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I have a 355 chevy with small dome pistons in it. I recently had a set of holley alluminum heads on it and the best I got out of the engine was a 12.58 in the 1/4. Everyone that I have spoken to about the engine said that the heads were to small. So I sold them Nobody can seem to give me a strait answer on what heads to go with. If anyone has any suggestions please let me know. Thank you
WHAT WAS THE PORT VOLUME ON THE HEADS? WHAT WHERE THE FLOW NUMBERS? HOW MANY R.P.M.S. DID YOU TURN THE ENGINE? WHAT WHERE THE LIFT VALUES ON THE CAMSHAFT?Quote:
Originally posted by shawn74
I have a 355 chevy with small dome pistons in it. I recently had a set of holley alluminum heads on it and the best I got out of the engine was a 12.58 in the 1/4. Everyone that I have spoken to about the engine said that the heads were to small. So I sold them Nobody can seem to give me a strait answer on what heads to go with. If anyone has any suggestions please let me know. Thank you
I've seen some magazine buildups and dyno tests with the Holley heads and frankly, they weren't that impressive. Get us the data that Erik asked you for so we can give you an intelligent answer.
Chambers are easy to size. Runners take a little trial and error. If you want to run 12's and under, 200-220 cc runners will probably be ideal. Give Air Flow Research a call, they make some of the best heads and will point you in the right direction. For the chambers, smaller is better, but so are flat top pistons. You want to run the smallest combustion chamber you can along with a flat top piston while still meeting your target compression ratio and having enough room around the valves to get good airflow.
how heavy is the car or truck? how big is the cam ? what is the cfms of the carb? how much cr ? how big are the headers what gear in the rear end. what is the stall on the converter what is the 60 feet do you have a good fuel pump .how do you know the heads are bad?? there is way to many things. could be the heads?? or it may be many things or it may be you need more engine to move what you have. was it tune in good .did you try deferent cam. intake. carb.how much do you want like HP or 1/4times ??Quote:
Originally posted by shawn74
I have a 355 chevy with small dome pistons in it. I recently had a set of holley alluminum heads on it and the best I got out of the engine was a 12.58 in the 1/4. Everyone that I have spoken to about the engine said that the heads were to small. So I sold them Nobody can seem to give me a strait answer on what heads to go with. If anyone has any suggestions please let me know. Thank you
YOU STATE SMALLER CHAMBERS ARE BETTER.NOT ALWAYS.SOMTIMES IF THEY ARE TO SMALL THE ACTUALLY (SHROUD) THE VALVES.Quote:
Originally posted by 76GMC1500
Chambers are easy to size. Runners take a little trial and error. If you want to run 12's and under, 200-220 cc runners will probably be ideal. Give Air Flow Research a call, they make some of the best heads and will point you in the right direction. For the chambers, smaller is better, but so are flat top pistons. You want to run the smallest combustion chamber you can along with a flat top piston while still meeting your target compression ratio and having enough room around the valves to get good airflow.
The heads that I had were 184cc intake runners and if I remember correctly the chamber size was 72cc. The car is a 74 nova weighs 3190 with 410 spool in the rear end. I was shifting the car at 6500 rpms. The converter is a 3000 stall The carb is a 750 holley vac seconary. No I don't know that the heads were the problem. Have a good carter elctric fuel pump. Not real sure on what size the headers are. The 60 foot times were 1.7
what was the lift on the cam,and cr and how tall on the rear tires. i do not think the heads were bad. but what times did you want to see?? the amount you have told me i think it will run some were in the low 12s with what your have. your 60 foot be a bit better it may like more gear and 3500 on the stall.
the lift on the cam was 507intake 532 exhaust duration is @.50 242 intake and 250 exhaust. The rear slicks were 28x9 15 I was lookin to get somewhere between mid 11's real low 12's
try some more gear rear like a 430 or 456 and if this cam is a solid cam you may need to go bigger. but how much cr do you have??? work on you 60 foot. you need to work on the suspension . look at you torque converter it may be going bad . if you drive this on the street go with 430
I guess I don't know what cr is No I don't drive it on the street and yes it is a solid cam
CR is compression ratio .on the intake i would look at a single plane or rpm air gap
Thanks it is supposed to be around 12.0 to 12.5:1 I am running a single plane high raise on it now But the question still remains what heads should I buy?
WHEN YOU CROSS THE FINISH LINE HOW MANY R.P.M.S. ARE YOU TURNING?
Hands down, AFR 195 heads, are the best flowing head out there for their size, and they should be a great flowing head for you. Go to their website and check out the 180's and the 195's.
www.airflowresearch.com
across the line is usually right around 62-6500
I THINK YOUR HEADS ARE ALLRIGHT.I WOULD NOT GO OUT AND SPEND THE MONEY ON HEADS.I DON'T THINK IT WOULD REALLY MAKE THAT BIG A DIFFERENCE.THE PROBLEM I THINK IS YOUR STALL SPEED BEING TO LOW LIKE PAT HAD SAID.I WOULD PUT A LOOSER STALL IN 3,500 TO 4,000 AND I WOULD ALSO LOOK AT YOUR SUSPENSION.MAYBE YOU ARE NOT (HOOKING UP) AS WELL AS YOU THOUGHT.Quote:
Originally posted by shawn74
across the line is usually right around 62-6500
yes and i think the cam is to small. if you have 12 to 1 it could take more. like erik said and i said to work on the suspension. the holley heads may not be the best. but i shure do not think it was all your promblems.and would of put you in the low 12s with not very much work
Well I wish I would have found you guys about a month ago because I sold the heads So I still need to buy a pair. What would you recomend?
Call AFR and talk with one of their tech people about your application so they can make a recommendation. I guarantee you will be pleased with these heads.
THE AFR'S ARE GOOD HEADS.THE PROBLEM IS THE FLOW DATA IS FROM 1998 AND SINCE THEN MUCH ADVANCEMENT HAS BEEN MADE.I WOULD NOT GET TO EXCITED ABOUT ANY GIVEN BRAND NAME.ON THE DYNO OR AT THE TRACK THERE REALLY WON'T BE A LARGE DIFFERENCE FROM HEAD TO HEAD AS LONG HAS THE PORT VOLUME IS ABOUT THE SAME.THE WHOLE IDEA IS TO HAVE A SMALLER PORT VOLUME WITH HIGHER FLOW NUMBERS.Quote:
Originally posted by rumrumm
Hands down, AFR 195 heads, are the best flowing head out there for their size, and they should be a great flowing head for you. Go to their website and check out the 180's and the 195's.
www.airflowresearch.com
I recommend AFR because I have personal experience with them and they have met my expectations in every way. I cannot recommend Brodix or other good flowing heads because I have no experience with them. A test done around a year ago by Chevy High Performance magazine compared all of the aluminum heads on the market, and AFR topped each category. But you are correct about the right head for the right application. Too big or too small is not good, especially when you are paying out $1200.00+ for a set. Hence the reference to calling the tech dept.
Great heads over good heads will get you a couple cars lengths which converts to maybe a tenth or so.Quote:
Originally posted by erik erikson
WHEN YOU CROSS THE FINISH LINE HOW MANY R.P.M.S. ARE YOU TURNING?
But, there's nothing that will get you down the 1320 more efficiently than proper gearing.
If you shift at 6500 rpm then you should be crossing the finish line at 6500...that's the key to the right gear.
I agree, it seems you should be getting at least to the low 12's
BTW, aluminum heads save you weight which is a good thing but they have to be extremely hot to make the same HP as an iron head making everything else equal.
Aluminum absorbs combustion heat and you don't get the expansion of the gases like you do with an iron head. With aluminum just make sure that the head is already very hot before your run.
Besides the things above, the key to putting together a real runner is to have all components matched to run at the same RPM range.
Starting with cubic inches and bore vs stroke ratio (is this an rpm'r or a torque'r). Then match all these things: Carburation, intake manifold, head port and valve size, compression, cam, headers, tranny and rear end gears to that rpm range.
Where many guys get in trouble is they tend to copy what other guys are running that have different applications instead of figuring out for themselves what will work best for their own application.
This is the difference between the pack and the guy that takes home the trophy every week.
Shawn, just keep at it and you'll get there.
ha shawn heres a good idea i use them and when there ported and polished they flow better then the bowtie heads
The '96 and later smallblock "Vortec" 350 cast iron heads are a very hot item. These "L31" heads with casting number 10239906 and 12558062 or PN-12529093 (bare), flow great numbers for a production head, even better than the Phase 2 Bowtie cast iron head, when fitted with 2.02/1.60" valves and bowl ported. The complete heads (PN-12558060) come with 1.94"/1.5" valves and pressed in rocker studs, but can easily be fitted with 2.02"/1.6" valves and screw in studs. Chamber volumes are 64cc and intake port volumes are 170cc. The Vortec heads have raised intake ports and "fast burn" chambers. The heads require the use of narrow body "self-aligning" rocker arms and center bolt valve covers. They will bolt to any Gen.1 block.
The price per pair for new complete Vortec "L31" 350 SBC heads (PN-12558060) is about $485.00