Firewall Clearance for HEI Conversion
Thread Starter
Instructor
Joined: Oct 2004
Posts: 159
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From: North of Boston Massachusetts
Firewall Clearance for HEI Conversion
I am replacing the stock distributor in a 1971 350 with an HEI unit. I don't think I should have any clearance issues, but I am unable to check at the moment because the body is off the frame. (In comparing the 2 distributors, the HEI unit is significantly larger in diameter)
Thanks
Thanks
Advanced
Joined: May 2006
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From: Brighton Ontario
Some cars I have done have hit the washer cover on the wiper motor, on those cars, I upgraded to the newer style motor, with no washer pump gearing and a flat cover, and used an electric washer pump. 
It appears on some cars, a little less clearance to the washer assy than others. Make sure you check yours, especially taking into consideration, some engine flex/movement while driving.
It appears on some cars, a little less clearance to the washer assy than others. Make sure you check yours, especially taking into consideration, some engine flex/movement while driving.
Thread Starter
Instructor
Joined: Oct 2004
Posts: 159
Likes: 1
From: North of Boston Massachusetts
Originally Posted by stingrai
Some cars I have done have hit the washer cover on the wiper motor, on those cars, I upgraded to the newer style motor, with no washer pump gearing and a flat cover, and used an electric washer pump. It appears on some cars, a little less clearance to the washer assy than others. Make sure you check yours, especially taking into consideration, some engine flex/movement while driving.
It appears on some cars, a little less clearance to the washer assy than others. Make sure you check yours, especially taking into consideration, some engine flex/movement while driving.Is that the standard configuration for a '75 and later - i.e. a remote electric pump versus a motor mounted pump?
Safety Car
Joined: Nov 2002
Posts: 4,181
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From: out of nowhere
I also have a 69' wich i converted to HEI. The only concern you may have is the tach. Unless you are going with an aftermarket tach too. The standard distributor doesn't have the (cable?) same drive system to run the stock tach.
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Joined: May 2006
Posts: 90
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From: Brighton Ontario
You can install a 1975- 1976 Tach, which is elect, and would fit in your dash, lots of these available used if you look, this will leave it stock in appearance, and yes , newer cars that came with HEI would have the flat wiper motor, and electric washer.
Thread Starter
Instructor
Joined: Oct 2004
Posts: 159
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From: North of Boston Massachusetts
Thanks for the feedback.
Fortunately, the tach won't be a problem because I purchased a HEI unit that has the tach drive gear on it. The only new wrinkle is the wiper motor and washer pump - and it sounds like the workaround is to use a setup similar to a '75.
Fortunately, the tach won't be a problem because I purchased a HEI unit that has the tach drive gear on it. The only new wrinkle is the wiper motor and washer pump - and it sounds like the workaround is to use a setup similar to a '75.
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Thread Starter
Instructor
Joined: Oct 2004
Posts: 159
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From: North of Boston Massachusetts
Originally Posted by ahoover
Obviously your ignition shielding won't fit, but '75 (HEI) still had a chrome distributor cover and side shields.
My ignition shielding was removed long ago by some previous owner; as such, I never gave it much thought. However, I do like the idea of adding the '75 chrome pieces.
Thanks
Drifting
Joined: Feb 2005
Posts: 1,438
Likes: 2
From: Melrose Florida
I put a stock GM HEI on my tripower big block with no fit problems, it is tight behind the rear carb, though.
Also, I put the distributor in where it fit best, set up wires and timing from there.
Also, I put the distributor in where it fit best, set up wires and timing from there.
Drifting
Joined: Jul 2002
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From: The only Corvettes in Highett Victoria
Caution
Marathon,
I too, have a tach drive HEI distributor in my '74 and the thing to watch for is the clearance between the "square" boss on the dist. where the wires go and the air cleaner. This boss sticks out at about 10 o'clock if you're behind the engine and you have to have it here to get the tach cable to come out at about 9 o'clock so it has a smooth bend into the dash. You need the vacuum advance canister at about 3 o'clock so dummy it up on your engine this way while it's out of the car and see if you have clearance.
Regards from Down Under
aussiejohn
I too, have a tach drive HEI distributor in my '74 and the thing to watch for is the clearance between the "square" boss on the dist. where the wires go and the air cleaner. This boss sticks out at about 10 o'clock if you're behind the engine and you have to have it here to get the tach cable to come out at about 9 o'clock so it has a smooth bend into the dash. You need the vacuum advance canister at about 3 o'clock so dummy it up on your engine this way while it's out of the car and see if you have clearance.
Regards from Down Under
aussiejohn
Thread Starter
Instructor
Joined: Oct 2004
Posts: 159
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From: North of Boston Massachusetts
Originally Posted by aussiejohn
This boss sticks out at about 10 o'clock if you're behind the engine and you have to have it here to get the tach cable to come out at about 9 o'clock so it has a smooth bend into the dash. You need the vacuum advance canister at about 3 o'clock so dummy it up on your engine this way while it's out of the car and see if you have clearance.
