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intake and head mismatch?

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Old Aug 30, 2012 | 01:49 PM
  #1  
Firebirda7x's Avatar
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From: Laconia, NH
Car: 1986 Firebird Trans Am
Engine: Chevy 355
Transmission: Built 700R4
Axle/Gears: 9 bolt 2.77
intake and head mismatch?

Hello third gen. I am considering replacing my intake, carb, and heads if I cant make this combo i have work.

The previous owner of my 355 has a 600 CFM holley carb planted on a Edelbrock Bowtie II victor Jr intake (part # 2972) and has stock 441 heads. The cam is unknown (sounds nice though!) and I added Headman 1 5/8 headers.

I am almost certain that there is stepping going on inside those heads..i dont know if he ported them but even if he did why did he use this intake? And assuming they were ported, can they still work with this intake? is there some weird combo people used to use? He went through the trouble to put in a nice ignition system, chromed everything, and used a gear set instead of a chain (which sounds horrendous, imo).

With all the collective experience out there, has anyone else done this and had success or is there no rhyme or reason to his setup? My money is on the latter and I would rather throw on vortec heads and a new intake and carb...but if this combo will work i would rather save the $800 and keep this for a bit.
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Old Aug 30, 2012 | 04:58 PM
  #2  
FtrSpeedy's Avatar
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From: Iowa
Car: 14 scion tc/91 camaro rs
Engine: 2.5/ 360 pooch
Transmission: 6spd man/th350
Axle/Gears: na/2.73
Re: intake and head mismatch?

Sounds like he matched the intake to the cam, will it work? What are your plans for it? Bigger question is whats the cam specs
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Old Aug 30, 2012 | 07:04 PM
  #3  
Firebirda7x's Avatar
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From: Laconia, NH
Car: 1986 Firebird Trans Am
Engine: Chevy 355
Transmission: Built 700R4
Axle/Gears: 9 bolt 2.77
Re: intake and head mismatch?

Cam is unknown.
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Old Aug 30, 2012 | 07:34 PM
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Damon's Avatar
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From: Philly, PA
Re: intake and head mismatch?

The standard 2975 Vic Jr. doesn't have very large ports in stock form- 1.90" x 1.10" according to Edflebrock. For comparison, the entry level Performer has 1.88" x 1.14" port openings- nearly identical and not that bad a mismatch for a near-stock set of heads.

I'm guessing he put on a single plne because it just looks cooler than a dual plane, not because it's going to make more power.

Gear drive..... I haven't found the application yet that required one. I also don't like the noise.

I get the feeling the previous owner was more into how things looked and sounded than the actual performance.

Last edited by Damon; Aug 30, 2012 at 07:38 PM.
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Old Aug 30, 2012 | 07:37 PM
  #5  
FtrSpeedy's Avatar
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From: Iowa
Car: 14 scion tc/91 camaro rs
Engine: 2.5/ 360 pooch
Transmission: 6spd man/th350
Axle/Gears: na/2.73
Re: intake and head mismatch?

I wouldnt worry bout heads an intake till you know the cam. There should be a stamped number on the front of the cam. Then look up the part number.
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Old Aug 30, 2012 | 08:14 PM
  #6  
Firebirda7x's Avatar
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From: Laconia, NH
Car: 1986 Firebird Trans Am
Engine: Chevy 355
Transmission: Built 700R4
Axle/Gears: 9 bolt 2.77
Re: intake and head mismatch?

If I'm going through the effort to remove the cam should I just replace everything at once? There's a lot of potential there when everything is..u know...working together
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Old Aug 31, 2012 | 08:49 PM
  #7  
Atilla the Fun's Avatar
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From: Northern Utah
Car: seeking '90.5-'92 'bird hardtop
Engine: several
Transmission: none
Axle/Gears: none
Re: intake and head mismatch?

Considering the reasonable cost of a cam swap ( HF ) I feel it's worth it to have known specs. However, hard to do a good job picking a cam if you don't know the heads and compression. Running a mystery small-block is fine when you don't care about MPG or emissions, so long as you can get good driveability. If I liked it, I'd start by playing with gearing and maybe a torque converter. You're never going to make excellent power with those heads, and if the pistons are dished, then a healthy cam will hurt the lower RPM where those heads do work, sort of. Swapping an RPM AirGap with a 750 will dramatically outperform what you have, even with the rest of the combo. Either accept what you have, or start buying parts.
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Old Sep 1, 2012 | 09:42 AM
  #8  
Firebirda7x's Avatar
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From: Laconia, NH
Car: 1986 Firebird Trans Am
Engine: Chevy 355
Transmission: Built 700R4
Axle/Gears: 9 bolt 2.77
Re: intake and head mismatch?

T
Originally Posted by Atilla the Fun
Considering the reasonable cost of a cam swap ( HF ) I feel it's worth it to have known specs. However, hard to do a good job picking a cam if you don't know the heads and compression. Running a mystery small-block is fine when you don't care about MPG or emissions, so long as you can get good driveability. If I liked it, I'd start by playing with gearing and maybe a torque converter. You're never going to make excellent power with those heads, and if the pistons are dished, then a healthy cam will hurt the lower RPM where those heads do work, sort of. Swapping an RPM AirGap with a 750 will dramatically outperform what you have, even with the rest of the combo. Either accept what you have, or start buying parts.
Well I went thru the effort to rebuild my 700r4 with one of Probuilt automatics 650 HP kits and a 9" edge racing converter (for future plans). Because of what you mentioned about my mystery small block is why I was uncertain about what to do next. If I got the 062 vortec heads, should I mat h a cam to those and my intake or get a dual plane manifold? I don't see many people using the one I have now, even when they would use an open Plenum design.
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Old Sep 1, 2012 | 10:05 AM
  #9  
Atilla the Fun's Avatar
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From: Northern Utah
Car: seeking '90.5-'92 'bird hardtop
Engine: several
Transmission: none
Axle/Gears: none
Re: intake and head mismatch?

Considering the converter, I'd pull the heads and look at the pistons, if I couldn't borrow a bore-scope. Your local machine shop might have one. If they're not flat-tops, put the engine back to running while you build something better to put under your Vortecs.
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Old Sep 1, 2012 | 10:56 AM
  #10  
FtrSpeedy's Avatar
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From: Iowa
Car: 14 scion tc/91 camaro rs
Engine: 2.5/ 360 pooch
Transmission: 6spd man/th350
Axle/Gears: na/2.73
Re: intake and head mismatch?

If you plan on alot of street driving then ya switch cam head and intake. If you plan on near all track time then stick with your current intake.
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Old Sep 1, 2012 | 08:49 PM
  #11  
cuisinartvette's Avatar
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From: Sanctuary state
Car: 67 ******mobile
Engine: 385 Solid roller
Transmission: T-56
Axle/Gears: 4.11
Re: intake and head mismatch?

With the others.
That heads couldnt keep up with that intake no matter what you did

Sell it ditch the geardrive and get a head/intake thats designed to work together
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Old Sep 1, 2012 | 10:37 PM
  #12  
Firebirda7x's Avatar
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Joined: Oct 2010
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From: Laconia, NH
Car: 1986 Firebird Trans Am
Engine: Chevy 355
Transmission: Built 700R4
Axle/Gears: 9 bolt 2.77
Re: intake and head mismatch?

Actually I do have access to a borescope should I go in thru an intake valve on cylinder 1 and see if its a dome piston or flat top? If it's dome....I might as well redo the pistons huh
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