Stock rams horns do use 2 different lengths. Based on the pictures, it look like John's do, too.


Lawrenceville, GA

I recently, (last summer, if you call that recent) installed a set of Johns Ramhorns on a customers truck and if I remember correctly the there were 2 different length bolts required and to use a conventional head fastener I had to whittle out a few places on the manifolds with a die grinder to get a socket on the fasteners.

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

You may have missed this information in previous threads, Stuey. The subject has come-up numerous times, but this is one of the more recent replies from Ted.

Ted Eaton wrote on 12/19/2013

The problem is not so much the heads and/or the gaskets but in the use of cast iron exhaust manifolds. Using gaskets in conjunction with the cast iron manifolds does speed up the frequency of broken or cracked manifolds. A thin film of hi-temp RTV in lieu of using any form of exhaust gasket seems to prolong the life of the manifolds.

With the exhaust manifolds being machined flat at the head mounting surface, then a thin film of RTV should suffice. For the same reasons the manifolds break when using gaskets with the iron heads, the manifolds will also break or crack when using them on aluminum heads with gaskets. Keep in mind that the exhaust manifolds for many of the as-delivered Ford engines did not use any form of exhaust gasket at the heads and simply relied on a good metal to metal fitment.

Again, this subject appears in multiple threads in the Forum 'SEARCH' archive. The message is consistent, gaskets used with cast iron exhaust manifolds result in heat transfer problems that invite breaks at the exhaust manifold to cylinder head attachment points.

Hope this helps.

NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

I'm installing a pair of Johns ram horn manifolds and i purchased a set of reduced head 12 pt ARP bolts from AlloyBoltz but at 1" long they fell short. Johns manifolds are plenty thick at the flange. I've since purchased normal head size bolts at 1.5", i like to use a header gasket and plain washer plus a spring washer which affects the length required. May be overkill but that's the way I work.stuey
UK (for the time being)

Can you confirm the correct length Paul?

Darrell Howard Whitefish, MT Outlaw 56 Ford F-100's

YBLock heads use the same length bolt in all the bolt holes for the exhaust manifold. Grade 8 is overkill, grade 5 should be all you need.

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

I'm installing a pair of Johns Ram Horns on a 272 B-Block. The previous owner/s replaced some of the stock bolts with whatever they had laying around. When installing these manifolds, is there one length of bolt that should fit both sides at each locations the manifolds mount to the head? Grade 5 or 8?

Darrell Howard Whitefish, MT Outlaw 56 Ford F-100's