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I am running into issues with JBA-1653 headers hitting on the shocktowers on my 65 with a 351w swap and TrickFlow Twisted Wedge heads. I had posted before and have now switched to Ron Morris Performance adjustable motor mounts. I have got the motor in the car with the header bolts on loose. I am unable to tighten the bolts because it causes the headers to hit when the header flange pivots to be flush with the head.


I have tried for hours adjusting the motor every way possible in the car in order to get the headers not to hit and there is no way. The instructions say to use 66 mounts but i assume the adjustable mounts can achieve this position. I even saw another mustang at good guys which had a 351w, Ron Morris and JBA 1653 on it and he said it fit fine.


At this point i am heating up my headers with oxy-acetylene and deforming them to fit. But i would like to know what in the world is going on.
 

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Do the flanges seat fully on the heads ? Some headers interfere with portions of the TFS head casting and have to be clearanced.
 

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[If you have to bail on the JBAs check with Mike Johnson at Doug Thorley Headers. I know that make a 351 swap header. If they fit like the Tri-Ys did in my stock head '65 289 you'll be set.
 

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rdnck1
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Do you have an export brace installed on your shock towers?
Agree, It could be your towers are not spread out to the proper location and a good export brace would get you there. They can be a pain to get spread out so research it just to have that check over with. Good luck, Jim
 

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BFH!
 

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As has been previously stated, the shock towers need the correct width between them which per the JBA instructions says a minimum of 33 3/4". I would check that you don't have any clearance issues before moving forward. Second, I'm not sure about the RM style mounts and if they'll work or not. You do need to use the 1966 style motor mounts and brackets, as stated in the instructions as well, as they push the engine up slightly higher and give it more clearance for the headers. I don't have any clearance issues in my car and have a very similar setup as yours but with stock 1966 style motor mounts and brackets. It's a very close fit but no rubbing or clearance issues.

 

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I installed the JBA 1653SJT headers with no problem in my 69 with the cast heads, standard motor mounts and shock tower reinforcements. Did they change the width of the towers from 65 to 69? 69's are about 40" apron to apron.

736197
 

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I installed the JBA 1653SJT headers with no problem in my 69 with the cast heads, standard motor mounts and shock tower reinforcements. Did they change the width of the towers from 65 to 69? 69's are about 40" apron to apron.

View attachment 736197
I believe the 67-70 cars are considerably wider than the 65/66 cars and that's why you can fit a big block 390-460 in a 67-70 mustang but can't fit anything wider than a 351w in a 65/66 car without taking out the shock towers or modifying them substantially. JBA says on their website a minimum of 33 3/4" is needed from apron to apron on a 65/66 car.
 

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I installed the JBA 1653SJT headers with no problem in my 69 with the cast heads, standard motor mounts and shock tower reinforcements. Did they change the width of the towers from 65 to 69? 69's are about 40" apron to apron.
Yes the shock tower width between the towers was increased starting in 1967 (to be able to install the 390 Big Block) but the overall width of the engine compartment remained the same as the 65-66's. The increase of overall width of the 67'+ bodies was done by increasing of the width of the outer body panels (ie fenders.)
 
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