Hey all

Hope this hasn't been beat to death already, but didn't find the answer so I'm asking.

Have an 87 vert, picked up a set of 113 heads real cheap. Don't really
want to run headers yet. Do I have to do anything to the stock manifolds to match up with the D ports, or anything to the intake for these heads. will probably port the plenum, and look for a new lower intake, accel etc... and a cam maybee. already have a 2.5 cat back with flowmasters and gutted precats. am I wasting my time without headers?

thanx

 

If you are swapping stock heads for stock 113's, very little gain will be felt. (Seat of the pants). You may pick up a tenth in the 1/4 mile. Then again, you may gain nothing.

 

I am going to port the 113's, stock heads needed valve guides so I just figured I'd get the these 113's done instead

 

I have been running a set of ported 113 heads for years. Car made respectable power and ran a good et. You will likely be pleased. Others will likely tell you to save your money and spend it on a set of aftermarket heads. This is up to you. Weigh the cost for both.

 

Get those heads worked. If you're going to go through the hassle of bolting up a new set of heads, make it worth it. Little porting, port-matching, and you'll really feel the increase.

 

You are far from wasting your time with having those heads ported and worked. Stock they are worth 10chp over your Al heads and porting brings another 30chp gain.

Since your '87 had Al heads, I believe the exhaust & intake will just bolt up to the #113s.

In addition to porting, do you have a plan for working those heads?

 

If stock has aluminum heads, they're 113's. The only production 113's that are any different would be new - LT4 valve springs and retainers and the outboard manifold bolt holes are counterbored for gasket retainers.

 

not sure exactly what I'm going to do to the heads? port, polish,
3 angle valve job, Stock size valves? also what cam does everyone reccomend?

 

Incorrect. Late 87-88s had a different aluminum castings than the 113s. Someone may chime in. I believe 89-91 ONLY had D-port aluminum 113s though.

 

Pretty sure 88-90 had the 113's, maybe 91, but I don't believe so, I think that was the year for the reverese flow heads. But someone please chime in for us to make sure!

 

I know for certain that the 88-91 had 113's,Just am un sure of the 87.The 86 had normal chevy exhaust ports,but the flow is not that much different at all.Either head ported would be nearly identical in flow given the same amount of work.I have been able to get over 240cfm on the intake at.500 lift.
Good Luck,
Duane Hawley

 

87 models made in approx the last 250 units had the 113 castings. I have confirmed this with my own and 2 others.

 

zapc I strongly suggest you pick up a copy of David Vizard's book on working #113 heads. He would suggest a 5-angle valve job, some chamber cleanup, pocket porting, flashing smoothing and either 2.00"/1.56" valves with stock seats or 2.02"/1.60" valves with larger seats. The trick with these heads is to not remove much material; you want to maintain close to stock port volume but increase flow and swirl that is already pretty good in stock form.

With the the head work you need to include a set of ProMagnum RRs, new springs and going with 7/16" rocker studs is a good idea too. Whether you go with 1.52:1 or 1.60"1 would depend on cam choice.

For a good street machine I would select a good cam with lift (including chosen RR ratio) as close to .520" as possible, without going over. Then you can use single springs and no valve pocket machining will be needed.

The advantage of the "D" port heads is that, while the exhaust gas mainly flows from the top of the port, the "D" port ledge on the bottom tends to minimize reversion during valve overlap phase.

 

On the right engine, 113's WORKED the correct way can make serious power.

They powered my former car to 120 mph in the 1/4 with an 11.80 e.t.

 

For Info. As far as I know, 86 verts and all 87's, or it seems most (thanks Pete K) had aluminum '128' heads. 86 coupes had cast iron heads. All '88' on vettes had 113 D-ports. These, again as far as I know are similar to the ZZ* series heads but have different valve springs and less retainer to guide clearance than the ZZ*'s (allegedly).
The 128 heads have always had a reputation as being inferior to the 113's. The exhaust port in standard form certainly is, it is very small on the short turn radius. However it responds to porting techniques just like any other traditional small block head.
When the 88 vette was introduced, I remember reading an article, albeit unsubstantiated that compared flow figures between the two and while the 113 exhaust flowed better, the peak flow of the intake on the 128's flowed ever so slightly more than the 113's.
There are other differences in the two heads also, in that the 128 heads were fitted with an exhaust valve rotator. To accomodate this, the valve spring seat was lowered approximately 0.125" or so. Therefore to delete the heavy exhaust valve rotator on the 128's, you need to shim the spring accordingly to achieve the correct spring installed height.
My 87's 128 heads although both 128's were certainly not twins, there were slight subtle differences in port dimensions between the two 'original' castings. I am currently in the process of porting them and matching them dimensionally. Obviously 'as cast' heads all have small variations anyway, so that isn't unique to the 128's. Also on my 128's I have had to cut the guide/spring seat lengths down a little to accomodate the 0.527" lift of my new cam. I don't know what lift the standard 113 assemblies will allow without modification.
Having to perform this 'extra' work may be why some head porters don't like the 128's. Lingenfelter and Callaway didn't seem to have a problem with them as far as I am aware. Hope this helps.