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

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

Can you confirm the correct length Paul?

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

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)

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 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?

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


Lawrenceville, GA

The manifolds should take (4) 1-1/2" and (3) 2" bolts per side

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

I have the Speedway version. I used the bolts (and gaskets) that came with the kit. IIRC all bolts are the same length. The breakage issue is news to me. The rebuild kit had exh manifold gaskets as well. Could it be over torqueing is part of the cause? It's only like 25 ft/lb. required.

Oh and BTW, I'm really surprised nobody here has mentioned a modified 9/16 socket. I have one I shortened back in my SBF days. It came in handy when torqueing the center bolts on these ram horns and it got used for combo manifold install on both my 223 and 240/300 sixes.

Use in conjunction with a wobbler extension or a U joint.

I've just been out to measure the manifolds flanges. the two outside and the centre are 3/4" the other four are 1" thick. aaaargh! up until now I'd only hung the manifold on the two outside bolts now I need 8 longer bolts. For comparison I have an EDB 9431 B the flanges measure 3/8" except the slotted end which is 1/2". Ain't no wonder they crack at 3/8". I'll use the composite gasket that John supplied to reduce dissimilar metal corrosion on the ally heads and risk a cracked manifold. The heads are worth more than the manifolds and at 3/4" thick the risk of cracks must be reduced. John, why two different thickness's ?The socket access is no problem using the small head ARP bolts and a 3/8 drive 3/8 socket.
stuey