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340 pushrod issues #3065110
08/04/22 10:24 AM
08/04/22 10:24 AM
Joined: Nov 2009
Posts: 146
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mopar873 Offline OP
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mopar873  Offline OP
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Hi Guys,

Well after the last post I had, we ordered a full rocker/shaft/hold down kit from Harland Sharp for this engine. Just a breakdown, its a 1970 340 block, with untouched X heads. The engine owner purchased a Howards hyd roller cam and retro fit lifters. When we started to measure for pushrod length, we realized that the pushrods have some pretty severe clearance issues. Maybe this is normal for a set up like this, but it looks like the pushrod hole in the head would be much more effective if it was oval and not round. It's possible the pushrod cup in the lifter is a bit higher than oem, and if so that might account for some of the clearance issue, but even if you simulate the cup being deeper, there still will be problems. I guess I'm posting to see if you Guys have run into this before. We purchased the rocker kit from Mancini's, they were unaware of ever hearing anything like this before.
Thanks!

Re: 340 pushrod issues [Re: mopar873] #3065127
08/04/22 11:11 AM
08/04/22 11:11 AM
Joined: Jan 2003
Posts: 5,434
Indiana
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YO7_A66 Offline
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YO7_A66  Offline
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Indiana
What ratio is the new set of rockers?
Untouched X heads with hydraulic roller lifters may equal opening up the pushrod holes.
5/16” pushrods?
BR3 may be able to help with your situation, but the new lifters are taller than the OE making the clearance a possible issue.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.) Solid FT, Yella Terra 1.65 rockers, 9.7:1, 63cc Sidewinders (Bowl Ported),RPM intake, QF SS-750 Annular DP, MSD Street Fire Ign., & TTI's. 727/Dynamic 9.5" 3800, TF-2, & 3:91's
Re: 340 pushrod issues [Re: YO7_A66] #3065130
08/04/22 11:23 AM
08/04/22 11:23 AM
Joined: Nov 2009
Posts: 146
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mopar873 Offline OP
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mopar873  Offline OP
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They are 1.5s. I agree, the higher cup height isn't helping at all. I did a bit of internet surfing on this after I posted, and it sounds like some of this comes with the territory.

Re: 340 pushrod issues [Re: YO7_A66] #3065131
08/04/22 11:23 AM
08/04/22 11:23 AM
Joined: Nov 2009
Posts: 146
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mopar873 Offline OP
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mopar873  Offline OP
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Yes, 5/16" pushrods

Re: 340 pushrod issues [Re: mopar873] #3065132
08/04/22 11:26 AM
08/04/22 11:26 AM
Joined: Mar 2006
Posts: 9,048
MI, usa
dvw Offline
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On mine, the Crane Hyd roller lifters were much taller than a factory flat tappet. The pushrod angle is far more severe resulting in pushrod to head contact.
Doug

Re: 340 pushrod issues [Re: dvw] #3065133
08/04/22 11:27 AM
08/04/22 11:27 AM
Joined: Nov 2009
Posts: 146
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mopar873 Offline OP
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mopar873  Offline OP
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Got it, thanks for the replies Guys. Time to get out the Dremel...

Re: 340 pushrod issues [Re: mopar873] #3065169
08/04/22 01:24 PM
08/04/22 01:24 PM
Joined: Jan 2003
Posts: 14,071
So. Burlington, Vt.
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fast68plymouth Offline
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fast68plymouth  Offline
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So. Burlington, Vt.
What you’re experiencing is why the heads that were used with factory HR lifter cams had much bigger PR holes in them.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads






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