7000-8000rpm small block chevy?

[buickbear]

Hi, Here in about 4 months I will be swaping a sbc-v8 into my fiero:devil: . I really want to turn a 350ci into a 327ci or 302ci, from what I have been told all you really do is change cranks. But I would really like the motor to turn between 7000-8000rpms:rockon: and still take a beating. My question is, can it be done, and what parts would I need to do it?

Any info would help greatly.:D

[Trevor86TA]

A short stroke, lightweight rotating mass and quality valvetrain parts are definately something you are going to want.

[Firebirdjones]

Trevor hit the nail on the head if you want something durable that will last with high rpms.

350 and 327 share the same bore. For a 327 crank to drop in a 350 you will need a 327 crank from 68 or newer.
1967 and back 327's had a smaller main bearing journal,,,,in 1968 the main bearing journal size was increased to the same size the 350 is.
Keep that in mind if you want something to just drop in.

I don't know if they make main bearing spacers or not for installing the smaller 62-67 cranks. I know spacers are made for the 400 small blocks to install 350 cranks for the 377 ci so spacers may be a possibility for the 327 conversion as well. Something you would have to research though.

Something else to research would be aftermarket crankshafts, like scat, lunati, etc...they may actually make an aftermarket rotating assembly balanced and ready to go with good parts like trevor mentioned just for the combination you are looking for.
This is probably the route I would take,,,,I only have 3 spare 327's left,,,and good cores are getting so hard to find now,,,,chances of you finding a good usable crank are not that great.

One last possibility is the 307 chevy motor,,,which uses the same stroke crank as the 327,,,,these may be easier to score,,,and the 307 were all large journal so it would drop right into a 350,,,but they are all cast cranks though,,,,not something I would want to spin to 8,000 on a regular basis. Hope that helps,,,,,,,,,Larry.

[Chris 96 WS6]

I don't understand why you want to reduce the displacement of the motor. Sure you might have more RPM potential (IMO this is more due to cam selection and head flow than strictly displacement/stroke), but you're going to give up tq across the whole RPM range and essentially you will have to spin it higher to make the same HP.

Other than as a novelty or due to racing class rules, I never understand the desire to destroke a motor.

[Trevor86TA]

I shift my 400sbc at 5300rpm and I am sure it will like longer than a 327cid motor making the same power and turning 7500rpm.

It was probably a lot less costly to build as well and is more street friendly.

[buickbear]

Thanks for the info now I know what to look for and what to work on.

The main reason for the rpms is it will suit my needs better. With a car that is 2600lbs with a v8 to much tq will just spin tires and go to waste.
So if i can get 250tq and 350hp the car will be more stable(not so spin happy).

[buickbear]

oh, Can you get decent MPG with a carbed sbc?:dontknow:

[Chris 96 WS6]

Thanks for the info now I know what to look for and what to work on.

The main reason for the rpms is it will suit my needs better. With a car that is 2600lbs with a v8 to much tq will just spin tires and go to waste.
So if i can get 250tq and 350hp the car will be more stable(not so spin happy).

That's what proper gear selection is for.

[Firebirdjones]

It's just personal preference really. Most of the younger crowd wouldn't understand the fasination with 327's.
I currently have cars with big blocks, small blocks, and everything in between. I have run nothing but 327's in my 56 nomad along with a 4-speed since the mid 80's. There is just something about 327's,,,still small enough stroke to spin some rpms,,yet the bore is large enough to make some horsepower with good cylinder heads. My Nomad runs high 12's with that little motor, an old muncie, and 4.56 gears. Not too shabby considering this car is way over 4,000 lbs. Can't knock the 327's until you try them. I guess it's an old school thing. Larry.

[Firebirdjones]

Oh ya,,,,as far as longevity with the high rpm 327's,,,,the current 327 in my nomad has been in there since 1992 and still runs strong, shifting at 7,200 rpms on occasion but try to keep it around 6,800 or so,,,only have changed valve springs every 5-6 years or so,,,thats it. Larry.

[Red Devil]

In the real world, outside the race only applications, built properly, a 350 and even a 383 will spin with any 327 you put together. In building a 327 for anything but class reasons you are short changing yourself and your wallet or are obstinately stubborn... which is of course better than the delusional 305 crowd. ;)

[Firebirdjones]

Ya but the 383 idea just doesn't fit with the era of the car too well,,,,back when the 5-6 and 7's were still fairly new it was the hot ticket to drop in a 327. It just goes with the car. Besides like I said,,,it takes a certain person to appreciate them, and there is something to be said about going fast with a little motor. Anyone can go fast with a big motor. For my Nomad to go the quick at it's race weight is flying for a little motor,,,but there are faster ones out there. Buddy of mine has a .030 283 in his 55 chev 2 door sedan,,,with 4 speed and all,,,,ALOT of gear,,all steel, full weight car, even runs ported 283 power pack heads on it and it runs 11.70's at 114 :lol: It's just old school and very cool,,,the younger crowd will never get it. Larry.

[Red Devil]

I was speaking to practicality, not nostalgia. Even some older guys like practical over nostalgic... but if it makes people feel better, I'll be happy to tell them a 383 is a 327. :devil:

[Firebirdjones]

I sharp eye can spot that 383 verses a 327 if you know what to look for ;)

[Red Devil]

A sharp eye usually looks elsewhere for their fun/money too. :lol: I sure do miss those days...

[buickbear]

One of the biggest reasons I want a 327 or 302 is because of the old gassers and trans-am z28 camaro:devil: . I was really wanting to go for a trans-am fiero theme. The only problem is the cost and the MPG. If I order parts from summit to spin 7000-8000rpms:notworthy the engine will run me about 2-3k. I need to find out if I can use any stock parts to save money. Also I was wanting to get around 15-18mpg city and 20mpg+high:thumbsup: way. I think with the wieght of the car and the 5 speed 3.73gears it might work?

[RamAirZ]

on a sidenote, you can build a 350ci motor to spin7Krpm+ pretty easily. I used to shift my Iroc at 7300rpm, and if I had swapped valve-springs I probably would have ran it up around 7800rpm. It was a Lunati Solid Roller cam with hardened pushrods, comp camps dual valve springs and Magnum 1.5 Roller Rockers (1.6's would cause piston to valve clearance problems lol). And I'd like to know who can spot a 383 just by looking at the engine :D Now they have their own unique exhaust tone, but just staring at the engine in the car you wouldn't know ;) Swap out a crank, due some clearancing on the block and oil pan and slap the original pan back on and go to town. We have a 1962 Corvette in our shop that LOOKS completely original but is running a 525hp 383 under the hood. Still sporting factory air cleaner, UGLY painted valve covers etc. But when you start it up it doesn't sound original lol. Good luck on your engine build, I was going to do the same for my LSx engine, using a 4.8 crank (3.27 stroke) and a 6.125 rod. Would have essentially made a 312ci (with an LS1 bore size) rev happy monster. But the motor is going in the 4x4 now so that wouldn't be a wise idea

[Firebirdjones]

Piece of cake. Back when 327's came out,,,,PCV systems were unheard of,,,,so for crank case breathing a pipe was used on the back of the motor near the distributor. Very unique.

So anyone claiming to have a 327 but is really running a newer 350 block or stroked 383,,,,a sharp eye would look for the breather tube in the back,,,,,no breather tube? no 327. Now someone could always go through the trouble of blocking off the breather under the intake and cap off the tube in the back of the block and then run modern style valve covers with breathers on a 327,,,,but there is no real reason to go through that trouble unless you are trying to hide the fact that you are actually running a 327,,,which makes no sense.

The other not so sure way but a quick hint to what is going on is looking at the balancer.

Lower horsepower 327's would use a small 7 inch balancer,,,,only the high HP versions had the 8 inch. If you build a 383 using the 400 crank,,,of course those all came with 8 inch balancers,,,,
This is assuming people are using the factory style balancers.

[RamAirZ]

Piece of cake. Back when 327's came out,,,,PCV systems were unheard of,,,,so for crank case breathing a pipe was used on the back of the motor near the distributor. Very unique.

So anyone claiming to have a 327 but is really running a newer 350 block or stroked 383,,,,a sharp eye would look for the breather tube in the back,,,,,no breather tube? no 327. Now someone could always go through the trouble of blocking off the breather under the intake and cap off the tube in the back of the block and then run modern style valve covers with breathers on a 327,,,,but there is no real reason to go through that trouble unless you are trying to hide the fact that you are actually running a 327,,,which makes no sense.

The other not so sure way but a quick hint to what is going on is looking at the balancer.

Lower horsepower 327's would use a small 7 inch balancer,,,,only the high HP versions had the 8 inch. If you build a 383 using the 400 crank,,,of course those all came with 8 inch balancers,,,,
This is assuming people are using the factory style balancers.


Good job :D You could still run a 383 crank in the old 327 blocks if you have the journals machined down (kinda like the Pontiac guys with 455 cranks in 400 blocks) and still keep the blow-by tube. I know this tube you speak of, it sucks. Trying to make sure it's bolted right in the engine bay of a 62' Vette is a PITA plus trying to bolt down the oil pressure line with it there is a PITA as well. Now the Balancer one, you'd have to have a keen eye for the 7-8 difference but very good :thumbsup:

[five7kid]

The main reason for the rpms is it will suit my needs better. With a car that is 2600lbs with a v8 to much tq will just spin tires and go to waste.
So if i can get 250tq and 350hp the car will be more stable(not so spin happy).You don't have to spin to 7000 RPMs to do that.

Why aren't we talking about "real" solutions - Northstar or LS1. Lightweight. EFI = driveability and economy. They'll spin to the moon with minor mods. Etc., etc., etc. In a Fiero, the Northstar would even be pointed in the correct direction.

[Firebirdjones]

Cool RamairZ,,,,another old timer gear head like myself :lol:
I did the machine the crank method that you mentioned on my 70 Formula Firebird,,,,took a 428 crank I had laying around,,,,machined for the smaller 3 inch mains and stuck it in a .030 over 400 block for a 434 ci. pontiac. Takes some doing though,,,,the rear seal area has to be welded up as well and then remachined. :thumbsup: Larry.

[buickbear]

The reason for not doing a northstar or LS1 is the cost. Price of a good carbed sbc swap 4k tops other swaps a twice that much. Also it is very hard to tune the ECU after it is in the car, so some mods you could not do.

[five7kid]

It's the old, "Tell me how fast you want to go, and I'll tell you how much it'll cost you." Or vice versa, "Tell me how much money you have and I'll tell you how fast you can go."

You're going to spend about the same amount of money on any of those platforms to get a given amount of performance. The big difference is the Northstar or LS1 is going to weigh a lot less, therefore requiring less power, while being more rev-conducive than a Gen I SBC, therefore costing less to build to get the same results.

This started off as a "7000-8000 RPM SBC" discussion. You ain't gonna build such an engine for $4k. Then it moved to 350 HP - now we're talking about how many R's it takes to get to that level, and that is dependent upon the engine displacement (primarily). However, that was an estimated power need for how much an SBC weighs - a lighter engine would take less power to get the same results.

Oh, yeah, it was actually a 250-torque/350 HP engine. That torque/HP indicates peak HP occurs at more than 5252 RPMs, which plays right into the Northstar displacement. (You'd have to have 250 ft-lbs at ~7400 RPMs to get 350 HP.) You should be able to buy, rebuild, and tweak a Northstar to 350 HP for $4k (of course it won't have to be 350 HP, because it weighs less than an iron SBC). It certainly would cost no more than it would take to destroke an SBC and build it for 250 ft-lb/350 HP, because a destroked SBC will have to wind a lot tighter than normal to make 350 HP at 250 ft-lb, which is going to be expensive. All told, the Northstar would weigh less, and the EFI would make it more fuel efficient and certainly easier to drive than a carb'd 250/350 SBC would be. High-reving carb'd SBCs aren't a lot of fun to drive on the street - ask me how I know. (BTW, peak torque will probably have to be more than 250 ft-lbs in order to have 350 HP at 7400 RPMs - Peak HP & torque rarely occur at the same RPMs.)

So, you decide what you want: Do you really want an old-school 350 HP SBC that winds to (whatever) RPMs, or do you want an engine that has 350-ish HP and 250-ish ft-lb of torque with good manners and fuel economy?

Which is the most important to you?

[RamAirZ]

Cool RamairZ,,,,another old timer gear head like myself :lol:
I did the machine the crank method that you mentioned on my 70 Formula Firebird,,,,took a 428 crank I had laying around,,,,machined for the smaller 3 inch mains and stuck it in a .030 over 400 block for a 434 ci. pontiac. Takes some doing though,,,,the rear seal area has to be welded up as well and then remachined. :thumbsup: Larry.


The funniest thing is I'm still a young kid by some people's standards but my dad used to race hydroplanes, cars and motorcycles, owned his own shops for awhile, then I went to GM automotive engineering school, UTI and state college lol and currently work building old hot rods, resto-rods, and straight restorations right now. Been building cars for awhile and I'm into just about everything old and new. Our 62' Vette at the shop has the bypass tube on it still, mechanical tach drive (those gears were pieces of crap in the generator housing). I'm currently building a 455 motor for my 69' Tempest. Block should be here next week then fill with some block hardener, set the head/main studs and get it machined .060 over and start assembling. I like the new Viton seals out for the Pontiac's to fix the rear-main seal leak lol. Alot of guys use the 455 cranks in the 400's now, have em turned down. Some guys are turning them to use BBC rods on the rod journals, a bit longer and easier/cheaper to come by. I learned how expensive "real" Pontiac stuff was real quick lol. I plan on running an EFI setup and distributorless Ford EDIS ignition on my 455.

[Firebirdjones]

Thats cool RamairZ,,,my father just built a 474 for his GTO. Although chevys fill my garage I am also a big pontiac fan. I'll send ya a private message so we don't invade this post :thumbsup: Larry.

[Firebirdjones]

I don't want to take anything away from the LS1's,,,they are awsome engines,,,but in all reality,,,they are very expensive. It's just not cheap to buy a complete LS1 that is rebuildable. Most of them I see pulled out of wrecked cars with 70,000 plus miles are in the $2,000 range :eek: Thats a little pricey,,,,Especially when you compare prices for rebuildable old school Gen 1 small blocks.
I have built many small ci small blocks that spin tons of rpms without expensive parts and have had no problems with that. No high dollar cranks or rods.
It requires good machine work,,,bottom line. My current 327 in the Nomad,,,stock crank (turned), stock rods with ARP bolts,,,block .030 over, forged pistons, old camel hump heads, solid cam, etc...I have been spinning this motor to 7,000 rpms since 1992 and still going strong. Don't get me wrong,,, stronger aftermarket cranks and rods are a good idea in any build,,,but not always necessary, especially if the rotating assembly is lighter to begin with. I believe the high dollar cranks and rods start becoming a necessity as the cubic inches increase (ie: longer strokes)

As far as driveability,,,wow,,,now thats a subject that can go on with debate for several pages. Everyones view of that is different. I find my high strung 327 to be very streetable, even with a thumpy solid cam,,the muncie and 4.56 gears. I have driven it to Pigeon Forge and back on a couple of occasions from Ohio. But I personally like alot of gear,,,I could easily switch the 9 inch pumpkin out for a 3.50 geared unit,,,but it just wouldn't be the same. It's just a matter of what you get used to,,,

Don't get me wrong though,,, I like the LS1's,,,but they haven't had the luxery of being around for 50+ years and the prices reflect that. Maybe after 10-15 more years the prices will be more reasonable as long as they stay in production. Larry.

[snakeoilperformance]

ive seen a 358 spin more than your 327 could ever handle. 9000 sumthing. think screamed. oh, in a jerico clutchles 5 speed went mid to low 8s n.a

used to run the atco quick 8. back before the outlaw 10.5 bug took off.. miss those days:banghead:

[Firebirdjones]

Ya you can make anything spin high rpms if you throw enough money at them. My point was the little 327,,or at least the ones I have owned do it effortlessly with stock parts and very little money.

[snakeoilperformance]

Ya you can make anything spin high rpms if you throw enough money at them. My point was the little 327,,or at least the ones I have owned do it effortlessly with stock parts and very little money.

very true

[Firebirdjones]

In the stick shift class racing I am in,,,(UMTR) there are a ton of high rpm,,high strung motors racing old school style and turning more rpms than I care to try. Nothing but manual transmissions allowed,,,and it's really cool to hear screaming motors going down track grabbing gears. That should be required listening for every kid growing up. :thumbsup:

[snakeoilperformance]

yea man it is.. my dad has a 80 malibu with a big block and a clutchless jerico, but omg does that thing spin, sounds so awesome going thru the gears, watchin it jump all over ever time he shifts..