Hi Guys Well like I said the car seems to be working good after the 305 to 350 change. I gained almost 1 full second in my 1/4 mile times. I still have some bugs to work out but thats fine. Believe it or not I used everything off of my old 305 such as the dampner and the knock sensor and it seems ok for now. I may have trouble timing it right though. I want to replace the dampner with the correct one for the engine. Here are the casting numbers: on the block at the back 14093638 there is also k252 and 638 at the front. on the heads 254969 and 259116 Can you tell me the year and application of the block and heads. I think it came from an 87 motorhome? Does anyone know? I also added a 2040 Crane Compu Cam and the matching valve springs. will this affect how the dampner is? or affect how I time it? I have an ADS superchip for it as well but for the 305. How do i time it? With the stock chip as I did on the 305?? Thanks, Jamie James ------------------ Jamie James 1986 Iroc-Z 305 TPI 1.90 60 ft 14.15@ 95.75 1.74 60 ft 12.84@107.75 on the bottle. My IROC: http://personal.nbnet.nb.ca/jjames/homepage.htm [This message has been edited by KustomIroc (edited June 01, 2001).]

That # from the block is the same as mine. I am building a 350 for my car and I got my engine out of a 90 3/4 ton truck. Yours is a 4 bolt main, right?

The k252 means it as cast on Nov. 25, 1992.
k is Nov. a is Jan, b is Feb., etc. The 25 is the 25th, and the 2 means either 1952, 62, 72, 82, 92, or 2002. Well that casting # was only used from 1987 to 1995 so that rules out the rest. The 638 is just quick reference for the last 3 digits on the actual casting #.

As far as the heads go, I have no info for ya. Maybe look for other #s on the head. If they were production heads for that motor, they will have the centerbolt valve covers. If not, then I dunno. If they are newer, they will also have an 8 digit casting #. For ex. mine are 14102191. They are 76cc chamber, 1.94 int. & 1.5 ex. centerbolt valve cover heads. You may find the same 3 digit code like on the block somewhere on the heads. Usually the casting #s are in the rocker arm valley.

As for the damper, if it's an 8" and you have the proper timing cover, it'll work fine. The timing tab is different for different size dampers. So a 6 1/2" damper won't work on a tab for a 8" damper.

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92 RS w/t-tops 305 TBI Auto.
170K miles and don't burn a drop o'oil
-K&N Truck filter #1500 w, open ele.
air cleaner
-Dynomax 2 1/2" cat-back
-B&M TransPak
-Jet Stage2 Chip
-180* T-Stat w/ 185* Fan Switch
-JVC CD--Alpine speakers & 4ch. amp
Rockford 2ch. to 2 MTX 12" subs

[This message has been edited by AJ_92RS (edited June 02, 2001).]

Thank you,

That makes perfect sense. I put my 305 harmonic balancer and timing cover on it. I will purchase a 350 balancer and timing cover for it then. Should I buy a 92 one? I did order an 87 350 vette balancer but I do not want to put it on if it is not the right one.

What about the knock sensor? which one did you use?
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Jamie James
1986 Iroc-Z 305 TPI
1.90 60 ft 14.15@ 95.75
1.74 60 ft 12.84@107.75 on the bottle.
My IROC:
http://personal.nbnet.nb.ca/jjames/homepage.htm

[This message has been edited by KustomIroc (edited June 04, 2001).]

As long as the timing tab and damper match each other, then it should be fine. The crankshaft was the same for the 305 and 350. They have the same piston stroke (3.48"). The bore is different though. A 350 is 4.00" stock, and the 305 is 3.735". The added weight of the load on the engine is why they use a larger balancer. Trucks usually always come with an 8" balancer. I'm not sure about the 305.

You may have to post this so it catches others attention. I'm sure someone on here will know. Address the post as a balancer question though. That's what most people call it, even though it is a vibration damper.

As long as the timing mark lines up with the timing tab, the balancer is fine. Theres alot going around about '305' balancers, thinner or scalloped out rear area, etc etc. but if you go get a new one or an aftermarket balancer, it doesnt matter if its a 305 or 350, the only differences are diameter and pointer location. I have the old one off my 86 305 TA, and one off an 88 350 out of an Iroc, and they are exactly the same, no difference whatsoever. I had to get a new one for the TA, and it matched both of those as well. I asked the parts guy about them maybe being different, and so he looked and 350, 305, doesnt matter. And he does know parts, he isnt an idiot like many of them are.

What then is the advantage of having an 8" balancer? I know most trucks had them. Is it due to the foreseen load of pulling trailers and such? If they weren't any better, then why did/do they make them? Just so people like me can ask dumb questions? It seems like that is why GM does a lot of stuff they do, like killing the Camaro!!!!! And the Impala SS. "Let's make a really cool -ss car and then wait 'til it sells great, then stop making it!"

But anyway, back to my original question. Why? All I was saying is that I don't know whether they put the 6 1/2" or the 8" on the 305.

[This message has been edited by AJ_92RS (edited June 04, 2001).]