[hotrodsixtyseven]

I have a 67' Camaro with the original 327. It's a .030 over block with a stock crank and rods. I'm about to rebuild it with the exception of the rotating assembly. I've chosen AFR 180cc heads with 65cc combustion chambers 2.02'' intake 1.6'' exhaust, 1.5:1 roller rockers, an Edelbrock Air Gap intake, a Comp Cams Magnum hydraulic flat tappet cam 236/236 @ .05'' duration and .49''/.49'' lift with 1.5:1 rockers LSA 110 degrees. I've used a compression calculator to estimate the compression at about 10.25:1 assuming a 0 deck height and flat top pistons. The camaro has a Saginaw 4-speed with a 10 bolt rear. I was hoping for something a little bit peaky that is still street-able. This is not a daily driver but it's not a track car either. I can't decide on a carb however. I'm thinking about a street avenger 670 (vacuum secondaries) or a 700 double pumper (mechanical secondaries). Any suggestions about carb size would be helpful. In fact, any feedback about this combination at all would be appreciated. Not many people are building 327's anymore and it's hard to find any information.

[MI2600]

I would stay in the 600-650 cfm range with a vacuum secondary for the street.

In the back of mine mind I've always wanted to build a 327. I've got 3 blocks in the garage, but I keep building 400s...can't give up the inches.

[sheldonw]

i ran a 670 avenger on the last 327 i built it worked very well but the idle transfer and accelerator pump needed lots of tuning those carbs are not designed to run a camshaft with a lot of duration

[F-BIRD'88]

Your 327's CR with a felpro head gasket will be 9.6:1. If you want 10.25:1 you would want to order your AFR heads flat milled to 60cc. (Extra cost AFR factory option)
If you don't want to run it on 92 octane premimum gas, stick with 9.6:1

I would use a 750 cfm Holley HP carb or build your won using a 650-800cfm holley DP with a Proform center body.. A Edelbrock 750 Performer carb will work well also. What rear gear is in the car?

AFR heads really show their stuff (compared to other heads) at the higher valve lifts. Anything you can do to get the net valve lift up is all good.
This motor really needs a .550+" lift, torquey short duration little snotty mechanical street roller cam. Lunati VooDoo Cam #60130 or #60131(my pick)
A Comp Cams #12-702-8 is good too.
A 1.6 rocker arm ratio will help get the valve lift up to allow the heads to work their stuff.

Builds a snotty lil 327 with plenty of steetability for cruising.

[Bowtie man]

I would most likely go with a 600 DP or a 650 DP Holley with the 4 speed. What kind of gears in the rear or did I miss that area?

[hotrodsixtyseven]

I'm not sure how to tell what gears my rear end has. I looked at the differential and I couldn't find a casting number on it. Do I have to open it up and look at the gears to tell?

[F-BIRD'88]

Originally Posted by hotrodsixtyseven

I'm not sure how to tell what gears my rear end has. I looked at the differential and I couldn't find a casting number on it. Do I have to open it up and look at the gears to tell?

No you can calculate the ratio by jacking the rear of the car up off the ground on jack stands. With the trans in neutral, mark one of the rear tires with chalk or tape and mark the drive shaft. Rotate the drive shaft around while counting the number of turns until the tire has completed 1 revolution. If the drive shaft turns 3 times around, the ratio is 3.08:1. if it turns 3-3/4 turns the ratio is 3.73:1.
If both the right and left rear tire will turn in opposite directions, the rear is not a posi track.

You would want a 4.10 ratio for the cams I recomended and the comp 286H-10 hyd flat tappet cam you mentioned. 3.73 minimum for best street performance.

The factory ratio codes stamped on the rear axle tube and the posi diff tag on the diff cover are usually long gone.

[hotrodsixtyseven]

I tried the gear ratio test twice and I came up with 1 and 3/4 turn each time. I'm not sure if that is bad or good. It's definitely not a posi though.

[DoubleVision]

You can also remove the diff cover, turn the ring gear until you see the numbers stamped. Example 41 11. 41 ring gear teeth, 11 Pinion gear teeth, divide them and you got your answer. 41 divided by 11 = 3.73:1

[F-BIRD'88]

When checking the ratio using this method on a non posi diff you often get the 2:1 right-left axle "differential" action of the rear end that allows you to go around corners. Have a buddy hold one wheel from turning or leave it touching the ground and try again (only jack up one rear wheel off the ground).

because one wheel is locked from turning, the 2:1 differential effect will double the number of driveshaft revolutions for 1 tire revolution.

Unless you lock one wheel during this ratio test on a non posi axle, the 2:1 diff action is not consistant, resulting on a inaccurate driveshaft rev count.

A "Posi" rear axle diff has preload springs in it that allow both wheels to spin together when both are off the ground during this ratio test.

If you don't have 3.73's or 4.10's and a posi trac limited slip diff, you're going to want to make that change to get best performance out of the 327 you plan on building. 2.73's are not going to be very good. The high performance camshaft you chosen needs a fair bit of rear gear ratio for best overall performance, unless you plan on resetting the land speed record.

[hotrodsixtyseven]

The casting number on the differential is Gm 10 on one side. The other says NF 3894859. I hope this helps.

[F-BIRD'88]

Originally Posted by hotrodsixtyseven

The casting number on the differential is Gm 10 on one side. The other says NF 3894859. I hope this helps.

no these are not axle ratio code numbers. usually they are a 2 or 3 digit letter code on the right axle tube facing the front of the car. Usually they are corroded off and cannot be read. Cannot be 100% accurate as often the axle ratio is changed if service was required or???????.
The driveshaft test is the only way to know other than ripping off the diff cover and counting teeth or reading the tooth count stamped on the ring gear.

[Bowtie man]

Best way to do it is get the count stamped on the ring gear. The numbers will be visible when you take the cover off the rearend. Hope you have at least 3.42's would be nice to have 3.73's or 4.10's.

[hotrodsixtyseven]

I've pulled the engine and discovered a few things. It's a two bolt main as I assumed. It has the stock forged small journal crank and forged rods. It was already bored .040" oversize so I had it bored .060" over at the machine shop. The pistons are forged Speed-Pro with four valve reliefs. I've changed the compression ratio to 9.75:1 to be more pump gas friendly. I'm thinking about a solid cam instead of hydraulic to prevent valve float at higher rpm. The block has been cleaned, bored, honed, and had fresh cam bearings put in. The decks were milled to achieve the deck height I wanted. They also put new freeze plugs in for me. To achieve a bit more lift I'm going with 1.6:1 roller rockers. Everything else is the same except the carburetor choice. I went big with a Holley 750 double pumper. I read too many articles with engines smaller than mine that used these carbs and got great results. Anyhow, I still haven't pulled the cover off of my differential to find the gears but I will be doing that some time in the future.

[Haulin327]

Draw a stripe on driveshaft and tire -rotate tire and do math.....close enough
327's are very Ratty little motors-
with low gears and 11 to 1 you could use a 780 !
Have fun !