cast dart 165cc test head for novice

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GARY C
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Re: cast dart 165cc test head for novice

Post by GARY C »

steve cowan wrote: Sun May 06, 2018 6:01 pm Gary,
thanks for sharing,i figure i can make around 420 as well
this thing has a lot of piston to bore,old trw pistons,5/64 rings
stock rods and bolts,like i said just a throw together while other motor is getting sorted want to still be able to race and have some fun.the other cam is comp solid F/T
270xos-8
adv 270-280
dur @ 0.050'' 240-246
LSA 108
lift 510-519 - 1.5 rockers
any advice on what intake - exhaust % ratio to work to ??
i am running 1.6-1.5 stud mount rockers and stud girdle at the moment
i will source some 1.5 rockers for intake.
if the intake has reasonable fitment i will run it first out of the box and proceed from there,i dont want to mess up a good intake.
Most SBC run best in the range of 36 to 38 total timing with some exceptions, my 306 had a giant dome and wanted 42+. The engine in the the dyno was never track tested.
On the 331 in the dyno sheet I wanted to see an Air Gap and a 268 to 272 cam with a 1.6 or 1.65 intake ratio to see how it ran down low, he was building it for a street rod not a race car and was some what disappointed with the sound and idle quality of the cam as I told him he would be, he wanted to change the cam after the dyno session but he ended up selling all of it before completing the project.
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Re: cast dart 165cc test head for novice

Post by GARY C »

BTW, I have run 2 brand new 830 annular booster carbs and both had a dead spot at the hit of the throttle regardless of what they were ran on and nothing I changed would get rid of it, I would defiantly start with a known good 750 carb and test from there.
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Re: cast dart 165cc test head for novice

Post by steve cowan »

Gary,
interesting tip on the 830,i really like the carb as i can get it to run really clean and lean on the street,i spent weeks and months testing and modifying PVRC to get a good WOT fuel curve ended up drilling PVRC up to 0.075''.
its amazing as it seems that the 750 carb is still the best bang for buck over the years.I want to make one change at a time before i commit to buying another carb
(I have 3 carbs)LOL
thanks for your help,

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Re: cast dart 165cc test head for novice

Post by Carnut1 »

steve cowan wrote: Sun May 06, 2018 8:41 pm Hi Charlie,
I agree 100% this is why I say I am taking it as being sceptical,
I ran the test 3 times and as far as rechecked bench with calibration plate, same results each time left me scratching my head.
On the photo of the laptop shows it lost cfm up to 0.400" which I expected right through the lift curve, and this is why I put up my results as I am trying to be as honest as possible, any hints Charlie??
Two things I cannot see well in pics, Has the other side of the intake been taped off or just foam? The remaining intake ports on the head I fill with foam and tape off as well.
Last edited by Carnut1 on Mon May 07, 2018 1:38 pm, edited 1 time in total.
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Re: cast dart 165cc test head for novice

Post by GARY C »

steve cowan wrote: Mon May 07, 2018 2:35 am Gary,
interesting tip on the 830,i really like the carb as i can get it to run really clean and lean on the street,i spent weeks and months testing and modifying PVRC to get a good WOT fuel curve ended up drilling PVRC up to 0.075''.
its amazing as it seems that the 750 carb is still the best bang for buck over the years.I want to make one change at a time before i commit to buying another carb
(I have 3 carbs)LOL
thanks for your help,

steve c
I didn't know you had a base line with it, mine were the more generic one that still had a choke horn and is a dead spot more than a bog. I tried squirters, pump sizes, cams, fuel levels and ever changed one to a billet 850 base plate to eliminate the tapered one but nothing fixed it, I have not done any internal changes to circuits.
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Re: cast dart 165cc test head for novice

Post by steve cowan »

Carnut1 wrote: Mon May 07, 2018 12:41 pm
steve cowan wrote: Sun May 06, 2018 8:41 pm Hi Charlie,
I agree 100% this is why I say I am taking it as being sceptical,
I ran the test 3 times and as far as rechecked bench with calibration plate, same results each time left me scratching my head.
On the photo of the laptop shows it lost cfm up to 0.400" which I expected right through the lift curve, and this is why I put up my results as I am trying to be as honest as possible, any hints Charlie??
Two things I cannot see well in pics, Has the other side of the intake been taped off or just foam? The remaining intake ports on the head I fill with foam and tape off as well.
Charlie,
Only foam and no tape, Mag2555 had mentioned previously to tape up extra ports
I didn't tape probably should of. And that could cause the way wood results, I am in the process of making a valve opening tool, inlet radius guides of various sizes, exhaust pipes of different sizes, flow balls.
I can't get any international assistance so a friend of mine is helping to make necessary tools before I do anymore testing
Thanks for your help

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Re: cast dart 165cc test head for novice

Post by Carnut1 »

A good sturdy opener is a must. Flex will not help accuracy. Thanks, Charlie
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Re: cast dart 165cc test head for novice

Post by steve cowan »

flowbench 001.JPG
flowbench 003.JPG
flowbench 004.JPG
flowbench 005.JPG
flowbench 006.JPG
flowbench 008.JPG
flowbench 007.JPG
valve opening tool works real nice,easy to flip from intake to exhaust,smooth operation from 0- 0.700'' lift,made radius inlet guide to suite the 165cc heads (1204) felpro,in the process of make guide for 1205,1206.
flowbench 009.JPG
flow checked a stock intake port on the 165cc head
208.8 @ 0.500'' @ 28''
allowed for correction and leakage
dart claim 210 cfm @ 0.500'' lift and 28 ''depression
going to recheck later in the week and flow the ported intake runner
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Re: cast dart 165cc test head for novice

Post by Scotthatch »

One of the problems with the company listed numbers is that sometimes they use a larger bore adapter then you are also when was your last calibration ? If you need spot on numbers you start your morning with a calibration for your days work ...
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Re: cast dart 165cc test head for novice

Post by steve cowan »

Hi Scott and thanks for replying,
I check calibration prior to using the bench whatever time of the day or night.
I only have 2 x bore sleeves
4.06"
and 4.125"
My engines are 4.030"
A big deal I found yesterday was allowing for leakage, the parameters are 0< 50 cfm
I believe this is where I was going wrong a couple of weeks ago and had over inflated flow #s
steve c
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