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Boss 302 / Clevor Advice!

12K views 17 replies 14 participants last post by  65fasback  
#1 ·
I've been researching these for a couple years now, so I know what needs to be done in terms of machine work on the heads and block, and the deal with the different C heads.

I've been trying to get a build plan together recently, and am looking to hear from anyone here who's built one or has a lot of knowledge about them. It's going to be going into an 82 fox (whenever I find one), and is going to be mostly a street car. I'm hoping to break the 400hp/tq mark at the flywheel, peak torque around 3500ish RPM.

I'm going to keep the stroke to 3", but will probably bore it to 4.03", to bring it to 306. KB-Silvolite supposedly makes a piston set that works for these, and uses the stock length rods, but I haven't called for details about them yet.

I found a place in the US that sells the aussie 2V irons, assembled for around $1200 a pair, and ported for an extra $500. I plan to use these, unported, but may get them ported if it's needed for the results I want. If I remember correctly they'll even machine them for the W block before shipping. I know the stock heads flow alot, and I should be able to get 400+ hp out of them with the right setups. Yes, I know about the CHI 3Vs also (I know somebody is going to bring them up), but I can't justify $2600-3000 just on the heads, even if they are the best.

I'm going to use the Edelbrock E-Boss 302 intake, as it seems to be the best option for a street purpose car, topped with an 800-850 Holley. I called them up the other day to try to get flow numbers on the intake but they wouldn't give them to me. The rep did agree with the carb size though. If anyone has any info on these intakes, or any input in general, I'd like to hear it.

The cam is where I'm having the most trouble. I've never been very knowledgeable in cam selection. I want to run a solid roller. I've been using an engine dyno program to assist me in that regard. According to the simulations, it seems low duration (200-215) works the best. I've heard the Cleveland heads like lots of lift. I think a Cleveland based cam on a 302 stick with less duration would be the best way to go? Any advice here would be appreciated also.

I've also heard the 4V heads can be streetable with the right setup as well. I'm not opposed to the revs, as long as it makes good low-end torque. I'll definitely spend time in the higher RPMS if there's power there as well. If anyone knows any streetable 4V builds, a screamer that isn't a pig down low, I'd be open to hearing them as well. Or just any build any of the members here have used.

The headers are going to be a PITA. I'd rather not have to get a pair custom made if it can be helped. Any tips here?
 
#2 ·
Doing a Cleveland in a Fox Mustang is really hard, 20 years back there were a couple of header choices. So finding headers will be tough, and the intake of course also.

The Aussie heads are 2V heads with closed chambers, good moderate heads. The 4V heads need(require) a lot more rpm than any other SBF heads. The reason people bash the 4V engines is due to bad(very bad) parts choices, trying to build a 5500rpm engine with 7000rpm heads. The 4V heads flow so well, stock, that 7000rpm is about the sweet spot to shift, for a 351 engine(not 408 or 302 etc). On a 302, they'd need 8000rpm to be wise to use, they will be soft on the bottom end because the head flow is so high and the intake and cam are mild rpm parts. Out of 100 351C 4V engines you might be able to find and test, 90% of them will have under 6k red lines, and all of them you'd say have a soft bottom end etc. But the small number of them which shift close to 7000rpm, those will be monsters. The 4V heads are the best small block head ever made, but they are not for mild or moderate engine builds, they need high rpm.

So decide on a shift point and redline limit. If you will push 6000rpm, the 2V heads will do great, those are better than 80% of aftermarket Windsor heads. GT40 heads of all types don't flow what the stock 2V heads do. They are over 225cfm I'm sure, but I've never tried to find or remember those figures. The 4V heads flow 250-275cfm unported, and in some stock racing class, people have gotten 350cfm from them(unported, they are only allowed to play with the valves and seats, areas next to the seats(those are .500" lift cam classes so .700" lift doesn't matter)).

The intake you should be aiming for a high dual plane, such as the RPM Air Gap made for the Cleveland or Windsor. I don't know if they made that for a Boss 302. The stock intakes were all mild dual planes, I wouldn't bolt that kind of intake to a Cleveland head. For your torque peak, learn to notice that the TP is usually 2/3 of the power peak. So if you have a 6000rpm power peak, the torque peak will be above 4000rpm. If you do what Ford did and choose milder parts to get the TP down, that won't make you happy. Please don't try to build a 5k mild street 302 with big heads, just to aim for a 3500rpm torque peak.

Cleveland heads needs different cam events than any other SBF heads, find a Cleveland cam expert. Don't guess yourself, and don't rely on software made for common Windsor heads to select a cam. The heads won't like it and you won't be as happy as if you paid for a proper C cam.
 
#5 ·
as i said before 2V heads are GARBAGE compared to 4V heads ... it is a complete myth started by aussie's & those that dont understand the 4VB head design that factory 2V heads are better than 4V heads...


500-550hp is not a problem with the right parts/intake on a 4VB 302...
 
#8 ·
351C-2V heads are great heads, but they are not in the same league as 4V heads. 2V heads are far better than any Ford Windsor heads, only high dollar aftermarket heads can match or better the 2V heads. But the same issues exist for those 2V heads, they take special cam events, and need better than a mild intake manifold. Nobody ports them, few people deal with Cleveland's at all. They can be ported well, but they're in the size range that makes them similar to aftermarket Windsor heads, lower rpm limits than the 4V heads.
 
#14 · (Edited)
It's not even going in a '69 or '70 Mustang he's trying to make a Boss clone out of. Seems like a lot of work to have a factory iron headed 302 in an '82 Mustang he doesn't even own yet.

Are you a teenager? That's not meant to be offensive. There's nothing wrong with not yet having your spirits crushed by reality. When I was a teenager I had all kinds of crazy build ideas I had to be talked out of.

My 306 put 324hp @ 6070 RPM to the tires with $1050 worth of old school TrickFlow 170cc heads (that's how much a pair cost back in 2012 or so). I don't know what that translates to at the flywheel but it's probably not far from your goal of breaking 400hp, and it was significantly less brain damage than what you're trying to do. There's better heads now than back then. 190 11r heads and a custom cam should put a 306 well over 400hp.
 
#15 ·
I have to agree with others on this post...it's one thing to be creating such a build for an early mustang, but for a foxbody, and the head budget mentioned, you'd be much better off with a modern aluminum head. Your intake, cam, and header options are considerably better too.
 
#16 ·
now hold on a sec, im not saying cleveland heads are worse... by far they arnt, not to many heads can boast of 400+ cfm and still be streetable... im just saying they arn't the cheapest way to make power anymore

to the OP... go with the blueprint heads for their 408, they make 440-480 hp and gobs of torque and are cheap, they sell them as heads by themselves