difference in 85,86 and 87 heads and pistons?

7000rpmisheaven · 11-30-2001, 11:14 AM

I know that the stock compression ratio for my 85 is 8.4. I have seen that stock compression for 87 is 9.5. Why makes the difference. Do the heads change the compression or do the pistons. Can I take the E7 heads off an 87 to raise the compression on my 85?

Chevyguy · 11-30-2001, 03:15 PM

The E-7 Heads would be a good swap for your motor. I am not sure of the chamber CC differences between the 85 and 87 heads. I suspect some of the difference is due to the pistons since the 87 has the forged units, 86 had flat tops with no reliefs, 85 Dunno

fiveohpatrol · 11-30-2001, 03:44 PM

i'm pretty sure the 87-up's were 9.0:1 not 9.5:1

you can find a set of E7s/ port the crap out of the exhaust ports/ gasket match the intake ports/ and have a set of heads that are night and day better than the 85 heads

If the way im thinking is correct, the 85 pistons with no valve relief's would actually result in more compression with an E7 head than an 87 piston with reliefs. I'll wait until PKRWUD gets on here and corrects me though

7000rpmisheaven · 11-30-2001, 03:57 PM

I've gotten down and dirty with my stang. The 85 pistons had reliefs. Each had 4 crescent shaped notches.
It sounds like the Ported E7s would be better anyway. I have never ported anything on my own. Maybe it is time to learn. Got any tips for a first time home porting job. Or would I be better off having someone else do it. If I do it myself what tools would I need?

fiveohpatrol · 11-30-2001, 04:09 PM

I had never done it before either. But then again I was shown by someone who has. Its really not very hard at all. Especially with so many cheap E7's heads out there just incase you screw one up

here's a link, i havent completely read it so im not sure how good it is
http://www.fordmuscle.com/archives/2...ng/index.shtml

all i used was one carbide bit and a die grinder. I used layout die around the intake and exhaust ports, put the gaskets on there and scribed an outline of the gasket around the ports. I then ground out as much as possible (and completely removed the huge thermactor bump) and smoothed it all out to the scribed lines.

hope this helps a little

fiveohpatrol · 11-30-2001, 04:14 PM

**** that link! you now have to have a subscription to read the full article. theres plenty of others out there. Try searching for this topic in the archives and see the other links posted about it

Stang Runner · 11-30-2001, 05:45 PM

How to Port your heads
And for the tools you need go http://www.eastwoodcompany.com/cgi-b...E=default2.htm and where it say "Search by keyword" Type "Port" and what you will need will pop up And more ??? just ask

Unit 5302 · 11-30-2001, 09:14 PM

The 85 had dished pistons. The 86 had forged flat tops. The 87 had forged with valve reliefs.

The 86 had 9.5:1 compresion I believe. 1987+ had 9.0:1.

The E7 heads should definately give you some power, but I'm not sure on the combustion chamber size of the 85 heads.

86GT · 12-03-2001, 03:47 PM

86 Heads = Boat Anchors
87 Heads = Great stock head, just get that air injection hump out of the exhaust port.

The 85 heads look to be the same as the 87s. I compared a set off an 85 4bbl Mustang, with a set I had off an 88. The chambers are the same size, within 1 cc or so. (If I'm wrong, someone correct me please). The runners, well I don't have a clue what their flow numbers are, but the measurements are the same too.
85 pistons and heads made 8.4:1, 86 Heads and Flat tops 9.2:1, 87 Heads and pistons 9:1. 85 Heads on 87 Pistons approx 9:1.

11-30-2001, 11:14 AM	#1
7000rpmisheaven Registered Member Join Date: Nov 2001 Location: germantown MD Posts: 283	difference in 85,86 and 87 heads and pistons? I know that the stock compression ratio for my 85 is 8.4. I have seen that stock compression for 87 is 9.5. Why makes the difference. Do the heads change the compression or do the pistons. Can I take the E7 heads off an 87 to raise the compression on my 85?

11-30-2001, 03:15 PM	#2
Chevyguy Backyard Mechanic/Chemist Join Date: Feb 2001 Location: Acton MA USA Posts: 435	The E-7 Heads would be a good swap for your motor. I am not sure of the chamber CC differences between the 85 and 87 heads. I suspect some of the difference is due to the pistons since the 87 has the forged units, 86 had flat tops with no reliefs, 85 Dunno __________________ 2001 Crown Vic Maurader Airbox/MAF, DR chip Edel IAS shocks Single exhaust :wtf: 93 P-71 Vic interceptor Backup car now 90 5.0 LX Notch SOLD 74 Chevy Laguna type S-3 454 under construction Currently apart undergoing bodywork.

11-30-2001, 03:44 PM	#3
fiveohpatrol I'd rather be basketweaving Join Date: Feb 2000 Location: Indianapolis Posts: 2,551	i'm pretty sure the 87-up's were 9.0:1 not 9.5:1 you can find a set of E7s/ port the crap out of the exhaust ports/ gasket match the intake ports/ and have a set of heads that are night and day better than the 85 heads If the way im thinking is correct, the 85 pistons with no valve relief's would actually result in more compression with an E7 head than an 87 piston with reliefs. I'll wait until PKRWUD gets on here and corrects me though __________________ NMRA O/C 9516 NA pumpgas stickshift 347 10.65@125.6, 6.73@100, 1.41 60ft

11-30-2001, 04:09 PM	#5
fiveohpatrol I'd rather be basketweaving Join Date: Feb 2000 Location: Indianapolis Posts: 2,551	I had never done it before either. But then again I was shown by someone who has. Its really not very hard at all. Especially with so many cheap E7's heads out there just incase you screw one up here's a link, i havent completely read it so im not sure how good it is http://www.fordmuscle.com/archives/2...ng/index.shtml all i used was one carbide bit and a die grinder. I used layout die around the intake and exhaust ports, put the gaskets on there and scribed an outline of the gasket around the ports. I then ground out as much as possible (and completely removed the huge thermactor bump) and smoothed it all out to the scribed lines. hope this helps a little __________________ NMRA O/C 9516 NA pumpgas stickshift 347 10.65@125.6, 6.73@100, 1.41 60ft

11-30-2001, 04:14 PM	#6
fiveohpatrol I'd rather be basketweaving Join Date: Feb 2000 Location: Indianapolis Posts: 2,551	**** that link! you now have to have a subscription to read the full article. theres plenty of others out there. Try searching for this topic in the archives and see the other links posted about it __________________ NMRA O/C 9516 NA pumpgas stickshift 347 10.65@125.6, 6.73@100, 1.41 60ft

11-30-2001, 03:57 PM	#4
7000rpmisheaven Registered Member Join Date: Nov 2001 Location: germantown MD Posts: 283	I've gotten down and dirty with my stang. The 85 pistons had reliefs. Each had 4 crescent shaped notches. It sounds like the Ported E7s would be better anyway. I have never ported anything on my own. Maybe it is time to learn. Got any tips for a first time home porting job. Or would I be better off having someone else do it. If I do it myself what tools would I need?

11-30-2001, 05:45 PM	#7
Stang Runner Registered Member Join Date: Jun 1999 Location: Walker, MI, USA Posts: 1,202	Hope this helps How to Port your heads And for the tools you need go http://www.eastwoodcompany.com/cgi-b...E=default2.htm and where it say "Search by keyword" Type "Port" and what you will need will pop up And more ??? just ask __________________ Engine: steel mounts, Under drive pulleys, K&N, GT-40 Intake ported Lower, No power steering, No A/C, Mac cold intake, 65MM TB, 255 Fuel pump, 24's, AFR 165 58cc, Rocker Arms 1.7with the stock Cam, 1 5/8 short headers, offRoad X-pipe Drive Train: 3.55, T-5 with a Pro 5.0 shifter 12.656@107.71MPH See It at www.T-racing.com/mustang.htm

11-30-2001, 09:14 PM	#8
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	The 85 had dished pistons. The 86 had forged flat tops. The 87 had forged with valve reliefs. The 86 had 9.5:1 compresion I believe. 1987+ had 9.0:1. The E7 heads should definately give you some power, but I'm not sure on the combustion chamber size of the 85 heads.

12-03-2001, 03:47 PM	#9
86GT Sniffed too much n20 Join Date: Oct 1998 Location: Ont, Canada Posts: 1,018	86 Heads = Boat Anchors 87 Heads = Great stock head, just get that air injection hump out of the exhaust port. The 85 heads look to be the same as the 87s. I compared a set off an 85 4bbl Mustang, with a set I had off an 88. The chambers are the same size, within 1 cc or so. (If I'm wrong, someone correct me please). The runners, well I don't have a clue what their flow numbers are, but the measurements are the same too. 85 pistons and heads made 8.4:1, 86 Heads and Flat tops 9.2:1, 87 Heads and pistons 9:1. 85 Heads on 87 Pistons approx 9:1. __________________ 2002 Windsor Weekend Q16 Qualifier

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