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ClemSparks
ClemSparks SuperDork
8/30/10 1:20 p.m.

Hey all,

Since I'm looking seriously into getting setup for a dirt oval racer...I thought I'd see what some of the engine wizzes here could tell me about putting together a reliable little chevy. It will be pushing around 3,200 lbs of car, likely with a spool in the rear and 8" wide wheels with tires no wider than 10"

My main goal is reliable and inexpensive. Third to those two would be a little bit of power. I don't want this to be an engine I have to take apart and refresh often. I'd really like it to last a couple of seasons without major fuss.

I don't expect to build a feature winning combo for peanuts, but I know I don't have to spend thousands putting together an engine for a hobby stock racer.

Here are the limitations: Stock iron heads (excluding vortec heads) with no porting and/or polishing (2.02/1.60 max valve sizes, 76 cc minimum), 2 BBL carburetor (rochester or Holley), and cast exhaust manifolds (excluding the 'rams horn' type). There are other limitations (like no domed pistons, 9.0:1 CR, cast iron intake) but I figure the heads, carb, manifolds are probably the ones to build an engine around.

So...where should I start? I figure a 350 2 bolt would be a good foundation (am I wrong, do I need a 4 bolt?). Stock crank. Will stock Rods with good rod bolts be ok?

Should I build for low-end torque, or high end power (relatively speaking)? Seems to me that low-to-mid range would keep things happier longer (a high-revving engine is going to need more frequent overhaul and such).

I don't expect any serious trade secrets out of this thread...but I'm pretty inexperienced at this and thought the rules-specific constraints might provide a fun excersice for some of the folks here.

Oh...there is a $425 claim rule on the engine (another racer can claim my engine for $425 if they want it). I don't figure I'll have an engine that anyone will want to claim, nor do I figure that I can actually put one together for that...but I'm all ears!

Heck...If I wasn't so worried about pissing people off, I should just show up with a junkyard runner and claim someone else's engine ;).

So what would you do? What parts, what tips, what considerations?

Thanks!
Clem

novaderrik
novaderrik Reader
8/30/10 1:44 p.m.

just use some hypereutectic claimer flat top pistons and do a stock rebuild on the bottom end. maybe spring to get it balanced.

no need for a 4 bolt block- in fact, the stock 4 bolt blocks aren't really any stronger than a 2 bolt block, which is good up to 500hp or so with studs.

get the stock rods resized and replace the stock cap bolts with ARP pieces. a slightly better choice would be the PM (powdered metal) rods that they started using in the early 90's with a quick resize and new ARP bolts.

i can't believe there are still classes that don't allow vortec heads- they are becoming dirt cheap. i can't remember the casting numbers right off hand, but try to find a set of 305HO heads for it- if you can't find some of those, then get the late 80's/early 90's Camaro L98 heads. they can also be found in Caprice cop cars and in some trucks.

does the class have a lift rule for the camshaft? if so, you can get cams that only have that much lift but have a ton more duration and overlap.

ClemSparks
ClemSparks SuperDork
8/30/10 2:05 p.m.

You know what...now that I look at it again, it does not specifically call out "no vortec heads." I was sure it did say that, but I don't see it now.

The track I'm looking at running has obviously cut and pasted the IMCA Hobby Stock rules (http://imca.com/rules/hobby-stock/) and manipulated them just a bit.

What the IMCA rules state is a list of approved casting numbers for heads and blocks. I'm not sure what Vortec casting numbers are, so I'll have to check into whether or not I can run them.

Thanks!

patgizz
patgizz SuperDork
8/30/10 3:28 p.m.

the vortec heads(and the 305HO heads) are ruled out by the 76cc minimum chamber rule.

i would throw a pos knocking $100 core in, run one race, throw down $425 and claim the best sounding and running motor in the race, and come back the next week with a good car.

the one place not to cheap out on a small block is the oil pump drive. whatever pump you choose, pick yourself up a melling IS55E oil pump drive with the steel collar built in instead of a standard drive with the separate nylon collar.

cheap small block parts abound, i've got quite a cabinet full of rings, pistons, bearings, timing sets, oil pumps, cams, and lifters that i have picked up cheap over the years because i'm always building stock 350's

novaderrik
novaderrik Reader
8/30/10 3:31 p.m.

it says 76cc or larger chambers, so that rules out all the heads i listed as well as vortec heads. might as well just find a set of early 882 heads and be done with it.

Pseudosport
Pseudosport Reader
8/30/10 3:38 p.m.

Can you run the stock cast LT1 manifolds fromt the 90's? I hear they flow pretty good for a manifold.

ClemSparks
ClemSparks SuperDork
8/30/10 3:53 p.m.
novaderrik wrote: it says 76cc or larger chambers, so that rules out all the heads i listed as well as vortec heads. might as well just find a set of early 882 heads and be done with it.

Cool guys...thanks! That's exactly the kind of stuff that I'm not up to speed on (chamber size vs head era, etc).

What I think I do know is that the "882" casting heads you're talking about are the legendary "Double Hump" or "Camel Hump" heads, right? With the 2.02 intake valves.

Those used to be the holy grail of performance factory heads...until the vortecs came out...which might help my plight a bit (I figure they aren't worth as much as they used to be now that the vortecs have dethroned them).

ClemSparks
ClemSparks SuperDork
8/30/10 3:55 p.m.
Pseudosport wrote: Can you run the stock cast LT1 manifolds fromt the 90's? I hear they flow pretty good for a manifold.

I think I probably can. I don't see them ruled out, so probably so. It seems like I could probably round some up from a B-body or F-body guy who has installed headers.

One of the guys on the track's forum classifieds has a set of "vortec" manifolds up for sale.

Thanks a lot for the discussion folks!

Keep it rolling!

Clem

ClemSparks
ClemSparks SuperDork
8/30/10 3:57 p.m.

So it sounds, thus far like the "insurance" items are:

Rod bolts
Oil pump drive

Any others I should know about?

Are Hypereutectic pistons necessary for a 9.0-1 engine (I'm sure there are more factors involved than compression ratio...)? Are they also an "insurance" item?

Thanks,
Clem

novaderrik
novaderrik Reader
8/31/10 5:28 a.m.

882 heads are nothing special- they are just the most common head that was ever put on 350's and 400's and are considered to be about the best of the worst of the heads. i think 441's are similar, but a heavier casting that is less likely to crack. the most common "camel back" heads are the 461 (or is it 462? my brain isn't working well right now) castings. good luck finding a set of those cheap- and if you do, sell them to someone that just has to have them to match the "3/4 race cam" in the 327 that's in their late 60's Corvette and use the profits to get a set of 882 or 441 heads rebuilt.

i'd definitely try to find a set of F body LT1 manifolds- i think they have a slightly bigger outlet than the similar Caprice LT1 manifolds. but they might fall under the "rams horn" rule, since they kinda sorta look similar.

914Driver
914Driver SuperDork
8/31/10 6:30 a.m.

Have you talked to Andy Nelson? That guy can build a small block!

44Dwarf
44Dwarf HalfDork
8/31/10 6:39 a.m.

A few places to look for good info are. MORTEC.com for casting numbers

And the WAR board. Weekend Auto Racer. http://www.auto-ware.com/autoware-bin/tech.pl

If you go with Hyper pistons be mindfull of total timming! Spend good money on a well built distributor is a must.

tuna55
tuna55 HalfDork
8/31/10 6:59 a.m.

I didn't see a displacement rule - start with a 400 if you can, they are out there. 50 cubic inches equals major torque.

ClemSparks
ClemSparks SuperDork
8/31/10 8:01 a.m.
tuna55 wrote: I didn't see a displacement rule - start with a 400 if you can, they are out there. 50 cubic inches equals major torque.

I didn't mention this one but "400 parts" are strictly forbidden.

internetautomart
internetautomart SuperDork
8/31/10 8:15 a.m.

wasn't there a factory aluminum 2bbl manifold? or was that only the 4bbl?
No matter what the rest of the setup is, you need to make sure the cam matches the power band you will be spending your time in.
If you want to virtual test a particular setup I still have a copy of desktop dyno on one of my computers I think.

ClemSparks
ClemSparks SuperDork
8/31/10 9:00 a.m.

Well, that's just it. I guess I'm looking for advice about what RPM range I should build this thing to perform well. I figure a 350 should be able to spin 6,000 rpm all season and last...right?

Will a 2bbl and stock heads and manifolds flow to keep up with that efficiently?

Or would I be better off building a stump puller suitable for an RV and put highway gears in the thing?

Clem

ClemSparks
ClemSparks SuperDork
8/31/10 9:07 a.m.
44Dwarf wrote: A few places to look for good info are. MORTEC.com for casting numbers And the WAR board. Weekend Auto Racer. http://www.auto-ware.com/autoware-bin/tech.pl If you go with Hyper pistons be mindfull of total timming! Spend good money on a well built distributor is a must.

Thanks 44! I spent a while looking over the WAR board. I'll be sure to check that out frequently for tips!

When you say "if you go with hyper pistons be mindfull of total timing!" are you saying that with the alternative being forged pistons?

And I'd love to hear elaboration about the distributor. I had planned on just running a stock GM HEI (maybe with some DIY tuning)...but respect your experience (you post some great stuff!) and would like to know if my plan is a poor one.

Thanks, Clem

ClemSparks
ClemSparks SuperDork
8/31/10 9:09 a.m.
novaderrik wrote: 882 heads are nothing special- they are just the most common head that was ever put on 350's and 400's and are considered to be about the best of the worst of the heads. i think 441's are similar, but a heavier casting that is less likely to crack. the most common "camel back" heads are the 461 (or is it 462? my brain isn't working well right now) castings. good luck finding a set of those cheap- and if you do, sell them to someone that just has to have them to match the "3/4 race cam" in the 327 that's in their late 60's Corvette and use the profits to get a set of 882 or 441 heads rebuilt. i'd definitely try to find a set of F body LT1 manifolds- i think they have a slightly bigger outlet than the similar Caprice LT1 manifolds. but they might fall under the "rams horn" rule, since they kinda sorta look similar.

All of that is usefull info...thanks!

I'll look into the LT1 manifolds. What it says in the rules is "no center dump manifolds".

Technically, I can run headers in this class at this track...but frankly, I'd just as soon run manifolds. Weird, but true.

Thanks,
Clem

zomby woof
zomby woof Dork
8/31/10 9:27 a.m.

I've built a bunch of these motors, so I'll tell you what I learned.

The flavor of the day head was the 441 castings when I was doing it. They sold for big money, while the worst possible casting (the 882) was routinely available for free. The reality was, that the 882 was as good as any of the other 76 cc castings, like the 336, 993,126, and 441, etc. We won many races with the 882 castings.

2 bolt block is fine, as is the stock cast crank, and rods.

Looks like no lift rule. We had one, so I can't advise you here, but run whatever your springs will take. 230-240 +/- degrees duration @ .050" should be about right. When we ran the paved track car, there was no lift rule, and ran a GK 230/480 cam. It was less than $75, and we didn't give anything up on the straights. I liked it so much, we used the same one on the street as well. You're building for midrange power. You won't make power up top anyway, with the small carb, intake, and exhaust.

If you have the option of running a little less gear, and a few hundred less RPM, do it. We could run the 2.56, or 2.73 gear for our track size. At the end of the day, the 2.73 car was no faster, but spun a lot more RPM at the end of the straight (6300 vs 6800)

You can go .060" overbore, so if you're going to bore, use it all. Claimer cast flat tops are fine. Use good rings, and bearings.

Run 40 degrees total timing (lock the advance out to eliminate any unwanted movement in there), and normal premium fuel. The HEI is a good distributor.

We flowed a bunch of cast 2 barrell intakes. I'll see if I can find the casting number of the one that worked best. It was an 80's EGR intake.

DEFINITELY run a header, if you can. Don't even question it. The worst header will be better than the best manifold.

Spend your money on good springs and shocks. You can get away with stock rear springs from different models of G/A body, but the proper ones up front are MANDATORY.

The most important things I learned at the track,

Don't always believe what the other racers are saying (see the head comment). Most are not mechanics, and don't know what they're talking about.

The difference between a well done reliable budget car, and an all out effort can be small, and often decided by the driver. We always ran up front with budget cars.

alfadriver
alfadriver Dork
8/31/10 9:36 a.m.
zomby woof wrote: The difference between a well done reliable budget car, and an all out effort can be small, and often decided by the driver. We always ran up front with budget cars.

How much do you think that it was quality tuning? Seems like if you really know what you are doing WRT tuning the engine and the chassis, you can do a lot more with a lot less money...

zomby woof
zomby woof Dork
8/31/10 9:41 a.m.

A lot.

My saying always was, "you can beat half the field with timing, and jetting".

It's more complicated than that, but most racers don't do this stuff for a living, and have no idea what they're doing. If you're a good mechanic, or have one helping you, you have a huge advantage.

alfadriver
alfadriver Dork
8/31/10 10:07 a.m.

Follow up question- how much is data acquisition allowed?

Kind of works towoard a MS kind of system my buddy and I are working on- buy the parts, assemble, and start taking data.

Sorry for the digression- I'm reading out of interest as opposed to inherent knowledge.

ClemSparks
ClemSparks SuperDork
8/31/10 10:25 a.m.

Wow Zombie...thanks a lot for all that advice!
Questions imbedded below.

zomby woof wrote: I've built a bunch of these motors, so I'll tell you what I learned.
The flavor of the day head was the 441 castings when I was doing it. They sold for big money, while the worst possible casting (the 882) was routinely available for free. The reality was, that the 882 was as good as any of the other 76 cc castings, like the 336, 993,126, and 441, etc. We won many races with the 882 castings.

Very good to know that I don't have to search for any holy grail heads. I've got some crusty old heads. I might just see about having them done up. with a valve job and some new good springs and valves. The rules dictate that we can't change the valve size though...are the heads you mention big valve heads, or does it really make enough difference to worry about it? Or is it a case of "some of them (882s) came from the factory with big valves, so we can run big valves"?
zomby woof wrote:
2 bolt block is fine, as is the stock cast crank, and rods.
Looks like no lift rule. We had one, so I can't advise you here, but run whatever your springs will take. 230-240 +/- degrees duration @ .050" should be about right. When we ran the paved track car, there was no lift rule, and ran a GK 230/480 cam. It was less than $75, and we didn't give anything up on the straights. I liked it so much, we used the same one on the street as well. You're building for midrange power. You won't make power up top anyway, with the small carb, intake, and exhaust.

No lift rule that I can see...but we do have constraints on valve springs...so that might limit the cam some...that's some thing that I'll just have to figure out, I suppose. Speedway has some roundy-round cams...and I love how they list the application for them. It's like "This cam is good for bombers with 2 bbl carbs. This one is good for cars on 1/2 mile tracks but you need good heads." and stuff like that. Very "dirt track friendly" catalog listings.
zomby woof wrote: If you have the option of running a little less gear, and a few hundred less RPM, do it. We could run the 2.56, or 2.73 gear for our track size. At the end of the day, the 2.73 car was no faster, but spun a lot more RPM at the end of the straight (6300 vs 6800)

I remember you posted this before...and it sounds good to me. I'll keep that in mind.

What length of track were you running that tall of a gear? I'll be on about a 3/8 mile high banked oval...I think folks are running upwards of 4.00 gears regularly. I'm mostly just curious. It would be WAY cool (cheaper) to be able to run a stock-ish gear ratio.

zomby woof wrote: You can go .060" overbore, so if you're going to bore, use it all. Claimer cast flat tops are fine. Use good rings, and bearings.

Does the overbore really make that much difference? My though has always been to overbore as little as possible...but I'm all ears.
zomby woof wrote: Run 40 degrees total timing (lock the advance out to eliminate any unwanted movement in there), and normal premium fuel. The HEI is a good distributor.

This sounds simple enough. Are there any problems with starting an engine at 40 degrees timing? That's the main fear I'd have. Especially when it's hot.
zomby woof wrote: We flowed a bunch of cast 2 barrell intakes. I'll see if I can find the casting number of the one that worked best. It was an 80's EGR intake.

I would LOVE to see this! Very generous of you to offer.
zomby woof wrote: DEFINITELY run a header, if you can. Don't even question it. The worst header will be better than the best manifold.

Duely noted. Some tracks let you run a header (because they're cheap anyway) and some don't. I figured "just in case" I wanted to run somewhere else, I'd stick with a manifold...but I'll be open to picking up some swap-meet headers for next-to-nothing and running those.
zomby woof wrote: Spend your money on good springs and shocks. You can get away with stock rear springs from different models of G/A body, but the proper ones up front are MANDATORY.

I'm ALL ABOUT chassis tuning...but I figure this will have to be learned the hard way, mostly. I'm not sure where to start, but this helps...thanks!
zomby woof wrote: The most important things I learned at the track,

Don't always believe what the other racers are saying (see the head comment). Most are not mechanics, and don't know what they're talking about.


And the ones that do are lying, right?
zomby woof wrote: The difference between a well done reliable budget car, and an all out effort can be small, and often decided by the driver. We always ran up front with budget cars.

I really hope to be in the same category as you! (running surprisingly well for the budget)

volvoclearinghouse
volvoclearinghouse Reader
8/31/10 10:34 a.m.

Find a way you can flip a switch to make the engine run on 5 or 6 cylinders, so at the end of the day, no one walks past your pits and thinks "man, he's got a good sounding engine!" and tries to claim it.

Also, some guys get pissed at claimers. Don't be a claimer.

96DXCivic
96DXCivic SuperDork
8/31/10 11:20 a.m.

How do you put a topic on your watchlist again?

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