With a 383 stroker kit, heads, and a moderate cam in an 89 350 TPI block, will the 2 bolt main motor be a problem? Can it handle the power? Is it worth it to try to find a four-bolt main block? I don't have much time or money left. Any help would be much appreciated. Thanks.

[This message has been edited by CamaroX84 (edited January 22, 2001).]

 

X84,

If the webs are adequate, you can add four bolt caps on the center three bearings to strenghten the bottom end. Splayed outer bolt caps are a little stronger than the factory four bolt caps, and are just enough for 423 HP on my 355. I don't take it to ridiculous RPMs, however, and a lot of the stress comes at higher RPMs.

The splayed cap sets can be had for about $180.00.

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Later,
Vader
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"I'm gonna talk about some freaky sheet now..."
Adobe Acrobat Reader 4.0
KaleCo Auto Parts

 

it'll be able to handle that without a problem..

but it always sounds better when you say you have a 4 bolt or splayed caps..


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My `91 Z28 Convertible

 

I know I'm just an old crusty curmudgeon, but I don't give a rat's *** what something sounds like, I only care how fast it goes and how long it lasts (because I'm CHEAP!!!).

IMHO the usefulness of 4-bolt mainshas nothing to do with horsepower, but everything to do with longevity at high RPMs. If the engine isn't going to go past 6500 RPM they're probably not worth the expense. Factory 4-bolts aren't really an improvement at all as far as I can tell. I have yet to ever blow up a motor for main bolts or caps; and I've only broke 2 cranks in my entire life, which covers alot of cranks. Every blowup I've ever had was rod bolts. If you're going to spend money on a motor, that's where the bang for the buck is.

As long as you have a TPI on it in anything even remotely resembling stock form (i.e. long runners) you're not ever going to see the RPMs where the number of main bolts matters.

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"So many Mustangs, so little time..."
ICON Motorsports

 

so what i wanna know.. is why in the heck the RamJet 350 is sittin on 2 bolt mains!? what is goin on w/that? so.. they put a full roller valvetrain in it... but 2 bolt mains? its not like it'd jack the price up more than a hundred or so bucks. so what does a person do if they want this engine, but want to eventually build it up some more?(for instance... a supercharger?) would it just be better to get it in an aftermarket set up, and build the engine yourself?

 

High-rev'n small blocks had only two bolt mains until 1968, when the 350 (with it's longer stroke) debuted. A good portion of the factory 400's only had two-bolt mains, and those "in the know" consider them the stronger version.

World Products is coming out with their own SBC casting soon. It has two-bolt mains with nodular iron caps. They argue that two bolts are adequate, and splayed caps distort the block. And, nodular has damping characteristics superior to steel.

As RB said, rod bolts are a better place to spend your money. To add to what he said, I've only lost lower ends due to oil pumps (and petroleum-based oil).

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LB9 w/ZZ3 cam, TBD heads, exhaust, paint, etc.).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

For the longest time, it was thought that the only high performance motors are with 4-bolt main. If the motor is built right, a 2-bolt main motor is going to be sufficient. I’ve run low 13’s with the stock 2-bolt L98 with squeeze as well as 12’s with squeeze motor with my 383 2-bolt main motor. As long as the bottom end has been thoroughly inspected by a competent machinist and you run quality bolt or studs like ARP’s, you don’t have a thing to worry about. I know guys running 11’s with blowers n squeeze running 2-bolt main blocks without any problems.
If anything, you’re going to blow a head gasket, melt a piston or throw a rod first before the mains give out on you. Unless you’re motor is going to be some high horsepower, spinning at 6000rpm+ all the time strip monster, don’t trip off only having a 2-bolt main block. Put the money to better use like going to some quality cylinder heads or something.


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N/A 406, TPIS Miniram, 58mm TB, 30lbs injectors, Custom Ground Elgin Cam, Ported TFS heads, SLP 1-3/4", & DFI computer.
11.70@117mph

 

This enigine will probably never see 6000 RPM. But will the 2-bolt main be a problem from WOT starts off the line? Isn't that pretty hard on the motor? Thanks for the help?

 

If that is all the RPM's you'll pull, a 2 bolt will be no problem.

But I do agree with Vader tho........

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350 4 bolt main, Speed-O-Motive 383 stroker kit, re-sized rods ground for clearance,TRW Forged pistons,10.7:1 compression,HPC Coated RPM intake, Speed Demon 750 cfm carb,World Products Sportsman II heads,2.02/1.60 valves, Comp Cam 1.6 roller rockers, Comp Xtreme 284 cam,240/246@.050 with .540 lift,Crane pushrods,Proform HEI and MSD6A box,HPC coated 1 5/8 headers, 2.5" exhaust with 40 series mufflers,TH350 with B&M 3000 stall, Powertrax NoSlip Locker, 4.11 gears.

 

You'll be fine with that engine if all your clearances are correct - and if your clearances are not correct, it doesn't matter if you have a 2 bolt or a 4 bolt. Get some good rod bolts - I like ARP Wave Loc Pro Series personally, but even the standard knurled ARP's will be better than the stock ones. Check all the clearances, and keep everything nice and clean, and you'll have a good running engine for a long time, providing you keep it well-maintained. Check my sig, the engine I just took out of my 82 Z28 is a two bolt, I shifted it at 6300RPM, and it ran 12.50's.

But I also agree with Vader, on the 383 I'm putting in there now, it has steel splayed caps - but this is gonna be a nitrous guzzling hellion

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82 Z28 350, Ported #882 Heads, Performer RPM cam and intake, hedman headers,650 Demon carb,
Trans: Turbo 350 w/ 4000 stall -- Rearend 7.5 w/ Richmond 4.10's, Auburn Minispool
Best ET: 12.52@107.2
Future plans: Dart headed, Roller cammed 383 in early '01


89 RS, L03 305, Hypertech Chip,cat delete, Dynomax exhaust,K&N open element Filter,160 stat, MSD coil --Trans:700R4 Corvette Servo -- Rearend: 7.5 GM 3.42 w/ posi-lock
New Best ET: 14.91 @92.9
http://www.bassettracing.cz28.com

 

Well I guess I'll throw in my two cents:

I think that what matters most when trying to decide to buy a 2-bolt or 4-bolt block is compression ratio. If you think about it, this makes sense. For every action there's an equal and opposite reaction, so the more the piston has the compress the air/fuel mixture, the more the air/fuel is gonna push on the piston, which will in turn try to force the crank out and could break a main bearing cap off.

After saying that, I've read that anything under 11:1 compression will be held perfectly fine by 2-bolt mains. I've also read that you can install "main supports" for 2-bolt mains which tie all the main bearing caps together. If one cap tries to come out, it's also held in by the other four. I have no experience with this, but to me it seems that this would be an excellent idea if a 4-bolt could not be used and the compressions was greater than 11:1.

Also, the new LS1 block have 6-bolt main bearing caps, but I don't know how that compares since the block is made out of aluminum. I'm also pretty sure at least one set of bolts on the LS1 blocks are splayed. Anybody correct me if I'm wrong.

Hope this helps,

Jason

 

I have run a 283 since 1971 and it is on its original rod bolts and and main bolts, it sees 6500 rpm on a regular basis. it have never been apart since 1971!!!! I am running it in a 1955 chevy and making atleast 325 horse.. I love 283 cause you can rev the **** out of them, great for cars with a stick, have only been beat by a handfull of cars, Kevin

 

Does ARP make an engine bolt kit, with strong main bolts, rod bolts, etc? Thanks.

 

yes..........check in a Summit book. Should have a complete kit for a smallblock chevy...
good luck!

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350 4 bolt main, Speed-O-Motive 383 stroker kit, re-sized rods ground for clearance,TRW Forged pistons,10.7:1 compression,HPC Coated RPM intake, Speed Demon 750 cfm carb,World Products Sportsman II heads,2.02/1.60 valves, Comp Cam 1.6 roller rockers, Comp Xtreme 284 cam,240/246@.050 with .540 lift,Crane pushrods,Proform HEI and MSD6A box,HPC coated 1 5/8 headers, 2.5" exhaust with 40 series mufflers,TH350 with B&M 3000 stall, Powertrax NoSlip Locker, 4.11 gears.