Hot Rods Building a 302 small block chevy

I'm building a 302. 283 block (bored to 4.00") 3.00" forged crank. I want to use 6.00" rods. now the snag- Pistons with a standard deck height 9.015 block-6" rods 1.5 stroke, I need 1.5 compression height pistons. I can't find them. I read on here to use standard 350 pistons but they are 1.560 compression height. Help

 

CP, JE, etc will make them. Just different # on the to change the pin height. It’s either that or a slightly shorter rod lengh.
If your starting from a 283 and want to be 50-60’s correct. Call it a 301. Old guys know what they are.

 

I built a similar setup before. I used 350 pistons and cut .060 off of the deck of the pistons. They were forged so there was plenty of deck to do that with. Your pistons may be different.

 

I am one of the "old guys" mentioned and when much younger built a number of 301s and later 377s. Their attraction is the quick revving and fairly high RPM potential. Now I mostly build long rod 406s, so I am not against using them. However I personally would not use them in a 301. When Chevy introduced the 302 so the Camaro could race in SCCA they had a pretty clean slate and didn't go the long rod route. Must have had a reason.

 

Following!

 

Long rods help with rod angularity issues on long stroke engines, but are not really needed on short stroke engines. Why make life difficult for yourself for little gain?

 

I’m with Jim,,,,,,6 inch rods are useless in that combo .
You won’t realize any gain at all,,,,,,but will spend more -money for the build .
That engine will be a high RPM monster,,,,you don’t need the extra rod .

edit,,,,,,,Jim didn’t say they would be useless there,,,,I did .
Jim is much more tactful than I am,,,,LoL .

Tommy

 

Back in the day, guys would bore the 283, 1/8" over, 301 cubic inches, get the oversize diameter pistons, put it back together and make some noise.

 

Been mulling over the same 302 project, I got a good s.j. 327 block and 283 crank but don't want to bend over for the nuts z-28 302 piston price
You might want to mock up and check your block and may find the pistons top dead center at about .020 down on a standard factory undecked block.
A 400 small block I recently checked ranged from .020 down on #1 cylinder to .028 down on #8 cylinder
So those two factors could get you .030 closer.
Also found a Silverlite cast 350 piston UEM-1436 with a compression height of 1.540, that gets another .020 closer.
If all the stars aline your now only .010 over the block deck.

Norb

 

Ross, Arias.. others have pistons, Arias spec sheet has numerous dimensions you specify. Give them a call. Arias blank was same part number my Dad ran in 1976.

 

Arias is now at CP Pistons. CP has a great listing of “off the shelf” for so many combinations it’s unbelievable. When Nick Jr was alive every GMC piston I ran came from him. Now I use Ross. Every manufacturer I have ever used has been good even back in the 60’s when I started with Tom Toros at Venolia.

 

Serious tuners have spent untold hours flogging engines with longer rods on dynos and the track..After trying different cams and even port changes there are small power gains that could matter in high buck racing...But not for the average garage builder..

 

OP has not been back since starting this thread.

 

It's true they used the 5.7" rods.

 

I'm using 5.7 rods in my current build. I like older long skirt TRW pistons as well. My current build has Std Bore TRW 302 pistons, old Alum Super Rods, GM steel 283 crank. I recently gave away a 67 sj camaro MN fresh 0.030 block with sj 302 nitrided crank, Alum Super Rods, Arias Pistons.

 

I bought a crank from the late great " I am Butch" for a 301 302 old school build a few months later he e-mailed me saying I needed radiused bearings, not familiar, fill me in please!

 

Racing prep, cranks would have larger radius in rod throws. Check with "Competition Products" catalog on line, ...bearings have great descriptions.
I just put a set in my 406 for a Stealth Crank build.

 

Pick the ring pack you want to use and then use whatever rod length that attaches the piston and crank together.

 

Dead set and hard headed???.. Maybe!

 

Those wanting to build a sj 302. Look for a 283 truck engines.. farm, commercial trucks, they can have a 302 forged steel crank single notch flange. Military vehicles too.

 

I don't care if OP gave up or not. It's good discussion.

Most info I've found, long rod matters more with longer strokes, the benefit is reduced side loading. Most of benefit is at high rpm for sustained use, piston speed comes into play. How many of us are building for 8K + rpm for sustained use.

I'd be inclined to spend money on heads first, then get the lightest rotating assy I can afford, before I specifically go for 6 or 6.125 rods. Also prefer stable ring lands versus very short compression ht pistons for long rods.

If a 6" rod works for the combo, I'll use it. I wouldn't add it just for the hell of it then pay up for rods, pay up for pistons, and have to run a very short piston with questionable ring seal.

 

I am liquidating (friend died) a 50 year collection of trifive cars & trucks and about 25 motors because of this discussion I will be checking for worthy blocks that I was just going to scrap.

 

I watched an interview with Dave and Ben Wenzel a couple of days ago regarding their 67 Z28 stock eliminator car which Ben bought new in 67. Dave stated that to get the 302 c.i., the bore from the factory was 4.002", not 4.00". Never heard or seen that stated before. The factory also increased the stroke to 3.005". Otherwise it would have been a 301 c.i. Doesn't really matter, just thought I would mention it. I did the math (which sometimes is reliable) and came up with 302.3 c.i.

 

What is on the print...+/- that would be the factory tolerance. NHRA also had tolerances on stroke, obviously shops stroked to max tolerance, some shops advertise their cranks that way.

 

302 cubic inch was important to meet the 5 liter engine size for some racing series, I believe.

As opposed to the back yard builder who just wanted some easy additional cubic inches from their high revving small block.

 

I recall reading it was for the TransAm racing?

 

Hope the OP knows you 'can' run pistons that are proud of the engine deck!
Also.....Cometic makes custom thickness head gaskets ( they are proud of them though!)
6sally6
Long running debate on the long rod theory...... I like the idea of light/short pistons on the end of the rod.
Less reciprocal weight is less weight to sling around at *+ grand!

 

Dyno would show +/-, Air gap intakes were Zero Gain. Just good for fuel anti percolating.

I suspect rod length changes location of what RPM peak torque occurs, no net power change.

 

Wait a minute ,,,,,,worthy blocks you were gonna scrap,,,,,,,this does not compute !
Please sell them to someone for scrap price before just destroying them .
Put them on here and pay it forward,,,,,charge shipping cost only .

Tommy