I just had my 360 built a year ago, and im unhappy with the performance. Ive been thinking of starting over and building a 408 or maybe a 412. I know you need a stroker crank. i just want to know how it works to provide more ci. also what clearance work has to be done to the block?
what des it take to stroke a 360 to 408?
- Thread starter tonyp1987
- Start date
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64physhy
Well-Known Member
What StrokerScamp said. And for clearancing, you'll have to do a little at the bottom of the piston bores for rod clearance if you use H-beam rods. I think I-beams will clear, but I'm not sure.
caferacerx
BAND MEMBER
$$$$$$$$$
412 Stroker
Well-Known Member
What are the specs on your current motor??? Honestly i just did the 360 to 408 thing, well mines 412" but anyway if you do it right it is expensive, I have around $6000.00 in mine. maybe thats high?? not sure, but I AM HAPPY with the results, have not had it to the track yet, but seat of the pants from the old 360 to this is incredible, but there is nothing wrong with a correctly built 360 either. Maybe you need bigger cam, etc...
Ive got a 360 with KB 10.1 pistons, oregon cam grind 474 lift, avs 750, edelbrock air gap intake,340 exhaust manifolds. i have around 4000.00 into this motor, and im not happy at all. I wish i could just start over. i just purchased a comp xe 268 cam and now i feel like i should have went bigger.
UOP
Well-Known Member
What heads are on it? Exactly what kind of performace are you looking for? It's entirely possible that some new heads and cam will get you where you want to go without the added cost of tearing into your fresh shortblock.
caferacerx
BAND MEMBER
412 Stroker
Well-Known Member
Well I might be wrong here, but those manifolds need to go IMO. To make good power it has to breath, HEADERS. and a crossover tube (equilzer) in the dual exhaust, and like UOP said what heads do you have?? valve size, torque convertor, you really have to build a motor with a big picture in mind or it won't work the way you want it, did you have it balanced?? is this a strip motor or a street motor?? give as much facts as you can on your current build.
I certainly agree with this. I would add headers/exhaust and see what you've got. If that is not enough do some head work or add aluminum heads such as the Eddy's. These upgrades will not go to waste if you do end up going to the 408. I haven't looked recently but both Comp Cams and Hughes Engines had some dyno results from various combinations. I know these articles are still on Hughes' site for reference (360 and 408 combos).
ps you might want to look at gearing too but more info is required on your intended use and expectations
moper
Well-Known Member
What about it don't you like exactly? Has this been run at the track? What is the rest of the cam specs on that Oregon cam?
64physhy
Well-Known Member
For that cam, and if the heads are relatively stock, a 750 might be too much for it, especially on the low end. The XE274 cam would be a good choice for all around performance, depending on the heads and compression ratio. The 750 would probably work better with that.
sorry i knew i was forgetting info. I have 2.02 1.60 cast heads. they are ported and polished and bench flow tested, Im running a 3.23 SG in my 8.75, i just purchased a set of used headman headers of this forum, i plan on going to 3.91's as soon as i sell mine and find some, im also running a stock 340 high stall. This car was originally a 273 car so someone before me had dual 2" with an h pipe put in. I am running 2.5" flowmaster super 40's with no tail pipes (Im getting lots of exaust inside the car). The guy that built my motor had the first cam go bad. so he got another regrind and now he was telling me that the pushrods are not long enough so he put stack adjustable rockers on and has them all the way down. I bought the new cam so i can run the stock hydraulic valvetrain. This is the second block ive had since building this motor cause the first one i purchased off craigslist was a used 30 over block with a hone job and was sold to me *** a fresh 30 over bore. so i had another block done. Ive had alot of bad experiences with this car.
Originally i wanted a good streetable and occasional race motor, but now im wanting to go for mostly race and summer weekend cruising. My car runs like crap most of the time so putting up with a streetable car is no biggy anymore. I just wanna go fast. lol. I would be happy with mid 12's.
64physhy
Well-Known Member
The 3:91's, a bigger cam, and some headers will wake it up without going to a stroker. Don't know what intake you have, but an Airgap would help too (with the other stuff). If it was just rebuilt a year ago, there's no sense in rebuilding it into a stroker, unless you have deep pockets.
412 Stroker
Well-Known Member
Ok, well first off dont take this the wrong way but whoever the guy is that is working on your motor scares the crap out of me, "The guy that built my motor had the first cam go bad. so he got another regrind and now he was telling me that the pushrods are not long enough so he put stock adjustable rockers on and has them all the way down. I bought the new cam so i can run the stock hydraulic valvetrain." this means the geometry of your valve gear is waaaay off, you bring up the rpms on this motor and you gonna scatter it or at least bend some valves, and if they hit the pistons...... what kind of a mechanic puts a motor together and doesn't check pushrod length?? even if you get a different cam most likely you will still need the correct pushrods, you need to do this BEFORE you go much further, maybe you'll need to find a different mechanic, where do you live?
moper
Well-Known Member
I was pretty sure there's more to this. What pistons were used? What exactly was done after the first cam went bad? I'm thinking you really don't know what you could have because of many things that might have been done better.
i live in portland oregon, this guy is just a backyard mechanic that was introduced through another guy i met. the machine shop told him that the cam went bad because there is no zinc in the oil anymore and now hes telling me that i have to run this 15 dollar additive for the zinc every oil change.
He told me that he used keith black 10 to 1 pistons with valve reliefs and file fit rings. I think they are forged. when the cam went bad the lifters did too.
412 Stroker
Well-Known Member
You really dont have to add additive except for the first 20 minute run it, i used Comp Cams break in oil for the breakin on the cam then I changed the oil and am running Valvoline VR1 racing oil which has zddp already in it. but you do IMO need the zddp with a flat tappet cam, not so with a roller.
dodge freak
Well-Known Member
Sounds like it should be alright. What is the gear ratio? If its 2.73 no wounder your displeased, a 3.55 would be great.
If its an auto trans a 10 inch converter would be a big help also.
dodge freak
Well-Known Member
Ok, I just read the full thread:read2:
I agree, what is up with the cam and pushrods. Cams going flat the metal can get on the pistons and bearings.
It should be a fun car with 3.23 gears and 10 to 1 pistons.
What is your cranking psi and vacuum at idle? How is the ignition system? Wires, dist, spark box etc. Old plug wires can cause missfires you may not feel but will cost power.
I agree, what is up with the cam and pushrods. Cams going flat the metal can get on the pistons and bearings.
It should be a fun car with 3.23 gears and 10 to 1 pistons.
What is your cranking psi and vacuum at idle? How is the ignition system? Wires, dist, spark box etc. Old plug wires can cause missfires you may not feel but will cost power.
moper
Well-Known Member
So what was done after the cam went bad? The engine should have been completely disassembled to bare block, cleaned, and then reassembled. If this wasn't done there could be damage to rings and stuff that is causing a severe drop in performance. I am also interested in what it has for cylinder pressure. It sounds like there are problems throughout the process. The size of the engine isn't holding you back. The execution of the build is.
412 Stroker
Well-Known Member
Moper you said it best: "The size of the engine isn't holding you back. The execution of the build is. until you find out exactly what you have or don't I wouldn't put too much more into it, you might need to redo it after all, and at that point the 408 IMO would be the way to go.
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