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#61
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As far as the heads, they are fixable. All depends on the direction you want to go and how big the bowls are. First you could have them furnace welded and re-port the heads, would require new seat and guide work. Only company I trust to weld is Midwest Cylinder Head. If the bowl is larger than 1.93 and smaller than 1.99, you can install larger 2.190” intake valves pending you can shrink the exhaust valve enough for .050” clearance in between. Not sure of the pushrod pinch, but anything you can do to widen that will allow the heads to work better with such a large intake throat, reducing the bulge at the straight wall will help too. I’m assuming the low lift is suffering from such a large bowl area, gaining valve lift could help and a faster ramping cam. Compression is always your friend too. The motor peaks at a very low RPM, power gains from raising peak 200 RPM to 300 RPM will show more power overall. Calvin Hill Hill Performance 708-250-7420 |
#62
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#63
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No.
And a cam lobe over .500” is also doable, but this is a street engine. C |
#64
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I have a LOT more to worry about. 60 people are depending on me to have the mill ready to roll. I will get back to you guys there, have not checked since last post. I am sure the usual suspects are taking their shots and maybe a few more guys too . I can take it. And I did appreciate the offer to check on Dan way back then. Things went bad between you and me on CV-1 threads but the Street Section is no place for that talk. I come here to get away from Race Section BS. "bad ass build coming along". Which one ? 700HPish 461 will be running by April I hope. 540 is still in the works. OP, I apologize. BTW, stick a bigger cam in it and you will love it. HOs rock on the street. |
#65
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Ok, just asking. .050 seemed like a lot, i was confused
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#66
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I agree with post 61.
I have saved many a mis ported head ( not only Pontiac ) that way and even a custom 2.14" valve might make things way better and those fit without going over to a smaller Exh valve + for just flow testing usage you can get them off the shelf in a Mopar 2.14" valve with the needed 11/32" valve stem. Also the SD455 heads do not have a great Exh port short turn do high lift flow is limited even as compared to a fully reworked iron big valve D port head so only reworking the Intake port to flow no more then 270 cfm@28" is where I would set the limit on a motor with under 11 to 1 compression. With a 2.19" valve the chamber will definitely need some unshrouding work to make it worthwhile it install that size valve in the first place,but the gain in valve size may be just enough to offset the CC increase of the chamber to have the compression you have stay near the same without milling the head.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! Last edited by steve25; 01-06-2020 at 07:32 AM. |
#67
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Isn't stock Pontiac valve guide spacing 1.98? If that's correct doing the math there is very little room for larger valves and no way to leave .050 between them.
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#68
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I don't know what the stock valve spacing is and all the Pontiac stuff is over in my nephews garage. That said a stock 2.11" intake and 1.77" exhaust will only have 0.40" clearance.with 1.98" spacing. Stan
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
#69
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I have used 2.14" Intake valves many times while running 1.77" Exh valves with no interference issues when hot.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#70
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I know 2.125 and 1.80 in an SD-455 head will nip each other on a few cylinders but still make good power.
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#71
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A fwiw.
Indy Cylinder Head is also well known for their excellent cylinder head repair work... http://indyheads.com/ .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE |
#72
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Please excuse the interruption but PY has a Troll that needs to be dealt with. In regards to your post; Your results are close to typical for most 4.5 inch stroke stock block builds we get phone calls about with the same complaint. I highly doubt your heads are causing a lot of power loss with your combination. You have enough power and torque to have a fun engine to drive. A few minor realistic things you can do to make your engine perform better; Make sure the cam is installed between 110-113 ICL. Make sure your valve springs have at least 150lbs. seat and 400lbs. open pressure Replace the RPM intake with a Torker II or Tomahawk manifold with at least a one inch spacer. Replace the 1.65 exhaust rocker arm with a 1.5 |
#73
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If 1.98 is right for guide spacing then there is around .017 clearance between valves with those sizes. So i can see a little nipping happening
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The Following User Says Thank You to slowbird For This Useful Post: | ||
#74
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“Replace the 1.65 exhaust rocker arm with a 1.5”
Curious, are you seeing gains by doing this with higher flowing heads as well?
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71 GTO, 463, KRE 295 cfm heads ported by SD Performance, RPM intake, Qjet, Dougs Headers, Comp cams HR 246/252 ...11 to 1 , 3.55 cogs, 3985lbs.....day three- 11.04 at 120mph ....1.53 60', 6.98 1/8 mile |
#75
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On ported or more efficient heads the split profile cams don't work as well. I swapped my exhaust rocker from a 1.65 to a 1.6 as well as loosening the lash .005 on the exhaust and picked up .10 in the 1/4.
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66 GTO Nostalgia Super Stock/Street Legal Car 421 CID, stock block, Wenzler Intake, 2- Carter 750 AFB's, 3.90 Gears, Full Factory Interior, Full Exhaust, Stock Suspension 3750LBS 9.77@136.99 Multiple NSCA/NMCA World Champion 66 GTO 389 3x2, 4 speed, 4.33 gear, Montero Red 33K original Miles 67 GTO 2dr Post, 428, Tri Power, 3.55 Gears 80 Trans Am Black SE Y84 W72 WS6 |
#76
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What were your cam specs when you did those changes?
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#77
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274/280@ .050
108 LSA/ 106 ICL .440 Lobe Old Cam was a 272/276 @ .050 108LSA/ 106 ICL .440 Lobe and was quicker all the way through the 1/4.
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66 GTO Nostalgia Super Stock/Street Legal Car 421 CID, stock block, Wenzler Intake, 2- Carter 750 AFB's, 3.90 Gears, Full Factory Interior, Full Exhaust, Stock Suspension 3750LBS 9.77@136.99 Multiple NSCA/NMCA World Champion 66 GTO 389 3x2, 4 speed, 4.33 gear, Montero Red 33K original Miles 67 GTO 2dr Post, 428, Tri Power, 3.55 Gears 80 Trans Am Black SE Y84 W72 WS6 |
#78
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First start up since the dyno run. Took two months just to get the drive shaft.
Gnarly. https://www.youtube.com/watch?v=QVzzzFoUWPg |
#79
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Unless your putting it in a locomotive, 570 ft pounds torque, will spin tires till you decide to quit, and with traction run a serious hellcat killing quarter mile, so where’s the disappointment?
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#80
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Hellcat with drag tires, 10s https://www.youtube.com/watch?v=bXv0uMc-jW4 |
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