Description
Vacuum Secondary Diaphragm for Holley 4150/4160 — 135-4 Replacement
Fix your Holley vacuum secondary carburetor with this direct replacement for the Holley 135-4 diaphragm assembly. When the secondary throttle plates won't open, you're leaving horsepower on the table — this diaphragm restores proper vacuum-actuated secondary operation on Holley 4150, 4160, Demon, and Quick Fuel 4-barrel carbs.
Key Features
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Exact 135-4 replacement — Same dimensions, rod length (2.054"), and spring housing as Holley OEM
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Ethanol-resistant rubber — Modern diaphragm material resists stiffening from E10/E15 fuels
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Pre-assembled — Diaphragm, rod, and spring retainer in one unit
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Includes housing gasket — Die-cut cork gasket for the diaphragm housing cover
Compatible Carburetors
| Series |
Models |
CFM Range |
| Holley 4150 |
0-3310, 0-4777, 0-4779, 0-80508 |
600-850 |
| Holley 4160 |
0-1850, 0-80457, 0-80570 |
450-750 |
| Demon |
Street/Speed/Mighty Demon (vac sec) |
575-850 |
| Quick Fuel |
HR, SS, Slayer (vac sec models) |
580-850 |
Symptoms of a Failed Diaphragm
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Secondaries never open — Engine feels like a 2-barrel; tops out early
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Slow or lazy secondary opening — Diaphragm partially torn; delayed opening
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Secondaries flutter — Diaphragm has a pinhole leak; vacuum signal inconsistent
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Rich condition at part throttle — Diaphragm leaking fuel into vacuum chamber
Quick Test
Remove the vacuum hose from the secondary diaphragm housing. Apply vacuum with a hand pump. The secondary throttle shaft should move and hold position. If it doesn't hold vacuum, the diaphragm is torn.
Frequently Asked Questions
Q: How do I know if I need 135-4 vs 135-3?
A: The 135-4 has a 2.054" rod length for universal Holley 4150/4160. The 135-3 has a shorter rod (Ford/Mopar OEM). Measure your existing rod.
Q: Will this fit Quick Fuel SS-series carb?
A: Yes. Quick Fuel vacuum secondary carbs use the same diaphragm assembly as Holley. Direct fit for HR, SS, and Slayer series.
Q: Can I convert to mechanical secondary using this?
A: This diaphragm is for vacuum secondary operation. To convert to mechanical, use this as a plug (block vacuum port) and install a mechanical secondary linkage kit (sold separately).
Q: How long does installation take?
A: 15-20 minutes. Remove the vacuum secondary housing cover (3 screws), swap the old diaphragm for new, replace the cork gasket. No carb removal required.
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