who are armchair mechanics.

I like the idea jrwwhitmire had, the use of a SD computer from a truck with a 351. Also, an aftermarket chip to help with the new parameters would help too I am sure.

So, from those who HAVE built a mild stroker and kept SD, what say ye??? Go:No Go for launch?

 

The Gen 1 Lightning guys have this subject pretty well documented at Gen 1 Lightnings Forum

 

Do it! I've been there, done that and the juice is well worth the squeeze. If you're going to rebuild, it's worth the small amount of extra money to stroke a 302 to a 347, 351 to a 393, etc.

Here's my story:

The 95 F150 below was mine; I bought it in 98 with 81k and had it until 2002ish with 150k. When it started to burn thru some oil, I took it to a local race/mechanic shop for a basic pull and rebuild; I asked him to juice it up a bit. The guy asked me if I'd be interested in putting a stroker kit in it, and I said..."Well, you have my attention!" They took out the factory 351, clearanced the block for the increased stroke, put in a Eagle cast steel crank, resized the factory rods, Keith Black forged 9.5:1 pistons, surfaced and rebuilt the stock heads with new springs, seals, and 3 angle valve job, Crane CompuCam with new pushrods. Totally balanced and blueprinted. New water pump and high volume oil pump. Still had the factory tune, intake, throttle body, everything else was stock. Pretty basic build, really. I intended to replace the intake system and have JET burn a custom tune for me, but never got around to it. It completely changed the powerband of the engine; from 4k plus, it started to fall of, but it had MONSTER torque and response from idle right on up. It had increased the torque so much, that I nailed it from a dead stop and shattered the rear differential carrier around the bearing support- it made a loud BANG! Soooo....I took the factory Trac-Lock 3.55's, and had the same shop put in 4.10's with an Auburn Pro in back and an Auburn Heavy Duty limited slip in front. BIG improvement, and 4:10's were the perfect change using 31" tires. I was worried about the mileage difference, but in all truth, it really did not change a noticable amount at all. The truck pulled excellently, and would smoulder the tires in a doughnut that would make a Mustang jealous. I eventually had the E40D rebuilt (more preventative than anything...it wasn't dead yet), and had them put in a TransGo shift kit and heavier stall convertor. Eeeeevery now and then it would grab rubber in 2nd gear if you were into it hard. The truck ran smooth, and with true 2.5 duals and Flowmaster 50 series exhaust thru factory manifolds, would literally set off car alarms. No funky idle, no computer issues with the speed density system, nothing. It still used the factory radiator, and actually ran slightly cooler and at a more consistent temperature than before. I'm absolutely positive that an upgraded computer and intake would have really woken it up big time, but I was very impressed with what that truck did. It was a long time ago, but it felt just as ballsy or more than my black 1997 F350 with the 5spd, 3.55, 7.5L does now; heavier truck of course. If the 460 in my F350 ever gets sick, I'd have no reservation about going big with it..a 540 perhaps??? Of course with 21,000 original miles, it's going to stay stock for a lonnnng time.

The moral of the story is DO IT!!

 

One thing I didn't mention is that if you go with a 5.8 computer, you'll lose your knock sensor, 5.8's didn't use them, so the computer won't recognize it.

 

The bottom line with SD and a naturally aspirated engine is you can do anything you want as long as the maximum airflow potential of the engine doesn't exceed the adaptive limits of the stock EFI and fuel systems(~300hp) and the motor retains a strong vacuum signal. There are numerous ways to get there, you can change the heads, cam, or intake, you could add a stroker kit, you can even combine some of these depending how much bigger/better the parts are, and in all cases it's a given that the exhaust system is improved, but you can't do all of them at once.

The one exception to this rule is forced inducion, with it you could potentially double the engines output without upsetting the EFI system, but that's only if most of the engine remains stock and an FMU is used to increase fuel pressure.