[jerethei]

im looking to build a 305 (they dont allow 350s) for my circle track car. i am limited to stock parts, and only a .030 overbore.
pistons must be cast dished pistons
cam is a .420 lift rule
i have 601 or 416 casting heads no vortec heads
stock aluminum intake manifold and must run a q-jet carb
I cannot gasket match or port.( no grinding of castings allowed )
the rules are very strict. i would like tips on the best pistons to use with the shallowest dish, the best cam to run (nonroller flat tappet hydraulic lifter and custom grinds are ok)
which bearings are best. the best bearing tolerances to use as well as end play would be much appreciated. also i have a 1 and or 2 piece rear main seal block which is best

the car is an 81 monte with a turbo 350 and 2.73 gearset run solely in 1st gear

the track is a 3/8 mile banked clay oval with medium to high bank

any and all info would be much appreciated

[vinniekq2]

can you use a 302?

[jerethei]

sadly no i cant use a gm 302. strictly a 305 in a gm car, and only a 302 ford in a ford car. i cannot intermarrage motor to car or id run a FORD 302 in my chevy ha. i can however use internals from different engines as long as the dimentions are similar. like using a 350 crank but they are heavier so i wouldnt.

[vinniekq2]

A 4 1nch bore would be nice. What about a 283 block bored 060 and a 3.1 stroke?

[Cridder]

I used to 5 angle grind the intake seats with the 5th angle basically being a plunge cut to open up the throat, Id flow it on the bench and pick about 20 cfm, pretty decent. theres no grinding so technically its a strait up valve job.

Many stock Chev heads have a horrible short side radius on the exhaust port, the 305 is no exception. There's a corner cast in there or just left behind by production and you can feel it with your finger, i used to grind this out, leave it with a rough finish, once the engine is run this mod is undetectable as the port gets carboned and looks like a normal port.
now she can breath a bit better.

Run your lifters at or very near zero lash, pry the clips out and put in 3/4" cir-clips, your cam can now behave a little like a solid on the top end and theres no pump up of the lifters.

try and make compression anyway you can because this will pull you out of the corners, factory 305s come with tin head gaskets but the aftermarket don't sellim, you can use 350 tins and they should still work.

You can dish a 305 flat top no problem on a lathe, pretty much all dished pistons are machined flat tops anyway, any good machinist could put a small dish in your set for you in about an hour and a half.

[jerethei]

Thanks for the tips. the pistons have to be cast dished pistons I have read that 96 and newer vortec pistons have the shallowest dish is there any others with shallower?

[cobalt327]

Originally Posted by jerethei

im looking to build a 305 (they dont allow 350s) for my circle track car. i am limited to stock parts, and only a .030 overbore.
pistons must be cast dished pistons
cam is a .420 lift rule
i have 601 or 416 casting heads no vortec heads
stock aluminum intake manifold and must run a q-jet carb
I cannot gasket match or port.( no grinding of castings allowed )
the rules are very strict. i would like tips on the best pistons to use with the shallowest dish, the best cam to run (nonroller flat tappet hydraulic lifter and custom grinds are ok)
which bearings are best. the best bearing tolerances to use as well as end play would be much appreciated. also i have a 1 and or 2 piece rear main seal block which is best

the car is an 81 monte with a turbo 350 and 2.73 gearset run solely in 1st gear

the track is a 3/8 mile banked clay oval with medium to high bank

any and all info would be much appreciated

Use an inverted dome piston w/a tight quench. KB sells a 10cc dish like this but you may be able to find a smaller dish elsewhere.

There are lift rules circle track cams by several manufacturers. I like Isky for circle track, but there are others that are good, too. The duration is what you will need to look at the closest, along w/the intake closing point. You'll probably find that a relatively close LSA will work well but I wouldn't go overboard w/it. Something in the 104 to 106 degree area is where I'd start.

I'd use a short travel hydraulic lifter and very little preload even though Crower makes a cheater (their word) lifter that looks just like a hydraulic but is a solid. No need to cheat- this sounds like a drivers class anyway, and if you go flying by everyone, you will get protested and torn down w/o a doubt. And if the scrutineers are worth their salt you will be caught.

There are fast bleed down like Rhodes and Rhodes V-Max lifters that could be useful for lowering the duration seen at the valve. Even though they also lower the lift, it's the loss of duration on the bottom end (you get it back above 3-4000 rpm) that would help more than the loss of lift will hurt when using a cam that has a ton of duration @ 0.050" lift. It would allow you to pull harder off the corners, while allowing for more top end than you could ordinarily get using the same cam w/normal hydraulic lifters. These lifters are also used where there is a vacuum rule because they increase the vacuum over a normal lifter at idle.

Note- There are other thoughts on lashing hydraulic lifters as well as camshaft specs. Study the subject carefully and see what you come up with.

I'd want 0.080" wall pushrods, screw in studs and guideplates and a spot on valve train geometry. The rest of that page has a number of points that need to be checked, too.

There are authorities on reworking 305 heads for max performance that hopefully will add their thoughts so I'll leave that to them.

Use as accurate of a rocker arm ratio as possible. This can make a big difference considering stock rockers have been measured to have as little as 1.35:1 ratios! You're already lift limited, so you want to keep what little you have. Instead of GM rockers, look into a set of Crane stamped rockers. There are others as well, but Crane is what I have experience with.

The carb could fill a book, suffice to say it needs to be spot-on and tuning it will matter a great deal. Be prepared to go to school if you don't know them well now, or to pay a good chunk o' change on a custom unit from Ruggles or Jet.

Ignition timing may also be important if the engine is cycling from relatively low to high RPM during the course of a lap. But if you are maintaining at least 3000 rpm, the timing really only needs to be set to the max power timing and left there. You might try experimenting w/a curve to see if there's something to be had, but don't be surprised if the lap times as as good w/the timing locked. No need for a vacuum advance, so remove it and use a lock out plate in its place. These were on production vehicles for a couple years during the '80s, but you can buy or make one easily enough.

The exhaust system can fill a book, too. I would give a hard look at using a single exhaust system. They can make superior low end torque and are lighter. Otherwise, use a crossover and if you have to run mufflers put them as far to the rear as you can.

There's just soooo much more, but given the scope of an internet post, that's about it for me. I'll end by saying that handling is as important- if not more so- than hp.

Good luck.

[BigEd36]

Too bad you can't use a 307, I would take a 307 over a 305 any day.

jerethei, post your rules or a link to your rules if you can, it would help us help you.

That's a weird piston rule, I've seen rules requiring a dish or flat top piston, but never a dish piston only rule. If allowed, a d-cup/reverse dome style piston like Cobalt327 mentioned would give you the best quench. In the KB listings the KB145 hypereutectic has a 12cc D-cup dish (it's the only dish piston I see listed). Is there a compression ratio rule? If using a brand of cast/hypereutectic piston other then KB be aware that many of the pistons have the "rebuilder piston" shorter compression height and would need extra block decking to get the piston's deck height where you want it for a good tight quench.

As far as running a 350 crank in a 305, the main factor in the heavier weight for a 350 crank is because of balancing for the larger (heavier) pistons in a 350. A 350 crank balanced for 305 pistons will need weight removed, which is MUCH better than having to have heavy metal added to a crank. If you ever need to have a bunch of heavy metal added to a crank to balance it, you may want to be setting on the commode when you get the bill, 'cause you're gonna sh**!!

Cobalt 327 has already mentioned Isky cams, which are good. Howards Cams also make lift rule cams, and has a pretty extensive listing of .420 lift rule grinds, most have multiple choices on the LSA of 106*, 108*, 110*, or 112*. Check 'em out here, scroll about 2/3 down the page to the lift rule cams. There's enough grinds that it would take 2 screen shots for me to post just the .420 lift cams as attachments. For a reasonable price you can have them grind whatever you want. Don't get carried away with the duration, remember the rpm ranges in the cam listings are for 350's, a 305 will move the band up a few hundred rpm. Unless you have a vacuum rule I don't believe you'll get much benefit from the Rhodes style lifters. I've raced on quite a few oval tracks, usually the revs only vary about 1000 rpm. Once you're under green I don't think you'll drop the revs enough for the bleed down feature to come into effect, unless you're geared too high. With 6.88 overall gearing (your 2.73's times 2.52 low in the TH350) that shouldn't happen. Actually, 6.88 seems like quite a bit of gear for a 3/8 with high banking, 2.56 or 2.41 ratios may help keep the engine in a better range in the power band.

I'll quote Cobalt327 because this needs to be emphasized: "handling is as important- if not more so- than hp." From what you've told us (and without seeing your rules) I suspect you're very limited on chassis mods and tires allowed, either DOT tires or a narrow, hard, hockey puck style tire. Once you have enough HP to spin tires, more HP only makes your car harder to drive. Especially if your track is normally dry-slick it doesn't take a lot of HP to run up front. A good driver in a good handling car with a solid engine that can finish races without destroying itself or overheating will put you with the leaders at the finish.

[cobalt327]

Big, the KB186 is spec'ed at 10cc according to Summit. Click on image for full description.



I found it odd, too that they specifically call for a dished piston. And a Q-jet instead of some type of 2-barrel.

I wonder if dishing your own piston would be allowed- or tolerated. If this is like so many other "hobby stock" classes, almost no protests are lodged because the whole lot is illegal in one way or another, so no one wants to be the one to cast the first stone.

[jerethei]

Hibbing Raceway - 2012 Pure Stock

There's the web address to my rules they are trying to pass using the Holley 500 2 bbl but so far its quadrajets my main goal is to make enough power to be able to run 2.56 gearswith the Turbo 350 and 215-70-15 avg size tire

[BigEd36]

The KB186 is for a 3.75" stroke with 5.7" rods. In a .030 over 305 it'll be a 334! The Summit listing doesn't show the same picture as shown on the KB website, wonder if the pistons have been changed recently. The attachment shows the KB listing for the KB186, the picture shows a very different piston than the Summit listing.

[BigEd36]

Wow! These rules are really serious about keeping things pretty stock. But.....if they don't enforce them the rules are worthless. Instead of keeping a level playing field for the low $$$$ teams, they're just handicapping them if they try to race by the rules and guys are trying to buy wins with illegal equipment and $$$$.

ENGINES

• 305 GM. 302 Ford only! No intermarriage of engine to frame.

ENGINES MAY BE BORED TO A MAXIMUM .030 OVERBORE

• No fuel injectors. No turbo.
• Aftermarket gaskets allowed.
• Carburetors- Must be Quadra jet (GM) or Motorcraft (Ford). Any stock OEM two barrel. Two (2) barrel carb on two (2) barrel intake. Four (4) Barrel carb on four (4) barrel intake. No adapters.
• Only choke mechanisms may be removed from the carburetor.
• No racing fuel or additives. (92 octane maximum).
• CAMSHAFT 420 MAX LIFT MAX LIFT AT THE VALVE. 421 IS ILLEGAL
• No HP stamped motors (HP=228.305).
• STOCK OR STOCK REPLACEMENT CAST DISH PISTONS ONLY
• No angle milling or performance enhancing work on heads or block.
• No vortex heads.
• No grinding of any castings. SURFACING TO CLEAN UP CYLINDER HEADS ALLOWED. Combustion chambers must still CC correct stock volume.
• Crankshafts may be cleaned up to .010 under, Mains and rods. One time only.
• No valve spring shims. Must have rotators. Spring shield may be removed.
• Head numbers allowed: 305

GM 305 cylinder head numbers allowed:
10065205 • 10065207 • 10159551 • 10159553 • 12509859
14010201 • 14014415 • 14014416 • 14014440 • 14020555
14022301 • 14022601 • 14022801 • 14039122 • 1403912
14101081 • 14102187 • 14102191
354434 • 358741 • 376450

302-(D80E, D70E, D50E). Heads must match the C.I.D.

Ford cylinder head numbers allowed:
F1ze • f3ze • f4ze. NO GT40P OR F77E CASTING NUMBERS ALLOWED


• Valves must be stock dimensions.
• No interchanging of rocker arms or ratios. 1.52:1 ON GM 1.60:1 ON FORD
• No offset key in crank. Damper must match CID.
• MAY DEGREE CAMS. DOUBLE ROLLER TIMING SETS ALLOWED
• No screw-in studs.
• Pinning of 3 studs per head max (per side)
• No roller cams.
• No balancing of motors.
• Intake manifold must match C.I.D. of motor.
• Stock distributor only. (Stock working order). Vacuum advance may be disconnected, but not removed.
• No propane or marine intakes.
• Must use stock oil pans. Valve covers may be altered to accept one breather. All holes in valve cover may be plugged. MAY USE ANY AFTERMARKET STEEL VALVE COVER(S) WITH UP TO TWO(2) BREATHERS ON DRIVERS SIDE VALVE COVER.
• Aftermarket air filters allowed.
• Thermostat may be removed.
• Alternator may be removed.
• EGR valve may be removed and holes may be plugged.

FORDS WILL BE EVALUATED AND REVIEWED MONTHLY ON COMPETITIVENESS. RULES MAY CHANGE FOR FORDS BASED ON THOSE EVALUATIONS.

STOCK OR STOCK REPLACEMENT CAST DISH PISTONS ONLY

emphasized all in capitals, wonder if the d-cup/reverse dome pistons will be allowed.

No valve spring shims. Must have rotators. Spring shield may be removed

- No shims? Guess you better not have old weak springs, how would you correct the tension?

No balancing of motors

Motors are balanced from the factory, how are they going to tell if you balanced it or the factory did. If an engine is rebuilt with the allowed .030 overbore it's gonna throw off the factory balance, and should be rebalanced unless the piston weights are very close.

[jerethei]

There's a Guy here who's building engines and wants 2500 bucks he gets custom ground came. And the lobe separation angle is 108 degrees but the lift isn't Max the motors have mad low end torque all on pump gas I'm looking for torque out of the corner more than top end I'm only hitting probably 5800 rpm before I let off. Any setup to help bite would be appreciated as well.

[jerethei]

They are quick to pull valve covers and drop oil pans but that's it. There is a bunch of whiners who are quick to throw down the protest fee to tear down someone. A Guy could argue that those pistons are dished being there's more than just valve reliefs in the pistons and aren't the technically a cast part which is then machined?

[jerethei]

Anyone know where I can get the 3.75 stroke crank and if any extra block machining is required?