Author Topic: Header fitment  (Read 3086 times)

Offline jeremy.farlow

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Header fitment
« on: June 18, 2020, 03:52:38 PM »
While I anticipate headers and their installation NEVER being easy... I did not foresee the troubles of the last two days.

My dad came over to help me stick the motor in the hole... it was the most satisfying aspect of 2020... for a couple hours:

Crap... I didn’t get the headers in place.

I tried them from the top... no chance.

I tried them from the bottom... way better, but still no cigar.

I pulled the pin out of one motor mount and tried to lift one side for clearance. Still not going.

Dad came back this morning and we got the motor in the hole again... installing the headers after the engine cleared the x-member, but before it settled into the mounts.

Headers contacted... badly... at two spots.

I really didn’t want to cut the frame.

But I did:






On the drivers side the cut wound up far enough through the top rail that it HAD to be plated in.

Bottom two pictures are final product, upper two are in progress.

I really didn’t want to bash up my headers... but I did:




As I was doing the heating and beating I didn’t want to do on the headers I was reminded that the exhaust port location on the AFR heads is raised.

The headers are stainless, long-tube JBA units supposedly for a big block application in this chassis. I cannot say how much the raised exhaust ports play here, but I have trouble imagining these headers would’ve fit the stock heads.

Definitely not without an amount of swearing and some likely tool throwing.

I can’t send them back now.

Hopefully they’ll go in with enough room to install gaskets now.

Otherwise there will be another post from me asking for header recommendations.

3/4 ton with a big block.




Jeremy

Offline jeremy.farlow

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Re: Header fitment
« Reply #1 on: June 18, 2020, 03:55:55 PM »
Sorry the drivers side pictures are so bad.

Offline fitz

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Re: Header fitment
« Reply #2 on: June 18, 2020, 05:44:02 PM »
I could never figure out why headers fit so poorly.
Back in the day I bought Blackjack alumacoated headers for my 69 camaro.  They were the $89 specials from Summit, so I understand, you get what you pay for.
 On my current 69 camaro I got Hooker super comp coated headers.  I want to say I paid $600 for them (15 years ago), and they still dont fit great.  If it wasn't for the Accell shorty spark plugs it would constantly be burning plug wires.

Offline ehjorten

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Re: Header fitment
« Reply #3 on: June 19, 2020, 10:15:10 PM »
I had a set of Doug Thorley Tri-Y headers in my 1991 V3500 with the 454 before I pulled it out. They fit perfectly!  I would have sent them to you to try, but now that you have clearanced your frame it seems unnecessary. I have the same issue with the 6.0 l LQ4 in it now...the "conversion" headers don't fit worth a darn. I found 2010 Camaro headers fit great, but the LH side doesn't play nicely with my stock 4L80e shifter linkage. I am probably going to have a custom header made for the LH side. I can't keep buying different headers and hoping they will work.

On a side note, I really wish I had a set of the ICE engine works header making kit!
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline JohnnyPopper

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Re: Header fitment
« Reply #4 on: June 20, 2020, 07:03:10 PM »
"I didn't want to...But I did" 2X!!  >:(

I feel your pain Jeremy, can't think of a pair that ever went in perfectly...



1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline jeremy.farlow

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Re: Header fitment
« Reply #5 on: June 20, 2020, 08:19:26 PM »
I. Don’t. Wanna!!!

Whelp... I didn’t want to do either, I guess I figured it was kinda like two wrong don’t make a right, but three lefts do?!?

Even if that big old motor swings back and forth I think the combo of relieving the frame and bashing the header tubes should compensate. Or at least leave room for my cool header-wrap:




Also... why buy something when you can make it for 10x cost and 100x aggravation?!?

Today’s project...

Oil filler for one valve cover option:







This is just the lathe work, I’ll put it in the indexing head on the mill tomorrow and put some finger-grip-reliefs on it, like the one on the bottom.

All of this came about after I broke the factory valve cover:


There was a piece of mold leavin’ on the gasket in just the perfect spot. I think I can fix the factory covers and plan to try, but the $100 eBay specials were too good to pass up.


Dad is coming back Monday morning to put the engine in again... third times a charm... hopefully.


Jeremy

Offline jeremy.farlow

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Re: Header fitment
« Reply #6 on: June 21, 2020, 05:18:35 PM »
I lied... the oil-filler cap went back on the lathe for one operation. Knurling is one of those things I WISH I didn’t like as much as I do... I figure every little bit helps though...:






Happy Father’s Day to all the dads out there!!!

Jeremy

Offline jeremy.farlow

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Re: Header fitment
« Reply #7 on: June 22, 2020, 10:00:25 AM »
SUCCESS!!!:






Jeremy

Offline wz7u

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Re: Header fitment
« Reply #8 on: December 08, 2021, 11:02:58 PM »
That is some nice machine work on that cap. I only wish I had something that nice on this engine. How much time do you have in something like that?

Your post lets me know exactly what to look for on my up and coming experiment in header-dom. They never go like the box says they will....

Big blocks unite!
'79 C20 454/th400 "Pearl"

Offline jeremy.farlow

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Re: Header fitment
« Reply #9 on: December 14, 2021, 11:55:53 PM »
The cap took the better part of an afternoon. I’m no machinist, but I’ve liked running a lathe since the first time I got the chance to.

I don’t remember exactly, but I would hazard I did that oil-cap while procrastinating something else… wiring… or maybe bashing my headers in…



Be safe



Jeremy