Rebuilding 1984 Corvette CrossFire Engine
Thread Starter
Heel & Toe
Joined: Jun 2003
Posts: 16
Likes: 0
From: Oldfort TN
Rebuilding 1984 Corvette CrossFire Engine
I have a few questions regarding the '84 CrossFire Engine:
I will be removing the 350ci CrossFire from my 1984 later next week and going to go through a TOTAL Rebuild...
Question 1: Is the 350ci Block a good foundation to begin with???
Engine will be Balanced and Blueprinted and we will also be replacing ALL Studs/Bolts with ARP...
If pistons are worn, we will be replacing with SpeedPro...
We are planning on going with a good Roller Cam and probably updating the Ignition with MSD Components...
Question 2: Are the Heads good enough to be worth Modifying???
We are planning on using the Factory Heads and doing the Porting & Polishing plus adding Roller Rockers with ARP Studs as well...
On this 1984, we will be eliminating ALL Computer Components...
We will be using an Edelbrock C-26 Dual Quad Intake Manifold mounting (2) Edelbrock 500cfm Carburetors...
We are going to be rebuilding the entire 1984 Corvette from the ground-up with this Engine, a Richmond 6-Speed R.O.D. Transmission, Recaro Electric Seats, and hopefully adding a Custom Dash Panel using AutoMeter Carbon Fiber Gauges...
We may have an issue with Clearances for the Dual Carbs. The Intake is a Low Profile, but if we will have clearance problems,
Question 3: Is there a Corvette Hood Scoop like the ZR-1 or similar that we will be able to use with the '84 Hood???
I have done quite a bit of reading here and also as one had mentioned, the CrossFire Vault...
Thanks for any response on these issues and I do appreciate all the help and advice from the Members here at CorvetteForum...
I will be removing the 350ci CrossFire from my 1984 later next week and going to go through a TOTAL Rebuild...
Question 1: Is the 350ci Block a good foundation to begin with???
Engine will be Balanced and Blueprinted and we will also be replacing ALL Studs/Bolts with ARP...
If pistons are worn, we will be replacing with SpeedPro...
We are planning on going with a good Roller Cam and probably updating the Ignition with MSD Components...
Question 2: Are the Heads good enough to be worth Modifying???
We are planning on using the Factory Heads and doing the Porting & Polishing plus adding Roller Rockers with ARP Studs as well...
On this 1984, we will be eliminating ALL Computer Components...
We will be using an Edelbrock C-26 Dual Quad Intake Manifold mounting (2) Edelbrock 500cfm Carburetors...
We are going to be rebuilding the entire 1984 Corvette from the ground-up with this Engine, a Richmond 6-Speed R.O.D. Transmission, Recaro Electric Seats, and hopefully adding a Custom Dash Panel using AutoMeter Carbon Fiber Gauges...
We may have an issue with Clearances for the Dual Carbs. The Intake is a Low Profile, but if we will have clearance problems,
Question 3: Is there a Corvette Hood Scoop like the ZR-1 or similar that we will be able to use with the '84 Hood???
I have done quite a bit of reading here and also as one had mentioned, the CrossFire Vault...
Thanks for any response on these issues and I do appreciate all the help and advice from the Members here at CorvetteForum...
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Re: Rebuilding 1984 Corvette CrossFire Engine (Outlaw1984)
I have a few questions regarding the '84 CrossFire Engine:
I will be removing the 350ci CrossFire from my 1984 later next week and going to go through a TOTAL Rebuild...
Question 1: Is the 350ci Block a good foundation to begin with???
Just like any other SBC. If the bottom end is in good shape, it should be good for any operating conditions under 6krpm
Engine will be Balanced and Blueprinted and we will also be replacing ALL Studs/Bolts with ARP...
If pistons are worn, we will be replacing with SpeedPro...
What compression ratio. I think you'll find the stock pistons to be more than adequate.
We are planning on going with a good Roller Cam and probably updating the Ignition with MSD Components...
Pick a profile that compliments the Xfire manifold. Not a high rev induction system. Should optimize for 5-5500rpm max.
Question 2: Are the Heads good enough to be worth Modifying???
Not IMHO.
We are planning on using the Factory Heads and doing the Porting & Polishing plus adding Roller Rockers with ARP Studs as well...
On this 1984, we will be eliminating ALL Computer Components...
ECM should be upgraded to 7747. IMO you lose a lot when dumping the ECM controls. I don't suppose you need to pass emissions?
We will be using an Edelbrock C-26 Dual Quad Intake Manifold mounting (2) Edelbrock 500cfm Carburetors...
IMO, too much carb for where the motor will be operating. The TB's can be bored to 2.2" with over 800cfm. I am using 2.13's with 750cfm. Should be plenty for a 350.
We are going to be rebuilding the entire 1984 Corvette from the ground-up with this Engine, a Richmond 6-Speed R.O.D. Transmission, Recaro Electric Seats, and hopefully adding a Custom Dash Panel using AutoMeter Carbon Fiber Gauges...
We may have an issue with Clearances for the Dual Carbs. The Intake is a Low Profile, but if we will have clearance problems,
Question 3: Is there a Corvette Hood Scoop like the ZR-1 or similar that we will be able to use with the '84 Hood???
Not any that don't look tacky.
I have done quite a bit of reading here and also as one had mentioned, the CrossFire Vault...
Keep reading
Thanks for any response on these issues and I do appreciate all the help and advice from the Members here at CorvetteForum...
I will be removing the 350ci CrossFire from my 1984 later next week and going to go through a TOTAL Rebuild...
Question 1: Is the 350ci Block a good foundation to begin with???
Just like any other SBC. If the bottom end is in good shape, it should be good for any operating conditions under 6krpm
Engine will be Balanced and Blueprinted and we will also be replacing ALL Studs/Bolts with ARP...
If pistons are worn, we will be replacing with SpeedPro...
What compression ratio. I think you'll find the stock pistons to be more than adequate.
We are planning on going with a good Roller Cam and probably updating the Ignition with MSD Components...
Pick a profile that compliments the Xfire manifold. Not a high rev induction system. Should optimize for 5-5500rpm max.
Question 2: Are the Heads good enough to be worth Modifying???
Not IMHO.
We are planning on using the Factory Heads and doing the Porting & Polishing plus adding Roller Rockers with ARP Studs as well...
On this 1984, we will be eliminating ALL Computer Components...
ECM should be upgraded to 7747. IMO you lose a lot when dumping the ECM controls. I don't suppose you need to pass emissions?
We will be using an Edelbrock C-26 Dual Quad Intake Manifold mounting (2) Edelbrock 500cfm Carburetors...
IMO, too much carb for where the motor will be operating. The TB's can be bored to 2.2" with over 800cfm. I am using 2.13's with 750cfm. Should be plenty for a 350.
We are going to be rebuilding the entire 1984 Corvette from the ground-up with this Engine, a Richmond 6-Speed R.O.D. Transmission, Recaro Electric Seats, and hopefully adding a Custom Dash Panel using AutoMeter Carbon Fiber Gauges...
We may have an issue with Clearances for the Dual Carbs. The Intake is a Low Profile, but if we will have clearance problems,
Question 3: Is there a Corvette Hood Scoop like the ZR-1 or similar that we will be able to use with the '84 Hood???
Not any that don't look tacky.
I have done quite a bit of reading here and also as one had mentioned, the CrossFire Vault...
Keep reading
Thanks for any response on these issues and I do appreciate all the help and advice from the Members here at CorvetteForum...
Thread Starter
Heel & Toe
Joined: Jun 2003
Posts: 16
Likes: 0
From: Oldfort TN
Re: Rebuilding 1984 Corvette CrossFire Engine (Outlaw1984)
Thanks Dominic Sorresso for the Info...
I am really wanting to do away with the ECM and all its tidbits and go back to something that I can actually work on. Get rid of all those sensors...
I had spoken with Edelbrock and they had stated that the Dual-Quad Intake and Dual 500cfm Carbs would be just right for this engine as it was developed for the 350ci CSB...
I remember having a 1972 El Camino that had Dual Carbs on it (327ci) and it would absolutely fly. Excellent low and mid range...
Just figured that I could do the same with this 350ci with no problems...
I do appreciate your help and any others that may jump in here...
I am really wanting to do away with the ECM and all its tidbits and go back to something that I can actually work on. Get rid of all those sensors...
I had spoken with Edelbrock and they had stated that the Dual-Quad Intake and Dual 500cfm Carbs would be just right for this engine as it was developed for the 350ci CSB...
I remember having a 1972 El Camino that had Dual Carbs on it (327ci) and it would absolutely fly. Excellent low and mid range...
Just figured that I could do the same with this 350ci with no problems...
I do appreciate your help and any others that may jump in here...
Thread Starter
Heel & Toe
Joined: Jun 2003
Posts: 16
Likes: 0
From: Oldfort TN
Re: Rebuilding 1984 Corvette CrossFire Engine (Outlaw1984)
BTW;
As I am doing a Complete Rebuild of my 1984 Corvette 350 ci Engine and will be doing away with the CrossFire and installing an Edelbrock C-26 Dual Quad Intake with (2) Edelbrock 500 cfm Carbs and also doing away with the Computer, I have found some heads that I believe will work (Thanks to JonM's recommendations) to install Aluminum Heads instead of having a Valve Job done to the old Cast Iron Heads...
My Question is, will the Following Heads work with my 1984 Corvette 350 ci Engine:
This is a complete pair of GM Hi-Pro Corvette aluminum cylinder heads. Ideal for small-block Chevrolet V-8 hot rod's, fresh water power boats and other high performance aplications. Casting number 10088113. This set of heads features screw in studs, 1.94" and 1.50 valves, 58cc combustion chambers, advanced D-shaped exhaust ports (enhances flow of burned gases) and centraly located spark plug holes to improve combustion efficiency, and HO 350 Corvette design springs. Heads have been completly professionaly rebuilt here at our shop. This set of heads does not have an intake manifold heat riser or EGR passages. The exhaust ports are .100" higher than production cast. Spark plug holes are angled and require 3/4" reach gasketed spark plugs (A/C spark plug number AC FR5LS). Heads are machined with accesory holes for power steering, alternator and A/C mounting. This set of heads does require the later model center pull down valve covers. GM suggests using a composition head gasket with stainless steel fire rings is recomended to prevent galvanic action between a cast iron block and aluminum heads. Help your hot rod loose 50 pounds by installing these heads.
I need to know something before these get gone and I DO NOT wish to buy these Aluminum Heads if they are not going to work on my 350...
Thanks in advance...
As I am doing a Complete Rebuild of my 1984 Corvette 350 ci Engine and will be doing away with the CrossFire and installing an Edelbrock C-26 Dual Quad Intake with (2) Edelbrock 500 cfm Carbs and also doing away with the Computer, I have found some heads that I believe will work (Thanks to JonM's recommendations) to install Aluminum Heads instead of having a Valve Job done to the old Cast Iron Heads...
My Question is, will the Following Heads work with my 1984 Corvette 350 ci Engine:
This is a complete pair of GM Hi-Pro Corvette aluminum cylinder heads. Ideal for small-block Chevrolet V-8 hot rod's, fresh water power boats and other high performance aplications. Casting number 10088113. This set of heads features screw in studs, 1.94" and 1.50 valves, 58cc combustion chambers, advanced D-shaped exhaust ports (enhances flow of burned gases) and centraly located spark plug holes to improve combustion efficiency, and HO 350 Corvette design springs. Heads have been completly professionaly rebuilt here at our shop. This set of heads does not have an intake manifold heat riser or EGR passages. The exhaust ports are .100" higher than production cast. Spark plug holes are angled and require 3/4" reach gasketed spark plugs (A/C spark plug number AC FR5LS). Heads are machined with accesory holes for power steering, alternator and A/C mounting. This set of heads does require the later model center pull down valve covers. GM suggests using a composition head gasket with stainless steel fire rings is recomended to prevent galvanic action between a cast iron block and aluminum heads. Help your hot rod loose 50 pounds by installing these heads.
I need to know something before these get gone and I DO NOT wish to buy these Aluminum Heads if they are not going to work on my 350...
Thanks in advance...
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Rebuilding 1984 Corvette CrossFire Engine (Outlaw1984)
Correct me if I am wrong, but this sounds like a relatively mild build up
1) The block should be fine.
2) The stock '84 heads CAN be improved, but money is better spent, starting over, headwise. The 113 castings are good heads for a mild build up. They are the second (and final) design L98 aluminum head. The Edlebrock Performer RPM heads are probably better. Goals and budget have a lot to do with parts selection.
3) No personal knowledge. There ARE high rise HOODS available.
Unsolicitated comment. Dual quads have a special, visual, impact. I can see the allude in using them, BUT, two carbs are twice the trouble. Since you have used them before, probably this advice is superfluous. Good luck, have fun, and...
RACE ON!!!
1984 Crossfire
Member NHRS
1) The block should be fine.
2) The stock '84 heads CAN be improved, but money is better spent, starting over, headwise. The 113 castings are good heads for a mild build up. They are the second (and final) design L98 aluminum head. The Edlebrock Performer RPM heads are probably better. Goals and budget have a lot to do with parts selection.
3) No personal knowledge. There ARE high rise HOODS available.
Unsolicitated comment. Dual quads have a special, visual, impact. I can see the allude in using them, BUT, two carbs are twice the trouble. Since you have used them before, probably this advice is superfluous. Good luck, have fun, and...
RACE ON!!!
1984 Crossfire
Member NHRS
Thread Starter
Heel & Toe
Joined: Jun 2003
Posts: 16
Likes: 0
From: Oldfort TN
Re: Rebuilding 1984 Corvette CrossFire Engine (Outlaw1984)
Thanks CFI-EFI for the Reply. I was beginning to believe I would not be able to get any answers to my question. Thank you...
I did run across another set of heads:
Edelbrock Performers (60759) - - $799.00 (Brand New - Still In Box)
170cc Intake Port Volume
60cc Exhaust Port Volume
70cc Chamber Volume
2.02" Intake Valves
1.60" Exhaust Valves
.575" Maximum Valve Lift
I had mentioned this in another thread, but a Member advised me to check out the Corvette Aluminum Heads on Ebay which is what I had originally found above...
If the Edelbrock will be a better choice for me, please advise...
I may change my mind on the Dual-Quad setup and go to a Single 4-bbl Carb instead...
Thanks again in advance...
I did run across another set of heads:
Edelbrock Performers (60759) - - $799.00 (Brand New - Still In Box)
170cc Intake Port Volume
60cc Exhaust Port Volume
70cc Chamber Volume
2.02" Intake Valves
1.60" Exhaust Valves
.575" Maximum Valve Lift
I had mentioned this in another thread, but a Member advised me to check out the Corvette Aluminum Heads on Ebay which is what I had originally found above...
If the Edelbrock will be a better choice for me, please advise...
I may change my mind on the Dual-Quad setup and go to a Single 4-bbl Carb instead...
Thanks again in advance...
Burning Brakes
Joined: Sep 2000
Posts: 806
Likes: 0
From: Baton Rouge LA
Re: Rebuilding 1984 Corvette CrossFire Engine (Outlaw1984)
Hi-rise hoods
http://www.vanacorvette.com/page4.htm
http://www.vanacorvette.com/page4.htm
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Verdad Gallardo
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Re: Rebuilding 1984 Corvette CrossFire Engine (Outlaw1984)
For your first question the block is a good block to build. The 624 heads suck use them for a flower pot or somthing they are light duty heads and are probably already junk if you have high miles and the car ran hot at all. If you want to run the duel quads make sure you have good heads and enough cam and keep in mind you will have to insatll a kit to lock up the TQ, get the proper TV linkage or fab it ( try bowtie.com), jumper the FP relay wire, and work out you assys since the air pump braket bolts to the crossfire manifold.
Thread Starter
Heel & Toe
Joined: Jun 2003
Posts: 16
Likes: 0
From: Oldfort TN
Re: Rebuilding 1984 Corvette CrossFire Engine (Outlaw1984)
Thanks Nitro Junkie, ejfagala, and efi for the response...
Nitro Junkie - I have checked out Vanacorvette and have even requested info on the 1984 to 2000 Conversion...
ejfagala - Thanks for the info on the block which was my Main Question as I am getting ready to build it. I just ordered the following for the 350 ci Rebuild:
Edelbrock Performer RPM Aluminum Heads (70cc, 2.02" Int, 1.60" Exh, Max. Valve Lift @ .575")
Crane Cams PowerMax Hydraulic Cam (H-288-2) with the 226/234 @ .050
Crane Cams Hi-Intensity Hydraulic Lifters (formerly Fast Bleed)
Crane Cams ChromeMoly Heat-Treated Pushrods
Crane Cams Energizer Roller Rocker Arms (1.5 Ratio / 3/8" Stud)
Edelbrock Performer RPM Air-Gap (1500-6500 RPM) Intake
Barry Grant Speed Demon 750cfm Carb
Melling High Volume Oil Pump
Richmond 6-Speed R.O.D. Transmission
We will be Blueprinting & Balancing the Complete 350ci Engine and hopefully we will be pulling this out of the 1984 Corvette to get started in the next few weeks...
Nitro Junkie - I have checked out Vanacorvette and have even requested info on the 1984 to 2000 Conversion...
ejfagala - Thanks for the info on the block which was my Main Question as I am getting ready to build it. I just ordered the following for the 350 ci Rebuild:
Edelbrock Performer RPM Aluminum Heads (70cc, 2.02" Int, 1.60" Exh, Max. Valve Lift @ .575")
Crane Cams PowerMax Hydraulic Cam (H-288-2) with the 226/234 @ .050
Crane Cams Hi-Intensity Hydraulic Lifters (formerly Fast Bleed)
Crane Cams ChromeMoly Heat-Treated Pushrods
Crane Cams Energizer Roller Rocker Arms (1.5 Ratio / 3/8" Stud)
Edelbrock Performer RPM Air-Gap (1500-6500 RPM) Intake
Barry Grant Speed Demon 750cfm Carb
Melling High Volume Oil Pump
Richmond 6-Speed R.O.D. Transmission
We will be Blueprinting & Balancing the Complete 350ci Engine and hopefully we will be pulling this out of the 1984 Corvette to get started in the next few weeks...
Waka, Waka, Waka!
Joined: Jun 2002
Posts: 2,435
Likes: 2
From: Richmond Virginia
CI 4-6-8 & 10 Veteran
St. Jude Contributor
Re: Rebuilding 1984 Corvette CrossFire Engine (Outlaw1984)
I just ordered the following for the 350 ci Rebuild:
Edelbrock Performer RPM Aluminum Heads (70cc, 2.02" Int, 1.60" Exh, Max. Valve Lift @ .575")
Crane Cams PowerMax Hydraulic Cam (H-288-2) with the 226/234 @ .050
Crane Cams Hi-Intensity Hydraulic Lifters (formerly Fast Bleed)
Crane Cams ChromeMoly Heat-Treated Pushrods
Crane Cams Energizer Roller Rocker Arms (1.5 Ratio / 3/8" Stud)
Edelbrock Performer RPM Air-Gap (1500-6500 RPM) Intake
Barry Grant Speed Demon 750cfm Carb
Melling High Volume Oil Pump
Richmond 6-Speed R.O.D. Transmission
Edelbrock Performer RPM Aluminum Heads (70cc, 2.02" Int, 1.60" Exh, Max. Valve Lift @ .575")
Crane Cams PowerMax Hydraulic Cam (H-288-2) with the 226/234 @ .050
Crane Cams Hi-Intensity Hydraulic Lifters (formerly Fast Bleed)
Crane Cams ChromeMoly Heat-Treated Pushrods
Crane Cams Energizer Roller Rocker Arms (1.5 Ratio / 3/8" Stud)
Edelbrock Performer RPM Air-Gap (1500-6500 RPM) Intake
Barry Grant Speed Demon 750cfm Carb
Melling High Volume Oil Pump
Richmond 6-Speed R.O.D. Transmission
btw: IMHO that is a MUCH better carb choice.
Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: Rebuilding 1984 Corvette CrossFire Engine (Fozzy_Bear)
Ok...forget all that about "if the pistons are worn" stuff...the block will need to be bored, which will require you to buy new pistons.
If you use flat top pistons, you will get about 9:1 compression, which is probably good for a street carbed car...unless you want to waste money on premium gas and backing down timing untill is has no performance, especially with a roller cam. (Roller cams made for street use have less overlap which results in more dynamic compression...which results in more pinging.)
If you use flat top pistons, you will get about 9:1 compression, which is probably good for a street carbed car...unless you want to waste money on premium gas and backing down timing untill is has no performance, especially with a roller cam. (Roller cams made for street use have less overlap which results in more dynamic compression...which results in more pinging.)
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Rebuilding 1984 Corvette CrossFire Engine (Fozzy_Bear)
Since the '84 came with 76 cc heads, the 70 cc Edelbrocks will raise the 9.0:1 compression ratio, slightly. With a decked block and a nice tight quench area, he should end up with a reasonable CR.
I applaude the switch to the single carb. I think it will provde all the performance and at least less than half the headaches of a dual carb set up. The cam seems a little "hairy" for a 350, but time will tell. Of course a distributer and all the other "ECM elimination" hardware will be needed. Good luck, and...
RACE ON!!!
1984 Crossfire
Member NHRA
I applaude the switch to the single carb. I think it will provde all the performance and at least less than half the headaches of a dual carb set up. The cam seems a little "hairy" for a 350, but time will tell. Of course a distributer and all the other "ECM elimination" hardware will be needed. Good luck, and...
RACE ON!!!
1984 Crossfire
Member NHRA
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Re: Rebuilding 1984 Corvette CrossFire Engine (CFI-EFI)
I agree with CFI. Some other concerns I would have.
1.The Performer heads are aluminum. You should increase compression by at least 1 point for them to work well.
2. The heads come with springs good for up to .575 lift. If you can, get bare heads and install the springs recommended by the cam manufacturer. If those springs are stiff enough for .575, you may run risk of them being too stiff for the cam you've chosen. Make sure you check seat pressures and install heights.
3. What about pushrod length? Good idea to get adjustable pushrod checker before you buy any.
1.The Performer heads are aluminum. You should increase compression by at least 1 point for them to work well.
2. The heads come with springs good for up to .575 lift. If you can, get bare heads and install the springs recommended by the cam manufacturer. If those springs are stiff enough for .575, you may run risk of them being too stiff for the cam you've chosen. Make sure you check seat pressures and install heights.
3. What about pushrod length? Good idea to get adjustable pushrod checker before you buy any.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Rebuilding 1984 Corvette CrossFire Engine (Dominic Sorresso)
2. The heads come with springs good for up to .575 lift. If you can, get bare heads and install the springs recommended by the cam manufacturer. If those springs are stiff enough for .575, you may run risk of them being too stiff for the cam you've chosen. Make sure you check seat pressures and install heights.
The .575" lift rating for the spring, has less to do with pressure than it has to do with lift, before coil bind. These heads are professionally assembled. It may be wise to get the seat pressure (intalled height) and open (at one certain point) and run the numbers by Crane, but I doubt he'll have any spring problems. Because he knows the lift limitations of the springs (heads), I would trust (although it's not listed) that the cam isn't over .575" with 1.5:1 rockers.
RACE ON!!!
[Modified by CFI-EFI, 12:38 PM 7/6/2003]
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Re: Rebuilding 1984 Corvette CrossFire Engine (CFI-EFI)
CFI,
I must respectfuly disagree regarding the springs. Its an expensive lesson that I learned. I bought my TFS heads with "springs good up to .550lift" Well, my cam has a .488/495. Except that the seat pressure for the TFS springs was 110lbs, while the roller cam I installed spec'd 132lb closed seat pressure. The issue isn't as much the lift, but the rate of valve acceleration. Rollers have much more aggressive ramp up than flat tappets. So they require higher spring pressures even tho they may have similar lift numbers. I would have had fairly significant valve float in the upper rpm range according to CompCams. I had already put the heads on and so the springs came off with the help of a air compressor. Also fortunate for me the spring seats had been cut fo 1.47"dia springs. Future TFS heads had that as an extra cost option.
I must respectfuly disagree regarding the springs. Its an expensive lesson that I learned. I bought my TFS heads with "springs good up to .550lift" Well, my cam has a .488/495. Except that the seat pressure for the TFS springs was 110lbs, while the roller cam I installed spec'd 132lb closed seat pressure. The issue isn't as much the lift, but the rate of valve acceleration. Rollers have much more aggressive ramp up than flat tappets. So they require higher spring pressures even tho they may have similar lift numbers. I would have had fairly significant valve float in the upper rpm range according to CompCams. I had already put the heads on and so the springs came off with the help of a air compressor. Also fortunate for me the spring seats had been cut fo 1.47"dia springs. Future TFS heads had that as an extra cost option.
Thread Starter
Heel & Toe
Joined: Jun 2003
Posts: 16
Likes: 0
From: Oldfort TN
Re: Rebuilding 1984 Corvette CrossFire Engine (Outlaw1984)
Here are the specs on the Edelbrock Performer RPM Aluminum 70cc Straight Plug Heads:
Intake Port Volume = 170cc
Exhaust Port Volume = 60cc
Chamber Volume = 70cc
Deck Thickness = 9/16"
Intake Valve Size = 2.02"
Exhaust Valve Size = 1.60"
Valve Spring Diameter = 1.45"
Rocker Stud Diameter = 3/8"
Pushrod Diameter = 5/16"
Maximum Valve Lift = .575"
Here are the specs on the Crane Cams PowerMax H-288-2 Cam:
Degree Duration @ .050 Int./Exh.: 226/234
Degrees Advertised Duration Int./Exh.: 288/296
Degree Lobe Separation: 114
Open/Close @ .050" Cam Lift Int./Exh.: 4 - 42 56 -(2)
Lash Hot Int./Exh.: .000 .000
Gross Lift Int./Exh.: .458 .473
Fair Idle, Moderate Performance Usage, Good Midrange Horsepower, 3400-3800 Cruise RPM, 9.75 to 11.0 Compression Ratio advised, Basic RPM 3000-6000...
BTW, if we do need to go with New Pistons, I will probably opt for the SpeedPro 9.72 64.0cc -6.1cc, flat, with 4 reliefs
Thanks for all the help guys as I will be new to this...
[Modified by Outlaw1984, 8:43 PM 7/6/2003]
Intake Port Volume = 170cc
Exhaust Port Volume = 60cc
Chamber Volume = 70cc
Deck Thickness = 9/16"
Intake Valve Size = 2.02"
Exhaust Valve Size = 1.60"
Valve Spring Diameter = 1.45"
Rocker Stud Diameter = 3/8"
Pushrod Diameter = 5/16"
Maximum Valve Lift = .575"
Here are the specs on the Crane Cams PowerMax H-288-2 Cam:
Degree Duration @ .050 Int./Exh.: 226/234
Degrees Advertised Duration Int./Exh.: 288/296
Degree Lobe Separation: 114
Open/Close @ .050" Cam Lift Int./Exh.: 4 - 42 56 -(2)
Lash Hot Int./Exh.: .000 .000
Gross Lift Int./Exh.: .458 .473
Fair Idle, Moderate Performance Usage, Good Midrange Horsepower, 3400-3800 Cruise RPM, 9.75 to 11.0 Compression Ratio advised, Basic RPM 3000-6000...
BTW, if we do need to go with New Pistons, I will probably opt for the SpeedPro 9.72 64.0cc -6.1cc, flat, with 4 reliefs
Thanks for all the help guys as I will be new to this...
[Modified by Outlaw1984, 8:43 PM 7/6/2003]
Waka, Waka, Waka!
Joined: Jun 2002
Posts: 2,435
Likes: 2
From: Richmond Virginia
CI 4-6-8 & 10 Veteran
St. Jude Contributor
Re: Rebuilding 1984 Corvette CrossFire Engine (BBA)
Hey Fozzy...you know a guy named Bill Bradsher?