hello all:

I have a set of heads from "I think" a 77 305 nova. can I use them on a 1986 305 trans am. The numbers on the old heads are 378450.


Im getting ready to rebuild, if I can do the work on the 77heads it will be a quicker turnaround when I pull the engine out of the trans am.

parts I have so far for the rebuild are:

Comp Cams double roller, Magnum timing set.
Edelbrock Performer non-egr intake.
Comp Cams Extreme Energy 256.
Comp Cams 1.60 ratio, Magnum roller tip rockers.
Comp Cams High Energy, hydraulic, lifter set

Parts not purchased.
Melling M-55 oil pump, shaft, screen and Mr G spring.
SLP single cat Headers "for what engine should these be?"
Chevrolet: 262-400, conical valve spring kit
Hypertech 160 degree, cool fan switch.


please give me a lashing if I have anything to stupid. but don't bring up the "why don't you rebuild a 350"
I an't paying no monster no 350.

 

When u do up a 305... what u get..... a mild 350.

Sorrry had too.

The heads will fit. Not much more worth saying about them.

 

Thanks for the info!

This is a Dyno2000 of the before/after rebuild. The engine is in bad shape now with 140k on it. I will get a BIG improvement for little cash and keep my 20 miles to the gallon. All I’m looking for is a good working motor with a little more juice than it had before

Are there any differences in the heads that will affect performance? I plan to do porting and change the rod holes to accept the 1.6 rockers.

Chuck

 

those 77 smogger heads are garbage. The combustion chambers are so big that you'll lose a ton of compression, and they don't flow. Keep your 86 heads. They don't flow too good either, but it's a lot better than those 77 heads, plus it'll keep your compression up.

 

376450.....75-81...262/267/305..6 or 7 exhaust bolt holes, 60cc chamber

Chambers are 2 cc bigger and I think these are a casting thats worth some porting. I know of one guy that has a set on a strong running 327.

 

Anyone else look at his dyno #'s there?

Your car does NOT have 220hp and 320tq stock, with an LG4 sorry. Try 165hp and around 250tq. The LB9's didnt even have that much power in 86.

86 IROC-Z
Trans Am A4 LB9 V8 9.5:1 5.0 (305) 190@4000 285@2800 TPI ---- ---- 2.73 3.42

DD is way wrong on anything unless u get every little detail on it correct.

86 IROC-Z
Trans Am M5,A4 LG4 V8 9.5:1 5.0 (305) 165@4400 250@2000 4bbl 3.23 3.73 2.73

https://www.thirdgen.org/newdesign/tech/techdb.shtml

Your gunna want different pistons in there to up the compresion if u want any power out of that thing.

Cams a good choice though, XE cams make very good power.

 

Forget the old heads. The ones you have now are much better. With 1.94" intake valves and basic porting, they will out-run those old heads no matter what you do with them.

You should consider pinning the rocker studs, or replacing them with screw-in. Just for insurance.

I really like my cam. But, I don't have any personal experience with the Comps.

You have flat-top pistons now, so you're okay there.

Wrong intake manifold. Get a Weiand Action+ EGR or GMPP spread-bore EGR.

Headers should be for '86-'90 TPI single-cat application. I'd suggest Hooker over SLP for cost reasons, if nothing else. Cat & cat-back for same application to finish it off.