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JTR motor mounts or frame pads need modifications?


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I dont have my JTR book handy, but someone just told me that the JTR V8 kit needs to have their motor mounts modified some or the actual frame pads drilled or elongated for the JTR mounts?

 

this person also told me that when the SBC is put in that it can slide forward or back in the mounts and then tightened down depending how far or forward i want the engine to sit.

 

Is this right?

 

sorry i dont have my book where i am this weekend and i need to know.

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Guest 77vegasz

The hole in your frame motor mounts needs to be slotted in both directions at least 1/4-1/2 inch. You can use a file or Dremmel tool etc.

 

I tried to skip this step, and my HEI was only about 1/8" off of the firewall, so I had to pull it and do this. Once done, it allows you some adjustment in your final placement.

 

Jon

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If you're running something like an LT1 then you don't absolutely have to slot the mounts but it does allow you to position other aspects of the install where you want them. When I first test fit my LT1 I hadn't slotted the mounts and everything seemed to fit good except that the shifter was a little further forward than I wanted it and to far to the left. So I slotted my mounts and was able to move the engine around until I had everyhting right where I wanted them. For the amount of work is to slot them it's worth the effort. Use a dremel, a file or a bur in an angle grinder. I used a wheel on my angle grinder and it took more material than I wanted.

 

Wheelman

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so if they are slotted to move the engine around a little, how would one know if the engine is in their perfectly straight and not cocked to one side a little bit?

 

i mean even a 1/4 inch off one side to the other forward or rearward is alot when the driveshaft alignment is in question and not perfectly right.

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That was the time frome to get the engine/tranny, radiator, hoses etc. in and all bolted up. the drive shaft would have to be after all that was done for measurement.

 

My son is now leaning towards a 3.1 stroker motor so now i dont know whats going on. the stroker engine we can just throw in and bolt it up and go, but im not sure what i need to talk him into doing now as the stroker engine we watched them dyno at Rebello racing yesterday sounded awesome and made 345 HP.

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When we did the LT1/T56 into a 280 I'm glad we slotted the holes. The tranny fit much better with the motor slid forward. I don't see any down side to slotting the holes. In four years I haven't read any posts here of motor mount failures due to the slotted holes.

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Guest 77vegasz

For the money, the V8 conversion will put a bigger grin on your son's face than the 3.1L stroker.

 

I used a B&M shifter with a cable, so tranny placement was not so crucial, I needed the movement to get the right amount of clearance for the HEI distributor.

 

The first time getting the engine in takes the longest, but with two People, it should go easily inside an afternoon. I have pulled mine several times and put it back in. I can pull it in undet 1 1/2 hours by myself and get it back in and ready to go alone in about 3.

 

Jon

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actually the sound of the 350 HP stroker engine we watched being dyno'd a few days ago sounded way better than any chevy with 350 HP we ever heard. the 1250 rpm idle also sounded like a dang race car compared to a same HP chevy. it also had a flat torque curve from 2000-6200 rpm with 300 ft/lbs. i have never seen a chevy engine with a flat torque curve like that before.

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i have never seen a chevy engine with a flat torque curve like that before.

 

I'm not going to start a flame war with that comment, but I have to tell you that so far, the Chevy is the best bang-for-the-buck combination you can come up with. Compare costs of building a 383 with 400 hp to a 3.1 stroker with 300 hp. But if sound is all you're going for, try a different camshaft...

 

Davy

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unflamed.

 

The v8 chevy will blow the doors off of the stroked 3.1. A mild 350 will have over 300 tq from 3K to 6K easy. My 406 dyno'd at 690HP and 552 tq with over 400 tq from 2800 to 7000rpm. My boys 350 dyno'd at 630hp and 520tq and made over 400 tq from 3200 to 7500. If this 260z don't fly we'll wish it did and flame it.

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A mild 350 will have over 300 tq from 3K to 6K easy.

 

Yes, I do believe that is in the ballpark. I researched my motor build and picked out a nice 'mild' cam that should have me at 350 hp and the same amount of torque or very close. Should make for some tire shredding fun :D

 

Davy

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what does it mean to slot the mounts i was trying to understnad this tread but sence i dont know what slotting is im lost. some fill me in

 

The JTR manual says to slot the mounting arms on the crossmember, NOT the engine mounts that bolt to the engine. The slotting allows your engine to slide back and forth one inch, giving you the optimum placement for the engine to your personal specs. Guys do it without slottign anything and it works fine, but for the ultimate setup, break out the Dremmel.

 

Davy

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The JTR manual says to slot the mounting arms on the crossmember, NOT the engine mounts that bolt to the engine. The slotting allows your engine to slide back and forth one inch, giving you the optimum placement for the engine to your personal specs

 

davy

thanks for clearing that up :D

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