1973 Intake manifold for L48

[Joseph A.]

I now have my 1973-1974 Technical Information Manual and I see I have a 1974 intake manifold on my 1973 350. Does anyone have a recommendation on where I should go to find the correct manifold with the intake casting # 3997770 or 3997771. Thank you-Joe 46306

[Michael W.]

Re: 1973 Intake manifold for L48

Is it a 340261? You might actually have the correct manifold if your car has a very late build date. I looked for several years for a 3997770 or 3997771 cast in June/July '73 for my L-48, never found one.

340261's in the same time period are relatively easy to find which makes me wonder if late '73s had the (supposed) '74 only casting number.

It would be interesting to collect more data on this and update the TIM as appropriate.

[Joseph A.]

Re: 1973 Intake manifold for L48

yes, it is a 340261 and it was a late engine build of June 21 on a July car assembly. From what I read though this is a different design including ERG valve etc. I'm having a difficult time identifying the parts as I even have a Holley on it. Thanks, Joe

[Joe L.]

Re: 1973 Intake manifold for L48

Joe-----

The GM casting #3997771 and casting #340261 are virtually identical manifolds. Both are equipped with identical EGR provisions. The primary difference between the manifolds is the configuration of the carb flange. However, both manifolds will mount the same Q-Jet carbs. So, there is absolutely no reason that the 340261 could not have been used on 1973 engines.

You mentioned the engine build date of June 21. However, you didn't mention the manifold casting date. That's the important thing here. If the date precedes the engine assembly date and, particularly, if it precedes the engine assembly date by 1 to 30 days, I would say that it almost certainly is original to the car.

The Holley carb, though, is definitely not original to the car. No Holley-manufactured carbs were ever originally used on a 1973 Corvette. Assuming that it is a Holley spread bore carb (i.e. with a Q-Jet style flange) it is likely a Holley replacement for a Q-Jet. Holley has manufacured Q-Jet replacement carbs for many years. Some of these are even 50 state legal for emissions requirements.

[Joseph A.]

Re: 1973 Intake manifold for L48

Thanks Joe, I'll check the casting date on this and if within the time frame, I'll be relieved as I will then only need to acquire the Q-Jet. Any ideas on where I could pick up a correct dated Q-Jet? Thanks-Joe 46306

[Michael W.]

Re: 1973 Intake manifold for L48

Either the Driveline or eBay is a good place to start.

[Roger S.]

Re: 1973 Intake manifold for L48

My July built, trim tag L20, '73 L82 has the 340261 intake manifold with a G143,7-14-73, date code. The engine block date code is G93, for 7-9-73.
Roger

[Harmon C.]

Re: 1973 Intake manifold for L48

Joe
The latest 771 dated intake I have seen is E-10-3 and I have some 202 carbs dated April- June 73 also but not for sale on this board.

Lyle