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Forum: Hot Heads Tech Talk

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on: Wed 31 of Dec, 1969 [23:00 UTC] reads:

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ron37
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270 hemi pistons
on: Mon 03 of May, 2021 [18:38 UTC] score: 0.00
I have a 270 Dodge hemi and a set of .030 NOS 315 hemi car pistons that I picked up years ago at a swap meet. So when I get the 270 bored, if I use the 315 pistons, will it raise original 270 compression ratio from 7.6 to 1 to the 315 ratio of 8.25 to 1? The one book lists the pistons as 8.5 to 1. My Tex Smith hemi book says 8.25 to 1. Any ideas?

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JustGary
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Anyone have *CURRENT* contact info for Carl Bills / Black Mountain Hemi?
on: Tue 27 of Apr, 2021 [18:48 UTC] score: 0.00
Please contact me, I have a tech question.
His phone, email & website are all disconnected. cry

Thanks.
Gary Burkholder
571-244-6576

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392PT50
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Head stud torque for aluminum heads
on: Sat 24 of Apr, 2021 [16:08 UTC] score: 0.00
Can anyone tell me the torque spec for Hot Heads aluminum heads with aluminum stands?

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Webmaster
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Re: Head stud torque for aluminum heads
on: Mon 26 of Apr, 2021 [18:21 UTC] score: 0.00
> Can anyone tell me the torque spec for Hot Heads aluminum heads with aluminum stands?
I use 100 ft.lb., have fun, Bob

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murbas
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331 hemi with backfiring problems
on: Sun 28 of Mar, 2021 [03:13 UTC] score: 0.00
i have a 331 hemi bored .040 over with 9 to 1 compression ratio, cam is an isky .485 lift 232 duration, 108 degree seperation, with dual holley 450cfm 4bbl's . headers are fenderwell exit with 3" collectors and baffles. car has a street/strip turbo 400 with a 3000 stall converter and 4.11 posi rear with 30" tall tires. i get backfiring occurring on ocasion under hard acceleration. can any help me with this problem ?

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Webmaster
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Re: 331 hemi with backfiring problems
on: Wed 07 of Apr, 2021 [16:42 UTC] score: 0.00
Murbas: Sounds like you're running too fat. According to the calculations I use, your 338 at 6,000 rpm will wants 587 cfm. Try a smaller carb and see if that fixes it. Have fun, Bob






> i have a 331 hemi bored .040 over with 9 to 1 compression ratio, cam is an isky .485 lift 232 duration, 108 degree seperation, with dual holley 450cfm 4bbl's . headers are fenderwell exit with 3" collectors and baffles. car has a street/strip turbo 400 with a 3000 stall converter and 4.11 posi rear with 30" tall tires. i get backfiring occurring on ocasion under hard acceleration. can any help me with this problem ?

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hemistude
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Re: 331 hemi with backfiring problems
on: Tue 06 of Apr, 2021 [19:47 UTC] score: 0.00
Is this a new build or has it been in place for a while and has run well in the past? Is it popping in the exhaust or through the intake? What does a compression check show? Is the vacuum steady or bouncy? Lots of clues can be had from those tests.

Does the mechanical advance work on your distributor? Have you confirmed the base and full advance timing settings? It should at full advance by 3000 rpm. You can rule out vacuum advance as the culprit -- it is not in play under acceleration.

If your full mechanical advance is between 28 and 32, then it shouldn't be popping because of SPARK timing. I always suspect VALVE timing next. Those "2 deg advance-straight up-2 deg retard" timing sets can be confusing to install. If that was set up wrong, it'll run but may give the symptom you are experiencing. Not necessarily the easiest thing to confirm but if everything else is right, that's all that's left.

Don't ask me how I learned this. confused Hope it helps,

Dave

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DaveBlakeman
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Re: 331 hemi with backfiring problems
on: Thu 01 of Apr, 2021 [15:35 UTC] score: 0.00
Lean condition ,, leaky plug wires . Bent valve stem .

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392PT50
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Breather setup?
on: Sun 07 of Mar, 2021 [20:48 UTC] score: 0.00
I need help finding a way to vent my 392 HEMI. I have the billet valley pan that has oil caps on either end. My valve covers are not an option. Does anyone have a setup that works that they'd be willing to share? Thanks!

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392PT50
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Re: Breather setup?
on: Mon 08 of Mar, 2021 [15:08 UTC] score: 0.00
> I need help finding a way to vent my 392 HEMI. I have the billet valley pan that has oil caps on either end. My valve covers are not an option. Does anyone have a setup that works that they'd be willing to share? Thanks!

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George
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Re: Breather setup?
on: Sun 07 of Mar, 2021 [22:12 UTC] score: 0.00
Try to replicate the oil fill cap/breather & tube that came on the engine where you have the front oil cap, that's how to get air in. Then use a grommet & PVC valve where the rear oil cap is. Or are you tlking a drag motor?

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392PT50
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Re: Re: Breather setup?
on: Mon 08 of Mar, 2021 [15:11 UTC] score: 0.00
> Try to replicate the oil fill cap/breather & tube that came on the engine where you have the front oil cap, that's how to get air in. Then use a grommet & PVC valve where the rear oil cap is. Or are you tlking a drag motor?

No, this is a street/strip truck. I'll see if I can come up with something like you suggest. I was thinking about a remote catch can/breather setup.

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George
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Re: Re: Re: Breather setup?
on: Tue 09 of Mar, 2021 [15:05 UTC] score: 0.00

> No, this is a street/strip truck. I'll see if I can come up with something like you suggest. I was thinking about a remote catch can/breather setup.

To breath properly you need a way to get fresh air in & suck out the old. The OEM set up the fill cap has a breather to let air in, Then replace the puke tube (draft tube) with a PCV set up. I'm sure your billet one looks better, but.....

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392PT50
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Re: Re: Re: Re: Breather setup?
on: Tue 09 of Mar, 2021 [19:40 UTC] score: 0.00
>
> > No, this is a street/strip truck. I'll see if I can come up with something like you suggest. I was thinking about a remote catch can/breather setup.
>
> To breath properly you need a way to get fresh air in & suck out the old. The OEM set up the fill cap has a breather to let air in, Then replace the puke tube (draft tube) with a PCV set up. I'm sure your billet one looks better, but.....

I think I'll plumb a barb in the front of the VP and run an inline PCV to the front port on the carb. then I'll plumb a fitting into the rear of the pan and run that to a remote breather. Think that would work?

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ron37
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330 Valve Springs
on: Fri 05 of Mar, 2021 [19:20 UTC] score: 0.00
A buddy is building a 330 Desoto. He had a hydraulic roller cam made for it. The grinder said use valve spring not over 130 lbs. A mechanic told him that high would cause abnormal wear on his new cam. I said the guy was probably thinking about flat tappet type cams. What do you guys think would be okay for a billet hydraulic roller cam. He said it is a lumpy style street cam with low end to mid-range 5000. I laughed as mid-range. 5000 isn't mid-range to me. Thought I'd drop that in there. I think he meant it keep building some to 5K. So give me some ball park number of what you would do.

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ron37
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Re: 330 Valve Springs
on: Mon 08 of Mar, 2021 [17:51 UTC] score: 0.00
The cam grinder said not to go over 130 seated pressure. I think he is using Comp Cams lifters, which I think are a quality lifter. So from what I know of what will be his usage and your input, the 130 spring will be fine. Thanks for the help.

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George
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Re: 330 Valve Springs
on: Sun 07 of Mar, 2021 [15:34 UTC] score: 0.00
What spring pressure did the cam maker specify?

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DaveBlakeman
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Re: 330 Valve Springs
on: Sun 07 of Mar, 2021 [15:33 UTC] score: 0.00
From Web Hydraulic roller (HR) cams require higher pressures to control the inertia of the heavier roller lifters and the faster acceleration of valve train components allowed by the use of the roller follower. Pure street small blocks should have 260-300lbs open pressure. For performance use, aim for 300-350lbs open. Racing small blocks that regularly see 6,000+rpm need over 400lbs open pressure. At these pressures, premium valve train components including a “billet” type cam are required. Even with these components, there will be reduced service life and the consequent need for more frequent parts inspection and replacement. Big blocks need closer to 300lbs open pressure for street driving and 350-375lbs is preferred for performance use. A racing big block needs 450lbs. As with small blocks, premium components including lifters are needed at higher pressures and rpm. As with solid lifter cams, seat pressures should be in the range of 105-125lbs for small blocks and 115-130lbs for big blocks for performance street cars. Blower cars and race cars will need higher seat pressures.

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DaveBlakeman
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Re: 330 Valve Springs
on: Sun 07 of Mar, 2021 [15:30 UTC] score: 0.00
A 130 lb spring pressure is not out of the ball park if it is seated pressure open about 320 lbs.

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DaveBlakeman
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Re: 330 Valve Springs
on: Sun 07 of Mar, 2021 [15:25 UTC] score: 0.00
Fact roller tappets are heavier than flat tappets Fact Roller cams have aggressive ramp angles . Theory at 130 lbs you will experience valve float very early on. You better do some google searching on this but do not run 130 lbs.


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