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ARP bolt lengths

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Old Jul 14, 2019 | 10:31 PM
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Default ARP bolt lengths

Hey everyone

I have some questions regarding the bolt lengths for my intake manifold and the auto trans pan:

1. Intake:
In a previous thread 'HeadsU.P. recommended the ARP-434-2101 bolt kit which are 1" UHL.

I've measured an original intake bolt and it is 1 1/8". Also not all the original intake bolts have the same length... I'm affraid that the 1" bolts will be too short because I'm gonna use lock washers.

ARP does also sell another kit with an UHL: 1.250"
https://www.summitracing.com/parts/arp-435-2101/

Will these bolts be too long? I'm concerned because I've read that there can be damage when intake bolts are too long. (It's for a 77 with original L48 heads and a performer intake)


2. Automatic transmission pan th350:
I think of buying these bolts:
https://www.summitracing.com/parts/arp-430-0401/

Will they fit? (I didn't meassure the length of the original bolts before I left for the US...)
I will be using a new aluminum pan:
https://www.summitracing.com/parts/sum-4338856/

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Old Jul 14, 2019 | 10:38 PM
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Why in the world would you use lock washers on the intake manifold bolts..? That's just a bad idea... Don't do it.

Lars
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Old Jul 15, 2019 | 07:26 AM
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Originally Posted by lars
Why in the world would you use lock washers on the intake manifold bolts..? That's just a bad idea... Don't do it.

Lars
Ok, then I'll just use normal washers.
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Old Jul 15, 2019 | 08:23 AM
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ARP Intake Bolts more or less have a washer built into them.
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Old Jul 15, 2019 | 09:05 AM
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and aftermarket aluminum intakes usually have thicker mount flanges, so you may need longer bolts. measure all 12 holes on old intake and new one.
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Old Jul 15, 2019 | 10:52 AM
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Call ARP in Ventura, CA and tell them your intake and head set up.
They have numerous intake manifold bolt sets available depending on your engine model, heads, and make and model intake.
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Old Jul 16, 2019 | 07:31 AM
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Drop the intake in place. Use a coat hanger or screw driver whatever to probe the holes for length. Subtract a tick to prevent bottoming. I believe its the center 2? bolts on each side that bottom out on pushrods.
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Old Jul 16, 2019 | 07:32 AM
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BTW, you can use .13c generic bolts on an intake. That being said, Jim2527 uses fancy bolts because he says they look 'nice'.

Last edited by jim2527; Jul 16, 2019 at 07:33 AM.
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Old Jul 16, 2019 | 09:30 AM
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That 13 cent bolt may cost you many pesos later on if it snaps off in the cyl head.

I really frown on people using your corner hardware bolts on engines. The bolt heads are too big restricting the use of box-end or socket movement. The bolt heads tend to gall the aluminum intakes. And last, they look cheap or . . . . . . . . look like shet.

ARPs intake bolts are not expensive. No worries about snapping one. The 12 point are easy to torque. And they look very professional.


ARP: please note I have not received my endorsement check in the mail yet.
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Old Jul 16, 2019 | 11:02 AM
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What do you guys think of the bolt length?
I'm in the bahama's now so can't measure or call someone succesfully (I'm from Belgium so high cists to call people here).

Original bolt length: 1 1/8"
ARP option A: 1"
ARP: option B: 1.250"

What should I get (best chance of fitting succesfully)?
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Old Jul 16, 2019 | 11:23 AM
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Originally Posted by Novusuhu
What do you guys think of the bolt length?
I'm in the bahama's now so can't measure or call someone succesfully (I'm from Belgium so high cists to call people here).

Original bolt length: 1 1/8"
ARP option A: 1"
ARP: option B: 1.250"

What should I get (best chance of fitting succesfully)?
Option B. If too long they can be washered or ground down. Your not making short bolts longer.

That being said, I used Moroso 38400 1-1/8 under head 12 point.
https://www.summitracing.com/parts/mor-38400

Last edited by jim2527; Jul 16, 2019 at 11:29 AM.
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Old Aug 30, 2019 | 02:41 PM
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Originally Posted by jim2527
Option B. If too long they can be washered or ground down. Your not making short bolts longer.

That being said, I used Moroso 38400 1-1/8 under head 12 point.
https://www.summitracing.com/parts/mor-38400
What intake did you use? Where it the original heads?
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