A buddy of mine is wanting to build a mild 302 for his 1993 F150 2WD. He is looking for sporty power, and I dont blame him. Me and him discuss and I try to help him as much as I can, but I lack the knowledge on Speed Density.

He was telling me a SD does batch firing, which to me makes me think of my 1978 Porsche 924 which is every injector one one bank fires at the same time. That is how a 924 works, kind of. Even when the intake for that cylinder is not open it is spraying, anyways!

If that is so, then couldn't he run a 351 cam and make his engine a 302HO clone? He plans on running a roller cam. I dont blame him there I would too, but I am wondering about the 351 cam working with batch firing. Cause I know to tell him, that if he can he has to do the plug wires like a 351 or 302HO...

Also what are the parameters you would have to keep a cam in to keep it working with Speed Density well. He showed me a cam that is slightly dual pattern but not enough to make much more power than stock. And it seems kind of whimpy with E7 heads. Which in that case I told him to get a set of GT40P heads for it, since they have better flow characteristics. I also mentioned bumping up to 1.94 intake valves and 1.54 exhaust valves.

Hope you guys can help me help him. Thanks in advance guys!

 

Honestly, I can't help you much with the small block specifics, but yes, the batch fire is just as you stated. The injectors on each side fire in unison.

GT40 heads are a very good upgrade for the 302. I know Conanski recommends GT40 heads and 1.7 rockers on the stock cam which is one of the best cams for low end torque. If you want to swap cams for a new one, I think you want to stick to cams with an LSA above 113° which produce more than 12-13 in Hg of vacuum.

Your best bet is probably to do some searches of the forum and focus on advice from Conanski; he seems to be the resident small block expert around here.

 

Well as long as the engine is batch fired, then that means a 351 cam can be used and everything be fine. I just wanted to make sure the information my buddy gave me was right. I am trying to get my buddy to go with a Ford Racing cam. Truck isn't used to haul, so it can get away by a slight change in the power curve.

I am trying to get my buddy to save up and get some cheap aluminum heads, and up his compression, but he insists on Cast Iron, which is fine, if thats what he wants.

GT40 heads are great upgrades with the GT40P only really flowing a slight bit better with 1.94 and 1.54 valves. You also then get the whole problem of exhaust manifolds, usually with tube headers on a 2WD, will need dimpling while 4WD's, never heard of anyone having any luck, would probably need a special set of headers. Lol be a great reason to do some fender well headers! haha.

And I can't get my buddy to touch 1.7 rockers. He thinks they will make his cam loose vacuum... But then again he didnt believe me the only thing different from a 302 to a 351 and 302HP is the cam and firing order, he thought he would need a different crank and stuff to go with a 351 firing order cam.... ANYWAYS, I got allt he answer I really need, was making sure batch firing was what I thought it was, the rest from here I can do in my sleep.

 

Yes the injectors fire in batches but those batches don't correspond to the left and right banks, it's #1,4,5,8 together and 2,3,6,7 together, and yes that means he can use a cam with the 351/HO firing order by just re routing the plug wires. the stock motor in that truck has a base(small) roller cam in it so adding a better one is pretty easy, the cam must have at least 114deg LSA and no more than 210 deg intake duration at 0.050" lift, and total lift should not exceed 0.500". The stock '94+ truck/Explorer cam with 1.7 rockers is a decent upgrade, or the Comp 35-512-8 with stock 1.6 rockers or aftermarket roller rockers. COMP Cams Xtreme Energy Camshafts 35-512-8 - SummitRacing.com
A cam like this and full exhaust system really wakes this motor up, if he puts more gear in the truck there are a few other cams that he could get away with including the 5.0HO cam with 1.7 rockers or the comp 35-349-8.

GT40 heads flow about 20% better than E7s and the P version flow about 30% better(about the same as aluminum Edelbrock Performers) so both are a healthy upgrade and you won't have any header fitment problems with standard GT40s so that's what's usually suggested.

 

Maybe a little off topic here, but just how much can you do to one of the engines before the SD becomes an issue. I want to do a mild build to my 351W but I'm not all sure what can be done before a MAF swap becomes necessary.