Page 1 of 4 123 ... LastLast
Results 1 to 10 of 33

Thread: How much improvement to expect from some new heads.

  1. #1
    Senior Member RACING JUNKIE
    Join Date
    Sep 2007
    Posts
    4,143

    How much improvement to expect from some new heads.

    Before I ask this I will say that ,yes,I do understand that every combination is different and nobody can say for sure what kind of numbers a certain car will run,especially without dyno numbers..but I just wanted your guys' opinion on how much potential for improvement I have.Here is what I have: Sorry this is so long..just wanted to give all the info.

    3050 lb 70 Nova,back halved with 12 pt cage,32 x 14 goodyears,ladder bars and coil overs with a 5.14 gear.Trans is a 1.76 powerglide with a brake and 8" converter. Engine is 13.0 to1 540. RIGHT NOW it has bone stock 074 Factory aluminum heads.(I will have new heads before next season) Victor 454-R with a stock 8896 1050 dominator. The camshaft is a crane solid roller .part number 138361. Grind number R-274/4334-25-14 SFO.

    lift is .737/.726
    dur@ .050 is 274/284

    LSA is 114 and the cam was installed @ 109 intake centerline. I have only made 4 passes on it so far.1st pass it went a 6.35 @ 108 mph with a 1.4 60'.. .Shifted it at 6800 but it felt like it ran out of steam a little ... it was 97 deg outside and miserable humid. The next week I lowered the air psi in the tires and it ran a 1.32 60' .I also shifted it @ 6400 to see how it did. This felt too early,but it ran a 6.28 but 0nly 104 mph( as I said it was 108 with the slower E.T. ) It cut out a little just as I shifted it..Upon inspecting it I found I had a broken valve spring..The springs were suposed to work with this cam..according to my local machine shop guy who checked them for me( they were nearly new but had been set up to a cam slightly smaller)They were manley 1.640. I made sure they did not stack up completely but I don't know what psi they checked at.The only reason I didn't have the eaxact springs for my cam is I knew I was going to get new heads over the winter.I only used the 074 because I had them and wanted to try out the car before winter. I haven't decided which heads I will buy yet..probably AFR 325 .Money issues will probably mandate an OUT OF THE BOX type head with no porting work..at least for now
    Anyway now for my question:

    Is an e.t in the 5.90's a reasonable goal for this combination with better heads? Again sorry for writing a book.

  2. #2
    Senior Member DYNO OPERATOR
    Join Date
    Mar 2007
    Location
    Texas
    Posts
    525
    JMO but with a maxed out set of good flowing heads you may make your goal of 5.90's. You are going to need around 70 or 80 more HP to get where you want to be. I hope you get what you want.
    Wesley
    60' 1.30
    5.58 @ 127.89

  3. #3
    Senior Member SENIOR BUILDER
    Join Date
    Sep 2007
    Location
    Div VI
    Posts
    122
    I ran a set of 781 steel heads, with larger valves and some porting, then upgraded to the afr 305s,,,the car ran .15 quicker, pretty disappointing,,so don`t get your hopes up,,I think your going to need an extra 130 hp to get that goal, I have found that once you get into the 10s - 1/4 mile,,it takes about 20 hp to get an extra 10th

  4. #4
    Senior Member DYNO OPERATOR
    Join Date
    Mar 2007
    Location
    Texas
    Posts
    525
    Quote Originally Posted by superstreeter
    I ran a set of 781 steel heads, with larger valves and some porting, then upgraded to the afr 305s,,,the car ran .15 quicker, pretty disappointing,,so don`t get your hopes up,,I think your going to need an extra 130 hp to get that goal, I have found that once you get into the 10s - 1/4 mile,,it takes about 20 hp to get an extra 10th

    superstreeter we are think about changing heads on my brothers truck how much HP do we need to shave 3/10th.
    Wesley
    60' 1.30
    5.58 @ 127.89

  5. #5
    Senior Member SENIOR BUILDER
    Join Date
    Sep 2007
    Location
    Div VI
    Posts
    122
    how fast is it now? and what do you have, give some details...

  6. #6
    Senior Member DYNO OPERATOR
    Join Date
    Mar 2007
    Location
    Texas
    Posts
    525
    Quote Originally Posted by superstreeter
    how fast is it now? and what do you have, give some details...
    Its running 6.28 in the 1/8th weight is 3050lb w/ 540 cid.
    Wesley
    60' 1.30
    5.58 @ 127.89

  7. #7
    Senior Member RACING JUNKIE
    Join Date
    Sep 2007
    Posts
    4,143
    Thanks for the reply guys..I never really thought it would go 5's just by changing heads...only reason I ask is I see other people on here with motors similar to mine with good heads running much faster ..plus,like I said only made 4 passes, So have not done any playing with timing and so forth. The car leaves hard and pulls hard the first half of the track but it really seemed to nose over on top when I took it to 6800...I have been told I am running too much timing for a big block (38 total distributor locked out). I just thought it was nosing over because it has stock factory heads on a relatively large engine(compared to the factory BBC).
    I haven't decided for sure which heads to get...as far as intake port size. The cost difference between the various AFR heads is trivial. On one hand I think I should get the 345 or 357 but on the other hand I am afraid I will go too big and hurt the short times too much. I don't want to take this thing past 6800 or so .I will also change the intake to a Dart or a Super Victor and I am not against a camshaft swap if I thought it would pick it up some.
    I haven't checked the stall..to be honest I actually forgot to look.I do leave flat against the converter with the trans brake...but I don't mash the throttle until just before I release it because this is a bottom bulb car with no delay box.The converter is an 8" Coan that I had built for a 14.1 454 that I had in the car with the same heads and intake. Cam was a .714 lift Comp cams roller with dur @ .050 262/ 272 with a 108 LSA. I did dead head the converter with that engine one time and it stalled at 5200 with the transbrake. I called Coan before I put it behind this engine to see if the converter could be modified for this combonation..I gave them my engine specs.He told me to try it as is and see how it did. The car ran 6.50's with the old engine and the 60' were always around 1.43 - 1.46 and MPH was 104....I thought that 80 more cubic inches would have picked it up more than 3 tenths.

  8. #8
    Member JOURNEYMAN
    Join Date
    May 2007
    Location
    San Dog
    Posts
    34
    Well from everything I read those 074 castings don't flow for crap stock, especially with what your doing. My AFR 305 heads decimate those numbers, JMHO but I bet in your case you will see a big difference with new heads.
    "Good people sleep peacefully in their beds at night, only because rough men stand ready to do violence on their behalf."

  9. #9
    Senior Member MASTER BUILDER
    Join Date
    Oct 2004
    Location
    Newport News, VA
    Posts
    139
    Quote Originally Posted by Tod74
    Thanks for the reply guys..I never really thought it would go 5's just by changing heads...only reason I ask is I see other people on here with motors similar to mine with good heads running much faster ..plus,like I said only made 4 passes, So have not done any playing with timing and so forth. The car leaves hard and pulls hard the first half of the track but it really seemed to nose over on top when I took it to 6800...I have been told I am running too much timing for a big block (38 total distributor locked out). I just thought it was nosing over because it has stock factory heads on a relatively large engine(compared to the factory BBC).
    I haven't decided for sure which heads to get...as far as intake port size. The cost difference between the various AFR heads is trivial. On one hand I think I should get the 345 or 357 but on the other hand I am afraid I will go too big and hurt the short times too much. I don't want to take this thing past 6800 or so .I will also change the intake to a Dart or a Super Victor and I am not against a camshaft swap if I thought it would pick it up some.
    I haven't checked the stall..to be honest I actually forgot to look.I do leave flat against the converter with the trans brake...but I don't mash the throttle until just before I release it because this is a bottom bulb car with no delay box.The converter is an 8" Coan that I had built for a 14.1 454 that I had in the car with the same heads and intake. Cam was a .714 lift Comp cams roller with dur @ .050 262/ 272 with a 108 LSA. I did dead head the converter with that engine one time and it stalled at 5200 with the transbrake. I called Coan before I put it behind this engine to see if the converter could be modified for this combonation..I gave them my engine specs.He told me to try it as is and see how it did. The car ran 6.50's with the old engine and the 60' were always around 1.43 - 1.46 and MPH was 104....I thought that 80 more cubic inches would have picked it up more than 3 tenths.
    You've touched upon several things here that would cause your problems. Back when I first built my 496 and was running on gas, I set the timing to 35 initially just to be safe until I got the thing on a dyno. Once on the dyno we picked up 35 hp just by advancing the timing from 35 to 38. Later on I played with 39 and then 40 and got a little detonation at 40 so backed it down to 38 and had no other problems. Now that I'm running alky I run 37* with no problems.

    You'll be surprised at how much you will pick up with good heads and you'll be surprised again at how much you pick up my having those good heads ported by someone who knows what they're doing. I had Curtis Boggs do my Bodix 2X heads and at the same time I installed a vacuum pump. The best I can figure I gained a total of 90 hp with those 2 changes and allowing maybe 20 hp from the vacuum pump that means 70 hp or more just from porting the heads.

    I think you are suffering from 2 major items. I think you have the wrong cam and your heads don't flow enough to support the power level you want. I don't think that motor will have the ummff to work well with a 114 LSA. I would think something on a 110 or 112 LSA. Even if you keep your current cam I would retard it a few degrees from the 5 degrees advance you have now. Maybe install it on a 112 or 111 ICL which should give you a little more top end. As far as the intake, there's no sense in changing it until you get better heads. Going with a larger intake now will just make the problem worse.

    I think some well researched dollars in heads, intake and cam will get you where you want to be. Give Curtis a call. You'll be glad you did.

    George
    http://www.gdmii.com/pics/81launchvidcapsig.jpg
    1981 Camaro @ 2594 lbs.
    496 cu. in. on 1150 Rupert alky
    Brodix BB2X heads touched by the magic hands of Curtis Boggs
    5.470@125.56 Best 60' 1.18
    www.motorsportsvillage.com

  10. #10
    Senior Member RACING JUNKIE
    Join Date
    Sep 2007
    Posts
    4,143
    Thanks gdmii

    I am not changing the intake now...I ment when I change heads I plan to change the intake. Like I said I used the top end parts from my old engine simply because I had them,and I wanted to run the car before winter. I only used that cam because that is what Crane recomended. I know a little bit about camshafts but not nearly enough...so I usually just get recomendations from crane and Comp cams and put the numbers into a Desktop Dyno programs and pick the one that looks like it works better.I know those things are not exactly accurate,but my thinking is that even though the power numbers are not exact,I can still compare two cams against each other. I think they recomended that cam because of the heads I have. I degreed it at 109 intake centerline because that was what the cam card said.


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Email us - Support@RacingJunk.com
Call us - 866.326.9227
Copyright © 2005-2016 RacingJunk.com All Rights Reserved.

Designated trademarks and brands are the property of their respective owners. Use of this Web site constitutes acceptance of the RacingJunk.com
Terms of Use, Classifieds Disclaimer, Privacy Policy, and Cookie Policy