I ordered teh Mr. Gasket embossed steel shim .018-.020 gasket. Part # 720-1130 , it says does not fit lightweight 305 heads.

Upon opening the package it says Note: must not be used on any post '77 lightweight head...

I have aluminum Pro Lightnings

on the card with the gaskets it shows a pic of a lightweight head compared to a heavy head. Only difference I see is on the lightweight one it has 2 bolt holes towards the back of where the header gasket goes...

I looked at my PLs and it has the 2 bolt holes like the pic that came with the gaskets..

Did I get the wrong ones, or am I ok?

 

Look at the water passages that run along the very outer edge of the head, under the exhaust flange. On the "heavy" heads, the outer surface of those passages, i.e. the outside of the casting, is nearly a straight line. On the "lightweight" heads, the outer surface of the casting is kind of dimpled in, in between the head bolt holes. If the water passage holes in the head gasket are as large as they were in the "heavy" heads, the "light" heads will not quite completely cover those holes. I doubt those heads are made like "lightweight" stock heads, but who knows... maybe an e-mail to ProAction might be in order?

The 2 bolts on the outermost part exhaust flange is a different matter altogether. Some accessory arrangements require those. They have nothign to do with "light" or "heavy".

 

I just noticed the pic on the card, of what you're explaining, I'll check it out. thanks RB

it's straight across,, shhwww, thanks RB for the help, thought I had wasted $28

 

I would have helped, but I was BANNED!

 

lmao, I couldn't believe you would post pics of your wife on the net like that, I mean good lord man, the woman's stomach was on the bed of the truck.

 

Lucy! You got some 'splainin' to do!

What happened Vader?

 

inside joke between me and him.

 

Yeah, and sadly, that was AFTER the "tummy tuck"...

So you're still planning on using all-metal head gaskets? Or are they the imprinted type?

 

Imprinted?

no clue what that means, all I know is the part # I listed above and the description Jegs gave embossed steel shim compressiond nominal thickness .018-.020

 

I sure wouldn't use those if it was my motor.... you'll be re-visiting that part of your motor sooner than you wish, I'd bet.

If it was mine, I'd use the regular old Fel-Pro 1010 gasket.

IMHO the couple of tenths of a point of CR isn't worth the chances of failure.

 

Well, my compression would have been like 8.5:1 with .040 gasket if I recall correctly.

I will only have put maybe 2-3k miles on the engine before I tear it back down again, hope it can last that long for me.

 

maybe i'm overlooking something here. but, he has aluminum heads. now the last thing i remember is not to use steel shim head gaskets on aluminum heads. because they will brinell the head. meaning it will indent the heads because the aluminum is softer than the steel. and thats a bad thing. you may want to check with the manufacturer on this before you put it together.

 

that's what I thought too, but I wasn't sure, I was told I could use steel shim, anyone ? before I ruin these heads

 

only one person to listen to in this case. pro lightning.

 

This is what Vader said, so I assumed the ones I got would work.

"Just the regular gasket - steel shell, fiber filler, soft steel 'O' rings around the cylinders. Just plain stock. "

 

Hey Mark: Did you ever get to measure the piston to deck clearance on your motor?

 

the ones you are getting are all steel. no fibers, no soft steel o-rings.

 

sure didn't, someone has the same motor as me and he measured, so I used the .030 value.

so, will the gaskets i jsut got work ok?

 

I don't know. I can't see it. I've never eyeballed that gasket.
I would have used a Felpro 1094 shim.
It will not Brinnell the head 'cause there is no ring as such.
The right composite type gasket has a non hardened steel or copper
"Preflattened Fire Ring"

Got any pics of the heads yet? I'm curious....

Was the "someone elses motor" a GM Good wrench like yours or
a stock motor or remanufactureed with dished pistons that looks like yours?
.030" seems low for a production good wrench motor.
It may very well be .030" but would be better to measure your's.
From what I've read on these motors more like .055"
Just trying to get and accurate idea on the cr.

 

No pics yet, sorry. I left my laptop at college so I can't download pics, I may be able to get something Friday.


The other motor was the same one as mine LM-1.

guess, I should call Pro Topline to be sure bout these gaskets then.

 

this is what I'm getting at. The LM-1 is a stock production motor
installed on the assembly line. The Goodwrench motor is an
overthe counter service replacement. Not the same thing.
The pistons may look the same but can and will have quite different actual installed deck heights. Its a slippery slope when you start assuming specs on your motor by measureing someones simular motor. The LM-1 has been a production motor since 1978 or so.

Talking to the tech guys at Pro Topline would be a good idea.
They should be able to advise you on getting the right gasket
for your motor. Ask them what they recommend for a "thin gasket".

 

thanks F for the advice as always, guess I'll have that deck clearance checked Fri....