I was reading another thread when there was mention of de-stroking a 350 into a 302. Has anybody on here done this before? How did it turn out? What kinda power were you getting?

I'm growing interested in possibly building one. Anybody have info on this kinda build? Seen it done? Anything? LOL

 

You'll need an aftermarket crankshaft and different pistons. It also depends on which type of block you're talking about. One piece or 2 piece main blocks differ on how they can be destroked.

Why would you want to go down in displacement? Considering most engines should be able to make 1 HP per cubic inch, you'll be losing 48 HP with the smaller displacement.

The old 302 "race engines" were designed to run at 8000 rpm. Trying to run a high rpm, high HP 302 on the street is a poor choice. You'll never be in the powerband.

 

I was thinking of hooking it to a 5spd and making a roadracer out of it. A high RPM screamer.

 

Why not build a high-RPM 350 instead?

 

The theory of bore and stroke related to rpm doesn't mean much if you use the proper parts. I spin my 540 BBC to 7500 rpm.

 

My 406 is a road race engine, it can see 8k.

 

I think it would be a way cooler idea than building a 305, you can get a crank from a 283, or an L99(if your building a gen II motor)

 

The journals are too small on a 283 crank to fit into the vast majority of 350 blocks.

 

what about spacers, they were frequently used to install 350 cranks in 400 blocks ages ago, I don't see why it wouldn't work now.

 

If you want to build a 302 parts bin engine, look for an older 327 small journal block, the older 327 has the same 4.00" bore as a 350 with the same smaller main journal sizes as a 283 crank. The later large journal 327 block is able to accept a 350 crank (2 piece rear main seal of course).

Both the old 283 and 327 small journals had the tough steel cranks, damn good engines! I don't think that thre were small journal 4 bolt main blocks for sure or not.

Yeah you did have to scream those 302's to make 'em run. But if Mark Donahue were still alive you could ask him about how they beat up on Parnelli Jones' Boss 302 Mustangs most of the time in SCCA Trans Am road racing. Those Sunoco blue Z28's were owned by Roger Penske, and I bet he still has some good memories about it all!
But you have to remember, the rules stated no more than 305 cubic inch, 5.0 Litre displacement in the Trans Am series. So Chevy used the 4.00" bore with the 3.00" 283 stroke to get 302".

 

good call on the old 327 blocks, and your very right about the displacement rules.

 

It's not the mains that are smaller but the con rod journals. You can't use a spacer on the rod bearings. If you found a 283 crank that was in good condition and not cracked, you would also need the small journal rods.

Of course everything would need to be rebalanced etc etc because you'll be using the larger 4" bore 302 pistons. You'll be spending the same amount of money, if not more, on a smaller displacement engine that's using 50 year old parts than building a good 350 with more common parts.

 

58-62 283 casting had super thick cylinder walls that supposedly can go the distance all the way to 4". I just think it would be so awesome to pop the cowl induction hood on a third gen Z-28 and have a 302 with a cross-ram on top! but good luck finding a cross-ram right!
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I see what your saying, I just think it'd be fun!

 

Both are smaller. A 283 has a 2.30" main, a 4" bore block has a 2.45" main from 1968-up.
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Good luck finding some on the market today.
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It might look cool for a show car, but it would get beat every time by a properly built 350, 383, 400, etc. using something more up-to-date than 40 year old technology.

 

true, but it would still be fun. or at least I think it would be.

 

Depends on your idea of fun. If it's sitting around looking at cars with the hood up, then a cross-ram might be fun. If it's going fast, then the bigger, newer engine is more fun.

 

you have to admit, that with the right heads and cam it would be quick, probably pretty fast, no 406 by any means, but it would be fast fun and looks fun.

 

Race Engineering offered them. I think they still do. I think they were about $150/set though.

 

It's true I could make a 350 do the same thing, but a high reving 302 would just be a different, and fun thing to do. I enjoy building and putting cars together as much as I do driving them. I have built 350s and now a 383 so I wanna do a different kinda project. To me getting there is half the fun, plus driving it on a road course would be fun. I'd have the only 302 powered 86 Z/28 on the track. LOL

I may not be able to get a cross ram but a six pack, or two 4 barrels? I just wanna do something different.

I like the idea of possibly doing a gen2 blocked 302. Do they even make a six pack or dual carb intake for gen 2 engines? I've never seen one.

I got another question, if I did build a high reving 302, what kinda gas mileage would one of these high winding 302s get on the street?

 

well, as for the gen 2 302, get a L99 crank like I said earlier, and it put it in a LT1 block, I have never seen a multy carb intake for a gen 2 motor, I know that gmpp has a single 4 bbl intake for them though. gas mileage would be very driver dependent, I bet you could get pretty good mileage if you keep the rpms down.

 

Looks like they've still got them, but when you consider that $150 is the price of a new crankshaft that's arguably better quality than an old 283 cast-off, then it doesn't make a lot of sense to use them.

 

sorry, stupid question, but would a gen II L99 crank fit into a gen I block?

 

Yes

 

would that require a special balancer?

 

Probably not, depending on how you decided to balance it.

 

the main reason I ask didn't really have to do with the balance of the motor, but because the LT1/L99 had a balancer pully, like the LS1 has.

 

A company called HeartBeat City builds replica cross rams I've seen them go upwards of $10K !!!!!

 

I'm not going to lie, I would make my own intake before I spent 10K on one!
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their website has them for 5K

http://store.heartbeatcity.net/store...take-manifold/

 

A good combo is a 283 crank w/ a 327 block (same journals of course check your sizes) (mortec.com) use soem mid 1980's 305 HO heads some LT1 Z28 springs, pick your cam ( DZ302's ran 4000-8000 RPM) and rev it to the moon. Built right it'll run like crap <4000rpm but from 4-8000rpm (10,000) with the right parts it
it'll go like a raped ape!!!! There actually no fun around town theres alot of cam duration needed to replicate a DZ sound

 

I still think it would be an awesome ride! but $5k is alot of money for an intake!

 

Ok, I've done a little more research into the l99 crank Idea, the ain problem I haves found is that it uses a balancer pully like an LS1, because of this, none of your accesorries would line up...right? so you would prob have to adapt an Gen II accesory drive to a Gen I motor, where, another problem arises, no waterpump (gen II motors had the water pump driven off of the camshaft), which could be solved by using an electric water pump, but would an electric pump for a gen I clear the Gen II accsessory drive?

 

Use an SBC balancer on it.

 

http://store.summitracing.com/partde...0&autoview=sku there is an eagle 3inch forged crank.....

now i think this engine is a cool classic engine, but i would never build one for a street car.....only for a show car, or maybe some sort of roadrace car....302s are not good for making a car quick or at least the originals werent. Now ive quoted this a time or two when people have talked of wanting to build a 302 so here ill quote it one more time.

"The good news was that the car had greater flexability at the top of each gear and a higher top speed; the bad news was that a freight train could accelerate from a stand still faster....and perhaps quieter." written by Randy Leffingwell in his Ameican Muscle book when talking about the Cross Ram 302...... 290hp@5800 and 290lb-ft@4200 i guess is pretty good power...

 

according to the "Chevrolet small block interchange manual" pg 41

"the dual-mass front vibration damper found on externally balanced gen. II engines is a two-piece design, which incorporates the crank serpentine belt pully. these dampers do not interchange to gen. I smallblocks."

I'm not positive, but the pics I've seen of a gen II damper makes it appear to bolt on using three smaller bolts as apposed to being pressed on and held by a crank bolt.

 

You're not interchanging the balancer, you're interchanging the crank.

 

I understand that, but what I'm saying is, is that if you put a gen II crank in a Gen I block, you would need to use a Gen II balancer (the balancer that goes with the crank) and It appears to me (I could be wrong) that the belts wouldn't line up right, because a Gen I has the pully mounted to the front of the balancer, the gen II motor the balancer is the pulley. the gen I and Gen II balaners aren't supposed to interchange, and I don't see a way to mount a gen I pully on a Gen II balancer.

 

No, you don't. An LTx uses the same crankshaft as a 1 piece RMS Gen I SBC.

 

No it wont run like a raped ape. Those springs wont take 8k. Neither will the crank, rod bolts, rods, etc. The entire bottom end would have to be built bulletproof to take those kinds of RPMS. 10K?? Yeah right.

 

Stephen 87 IROC I agree that you can make any motor turn high rpms, but I bet you had a ton of cash in your 540 to get it to turn 7500 rpms. I disagree with you however about bore and stroke relating to rpm, in a 302, the pistons don't have to travel as fast or far as they would in a 305 to turn the same rpm (mainly a durability factor), also, a bigger bore allows for bigger valves with less shrouding.

Apeiron, I thanks for clearing that up for me, I though the gen II motors had a completely different balancer than all of the Gen I motors.
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I've always wanted to make an older cavalier rear wheel drive and put a smallblock in it, I bet a 302 would be a great motor for it.

 

I've heard that those motors would just keep pulling harder up until 6500 rpms. but I've never driven one, and I'll prob never have a chance to drive a real one. they weren't built for low end torque thats for sure!

 

yeah i wouldnt be surprised if they kept pulling till around 6500, thats just the official ratings, they were good motors in their days, and today a 302 could be built to be alot more powerful and turn even more rpms, but i just hope someone wouldnt do it for a street car.

 

In a street car, the stroke is pretty much irrelevant as RPM's are dependent upon the valvetrain. High RPM's require airflow. Engine won't spin higher if there's no air to supply.

 

What are your spec's and how often do you take it down to refresh?

 

SB2 heads 011 castings from '03
Bowtie block
Bryant crank
Carrillo rods
JE pistons
Custom SR cam/50mm roller cam bearings
Dry sump
Long list, not very fun to type.

Gets torn down about every 6-800 miles. Depends on how hard the RPM's are.

 

That's all irrelevant unless you're comparing engines of equal displacement but with different bore and stroke.

They do have different balancers, but we're not talking about balancers, we're talking about crankshafts.

 

Ford had a successful 302 so there is no reason you cant build one too. I have been tempted to build one for years but have never come across the 327 block and 283 crank. You can build a decent 302 with out spending a fortune as long as you forget about 8000 rpm.

 

Gee, stekman, that kinda sounds familiar. Kinda reminds me of this:

https://www.thirdgen.org/forums/engi...t-fiction.html

Talk about a long time ago, huh?

 

And yet everyone puts a 351 in their Mustang.

 

[quote=Apeiron;3994095]That's all irrelevant unless you're comparing engines of equal displacement but with different bore and stroke.
quote]

I was refering to motors of similar displacement.

as for the ford 302 not being successful, it would have been very nice of ford to throw a 351 in the fox bodies factory, but those 302 motors aren't that bad, there are quite a few running around here that are pretty fast.

it's funny though, any time ford wants a bigger motor, they just change the deck height and screw everything up for the guys who want a bigger motor, but dont have a small fortune to get special headers a new intake, a new distributor, ect..

 

Funny you mention that LJ, exact thought crossed my mind earlier.

I thought we came up with that thread for reasons just as this...