the ellusive 352 sbc!

just wondered if anyone on here has ever put there foot down on one of the 352 small block chevy motors ive been reading about. ive been interested in the long rod motor theory and i know its a proven science but ive never talked to anyone that has actually put one through its paces......

 

I always thought a 352 chev was a 327 with a 3.5" stroker crank before they came out with a 3.48" stroke the 350's have??

 

I think the 352 cubic inch SBC he is talking about is a 400 SBC destroked with a 327 SBC crankshaft ... giving a big bore and a shorter stroke ... and room for a longer connecting rod. The large bore also unshrouds the valves.

 

Ahh...the OLD 352 was the ultimate 283 for those with enough money: Bore 283 to 4", with some risk of disaster, stroke to 3.5 with an expensive special crank. This was the ultimate before the factory started enlarging the SBC, the engine everyone with a '55 wanted.

 

Sumner has it archived for you here

 

I've got the block and crank. Plans are to put it in the '51 when I do the re-do. Strange, but this (and the similar article on the 351 that Ford should have built) were the topic of conversation just yesterday evening here at the hut.

 

Long rod small blocks kick ***.

That's all I'm giving away for right now.

 

Ever wonder why so many people have such fond memories of the performance they could squeeze out of their 265/283/301 small blocks?

I think rod ratio had a lot to do with it. Short stroke with the same rod length used for the bigger 327 and 350 makes for good power out of a small package.

I've always wanted to build one of the long rod 400 block/327 crank SBCs...maybe I'll get to before too much longer. Wonder how it woud run with a 6-71 on top of it?

 

real sweet- the timing doesn't need to be as harsh for ground pounding. easier on some parts such as rod bearings and valve seats...the big secret to long rod stuff is how long the piston "hangs out" at t.d.c. the only part you really, really need to pay attention to is a set of really good wrist pins-the ratio there makes for alot more movement than before. (well, comparitively speaking.)

if you were to apply the same theory to say...a guy with a wall full of Hemi's, He could build one serious sum***** of a motor for fractions of what a true stroker would cost.

My favorit of the bunch on the S.B.C. side of the fence is the 377- like a 383 in reverse. just big , dumb torque from a small motor.

The Olds variant using the deisel block and crank is a viscious ******* as well, but the compression ratio is really high...ethanol, anyone?

if the Buick bottom end was worth a damn against detonation, you could feasibly de-stroke a buick 455 and make good numbers.

Pontiac beat us to the punch and went ahead and built it themselves in the 428 Poncho (late 60's,early 70's) same power as a 455, higher revs, no super special parts, save for pistons with a higher wrist pin.

Caddy...there's a thought. have to look into that one. Problem is, there aren't many to choose from.

Ford. If good Ol' Henry had satyed with any one block design with as many displacement changes that weren't as all encomp***ing, the options would be very interesting.

Dodge stuff...I have heard of some of dodge's "other" motors being guinea pigged on, but the tight confines of a dodge block make for interesting issues when stroke changes occur.

I don't know enough about Studebaker engines to say either, or. but with the avalibility of so many different length aftermarket rods avalible, there has GOT to be some rod lenght changes avalible. I betcha pistons wouldn't be cheap, though.

I like engines....too much. I probably won't sleep much tonight .

 

Bruce Lancaster is correct. In the late 50s/early 60s, the 283 with +.125" overbore and the 1/2"stroker crank was THE small block combo to have. But, you couldn't rev it up like the 3" crank. In my hometown, the rumored 352 Chevy was Ronnie Patti's black on black '57 convert with column-shifted 3 speed. Don't know if it really had the big crank, but that ****er ran. vic

 

Not to veer too far off track here, but...

A 392 Chrysler already has a pretty good rod ratio of 1.78:1 since it has a loooong 6.951" rod. The 331/354 has an even better rod ratio of 1.83:1 with it's shorter stroke and a 6.625" rod. And with the Chrysler's deck height there's still plenty of piston above the wrist pin for some skirt strength.

Combine that with the efficient Hemi combustion chamber and thick cool-running castings and you have a motor that can stand gobs of compression on pump gas.

Chrysler was pretty far ahead of their time in the 50's when you really stop and think about it.

Chevy's lil' small block ain't too bad either though.

 

A couple of Ford motors have high rod stroke ratio's.

The 351M has a 6.58" rod and 3.5 stroke, for a 1.88 ratio. It was only made during the "smog" years with low compression and ****py valve timing. It was never a performance oriented engine.

The 429 has 6.605 rods with 3.59" stroke for a 1.84 ratio. Made with a few performance variants, the CJ, SCJ and of course the Boss was used in Nascar for a few years.

 

Can you help me understand why? I would think rpms and flat torque curves are all just a function of cam specs and cyl head breathing. There are plenty of heads on the market these days to feed a big inch sbc, unlike 25 years ago when the even best factory stuff was a bit restrictive for 350 ci.

Not trying to be a smart-***... just trying to understand your position.

 

I'm going to guess that with the longer rod, the energy keeps pushing the crank as it p***es 90* of rotation. With a shorter rod, that energy is pushing away from the crank centerline sooner, thus reducing efficiency sooner in the rotation.

Just a thought, though.... I'm no engineer. Hmm, didn't even sleep at a Holiday Inn last night....

 

Novadude-- Go to the link in the post by 53sled just above my post above. I've had that article on file for several years. I'm not a motor builder, but once I got the words straight and understood that dwelling "at" top dead center actually means dwelling NEAR top dead center, it all made sense. The link is to an article in Hot Rod, June 1997. There was an article on the Ford 351 in Fuel Injection Basics, but I don't know the date (probably around the same time as the hot rod article, and also written by Pete Saueracker). I have tried to reach Mr. Saueracker, but with no success. I would like to ask (1) if he had it to do over, would he change the formula and (2) what the engine was used in and how well it held up over time. If anyone here on the HAMB has the answers to these questions, I'd appreciate you posting. Thanks.

 

"at" and "near" can almost merge in long-rod engines...detectable movement (by dial indicator) on fairly long stroke ones can be so slight you can only place TDC within 3 degrees, which is why you have to use interference method, and I'd ***ume a short stroke one would increase the effect. I think part of the benefit is that the piston is exposed to higher pressures longer, as pressure drops rapidly low in the bore.

 

And I thought a 352 SBC was an old, tired, wore out 350 with tapered cylinder walls

 

And apparently now they're available in two flavors!

 

The guy that does my engine machine work has been building them for the roundy rounders because they really pull out of the corners and can run super high compression. It sounds like a great engine for the street with the cat piss gas we have now. I saved that Hot Rod article years ago too.

 

I built a 400 with a 327 crank for a friend years ago. His cl*** in racing limited the cubic inch displacement to 360 cubic inches. We found a 400 SBC block with only 2 freeze plugs per side ( forget the casting number ) ... most have 3 freeze plugs per side and are a dead give away on a visual inspection ... when trying to Bend the rules

Used a 327 crankshaft ( 3.25 stroke ) and rods from a 240 cubic inch 6 cylinder Ford. This was long before the availability of a bunch of custom rods for the SBC. Had a set of J&E pistons made with the correct pin placement for the rod and stroke ... Bad thing was finding connecting rod bearings. Had to use .040 over bearings for the Ford. Turned the Chevy rod journals a few thousands to match and make work. It ran real strong from the mid range on up. He got protested a few times but it always came out OK by the P&G Got the winner's check and the protest money too

The track went to a unlimited rule ... on displacement and then the 352 was too small ...

 

Stock 400 blocks ****... They crack on the front of the pan rail to the timing cover, steam holes to the center head bolt holes and then to the cylinder walls, thin cylinder walls because of core shift - not all. Four bolt mains are the worst ones. At least use a (509 casting) two bolt main block, or find a good used Bowtie block.

Big bore short stroke engines run AWESOME...Example Pro Stock drag racing. Just an example bore 4.690, stroke 3.550, rod 6.025.

I have saved enough parts to build one some day including the bowtie block which in my case has roller cam bearings.

Later - Eric

 

I understand the theory. I just don't believe rod length makes a damn bit of difference in the real world. Percentage wise, going from the shortest 400 5.565" rods to a 6.0" rod isn't a big change. I remember doing the math a long time ago, and piston position vs. crank angle for the two was barely different given the same stroke. Of course, in this article, they shortened stroke to 3.25", instead of the 'normal' 3.48 for a 350 ci chevy.

The long rod theory just never sat well with me, and struck me as more magazine BS. Then again, I've never owned one, so I really have no room to comment. You know what they say about opinions...

 

Around here the oval track boys were getting out of hand with big block chevys putting many compe***ors out of business. They couldn't afford the cost of aluminum blocks, exotic heads, etc, etc. So............. to combat the rising cost the big blocks were penalized with extra weight and the tire rule was limited to 12". Talk about killing an engine that needed 16"-18" tires to hold the corners. To come up with a combination we built a couple of 400" block/3.48" stroke/ 5.7 rod small blocks using factory parts and dominated the cl*** for over half a season until the experimenters fine tuned more expensive combinations to finally beat our cheap combination. with the lighter weight up front and the surprising power of the small block the big blocks would out power us on the straights and we'd get them 2 car lengths in the corners while the big blocks were pushing their way through the turns building tire heat on every lap.. Within a year the cost of racing was right back where it was with small blocks costing more than the big blocks and tire research made the cost of 10" tires right back in the range of the outlawed wider tires. Ain't racing fun?

Frank

 

400 bore with 327 stroke = 347.5"

Re: "327 crankshaft ( 3.25 stroke ) and rods from a 240 cubic inch 6 cylinder Ford"

Deck height: 9.025"
Rod length: 6.795"
1/2 stroke length: 1.625"
Maximum compression distance: .605" - this piston doesn't exist

I think you used Ford 300 rods?
Deck height: 9.025"
Rod length: 6.21"
1/2 stroke length: 1.625"
Maximum compression distance: 1.19"

Rod length is a really small variable, and most useful if there's something wrong with the basic plan (especially small ports). Most "comparisons" are not - there are more changes made than rod ratio, and both engines are not optimized.
Changes in rod length of less than 5% frequently don't show up even on a dyno. If you want to see something good, you need +5% change (SBC with 6" rod instead of 5.7" rod is +5.26%), and then modify all the existing tune-up stuff (LSA, CSA, plenum volume, spark, etc.).

 

This is interesting (even the parts I don't really understand)!

 

If I remember correctly,Sneaky Pete(Robinson)used a 352 in Chevy in his old AA/GD(the one with the jack that got outlawed because he was dusting AA/F cars).Watched him match race Garlits at Sanford Maine in June 1964(two days before I went in the Navy)and he damn near cleaned Big Daddy's clock.

 

as far as the olds deisel conversion yes they are nasty engines in a good way play with timing and a dremel tool on exhaust ports and power galore i ran methanol in mine and was very impressed.

 

We bored the engine .030 ... with head plates to get a good round hole ... and used the longer 240 rods. The J&E pistons were made up special and the pin was in the ring grove ... the pistons were fairly short ( light ) also.

Had a few engine that had to go .040 after wearing the cylinders out quickly ... On the dirt ... long rod ... short skirt piston ... high RPM

 

Street engine? I'd take a 400 block and put a 400 crank in it. Don't mean to rain a parade but 5.7 rods in a 406 really kick *** on the street. Big bore and short stroke long rod engines have great top end, but in a street car cubic inches (or blowers) are hard to beat. I've had 327s 350s 377s and even a 283. The 400 had the most bang for the buck.
Jeff