Throttle Springs....

[Larry S.]

I have a '66 427-450HP coupe and it only has 1 throttle return coiled spring on the linkage of the Holley carb.. I have been told this is incorrect and it should have 2 springs (a smaller one inside the larger one). What is correct for the car?

[Ronald L.]

Re: Throttle Springs....

Larry, Looks like you have an early car - how early and who said the single spring was wrong?

[Larry S.]

Re: Throttle Springs....

Thanks for the reply.
Yes, I have an early '66 ser.# 1508 (Sep. 25/65). It was being judged at a local meet here in Toronto area by the Ontario Corvette Club judging group.
I then assume that early '66 BB only had 1 spring on the linkage??

[Domenic T.]

Re: Throttle Springs....

I am curious,
What are the differences between the 435 and 450 HP 427?

DOM

I have a '66 427-450HP coupe and it only has 1 throttle return coiled spring on the linkage of the Holley carb.. I have been told this is incorrect and it should have 2 springs (a smaller one inside the larger one). What is correct for the car?

[Larry S.]

Re: Throttle Springs....

The 427-435HP engine first came out in 1967 (with 3-2 barrel carbs).

The 427-450HP engine was out in early 1966 models and during '66 production year, GM changed the HP rating to pacify (I believe) insurance/government agencies. It then became 425HP (but actually was the same engine. Therefore, a 450HP engine means an early production 1966 model. I am not sure when GM made the change to 425HP?
Anyone out there know when?

[Michael H.]

Re: Throttle Springs....

I have a '66 427-450HP coupe and it only has 1 throttle return coiled spring on the linkage of the Holley carb.. I have been told this is incorrect and it should have 2 springs (a smaller one inside the larger one). What is correct for the car?

Only one throttle return spring was used for all 427's for 1966.

[Domenic T.]

Re: Throttle Springs....

Thanks Larry,

DOM

[Joe R.]

Re: Throttle Springs....

You must be referring to the 425HP 1966 Corvette since there was no 435HP 1966 that I know of.
There is no difference between the 425HP 1966 and the 450HP Corvette Motor with the exception of the Decal on the AC.

Rumor mill says it was down played for insurance purposes.

Who really knows? Probably nobody!

JR

[Larry S.]

Re: Throttle Springs....

Only one throttle return spring was used for all 427's for 1966.

Thanks Michael,
I will pass that on to the Ontario Corvette club judge.

[Ronald L.]

Re: Throttle Springs....

This was early but not the last 450HP car, a search of this forum from Feb March I'm pretty sure has that answer. The very earliest 66 427 cars contained left over 65 components but I would not expect that in this case.

[David L.]

Re: Throttle Springs....

Larry,

The 1965 Corvette 396 (L78) used spring # 3869752 as per the 1965 AIM. The 3869752 spring is described in my 1966 Chevrolet Parts Catalog (effective Oct. 1965) as "7 1/2 free length - 25 coils".

The 1966 Corvette w/427 lists spring # 3887422 without any description. This number also appears in the 1966 AIM.

According to Chevrolet Parts History GM # 3869752 was replaced with GM # 3887422 in July 1966 for parts sold over the counter.

What is the free length and number of coils on your spring? Do you have a 3869752 spring?

Dave