Thread: what i need to do to my chevy 327

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I started on a monster project 2 years ago. I though it was more than I could handle. I bought a 1966 chevy C-10, i found it sitting in a barn about. It had moderate rust, and was loaded up with all kinds of junk and roots growing threw it. But all I could see is the potential it had. Two years later, along with countless hours out in the garrage and about five grand later I finished. Now im looking to get performance out of my 327 rebuilt to its original specs.
I want to put a tunnel ram on it, but i dont know how big a carb or if i need a new cam, what modifications i need to do. Or if thats the best way to go for performance. Any advice?
Thanks,
Antonio

Sorry, not enough info. What do you intend to do with this car? Daily driver, drive-in cruiser, dragstrip. Why do you want the tunnel ram? Looks? What 327 are you starting with? Original HP? What heads, cam, etc?

An engine is a system, not just a collection of parts. The carb, intake manifold, cam, heads (including compression ratio, valve size and runner size) pistons and exhaust all have to match up. Otherwise, any one of the combination will choke off all the others. All of these components have an RPM range where they work best. Mix them up, and you've got an expensive boat anchor.

What you do to the motor depends on what you want to do with the car. If you want solid power and driveability on the street, that's one thing. If you want a screamer that only works when you wind it up to 7 grand, that's another.

Tunnel rams are a pain on the street. It can be done, but they don't work very well at low rpms. They work best above 3500 RPMs. If you try to run one on the street, you better become a carb tuning wizard. Do a search on this site for "tunnel ram" and you'll find a bunch of info.

There are many ways to build a stout 327 that works well on the street. Chevy got 375 HP out of them a few years ago.

Think about what you REALLY want, then ask a couple more questions.

Tunnel Ram, stock specs??? That dosen't mix. To make an engine run properly, it needs to be able to pull a negative preassure ( Vacume ) and, a tunnel ram almost never allows that due to the larger amount of volume space ( EX. the plenum on a Edle performer will pull vacume faster due to the small space in the plenum, a tunnel ram, has a large space so, more volume ), you can fix and ajust things to help it but ither way, the tunnel ram will make power at the high end of the rpm scale, prolly start at 4k and end at 85-9k if you feel safe with those revs ( 327 should pull 8,500 at least ). Your best bet is to forget the tunnel ram and , if you want power, get a 6-71 blower, because by the time you tweak the engine to work with the tunnel ram, you would be able to mount a blower to the 327, as your 327 probably arleady has 8:1 which is optimal for a blown situation granit, there are tweaks you need to make to the engine to work with the blower like gaskets, and special carbs but, it will function better in a better rpm range, than a tunnel ram, without too much hassle.

Yeagh i was cosidering the blower origanly. I Just thought it might be to many engine modifications. What would i have to do to put in a blower, should i get a 8-71, 6-71, 4-71 ?
The engine is totaly stock i got it rebuilt at a local shop.
Thanks

Here are some specs. Dont know if it helps.
I aprreciate it the advice

Chev V-8 327
Bore Stroke liters Rod L L/S B/S Block Deck

4.00 3.25 5.35 5.7 1.75 1.23 9.025 .055

Gasket pin (height)
0.015 1.66

Originally posted by 66Chevy-C10
Yeagh i was cosidering the blower origanly. I Just thought it might be to many engine modifications. What would i have to do to put in a blower, should i get a 8-71, 6-71, 4-71 ?
The engine is totaly stock i got it rebuilt at a local shop.
Thanks

Go for the 471 setup on a stock engine you only need a maximum boost pressure of 6 pounds tops, I am giving this boost pressure because I assume by the word stock you have the stock compression ratio of 8.5 to 1 ?

It will also pleasantly surprise you that the 471 setup is more streetable than the tunnel ram.

When I was doing research about blowers several yrs ago, the concensus was stock parts, 5 pounds of boost and under.

So i can just slap a 4-71 blower on there. What modifications would i still need.
thanks

Apart from cutting a hole in the bonnet, not that much really, a cable trottle linkage. Run the 2 inch blower drive. with a short water pump. And a good radiator and fan to pull the air through. One thing you will find with blowers, the engines run hot when under boost. Recheck your timing and make sure that your ignition can give you a good spark. Now bar in mind this is a street fun combination, and not a hard core racing engine. But who knows ? you could get addicted to the kick in the pants feel that comes from blowers, and like some of us go all out. But have fun firstand start at the bottom rung on the ladder.

If you want a tunnel ram...Put one on it....On smaller stock engines I use a Weiand tunnel ram and Holley 390 cfm 4 barrels

we used this on a late 70's 265 bone stock and knocked down 18mpg and it had great throttle response ( this went into a 76 chevy monza) Also screened intake gaskets helped....You can also mod a divider into the tract to make a single plane tunnelram but that involves more tunning...

On 327's I still use the Offenhouser "crossram" manifold these pieces work extremely well....all depends on the look you want...

Originally posted by 66Chevy-C10
So i can just slap a 4-71 blower on there. What modifications would i still need.
thanks

7.5 compression ratio, 6 lbs. boost and dont turn it over 6000 rps, put a lot of gas in it and what other southerner said and have a good time and you will go fast.

[QUOTE]Originally posted by dr_bowtie
[B]If you want a tunnel ram...Put one on it....On smaller stock engines I use a Weiand tunnel ram and Holley 390 cfm 4 barrels

we used this on a late 70's 265 bone stock and knocked down 18mpg and it had great throttle response ( this went into a 76 chevy monza)

Dr. Bowtie, Is that a typo I see? Chevrolet made no 265s in the 60s oe 70s either. They only made 265s in 55-56 and 57s. most 57s had 283s.
Monzas were offered with a 4 cyl and a 262(different bore and stroke than a 265) They only had 110 hp. I think it was the 2nd year it was available with a 305 also, and it had a whoping 140hp. I would think the manifold would be about 6 inches to tall and the cfm would bt about 500 too many for either one of those little motors. Anyone that wants a Monza project I think I have one laying around that could be had.I believe its a 1980 model.

yep... was a typo...I meant 262.....you can never have too much cfm....it's all relative to venturi size that makes it work right!

we did a test on a 434 small block with a sheet metal intake and a 1150 dominator....switched the plate....used 2 1150 dominators...rejetted and picked up a 100 horses......

proves the theory...

I think I know more people who have run faster and better by going smaller on the carburator than the other way around.The same thing applys to camsafts. When you try to compare a well built race engine to a bone stock street motor, You can throw your theory out the window.Most of the time I agree with you. At least You can say I am consistant tonight. I have agreed with very little, on any thread. Maybe its just me! It's midnight.
Im outer here

Originally posted by dr_bowtie
yep... was a typo...I meant 262.....you can never have too much cfm....it's all relative to venturi size that makes it work right!

we did a test on a 434 small block with a sheet metal intake and a 1150 dominator....switched the plate....used 2 1150 dominators...rejetted and picked up a 100 horses......

proves the theory...

im gonna have to agree with riverhorse dr_bowtie, if you back up on some of your carb sizes you'll run a whole lot faster. 2-1150 dominators on anything is a lot of carb. i belive the venturi determine what cfm the carb will flow, so if the carb. is to big them the cfm is to much, so you can have to much cfm.