what should the gap be for a 509 merlin.when i got the engine it had 35% but a guy from the shop said it should be 70.thanks jeff
the plugs i running are accel 276
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69z 509 merlin 600 hp/620 torque pro street

[This message has been edited by jaw2 (edited 10-05-2002).]

Depends on the compression and what ignition your running.

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Black 69 camaro

it's 9.5 comp with a msd 6al with timing computer and a hei dist.

You should be able to open the gaps up to about .055" with that setup if you have a Hi-perf coil on the HEI.

If your plug wires are good it may take more than .055. I have found for street cars the more you can run the better it is.

That is interesting that you think he can open them up to .060 - My buddy is pestering me to do the same thing. I have the GMPP 350HO with 9:1 compression and the HYPERTECH Coil. I gapped my plugs to .040 and he almost had the big one. What do you guys think?

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1969, X-44, Export Model, Hugger Orange, Std. Int., BC Rear(soon to be a BT 12 bolt), PDB, GMPP 350HO, M22 Supercase, SSM Lift Bars, AirGap, Holley 750, FlowMaster American Thunder Exhaust, FlowTech Headers

You can open them up but if you do keep in mind that it forces the coil to fire with more voltage. This can make more power but it can be hard on your ignition parts. especially cap and rotor IMO - never had a coil go out though. It can also cause high RPM misfire with high compression engines. It's worth a try though IMO.

Thanks Eric68. We'll give 'er a whirl this afternoon.

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1969, X-44, Export Model, Hugger Orange, Std. Int., BC Rear(soon to be a BT 12 bolt), PDB, GMPP 350HO, M22 Supercase, SSM Lift Bars, AirGap, Holley 750, FlowMaster American Thunder Exhaust, FlowTech Headers

whould it be better to open them up more then 35 or does it really make a difference.thanks jeff

You can make more power with a wider gap until your ignition can no longer fire across the gap at mid-high rpm. With a stock HEI, I run .35", HEI with hotter coil/module, run .45", and with an MSD box, run .55". This is a good general rule for motors up to 11:1 or so compression.

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79' Z28...

thanks for the help.i'm going to set them at 55 and see what happens