360 in YJ

[tufcj]

It's hard to say with just a head, manifold and carb swap. I'd say somewhere around 50-75HP over stock, providing the carb is dialed in properly. The 291 heads have a little better compression, but actually don't flow as well as later heads. They also have a slightly smaller intake valve (1.62" vs. 1.68"). I've found that AMC V-8s respond VERY well to mild porting. Money or time spent for porting is always worth it. Next is cam selection. An engine is a big air pump, intake/exhaust get it in/out, but you cam helps push it thru. If you stay with a stock cam, that becomes your restriction point. I've had good luck with the Edelbrock Performer cam in my 360, I've also heard good things about the Summit 8600 or 8601 cams. I run a Crower cam in my AMX, but it's way too radical for off-roading.

Desktop dyno for my 69 390 estimated 450HP. It's balanced, 10.1:1 compression forged pistons. It's got 291 heads w/stainless valves (1.68/2.025) with some extensive port/polish work. Crower stage 3 "street beast" cam 282/292 duration, .512/.525 lift. Crane gold roller rockers, R4B intake, Hooker super comp 1 7/8" headers (jet hot coated), run thru dual 2 1/2" exhaust with an "X" pipe. Carb is an Edelbrock 750. I also run a 2500 stall converter (auto trans), and 3.73 gears in the rear. As soon as I get the interior in, we go to the dyno to get a real measurement. It feels and sounds strong, so I think the estimate is close.

Bob
tufcj

[mika01]

Wow! 75HP over stock, I'd getting close to 300HP! Thats fantastic! Probably not much for some of the harder sore guys out there, but for someone who is ditching his 258 its going to be almost triple what I have!! Now if I could just stay of the little pedal on right!
Thanks a bunch
PS sounds like you have one hell of a monster on your hands.

[Mudrat]

Probably not much for some of the harder sore guys ...

Um .. some of us are not harder, but DEFINATELY sore Mika

[mika01]

Darn that fat finger syndrome!

[fjr1300]

I am also putting a 360 in an 88 YJ with a 999 auto, from what I've heard I can use CJ headers - is this correct?

Thanks for any info

[mika01]

Not long ago there was a Jeep rallye in CT and I saw a couple of YJ's with the 360 installed and yes one of them had the CJ headers. I believe they were the Headmens. He ran it with dual exhaust and converters. Of course the exhaust is going to have to be customs but it did work. Now that I think about it the passenger side botom header tube was dented to clear the mounts. I trial assembled mine (not Headmen) and they clear nice.