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Bowed · 07-22-2004, 03:54 PM

I am putting a 454 in to a 79 blazer that originaly had 350/350 combo . The 454 came from a manual trans truck so I had to special order a 454 flexplate (remember the 454's are externaly balanced flexplates ) for the change over but when I installed the engine the holes on the flexplate are futher apart then the holes on the converter and will not bolt up . I have seen TH350's behind 454's so what am I missing here ?

Thanks.

Jonboy · 07-22-2004, 04:33 PM

Does the flexplate have dual pattern for the converter bolts? Most flexplates should be drilled that way.

Bowed · 07-22-2004, 05:28 PM

Only one set of holes . Ok , so that means the 350's and 400's have the same bell housing pattern but not the same converter bolt pattern and I have a 400 only flexplate . Right ?

Jonboy · 07-22-2004, 06:47 PM

That's what it sounds like. All Chevy engines have the same rear pattern, save for 60 degree V6's (2.8, 3.1, 3.4, etc) and the GenIII engines. Not sure about the 4 cylinders, as I am not really interested. The same trans would work behind a straight 6 or a 4.3 V6, or small block, big block, etc. Most small block flexplates have both sets of bolt holes. Looks like you may need to swap it out.

MSL · 07-22-2004, 08:12 PM

Did you repostion your motor mounts for the 454 application if you didnt it will be off.

MSL · 07-22-2004, 08:13 PM

also the bolt patterns are the same so is the flexplate.

SanitysBane · 07-22-2004, 08:41 PM

what is this talk about repostion the motor mounts? i didn't no problems here, my bro didn't in his 88 chevy, no problems there. your only moving it maybe 1 inch.

bigblock73 · 07-22-2004, 09:39 PM

Quote:

Originally Posted by MSL

Did you repostion your motor mounts for the 454 application if you didnt it will be off.

That only applies when you convert from a 6 cylinder to V8, and vice versa.

MSL · 07-23-2004, 08:35 AM

no you have to move your mount trust me i pulled my small block out and had to repostion the mounts. also a inch would make alot of difference in automotive.

bigblock73 · 07-23-2004, 08:46 AM

Quote:

Originally Posted by MSL

no you have to move your mount trust me i pulled my small block out and had to repostion the mounts. also a inch would make alot of difference in automotive.

Not me, mine lined up perfectly.

bigblock73 · 07-23-2004, 09:20 AM

About the flexplate/converter. I needed to purchase a dual pattern flexplate when I put in the 700r4, the one that came with the 454 would not line up with the 700's converter...I assume this is the same problem you are having.

SanitysBane · 07-23-2004, 12:36 PM

you don't need to change the mounts. i didn't and neither did my brother in his 88 truck. we both went from a 305 to a 454. and when i was looking at it, its more like 1/4 of an inch, not very much at all. all it does it moves the engine the slightest amount toward the radiator and away from the firewall. which is a good thing because then more of the fan shroud is covering up the fan, and you have more room to acess to the transmission bolts. there is no need to, and its to much work. it matter a slight amount if you must have every factory. but other wise, it doesn't matter.

07-22-2004, 03:54 PM	#1
Bowed Registered User Join Date: Oct 2002 Location: where it's hot Posts: 1,059	Stuck I am putting a 454 in to a 79 blazer that originaly had 350/350 combo . The 454 came from a manual trans truck so I had to special order a 454 flexplate (remember the 454's are externaly balanced flexplates ) for the change over but when I installed the engine the holes on the flexplate are futher apart then the holes on the converter and will not bolt up . I have seen TH350's behind 454's so what am I missing here ? Thanks. Last edited by Bowed; 07-22-2004 at 03:59 PM.

07-22-2004, 04:33 PM	#2
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	Does the flexplate have dual pattern for the converter bolts? Most flexplates should be drilled that way. __________________ 1974 Jimmy- 5.3/4L80e/NP241

07-22-2004, 05:28 PM	#3
Bowed Registered User Join Date: Oct 2002 Location: where it's hot Posts: 1,059	Only one set of holes . Ok , so that means the 350's and 400's have the same bell housing pattern but not the same converter bolt pattern and I have a 400 only flexplate . Right ? Last edited by Bowed; 07-22-2004 at 05:38 PM.

07-22-2004, 06:47 PM	#4
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	That's what it sounds like. All Chevy engines have the same rear pattern, save for 60 degree V6's (2.8, 3.1, 3.4, etc) and the GenIII engines. Not sure about the 4 cylinders, as I am not really interested. The same trans would work behind a straight 6 or a 4.3 V6, or small block, big block, etc. Most small block flexplates have both sets of bolt holes. Looks like you may need to swap it out. __________________ 1974 Jimmy- 5.3/4L80e/NP241

07-22-2004, 08:41 PM	#7
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	what is this talk about repostion the motor mounts? i didn't no problems here, my bro didn't in his 88 chevy, no problems there. your only moving it maybe 1 inch. __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer

07-22-2004, 08:12 PM	#5
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	Did you repostion your motor mounts for the 454 application if you didnt it will be off.

07-22-2004, 08:13 PM	#6
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	also the bolt patterns are the same so is the flexplate.

07-23-2004, 08:35 AM	#9
MSL Registered User Join Date: Mar 2003 Location: So.Oregon Posts: 765	no you have to move your mount trust me i pulled my small block out and had to repostion the mounts. also a inch would make alot of difference in automotive.

07-23-2004, 09:20 AM	#11
bigblock73 yeller Join Date: Oct 2001 Location: Twin Cities Posts: 13,826	About the flexplate/converter. I needed to purchase a dual pattern flexplate when I put in the 700r4, the one that came with the 454 would not line up with the 700's converter...I assume this is the same problem you are having. __________________ Jeff 73-87.com 73-87.com Facebook page 73-87 cab corner 6x9 speaker brackets for sale 67-72 cab corner speaker brackets for sale 47-54 cab corner speaker brackets for sale

07-23-2004, 12:36 PM	#12
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	you don't need to change the mounts. i didn't and neither did my brother in his 88 truck. we both went from a 305 to a 454. and when i was looking at it, its more like 1/4 of an inch, not very much at all. all it does it moves the engine the slightest amount toward the radiator and away from the firewall. which is a good thing because then more of the fan shroud is covering up the fan, and you have more room to acess to the transmission bolts. there is no need to, and its to much work. it matter a slight amount if you must have every factory. but other wise, it doesn't matter. __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer



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